Anesthesia ITE Flashcards
Fenoldopam produces rapid vasodilation through activation of D1 dopamine receptors and is the best for controlled hypotension
Pyridostigmine can be used for prophylaxis against nerve agent exposure, while atropine and pralidoxime chloride can be used for the treatment of nerve agent exposure.
ketamine can cause rotary nystagmus and blepharospasm and should be avoided in ophthalmologic surgery.
Airway reflexes under ketamine anesthesia are maintained
obstructive apnea is one that lasts longer then 10 seconds with an >90% air flow reduction despite respiratory effort
central apnea is one that lasts longer then 10 seconds with >90% air flow reduction without respiratory effort.
Apnea hypopnea index (AHI) is the average number of disordered breathing events per hour. OSA severity is determined by the AHI as follows: mild (5-15 events per hour), moderate (16-30 events per hour) and severe (>31 events per hour)
Pacemaker placement is indicated for second-degree (type II) AV block (D), third-degree AV block, any symptomatic bradyarrhythmia, and refractory supraventricular tachyarrhythmias.
Use of carboprost tromethamine for treatment of uterine atony should be avoided in patients with asthma. Methylergonovine should be avoided in patients with hypertension or preeclampsia
Induction is the process of electrical current generation when a wire moves through a magnetic field. Electrical resistance in the wire results in heat production and thermal injury when a coiled wire is present on the patient
Acute normovolemic hemodilution (ANH) is a useful method of autologous blood procurement in patients with rare blood cell antibodies and/or preference for not receiving allogeneic blood transfusions that are having surgical procedures with anticipated large amounts of blood loss
risk factors for nitric oxide toxicity. These risk factors include gastrointestinal malabsorption syndromes (eg, pernicious anemia), extremities of age, alcoholism, malnutrition, and a strict vegan diet (which can lead to vitamin B12 deficiency). Nitrous oxide irreversibly inhibits enzymes involved in DNA synthesis, specifically methionine synthetase, leading to reduced DNA synthesis, and, ultimately, megaloblastic anemia
Skin color: 0 Cyanotic 1 Acrocyanotic (pink chest, cyanotic extremities) 2 Pink
Heart rate: 0 Absent 1 < 100 bpm 2 >100 bpm
Reflex irritability: 0 No response to stimulation 1 Grimace and/or feeble cry when stimulated 2 Active, strong response to stimulation
Muscle tone 0 Absent, 1 limp Some extremity flexion 2 Active movement
Breathing 0 Absent 1 Weak, irregular, slow, shallow, or gasping 2 Strong, regular, crying
Hepatic clearance of a drug is the amount a drug is removed per unit time and is a product of hepatic blood flow and the extraction ratio. Drugs with a high hepatic extraction ratio (flow limited) are rapidly and extensively removed by the liver and are dependent on hepatic blood flow and protein-binding. Drugs with a low hepatic extraction ratio (capacity limited) are more dependent on hepatic metabolic function
Cerebral venous blood flows from the deep and superficial veins into the cerebral sinuses (straight sinus, occipital sinus, and superior sagittal sinus) which all join at the confluence of sinuses and travel through the bilateral transverse sinuses which turn into the sigmoid sinuses that eventually exit the skulls through the jugular foramina where they then become the internal jugular veins.
Avogadro law states equal volumes of all gases at the same pressure and temperature will contain the same number of molecules.
Boyle law says a change in gas volume is inversely related to the pressure on the gas. As the pressure increases, the volume will decrease
A jugular venous oximetry (SjvO2) catheter is usually utilized in the setting of neurological injury in the ICU & is inserted in a retrograde fashion into the internal jugular vein. The proper location is at the level of the C1-C2 vertebrae in the internal jugular vein just below the jugular foramen. Measurements are used to estimate cerebral tissue oxygen extraction and delivery
Metformin should be taken until the day of surgery but held on the day of surgery and resumed when oral intake is resumed as long as there is no evidence of or concern for renal or hepatic dysfunction.
Post-dural puncture headache (PDPH) typically presents with pain that changes with positioning
Basilar migraine describes a headache which classically starts with an “aura” and includes basilar symptoms such as vision changes, coordination disturbances, and dizziness
Radiation exposure to the anesthesiologist is related to the distance from the scanner; however, it is inversely proportional to the square of the distance
Sedating patients with non–operating room anesthesia (NORA) in the computed tomography (CT) scanning area has a higher risk of complications overall compared to sedating patients in the operating room
AKI defined as an increase in serum creatinine by 0.3 mg/dL over 48 hours, an increase in serum creatinine to ≥1.5x baseline within 7 days, and/or a urine volume of < 0.5 ml/kg/hr for ≥6 hours
During an autonomic hyperreflexia episode, the intense sympathetic response below the level of a spinal cord injury (SCI) can cause acute hypertension (≥ 20-40 mm Hg above baseline), reflex bradycardia, cardiac arrhythmias, and myocardial infarction. Hypertension can further lead to headaches, blurred vision, retinal or intracranial hemorrhage, stroke, seizure, and/or cerebral edema. Additionally, the intense vasoconstriction leads to cool, dry, pale skin of the lower extremities. The reflex cutaneous vasodilation above the level of the spinal cord Injury leads to nasal congestion, diaphoresis, and warm, flushed skin on the upper extremities, shoulders, neck, and face
Autonomic hyperreflexia (AH, or autonomic dysreflexia) is a syndrome that may occur in patients with spinal cord injuries (SCIs) above the level of mid-thoracic (T5-7) level.
Cervical spine instability may be present in patients with rheumatoid arthritis. The atlantoaxial joint is commonly affected and instability can result following ligamentous laxity that occurs from pathologic destruction of the ligament. The transverse and alar ligaments provide support for the atlantoaxial joint. The alar ligaments secure the odontoid to the anterior foramen magnum but are not the most common ligaments affected by rheumatoid arthritis
Brainstem manipulation or pressure on the brainstem can cause significant hemodynamic derangements. The Cushing triad of hypertension, bradycardia, and breathing alterations are due to brainstem compression (from either cerebral edema pushing down on the brainstem or from surgical manipulation intraoperatively
When a transurethral resection of bladder tumor (TURBT) is performed under spinal anesthesia, the obturator nerve may require additional measures to prevent activation of the nerve because of its proximity to the inferolateral bladder wall and bladder neck, especially when monopolar electrocautery is used, because of increased electrical current leakage leading to a muscle spasm
Electroencephalogram (EEG), somatosensory-evoked potentials (SSEPs), motor-evoked potentials (MEPs), and visual-evoked potentials (VEPs) are all affected in a dose-dependent manner by inhaled anesthetics. Auditory-evoked potentials are the most resistant to the effects of volatile anesthetics.
The wind-up phenomenon is caused by repeated stimulation of peripheral C fibers, resulting in increased action potentials at the dorsal horn causing an amplified response.
In the metabolism of lactate in lactated Ringer’s solution, the final end product is bicarbonate (HCO3-).
Hurler disease is part of the mucopolysaccharidoses syndromes. It is associated with skeletal abnormalities such as thick ribs, macrocephaly, and abnormal TMJ joints. It is also associated with cardiac lesions such as aortic and mitral valve lesions, and coronary artery narrowing. It is associated with mental retardation and increased intracranial pressure. Lastly, these patients may be difficult to intubate due to macroglossia, thickened and abnormal pharyngeal tissues and high epiglottis
Bacterial infection from transfused blood products is by far the most common type of transfusion-related infection.
Constrictive pericarditis is best managed with midline sternotomy to remove as much of the constricting parietal and epicardial pericardium as possible
Bupivacaine has the lowest cardiac-to-CNS dose toxicity ratio (2:1) AND the highest relative potency for cardiac toxicity of all local anesthetics. Ropivacaine has a 2:1 ratio.
Inverse ratio ventilation the inspiratory phase is prolonged relative to the expiratory phase. (IRV) can be used in cases of refractory hypoxia that does not respond to appropriate optimization of PEEP and/or FiO2, you will see an increase in the mean airway pressure
Esmolol, neostigmine, & oral contraceptives can decrease pseudocholinesterase activity.
Cholinesterase inhibitors & lithium prolong the duration of succ,
Antibiotics, antiarrhythmics, ketamine, local anesthetics, dantrolene can increase duration of action of neuromuscular blocking drugs.
Dibucaine, local anesthestic, inhibits pseudocholinesterase activity.
Dibucaine number (DN) is the % of inhibition of pseudocholinesterase activity.
Normal DN s 80. Abnormal DN is 20
Succinylcholine acts on all ACh receptors both parasympathetic & sympathetic. Succ can decrease HR & contractility at low dosages but increase them at high dosages.
Succinylcholine can cause postoperative myalgia due to the fasciculations. Pre dosing with rocuronium can prevent it
A priming dose of rocuronium can lead to a faster onset time of the neuromuscular blockade
Major complications of jet ventilation include barotrauma, high PEEP, increased risk of airway fires, hypercarbia, laryngospasm, gastric insufflation, and necrotizing tracheobronchitis as well as complications associated with the inability to monitor end-tidal CO2 and tidal volumes
Neonatal lobar emphysema is more common in the left upper lobe. It typically presents at birth and may be mistaken for tension pneumothorax. Imaging of the chest should be obtained to confirm the diagnosis. Cardiac imaging should be obtained to look for associated cardiac comorbidities, which may be responsible for the neonatal lobar emphysema.
Releasing an extremity tourniquet usually results in a transient increase in end-tidal carbon dioxide (EtCO2) with a normal waveform on capnography.
Electrolyte and acid-base abnormalities including hypokalemia, hypomagnesemia, hyponatremia, hyperuricemia, metabolic acidosis, and respiratory alkalosis are common in patients with heavy chronic alcohol use.
Graft thrombosis is an emergency as pancreatic grafts are low-flow organs and require constant blood flow. Graft thrombosis should prompt a re-exploration.
Pancreatic transplantation is often performed in conjunction with renal transplant in patients with diabetes. Pancreas transplants are exquisitely sensitive and require constant blood flow
Myopia (nearsightedness) increases the complications of a retrobulbar block
In the setting of insulin deficiency, glycogenolysis and gluconeogenesis are stimulated by an increase in the glucagon to insulin ratio. Hypoglycemia is further prevented in the setting of fasting by an increase in lipolysis via beta-adrenergic stimulation. The acceleration in lipolysis leads to the release of glycerol and free fatty acids from the breakdown of stored triglycerides in adipose tissue. Proteolysis is increased in prolonged starvation as amino acids are transported to the liver and kidney to be used as substrates for gluconeogenesis
In patients who have suffered a burn injury, the acetylcholine receptors typically start to increase after 2-3 days.
In general, succinylcholine should be avoided after 1-2 days as fatal hyperkalemia may ensue
In patients with multiple sclerosis, succinylcholine should be used very cautiously because they may have denervation or misuse myopathy leading to a higher risk for hyperkalemia.
Age Group Blood Volume
Premature infant 90-105 mL/kg
Full-term newborn 80-90 mL/kg
Infant 3-12 months 70-80 mL/kg
Child 1-12 years 70-75 mL/kg
Adult male 65-70 mL/kg
Adult female 60-65 mL/kg
Sequential Organ Failure Assessment score (qSOFA) can be used to identify adult ICU patients with a suspected infection that are likely to have a prolonged ICU stay or poor outcome.
It is scored 0-3 with one point each for altered mental status (GCS < 15), respiratory rate ≥22, and systolic blood pressure ≤100 mm Hg. A score ≥2 indicates a worse prognosis.
Dexmedetomidine is a central alpha-2 receptor agonist with multiple effects including sedation, anxiolysis, mild analgesia, and hypnosis. Dexmedetomidine is said to emulate normal sleep as is evidenced by the fact that patients will usually respond to things that would awaken them from normal sleep and they have a normal EEG pattern.
Dexmedetomidine induces sedation by stimulating the locus coeruleus which ultimately leads to a decrease in histamine release from the tuberomammillary bodies and induces a sleep state. A major advantage of dexmedetomidine is that respiratory drive is preserved, and awakening for neurologic evaluation or commands in the ICU or during operations is maintained.
Progression of the hypercarbia will result in profound acidosis and resultant hypotension and cardiac arrhythmias. Sympathetic stimulation can lead to normalization of blood pressure or even hypertension with profound hypercarbia. Profound hypercarbic narcosis will tend to present around a partial pressure of 100-120 mmHg.
Acute hyperoxia can manifest with CNS toxicity, presenting initially as a grand-mal seizure. Prolonged exposure can result in pulmonary and ocular toxicity due to increased oxygen free-radical formation
Hydroxyethyl starch at large doses (20 mL/kg/day) can result in developing a coagulopathy.
Dextrans (colloid solution) have an antithrombotic effect. One of the side effects of the use of dextrans is decreased von Willebrand factor (vWF) levels.
Most pulmonary pathology results in a decreased diffusing lung capacity of carbon monoxide (DLCO).However, The DLCO has been found to be increased in patients with asthma, with obesity, and at high altitudes. Factors that increase the amount of blood exposed to the ventilated air, such as polycythemia, heart failure, left to right shunt, and pulmonary hemorrhage, also increase the DLCO
Neuraxial labor analgesia does cause a slight (~15 min) prolongation of the second stage of labor as well as a maternal fever
The trachea can be anesthetized by transtracheal injection of local anesthetic through the cricothyroid membrane.
Potential complications of brachial artery cannulation include median nerve damage, distal ischemia due to lack of collateral circulation, and catheter-related bloodstream infections.
When providers are monitoring for ischemia, the transgastric midpapillary short-axis view is preferred because it allows the provider to visualize the myocardium perfused by the three coronary arteries in a single image
Postdural puncture headache typically presents 6-72 hours after dural puncture and is commonly accompanied by nausea and neck stiffness, as well as ocular and auditory manifestations. The incidence is approximately 50% when the dura is accidentally punctured with the epidural needle, but only in the low single digits if using a spinal needle, particularly when using a small-diameter pencil-tip needle.
Therapeutic blood patch is very effective (90%), but prophylactic blood patch is not.
Prothrombin complex concentrate contains factors II, VII, IX, X. PCC is now preferred over plasma for a correcting coagulopathy.
In general evoked potential amplitude in neuromonitoring can be decreased by anemia, volatile anesthetic, nitrous oxide, ischemia, & hypoxia
Peritoneal dialysis is the preferred dialysis modality for patients who are intolerant of the hemodynamic changes induced by hemodialysis. This may include patients with a history of unstable angina, severe aortic stenosis, or heart failure with severely reduced ejection fraction. Peritoneal dialysis is preferred in the pediatric group
The fetus usually tolerates mild to moderate decreases in maternal PaO2 during 2nd trimester. This is secondary to the fetal hemoglobin having a very high affinity for oxygen with a leftward shift of the oxygen-hemoglobin dissociation curve.
By 8 weeks gestation an increase in cardiac output of 50% occurs, this is accompanied by a drastic decrease in systemic vascular resistance. After approximately 20 weeks gestation, in the supine position, the gravid uterus places pressure on the great vessels, which may cause a decrease in uteroplacental blood flow. Blood volume and plasma composition also change during pregnancy. In the first trimester, the blood volume expands and will continue to increase until term. Plasma volume increases faster than the increase in red blood cell mass thus dilutional anemia occurs. A hypercoagulable state is achieved due to increases in fibrinogen, factors VII, VIII, X, and XII. Platelet turnover is enhanced. The respiratory system changes mainly due to an increase in alveolar ventilation by 30% or more by mid-pregnancy. A chronic respiratory alkalosis is seen with a slightly alkaline pH. Oxygen consumption increases as metabolism changes, PaO2 may slightly increase. Functional residual capacity decreases as the uterus expands pushing the diaphragm upward, resulting in decreased oxygen reserve
Treatment of complex regional pain syndrome type II consists of physical therapy, tricyclic antidepressants, gabapentin, sympathetic blocks, somatic blocks, spinal cord stimulators, and intrathecal medications.
Patients with known inducible ischemia may receive even more benefit from beta-blocker therapy. It is known that beta-blocker therapy should not be started within 1 day of surgery as that significantly increases the risk of stroke and death. Thus the recommendation is to initiate therapy at least 2 days, but preferably 7-45 days prior to surgery.
Cerebrospinal fluid lavage is a rarely used method to quickly reverse a high/total spinal blockade. Involves removing 10–20 mL of CSF from the intrathecal space and replacing it with the same amount of volume of sterile fluid
Meyer-Overton correlation describes the linear relationship between anesthetic potency and solubility in oil such as olive oil. The hypotheses of inhaled anesthetics with lipid membrane target sites were predominant before shifting to the more current protein-target-based theories.
the first-line treatment for symptomatic bradyarrhythmia is atropine, 1 mg IV, repeated every 3-5 minutes to a maximum of 3 mg. If atropine is ineffective, the next step is to attempt transcutaneous pacing or administer dopamine or epinephrine by infusion
A few situations exist that necessitate lifelong anticoagulation for these patients. These include patients who have had 2 or more venous thromboses, patients with 2 or more hereditary hypercoagulable disorders, patients with one spontaneous life-threatening thrombosis, and patients with one spontaneous thrombosis at an unusual site. INR goal for warfarin for these patients is 2-3; the same as the general population
Geriatric patients require a reduced dose of most medications due to decreased central compartment volumes which contributes to high initial concentrations. Increased body fat percentage can increase the volume of distribution for lipid-soluble drugs, causing an increased duration of action. Hepatic and renal clearance is decreased, increasing the duration of action. Albumin levels are reduced, although this is not thought to significantly contribute to plasma concentration differences.
Standard error of mean (SE)
Standard deviation (SD)
Sample size (n)
SE = SD / √n
The standard error of the mean describes the precision of the sample mean to the population mean 
Tracheoesophageal fistula and esophageal atresia are commonly associated with other congenital abnomalies, the most common being cardiac anomalies. Associated cardiac anomalies include coarctation of the aorta, tetralogy of Fallot, atrial septal defects, ventricular septal defects, and atrioventricular canal.
Metabolic acidosis, which results from ketone production in brown fat metabolism (nonshivering thermogenesis), is maladaptive in the neonate and is the most critical consequence of a decrease in temperature. Neonates use nonshivering thermoregulation to control body temperature to metabolize their brown fat
The great anterior radiculomedullary artery, also known as the artery of Adamkiewicz, is a vital arterial structure that supplies blood to the spinal cord. It typically arises from the left and at T9-T12 within the spinal cord. It supplies the watershed zone of the lumbar and sacral spinal cord.
Elevated preop creatinine, complex cardiac procedures, emergency surgery, and preop intraaortic balloon pump carry the highest risk for post cardiopulmonary bypass acute kidney injury. Acute kidney injury occurs in up to 30% of patients following cardiac surgery.
Total parenteral nutrition is a common cause of jaundice in postoperative and acutely ill patients by producing cholestasis and biliary sludge.
Effective prophylactic medications for the prevention of emergence delirium in children who are undergoing general anesthesia with volatile anesthetics include a single IV dose of ketamine, propofol, midazolam, fentanyl, or dexmedetomidine at the end of surgery
Volatile anesthetics decrease mucus clearance, increase respiratory rate, decrease tidal volumes, cause a depression of the central response to hypercapnia and hypoxia, and have the potential to exacerbate acute lung injury with their proinflammatory actions.
excessive oxygen administration does have predictable and potentially deleterious effects. Hyperoxia will tend to cause systemic vasoconstriction and pulmonary vasodilation. Excess dissolved oxygen in the plasma may cause an increase in circulating reactive oxygen species which mav increase the oxidative stress on the body’s systems.
Lumbar sympathetic blocks are effective methods for first-stage labor analgesia.
Epidural analgesia is effective for treating pain in the first and second stages of labor. T10 to L1 spinal segment coverale is required to relieve the pain of contractions and cervical dilation.
Pudendal nerve block helps relieve pain during the second stage of labor. The pudendal nerve includes somatic nerve fibers from S2-S4.
Inhaled anesthetic agents exert the most powerful negative effect on the neonate, and exposure in-utero should be minimized immediately prior to delivery through communication with the surgical team and rapid delivery of the fetus following induction of anesthesia. Benzodiazepines have been associated with fetal hypotonia (“floppy baby syndrome”) when administered during labor and may have detrimental effects for hours to weeks following delivery.
Material Ingested Minimum
Fasting Period
Clear liquids 2 hours
Breast milk 4 hours
Infant formula 6 hours
artificial milk, light meal 6 hours
Fried, fatty foods, meats 8 hours
In infants and young children, there should be a small air leak around the endotracheal tube at peak i tion pressures of approximately 15 to 25 cm H2O
Patients with known hypertrophy of the intraventricular septum experiencing hypotension should be treated with fluid & alpha agonists such as phenylephrine
Methylene blue is used with Vasoplegia associated with cardio pulmonary bypass as a nitric oxide scavenger to help improve blood pressure, refractory to other medication’
Patients who have allergies to avocados, bananas, and kiwis have been shown to have antibodies that cross react with latex 
Epidural infusions containing local anesthetics have been shown to reduce the incidence of postoperative ileus.
Surgical insult leads to the release of many inflammatory mediators, including histamine, bradykinin, prostaglandins, and catecholamines. These inflammatory mediators activate peripheral nociceptors, leading to signal transduction via pain fibers that ultimately cause the release of substances such as substance P, calcitonin gene-related peptide, and y-aminobutyric acid in the central nervous system.
Goals for a patient presenting with acute stroke include normothermia, normotension, euvolemia, normal blood glucose levels, avoidance of hypoxemia, avoidance of hyperoxia and rapid fibrinolysis
Hepatopulmonary syndrome (HPS) is the dysregulation of the vascular tone that controls blood flow through the pulmonary vascular bed that occurs in cirrhotic liver disease. This regulation will result in an increase in intrapulmonary right-to-left shunting, which will result in arterial hypoxemia. Because of the pathophysiology of this hypoxia, this hypoxia is unlikely to respond in a significant fashion to increases in the (Fi02).
Sepsis and septic shock are medical emergencies and should be rapidly and aggressively managed as soon as a diagnosis is made. Broad-spectrum antibiotics should be initiated within the first hour. Sepsis-induced hypoperfusion should be treated with at least 30 mL/kg of intravenous crystalloid within the 3hr used in combination with volume resuscitation to target an initial MAP of 65 mmH and the recommended initial vasopressor is norepinephrine.
Hepatic blood flow is regulated the hepatic arterial buffer response. The hepatic arterial buffer response is a system in which changes in portal vein blood flow result in reciprocal changes in hepatic arterial flow through production and washout of adenosine, a vasodilator.
When portal vein blood flow decreases, increases in adenosine lead to arterial vasodilation, and, therefore, increased hepatic arterial flow, and vice versa
portal vein normally supplies approximately 75% of the total liver blood flow, and the hepatic artery provides the remaining 25% of total liver blood flow. Each supplies approximately 50% of the total oxygen content to the liver
The hepatic arterial buffer response is unaffected by intravenous anesthetics.
BPAP adds pressure support ventilation (PSV) to CPAP. BPAP acts to support minute ventilation through PSV, and hypercarbia is an indication to initiate BPAP. Specific contraindications to BPAP include cardiopulmonary arrest, inability to protect the airway, the continuous presence of bodily fluids in the oropharynx, facial trauma, severe agitation, and hemodynamic instability
Most priming solutions for cardiopulmonary bypass are crystalloid based and can include additives such as heparin, mannitol, corticosteroids, and colloid solutions. Adding colloids can reduce the drop in systemic vascular resistance seen with crystalloid priming solutions.
Etomidate induces anesthesia via modulation of the GABA A receptor, and is metabolized by hepatic ester hydrolysis. Etomidate is known for cardiovascular stability, maintenance of cerebral perfusion pressure, and adrenal suppression.
For every decade of life after 40 years, the minimum alveolar concentration (MAC) of volatile anesthetics is reduced by 6%, and for every decade before 40 years, MAC is increased by 6%.
Beta-blockers and statins should be continued in the perioperative period. Clonidine should generally be continued perioperatively to prevent withdrawal symptoms.
Line isolation monitors monitor the amount of leakage present in an isolated (ie, nongrounded) power system, such as that in the operating room. They typically sound an alarm when a piece of equipment with excessive leakage (ie, equipment with a shorted circuit with low impedance) is plugged into the operating room outlet. The threshold for alarm is typically 5 mA of leakage, to prevent a macroshock which requires 10 mA. Sounding of an LIM alarm does not mean that a macroshock has occurred but that leakage is sufficient to put the patient at risk should further grounding occur.
There are two types of Ischemic optic neuropathy (ION) which involve either the anterior or posterior optic nerve. Anterior ION is less common and involves temporary hypoperfusion of vessels supplying the anterior optic nerve. Cardiovascular disease, CABG, and spine surgery are risk factors. Disc edema is present in anterior ischemic optic neuropathy. Vison loss is unilateral
Posterior ION is more common and most cases involve spinal surgery. It is caused by decreased oxygen delivery to the optic nerve in the lesser perfused, posterior portion. Hypoxic insult can manifest slowly over days with bilateral involvement being more common. Risk factors include male sex, obesity, use of a Wilson frame, prolonged anesthetic, increased blood loss, and lower percent colloid administration.
Peripheral nerve anatomy from the inside-out is endoneurium, perineurium, epineurium. The endoneurium wraps individual axons. Most blocks are performed by placement and injection of local anesthetic outside of the epineurium.
Arterial oxygen content (CaO2) is described by the following equation:
CaO2 = (1.39 * SaO2 * Hgb) + (0.003 * PaO2)
Excess ammonia combines with glutamate to form glutamine. Glutamine acts as an osmotic agent resulting in the swelling of astrocytes and ultimately cerebral edema.
Lactulose decreases the intestinal absorption of ammonia by decreasing the intestinal pH and trapping ammonia as the ammonium ion, which can no longer cross the intestinal membrane and be absorbed.
The difference nce between the sum of the strong cations minus the sum of strong anions is the strong ion difference (SID). Vomiting results in an increase in the SID because there is a loss of large amounts of chloride (a strong anion), increasing the difference between the strong cations and anions. A normal SID is 40 mEq/L; lower values indicate acidosis, and higher values indicate alkalosis.
Large volume infusion of fluids with zero SID (such as normal saline) will decrease the plasma SID (normally 40 mEq/L). This results in dilutional acidosis. This is true for large saline infusion where the metabolic acidosis results due to reduction in SID, not the hyperchloremia.
Strong ion difference (SID) can be reduced by infusing large volumes of fluid that has a SID of zero, such as normal saline
A standard dose of ketorolac provides analgesia equivalent to 6-12 mg of morphine administered by the same route.
Ketorolac inhibits platelet Agregation and prolongs bleeding time. It and other NSAIDs should therefore be used with caution in patients at risk for postoperative hemorrhage.
Substance P is a neuropeptide that interacts at neu-rokinin-1 (NK) receptors. NK, antagonists inhibit substance P at central and peripheral receptors.
Aprepitant (Emend), an NK, antagonist, has been found to reduce PONV perioperatively and is additive with ondansetron for this indication.
The 5-HT3, receptor mediates vomiting and is found in the GI tract and the brain (area postrema).
The 5-HT4, receptors are responsible for smooth muscle contraction and platelet aggregation
5-HT5 receptors in the GI tract mediate secretion and peristalsis
5-HT6 and 5-HT7, receptors are located primarily in the limbic system where they appear to play a role in depression.
serotonin is a powerful vasoconstrictor of arterioles and veins.
Because nitrous oxide exists in both gas and liquid forms, Boyle’s law cannot be used to determine the amount of remaining nitrous oxide if liquid is present because the pressure will remain constant at ~745 psig. To determine the amount of nitrous oxide remaining when the liquid form is present, the cylinder must be weighed, and the tare weight must be subtracted to calculate the amount of nitrous oxide remaining
Colors for the most commonly used gases are
Black: Nitrogen
Blue: Nitrous oxide
Brown: Helium
Gray: Carbon dioxide
Green (white): Oxygen
Yellow (white and black): Air
ECT requires minimum seizure duration of 25-30 seconds to ensure adequate antidepressant efficacy. Methohexital or etomidate are the best options depending on patient circumstances. Avoidance of etomidate in patients with baseline hypertension or CAD is advisable as it does not blunt the sympathetic surge associated with ECT.
Midazolam is a benzodiazepine that will decrease seizure duration thus should be avoided as an anxiolytic or induction agent during electroconvulsive therapy
Umbilical artery blood is thought to be representative of the acid-base status of the fetus, while umbilical vein blood is thought to be representative of placental function. Umbilical artery blood gases immediately following the delivery of a normal neonate will be acidotic, following approximate values: pH of 7.27, pCO2 of 50 mmHg, pO2 of 18 mmHg, and base excess of -2.7 mEq/L.
The most important initial step in management of an incompetent inspiratory valve is to increase fresh gas flow such that rebreathing will be minimized or eliminated.
The adjustable pressure limiting (APL) valve is a safety feature of the anesthetic machine that releases excess circuit gas to the scavenger system. The main feature of the APL valve is that it allows the anesthetic provider to control the breathing system pressure during spontaneous and manual ventilation.
during mechanical modes of ventilation (eg, volume control), the function of the APL valve is negligible. If this valve is not closed sufficiently, excessive loss of circuit volume due to leaks prevents manual ventilation. However, if the valve is closed too much or is fully closed, a gradual increase in pressure could result in pulmonary barotrauma, gastric insufflation, or hemodynamic compromise.
peripheral nerve stimulators connect the negative pole to the needle and the positive pole to the patient’s skin so that the negative current emanating from the needle increases the likelihood of generating an evoked response.
National Fire Protection Association authors the Health Care Facilities Code, which includes standards for electrical systems, HVAC, gas, and vacuum systems, among others
persistent bilateral headache that stems in the neck and radiates to the top of the scalp
This is a sign of Occipital neuralgia. Occipital nerve block is both diagnostic and therapeutic in treating occipital neuralgia.
Smoke inhalation injury can lead to acute respiratory distress syndrome, (ARDS), 2 to 3 days later after exposure
Necrotizing tracheobronchitis is a complication of high-frequency jet ventilation
The mainstays of treatment of Flail Chest include aggressive pulmonary hygiene, adequate analgesia with thoracic epidural analgesia being effective. Surgical intervention is not routinely performed unless the patient has additional underlying injuries or does not respond to conservative management.
Flumazenil is a short-acting competitive antagonist of benzodiazepines. Flumazenil has the shortest half-life of all benzodiazepines, with a duration of action of about 45 minutes to one hour. Therefore, any patient who has received flumazenil should be observed for recurrent sedation.
Flumazenil can cause seizures as well.
Term infants develop a normal physiologic anemia by age 8-12 weeks, with a Hb concentration of 10.5-11.5 g/dL. Preterm infants develop a physiologic anemia earlier, by 6 weeks, and with a lower Hgb 7-10 g/dL.
Cerebellum receives large quantities of information from the brain, spinal cord, and vestibular system, supporting proper coordination of movements in agonist-antagonist muscle groups for appropriate balance and fine motor function. Disruptions in cerebellar functions, as in a stroke or congenital ataxic disease (ie, Friedreich’s ataxia) can lead to a variety of symptoms including intention tremor, nystagmus, and dysarthria.
Dantrolene should be administered as a rapid 2.5 mg/kg IV bolus as soon as a diagnosis of MH is suspected.
Malignant hyperthermia-susceptible patients have RYR1 defects that, in the presence of a triggering agent (succinylcholine or any volatile anesthetic), cause prolonged opening of the channel which leads to sustained muscle contraction. This produces a generalized hypermetabolic state characterized by increased CO2, lactic acidosis, and heat production which can progress to muscle cell breakdown leading to hyperkalemia and rhabdomyolysis
Hypokalemic periodic paralysis is an autosomal dominant disease with incomplete penetrance due to mutations in either voltage-gated calcium (familial form type 1) or sodium (familial form type 2) channels in the muscles.
Patients will Hypokalemic periodic paralysis present with flaccid paralytic attacks after eating a carbohydrate-heavy meal and during exercise. Other factors that precipitate these attacks include high salt-containing meals
Unlike most anesthetics which directly depress the RAS, ketamine exerts its effects on the thalamus, causing dissociation of the reticular activating system from the cerebral and limbic cortices.
Ginseng, in particular, may cause intraoperative hypoglycemia if patients are taking it preoperatively
Ephedra, also known as ma huang, is used for weight loss and to increase energy. It is a sympathomimetic that increases heart rate and blood pressure.
Garlic is used to modify the risk of atherosclerosis as well as reduce blood pressure. It inhibits platelet aggregation and increases fibrinolysis.
Hetastarch may lead to platelet dysfunction by causing a reduction in the availability of glycoprotein IIb-IIIa on platelets.Hetastarch decreases factor 8 & von williebrand factor levels
Pressure in the “laryngospasm notch” just anterior to the pinna of the ear and under the angle of the mandible may be attempted at this time in order to stimulate and awaken the patient in an effort to proceed through stage 2 of anesthesia faster. This is referred to as the Larson maneuver.
Hypertonic solutions (eg, hypertonic saline, mannitol) are used for volume resuscitation in patients with traumatic brain injuries (TBI) to increase cerebral perfusion pressure (CPP), increase serum sodium and osmolarity, and decrease intracranial pressure (ICP) and cerebral edema.
A preoperative coronary catheterization is indicated for patients who fail a stress test or have refractory angina.
with open globe injuries, several steps should be taken to avoid further injury to the eye:
- Ensure adequate depth of anesthesia prior to laryngoscopy. Coughing and bucking cause a large increase in IOP and should be avoided.
- Avoid succinylcholine, if possible, as it can increase IOP.
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with open globe injuries
- Propofol is preferred over etomidate or ketamine since the latter two drugs can cause myoclonus and nystagmus, respectively.
- Avoid nitrous oxide as it can cause enlargement of intraocular gas bubbles and increase IOP.
- Use caution with retrobulbar blocks as large volumes of local anesthetic behind the eye can increase IOP.
- Attempt to avoid coughing and bucking with emergence.
The most common sequela is gastric distension when the treatment of laryngospasm is continuous positive airway pressure of 100% oxygen in combination with airway manipulation to stent open the airways
Pruritus is a side effect of opioids and is particularly prevalent with neuraxial opioids (60-80%). Nalbuphine is the drug of choice for the treatment of pruritus induced by neuraxial opioids.
In surgeries that are classified as low risk, preoperative laboratory testing is generally not required, especially in asymptomatic stable patients even if they have a medical history of cardiac disease
For patients undergoing moderate-risk surgeries, an ECG should be considered for those with known cardiac or cerebrovascular disease or cardiac risk factors. For patients with no cardiac risk factors undergoing moderate risk surgeries, generally, no preoperative testing is indicated.
For patients undergoing high-risk surgeries, ordering an ECG preoperatively should be considered for patients with known cardiac or cerebrovascular disease or without heart disease but with risk factors.
Ordering an echocardiogram preoperatively should be considered for patients with a history of heart failure with no prior echocardiogram in the past year, heart failure symptoms, or unknown functional capacity. However, obtaining a preoperative echocardiogram is not indicated for asymptomatic patients with known cardiac disease or patients undergoing low-risk surgery.
A stress test is indicated if there is concern that the patient’s heart will not be able to tolerate the procedure. If The patient is able to tolerate >4 metabolic equivalents with an ability to walk for 1 mile, so there is no indication for a stress test.
Transient neurologic symptoms (TNS) are characterized by pain in the buttocks and legs that develop within a few hours and, at time, up to 24 hours after spinal anesthesia. The first-line treatment for TNS is NSAIDS, followed by opioids if the pain is severe and does not resolve.
Acupuncture can help prevent PONV
Acupuncture is good for pain control
Gate Theory
Spinal cord stimulators activate the larger Aα and Aβ fibers to a greater degree compared with the smaller nociceptive Aδ and C fibers. This closes the gate in and impedes conduction of pain sensation past the substantia gelatinosa of the dorsal horn of the spinal cord
Stimulation of large nerves will eventually lead to activation of GABA and decreased Glutamate excitatory mechanisms to decrease pain stimulation
Reynolds number measures laminar vs turbulent flow
Reynolds number <2300= laminar flow
Reynolds number >4000= Turbulent flow
RN=(FpL)/viscosity
Echinocandins are the preferred first line treatment of candidemia. They act by inhibiting 1,3-beta-D-glucan synthase and cell wall synthesis.
Amphotericin B acts by disrupting the fungal cell membrane by binding to ergosterol in the membrane and creating pores.
First-order elimination of medication will result in a constant fraction of medication eliminated per unit of time. Zero-order elimination will result in a constant amount of medication eliminated per unit of time
Most medications are eliminated by first-order kinetics.
drugs that are eliminated by zero-order kinetics are ethanol, cisplatin, phenytoin, and salicylates (at high doses)
Myasthenia gravis is an autoimmune disorder in which autoantibodies target the alpha subunit of muscle-type nicotinic acetylcholine receptors preventing activation of the receptors and their ultimate destruction. Patients typically present with diplopia, ptosis, dysarthria, and proximal limb muscle weakness that worsens with activity and improves with rest.
Antibodies targeting presynaptic voltage-gated calcium channels are involved in Lambert-Eaton syndrome. This disease presents with proximal limb weakness that improves with increased activity. The antibodies targeting the voltage-gated calcium channel reduce the calcium influx into the presynaptic terminal and the release of acetylcholine at the neuromuscular junction
The posterior pituitary secretes oxytocin and vasopressin, which are both synthesized in the hypothalamus in the paraventricular and supraoptic nuclei. They are then transported down the infundibular stalk to the posterior pituitary for release.
Stroke volume variation (SVV) can be used to assess fluid responsiveness. SVV is accurate when the following conditions are met: mechanical ventilation , tidal volumes ≥ 8 mL/kg, and normal sinus rhythm. Inaccurate values can result when the patient is spontaneously breathing; there is the presence of arrhythmias, elevated intra-abdominal pressure, or right heart failure; the thoracic cavity is open during surgery; there is a high respiratory rate; and there are low tidal volumes/low lung compliance.
Type I alveolar cells are the thin epithelial cells that allow gas exchange between the alveolus and the pulmonary vasculature.
Type III alveolar cells, also known as alveolar macrophages, function as part of the immune system of the lung. They are able to migrate and ingest foreign material in the lungs.
Type II alveolar cells are metabolically active cells and secrete the lung surfactant. They also play a role in pulmonary defense through the secretion of inflammatory mediators. When type I alveolar cells become damaged during acute lung injury, new type I alveolar cells are regenerated through replication of type II cells.
Crouzon syndrome is caused by a fibroblast growth factor receptor gene mutation and results in early closure of cranial sutures causing the syndrome of a hypoplastic midface, bulging eyes, beaked nose, and underbite.
Klippel-Feil syndrome presents with a fused cervical spine due to lack of segmentation of the cervical spine . Cervical rotation is reduced more than flexion and extension. Cervical immobility can present a challenging intubating condition
Pierre Robin sequence results in micrognathia, glossoptosis (tongue that falls to the back of the throat), and cleft palate. Patients present with airway obstruction and feeding difficulties. The airway improves as the child ages and intubating conditions improve with age.
Treacher Collins syndrome is inherited in an autosomal dominantly pattern with variable penetrance. It results in zygoma and mandibular hypoplasia. It is associated with ear deformity, deafness, and mental retardation. Unlike Pierre Robin sequence, this syndrome becomes more challenging to intubate with age
Chronic opioid therapy leads to increased prolactin levels, and decreased testosterone, estrogen, cortisol, LH, and FSH.
Epidural-administered hydrophilic opioids (eg, morphine, hydromorphone) have a slower onset, a longer duration of action, a higher incidence of side effects, a delayed respiratory depression, an extensive cerebrospinal fluid spread, and a delayed onset of analgesia compared to lipophilic opioids (eg, fentanyl). This is mainly due to their low lipid solubility of hydrophilic opioids.
Static compliance is calculated by using the equation TV/(Pplateau - PEEP), where TV = tidal volume, Pplateau = plateau pressure, and PEEP = positive end-expiratory pressure. The Pplateau is the pressure during an inspiratory hold in a mechanically ventilated patient.
An upper extremity tourniquet should be inflated to at least 50 mm Hg above the systolic blood pressure. A lower extremity tourniquet should be inflated to at least 100 mm Hg above the systolic blood pressure.
Former premature infants having procedures under general anesthesia who are younger than 45-weeks post-conceptual age should be admitted for overnight observation to the hospital. Further, former premature infants with prior observed apnea episodes and anemia are at higher risk for apnea.
Note that for full-term infants, case reports of apneic episodes have been noted at birth so guidelines generally recommend waiting until post-natal age of greater than 4 weeks prior to discharging without observation.
Hydromorphone is metabolized into the neuroexcitatory compound hydromorphone-3-glucuronide, which accumulates in renal failure and may cause myoclonus.
Meperidine is broken down into the neuroexcitatory metabolite normeperidine; this can result in seizures, agitation, and myoclonus if the normeperidine is not cleared by the kidneys.
Surgical stress leads to the increased secretion of glucose from counter-regulatory hormones and peripheral tissue resistance to insulin, resulting in hyperglycemia.
Etomidate inhibits 11β-hydroxylase resulting in decreased synthesis of cortisol and aldosterone.
The 2016 American College of Cardiology/American Heart Association guidelines includes the recommendation that elective noncardiac surgery requiring interruption of dual antiplatelet therapy in patients treated with drug-eluting stents be delayed optimally until six months after stent placement but may be considered for time-sensitive surgeries after three months.
Dual anti platelet therapy may be interrupted for elective noncardiac surgery after one month after bare-metal stent placement.
An action potential, propagated by sequential voltage-gated sodium channel depolarization along the axon, arrives at the axon terminal boutons and opens voltage-gated calcium channels to allow for calcium influx, which in turn triggers the exocytosis of acetylcholine into the neuromuscular junction. In particular, synaptotagmin of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins acts as a calcium sensor that triggers fusion in docked vesicles
Pregnancy is a prothrombotic state with increased levels of many clotting factors. Factors VII, VIII, IX, X, and XII levels are all increased. In addition there is a decrease in factor C & S levels. This causes shorter PT and PTT times. However, not all factors are increased during pregnancy with factors XI and XIII levels decreasing slightly.
Liver transplantation can be divided into three phases: pre-anhepatic, anhepatic, and neohepatic. The pre-anhepatic stage starts when incision begins and ends when the portal vein, hepatic artery, and inferior vena cava (or hepatic vein) are cross-clamped. The anhepatic phase begins with the cross clamping of aforementioned vessels and ends with removal of the native liver and implantation of the allograft. Reperfusion of the allograft, via unclamping of the portal vein, signals the beginning of the neohepatic phase of liver transplantation.
Erythropoietin may be helpful for Jehovah’s Witness patients but requires four to six days to stimulate erythropoiesis
Albumin is not allowed in Jehovahs witness patients.
Minimize phlebotomy in Jehovah’s Witness patients
Cardiopulmonary bypass would likely be an acceptable technique for Jehovah’s Witness patients
High fractional inspired concentrations of oxygen (FIO2) lead to formation of reactive oxygen species (ROS). An important pathway involved in ROS formation is activation of NADPH oxidase (NOX) reactions in cellular mitochondria which cause cellular damage.
Oxygen toxicity of the neonate usually manifests as chronic lung disease and central nervous system diseases (i.e. retinopathy of prematurity). When administering oxygen to a neonate, always start with the lowest possible amount of oxygen and titrate FIO2 levels to maintain SpO2 > 94% or PaO2 > 100 mg Hg.
Critically ill patients and neonates have been shown to be deficient of anti-oxidant mechanisms and thus are more susceptible to oxygen toxicity.
Glucose transporters 1,2, 3, and 5 are insulin-independent transporters, while GLUT4 is the only insulin-dependent transporter. Glucose transporter 4 is responsible for most glucose uptake into adipocytes and striated muscle (skeletal and cardiac),
GLUT 1 is found in the cornea, CNS, placenta
GLUT 3 is found in most cells, CNS
GLUT 5 is found in kidneys 
GLUT 2 is a bidirectional transporter, responsible for glucose uptake into the liver.
Meperidine blunts the shivering response to hypothermia which reduces total body oxygen demand
Induced hypothermia following cardiac arrest can reduce ischemic injury and improve neurologic outcomes. It is accomplished by various cooling methods for a duration of 12-24 hours post-resuscitation with a goal temperature of 32 °C to 36 °C.
Jackson-Rees modification circuit is also known as the Mapleson F circuit. It is similar to the Mapleson D except that it has no APL valve or carbon dioxide absorber, and it has a hole at the end of the reservoir bag for venting of the gases (a valve can be added at the hole for more precise control). The FGF that is required to prevent rebreathing during spontaneous ventilation is 2.5 to 3 times minute ventilation and 1.5 to 2 times minute ventilation during controlled ventilation.
The Mapleson A system is the only type of Mapleson system that has the fresh gas inlet near the breathing bag and not near the patient. It is most efficient for spontaneous ventilation. To prevent rebreathing, the FGF must be equal to minute ventilation.
Bain circuit is a Mapleson D system with a modification such that fresh gas flows occur through a narrow inner tube nested within the outer corrugated hose. The fresh gas empties into the circuit nearest the patient. Exhaled gases exit through the corrugated tube around the central tubing exchanging heat with the central tubing. There is no carbon dioxide absorbent in the Bain circuit. Mapleson D systems are the most efficient for controlled ventilation
The circle system is the most common breathing system, and a carbon dioxide absorbent is used.
 most efficient circle system with the highest conservation of fresh gas is one in which the unidirectional valves are closest to the patient with the APL valve immediately downstream of the unidirectional expiratory valve.
Pregnancy increases oxygen consumption by 40-75% as a result of progressively increased tissue metabolism
Increased cardiac output during pregnancy increases maternal oxygen consumption. In fact, two-thirds of this increase is attributed to fetal, placental, and uterine metabolism increase.
The two most commonly used types of electrocautery are monopolar (single electrode and dispersion pad) and bipolar (two electrodes near each other). Numerous risks are associated with electrocautery, including the risk of burns when the return pad is not placed correctly, the risk of a fire ignition source, the risk of exposure to smoke plume, and the risk of interference or damage of implanted devices such as pacemakers and defibrillators.
It is known that viral particles can be found in the surgical smoke plume generated from electrocautery units.
Biophysical profile (BPP) components consist of a non-stress test (NST) and observation of fetal breathing, fetal movement, fetal tone, and amniotic fluid volume.
Each BPP component is scored as either a 2 or 0. A score of 8 or 10 is normal, a score of 6 is equivocal, and a score of 4 or less is abnormal, suggesting fetal hypoxia.
Fetal tone is the earliest to function, at 7.5 to 8.5 weeks of gestation. At 9 weeks, the fetal movement center begins functioning. At 20-21 weeks of gestation, fetal breathing begins. During periods of hypoxia or asphyxia, fetal heart rate is the most sensitive to reflect changes, whereas fetal tone is the last component to decrease.
In patients with chronic aortic stenosis (AS), the atrial kick can contribute up to 40% of the left ventricular end-diastolic volume and is crucial to the maintenance of an adequate cardiac output. Every effort must be made when inducing and maintaining anesthesia in these patients to ensure continued sinus rhythm so as to benefit from this atrial kick, and Afib must be immediately recognized and treated.
Hypothermia also occurs with regional anesthesia. The thermoregulatory center incorrectly judges skin temperature in blocked regions to be abnormally elevated.
Hepatic synthetic function can be assessed by measuring the synthetic products of the liver such as factor VII (or PT), fibrinogen, and albumin. The first of these products to decrease is factor VII which has a half-life of four hours and can be measured by assessing PT. Albumin takes longer to decrease as its half-life is 20 days.
Hypothermia reduces both the arterial partial pressure of carbon dioxide and the arterial partial pressure of oxygen because a decreased temperature causes an increase in gas solubility in the blood.
Awake fiberoptic intubation in children is rarely used due to patient cooperation but is the safest option, especially for patients with known difficult ventilation. Successful awake intubation often requires adequate topicalization of the oropharynx and some form of sedation. In patients who are difficult to ventilate, placing a laryngeal mask airway may be a useful first step to achieve ventilation prior to attempting tracheal intubation
Though modern volatile anesthetics do inhibit hypoxic vasoconstriction in a dose-dependent manner, this effect appears to become significant only at 1.5-2.0 MAC or greater. No benefit in oxygenation has been demonstrated with TIVA compared to volatile anesthetics around 1.0 MAC during one-lung ventilation
Protamine is a cationic protein that binds to the highly negatively charged heparin, neutralizing it. Independent factors for protamine reactions include a documented fish allergy, history of nonprotamine medical allergies, and use of NPH
3 different types of protamine reactions:
Type I reactions result in isolated mild hypotension with normal filling and airway pressures.
Type II reactions are characterized by moderate to severe hypotension with anaphylactoid features such as bronchoconstriction.
Type III reactions result from large heparin-protamine complexes that deposit in the pulmonary circulation resulting in the release of vasoactive mediators causing severe hypotension, elevated pulmonary artery pressures, and potentially right ventricular failure. This collapse of the cardiovascular system may result in the requirement for the patient to be reinstituted on cardiopulmonary bypass.
Criteria for extubation include
Resolution of the process that initially necessitated mechanical ventilation
Hemodynamic stability
Adequate oxygenation on minimal FiO2 (< 40%-50%)
The ability to protect the airway and clear secretions
Favorable respiratory mechanics values include a negative inspiratory force > −20 cm H2O, a RSBI (rapid shallow breathing index) of < 105, and a vital capacity of > 10 mL/kg.
Studies have shown increased concentrations of endorphins in the CSF after acupuncture treatment and acupuncture-induced analgesia can be prevented or reversed by administration of naloxone
Acupuncture releases ACTH, rise in serum ACTH levels suggests that adrenal stimulation and subsequent cortisol release may play a role in acupuncture-induced analgesia.
Intrathecal drug delivery (ITDD) systems are used to treat patients with severe chronic cancer or non-cancer pain. Complications from the use of these ITDD include the formation of intrathecal granuloma, hypogonadism, and lower extremity edema.
Fentanyl does NOT cause IT granuloma.
Morphine & hydromorphone can cause IT granuloma
There is a long list of risk factors for preeclampsia including antiphospholipid antibody syndrome, prior preeclampsia, chronic hypertension, diabetes mellitus, obesity, and use of assisted reproductive techniques.
Smoking, however, actually decreases the risk of preeclampsia by 30% to 40%.
Aspirin causes a 10% to 20% reduction in the risk of developing preeclampsia
Meralgia paresthetica is a mononeuropathy of the lateral femoral cutaneous nerve
Meralgia paresthetica is caused by compression and stretch injury of the nerve as it passes around the anterior superior iliac spine beneath or through the inguinal ligament.
Meralgia paresthetica is frequently associated with pregnancy and delivery.
Symptoms worsen with standing or wearing tight clothing
Contraindications to IABP placement include moderate to severe AI, aortic disease, and severe peripheral vascular disease. Common indications for IABP counterpulsation include cardiogenic shock, failure to wean from CPB, Myocardial infarction, augmentation during percutaneous coronary interventions, and bridge to transplantation or VAD placement.
The glottic closure reflex is primarily initiated by stimulation of the internal branch of the superior laryngeal nerve, which provides sensory innervation to the supraglottic region of the hypopharynx. The recurrent laryngeal nerves then mediate vocal cord adduction. Both the superior and recurrent laryngeal nerves are branches of the vagus nerve (CN X).
Continuous epidural analgesia (CEI) is superior to patient-controlled epidural analgesia (PCEA) for the control of postoperative pain. Epidural analgesia is superior to systemic patient-controlled analgesia (PCA), which provides better pain control than traditional nursing administered systemic opioids
Lithium potentiates nondepolarizing neuromuscular-blocking drugs (NMBDs) via 2 different mechanisms. First, it activates potassium channels in prejunctional neurons, which interferes with transmission of an action potential to the nerve terminal. Second, it activates potassium channels on the postsynaptic myocytes, which inhibits muscle contraction.
Milrinone is a selective phosphodiesterase (PDE) III inhibitor that is often used in the treatment of severe congestive heart failure. Inhibiting PDE III impairs cAMP breakdown, therefore allowing increased intracellular levels of cAMP. This leads to an increased influx of intracellular calcium stores, thereby enhancing cardiac ionotropy.
Milrinone increases cAMP levels & smooth muscle vasodilation and decreased peripheral vascular resistance. Milrinone is also a potent pulmonary vasodilator leading to its use in the treatment of pulmonary hypertension.
common side effects of milrinone include arrhythmias, hypotension, and thrombocytopenia
Fractional excretion of sodium is a useful test for patients presenting with oliguria to help differentiate the etiology. Fractional excretion of urea should be used for patients who are also taking diuretic medications
Microlaryngeal tracheal tubes are designed with a smaller internal diameter but with a length and cuff size appropriate for the adult airway.
Changes in the arterial waveform in the periphery compared to the aorta include a steeper systolic upstroke, higher systolic peak, later dicrotic notch, lower end-diastolic nadir, and wider pulse pressure.
features designed to prevent against delivery of a hypoxic gas mixture include the pressure fail-safe valve, the flow proportioning system, and the way in which the flowmeters are configured
The amount of lidocaine that can be safely infused during tumescent anesthesia procedures is approximately 35 to 55 mg/kg.
Tumescent liposuction involves the injection of very large volumes of saline solutions, which can lead to volume overload and pulmonary edema.
Large volumes of lidocaine may be safely injected because the majority of lidocaine is aspirated during the procedure.
In general, the needle of a peripheral nerve stimulator is close enough to the nerve for blockade when a motor response is elicited between 0.3 mA and 0.5 mA of current.
Nerve stimulation is less effective in patients with diabetes and becomes unreliable after the injection of saline or local anesthetic. The incidence of nerve injuries is the same with nerve stimulation and ultrasound guidance techniques for peripheral nerve blocks.
In patients with congenital heart disease, propofol is generally avoided due to its myocardial depressive and systemic vasodilatory properties. Ketamine, etomidate are acceptable induction agents, although their side effects and limitations should be considered.
Coronary perfusion pressure: Coronary perfusion pressure (CPP) is represented as the difference between the aortic diastolic pressure (AoDP) and the left ventricular end-diastolic pressure (LVEDP). CPP = AoDP - LVEDP
The incidence of diabetes insipidus in organ donation patients after brain stem death is 65%
A reduction in the production of anti-diuretic hormone (ADH) causes diabetes insipidus.
After brain death, the anterior and posterior pituitary fail causing a dramatic fall in homeostasis.
In type I diabetics, insulin must be continued. However, a decrease in dose should be made for the night before and morning of surgery.
Most experts agree that a HbA1c as close to normal (6% to 8%) is recommended before elective surgery can proceed.
the pulmonic valve is the farthest from the transesophageal echocardiography (TEE) probe, making visualization difficult. In addition, TTE has greater flexibility in probe positioning and angulation compared to TEE. Therefore, the pulmonic valve may be better visualized with transthoracic echocardiography (TTE).
Although not routinely necessary, the anticoagulant effects of enoxaparin can be monitored by measuring factor Xa activity. Unfractionated heparin is monitored using either aPTT or ACT, depending on the clinical situation.
Endotracheal tubes are vulnerable to ignition when exposed to a CO2 laser. Polyvinyl chloride (PVC) is the most likely endotracheal tube material to combust when exposed to a laser
Silicone was the most combustion-resistant
The current recommendation for failed prophylaxis of postoperative nausea and vomiting is to use a medication from a class different that used for prophylaxis.
Conditions and Comorbidities That Increase Risk of Complications During MAC
Age >70 years
Severe anxiety disorders
ASA physical status of III or IV
Chronic liver disease (MELD score >10)
Chronic renal failure
Morbid obesity (BMI ≥40 kg/m2)
Obstructive sleep apnea
Pulmonary hypertension
Severe cardiovascular disease (coronary artery disease)
Complications after thyroidectomy commonly include hypoparathyroidism and temporary hoarseness. More rare complications include recurrent laryngeal nerve damage, tracheal compression secondary to tracheomalacia or hematoma formation. Extremely rare complications include Horner syndrome and injury to the trachea or esophagus.
In carcinoid syndrome, a neuroendocrine tumor secretes vasoactive substances such as serotonin, which stimulates fibroblast growth and fibrogenesis, resulting in cardiac valvular fibrosis in ~60% of patients. This primarily affects right-sided heart valves because the vasoactive substances are inactivated by the lungs. Tricuspid regurgitation accounts for ~90% of valvular lesions in carcinoid syndrome, but tricuspid stenosis, pulmonic regurgitation, and pulmonic stenosis can also occur in carcinoid syndrome
Burst suppression is the desired EEG pattern when using an infusion of pentobarbital (also applies to infusions of propofol or etomidate). It allows a maximal reduction in CMRO2 while indicating that regular EEG activity will return predictably following cessation of the infusion.
Beta waves= high freq, low amp, arousal
Delta waves= low freq, high amp, deep sedation
Indications for EEG monitoring during anesthesia are carotid endarterectomy, cardiopulmonary bypass procedures, and cerebrovascular surgery such as aneurysm surgery requiring temporary clipping or vascular bypass procedures.
Common indications in the intensive care unit are barbiturate coma for patients with traumatic brain injury and when subclinical seizures are suspected.
Multiple stress situations lead to increased release of AVP, also known as antidiuretic hormone (ADH).
ADH causes vasoconstriction via V1A receptors, water retention via V2 receptors, and potentiates the effect of corticotropin-releasing hormone (CRH) on pituitary ACTH
In septic shock, after an initial increase the ADH concentrations decrease to extremely low levels.
Lower Extremity Dermatomes Anatomical Landmarks the Dermatome Identifies
L3 Medial knee
L4 Anterior knee, Medial malleolus
L5 Dorsal foot, 2nd toe, 3rd toe
S1 Lateral malleolus Fifth toe
Perioperative pediatric fluid management for healthy children involves a 20- to 40-mL/kg bolus of an isotonic salt solution for two to four hours.
Shoulder dystocia is a fetal life-threatening emergency. Nitroglycerin provides fast-onset uterine relaxation to assist with obstetric manipulation and delivery.
Adequate uterine relaxation is critical during an EXIT procedure in order to maintain uteroplacental circulation and fetal gas exchange. This can be accomplished with high-dose volatile anesthetics and/or nitroglycerin.
All volatile anesthetics undergo degradation by absorbents that contain sodium and/or potassium hydroxides. Sevoflurane will degrade to form compound A, desflurane (and to a lesser extent isoflurane) will degrade to form carbon monoxide
Baralyme is the most likely to cause carbon monoxide (CO) formation with desflurane. Soda lime can also form CO
Lorazepam formulations contain propylene glycol to enhance plasma solubility. With prolonged infusions, propylene glycol toxicity can occur. Propylene glycol is metabolized to lactic acid in the liver, and its toxidrome is heralded by lactic acidosis, delirium with hallucinations
Recurarization, or reparalyzing, occurs when neostigmine’s duration of action is shorter than that of the NMBA used. Recurarization can be prevented by ensuring that the patient has an appropriate train-of-four (TOF) count prior to administration of neostigmine and by avoiding the use of a long-acting NMBA such as pancuronium. Neostigmine is metabolized by the liver and excreted by the kidneys; thus, decreased renal function will prolong the effects of neostigmine, which helps outlast the effect of NMBAs that are excreted renally, such as rocuronium and vecuronium
Amniotic fluid embolism (AFE) closely resembles a severe systemic inflammatory response resulting in hypotension, noncardiogenic pulmonary edema, and coagulopathy. The clinical presentation is in two phases, (1) severe pulmonary hypertension with right ventricular dysfunction and (2) left ventricular failure and pulmonary edema. Treatment of AFE is primarily resuscitative and includes endotracheal intubation, fluids, vasopressors/inotropes, and blood products.
Deep brain stimulation (DBS) is an established treatment for movement disorders; the subthalamic nucleus (STN) and the internal globus pallidus (GPi) are the most common targets for DBS treatment in Parkinson disease.
Sevoflurane causes the most emergence agitation/delirium.
Isoflurane and halothane cause less emergence delirium than desflurane
Anesthesia dolorosa is pain in an area that lacks sensation, often involving the face. Anesthesia dolorosa is a feared complication of neurolytic blocks for the treatment of trigeminal neuralgia
Ficks equation
VO2= Q(CaO2-CvO2)
Q= cardiac output
VO2=oxygen consumption
CaO2= arterial oxygen content
CvO2= venous oxygen content
The shunt fraction can be easily calculated by using the simplified shunt equation Qs/Qt = (1− SaO2) / (1 − SvO2), where Qs is pulmonary physiologic shunt, Qt is cardiac output, SaO2 is arterial oxygen saturation, and SvO2 is venous oxygen saturation.
Propofol increases hepatic blood flow
Pediatric patients can potentially develop a venous air embolism (VAE) during craniotomies in both the supine and prone position because their relatively large heads sit above the level of the heart in both positions. Children are also more likely to become symptomatic from a VAE because their smaller circulatory volume and heart size are more easily overwhelmed by smaller volumes of entrained air.
Norepinephrine is significantly metabolized by pulmonary endothelial cells as are serotonin, bradykinin, and angiotensin-1.
All personnel and items must be screened prior to entry of Zone III, with non-MRI compatible items such as an infusion pump not allowed closer than Zone III. Zone IV is the MR scanner room and is only accessible via Zone III. Only MRI safe items should be brought into Zone IV.
The muscles of the larynx are innervated by the recurrent laryngeal nerve, with the exception of the cricothyroid muscle, which is innervated by the external (motor) laryngeal nerve, a branch of the superior laryngeal nerve.
The posterior cricoarytenoid muscles abduct the vocal cords, whereas the lateral crico-arytenoid muscles are the principal adductors.
Bronchopulmonary dysplasia is a sequela of respiratory distress syndrome & often seen in preterm infants less than 32 wks gestation. Bronchopulmonary dysplasia is a chronic disease of the airways and lung parenchyma. Exogenous
surfactant & bronchodilators
decrease the incidence and severity
Nasogastric tubes and larger bore tubes are associated with increased risk of otitis media and sinusitis when used for a long time. Placing a gastric tube beyond the pyloric junction has not been shown to reduce the risk of pulmonary aspiration
The mechanism of action for the termination of blockade by succinylcholine occurs via diffusion away from the neuromuscular junction.
Pseudocholinesterase is another name for butyrylcholinesterase
Initial treatment for hypercalcemia should be aimed at volume correction with normal saline or plasmalyte. With restoration of the patient’s fluid deficit furosemide can be used to decrease calcium levels.
Methylene blue is also an inhibitor of the enzyme monoamine-oxidase (MAO), mostly MAO-A, and as such it may precipitate serotonin syndrome if coadministered with selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), or other MAO inhibitors.
Methylene blue is a useful therapy for catecholamine-resistant vasoplegic shock, which may occur during the reperfusion of a transplanted liver, or after cardiopulmonary bypass, due to its inhibitory effects on nitric oxide leading to increase in SVR
Immature extrajunctional acetylcholine receptors contain a γ subunit rather than the ε of the mature form. The other four subunits: two α1 subunits one β1, and one δ are the same.
Immature subunits are present in the fetal state and states of immobilization, burns, upper or lower motor neuron injury, and sepsis and are associated with increased efflux of potassium and hyperkalemia following activation by depolarizing drugs such as succinylcholine.
Inferior medial pontine syndrome is typically caused by unilateral infarction of the inferior pons, resulting in contralateral hemiparesis, internuclear ophthalmoplegia (impaired adduction of the ipsilateral eye with nystagmus of the abducting eye), and ipsilateral facial muscle weakness. Structures affected in the infarcted regions include cranial nerves VI and VII, the corticospinal tract, and the medial longitudinal fasciculus.
Lateral pontine syndrome results from infarction to the lateral pons, mainly due to occlusion of the anterior inferior cerebellar artery or perforating branches of the basilar artery. Patients will present with contralateral loss of pain and temperature. Ipsilateral symptoms include facial muscle weakness, decreased salivation and lacrimation, loss of taste from the anterior two-thirds of the tongue, Horner syndrome, limb and gait ataxia, loss of pain and temperature sensation in the face, vertigo, nystagmus, and hearing loss.
In selected high-risk patients and as part of a multimodal blood conservation plan, sequestration of platelets through high-yield plasmapheresis creating platelet-rich plasma prior to bypass and infusion of these platelets after bypass can help conserve blood during adult cardiac surgery by protecting these platelets from damage that would otherwise occur during bypass
Long QT syndrome (LQTS) is characterized by inherited or acquired prolonged QT interval viewed on electrocardiography and can lead to torsade de pointes and ventricular fibrillation. Patients with congenital LQTS should be treated with nonselective ß-blockers such as nadolol and propranolol and/or have an implanted cardiac defibrillator.
Omphalocele has a high incidence of co-occurring congenital heart disease (20%-35%); ventricular septal defects or atrial septal defects are the most common cardiac anomalies.
Osteogenesis imperfecta is associated with brittle bones that are vulnerable to fracture, joint laxity, joint subluxation, blue-tinted sclera, hearing loss, restrictive lung physiology, cardiovascular anomalies, and there is increased risk of bleeding due to collagen and platelet dysfunction.
These patients can be difficult to intubate and backup airway equipment should always be readily available
Beat to beat variability of 5-25 BPM from baseline is part of a normal fetal heart rate. Fetal early and variable decelerations are normal. Late decelerations (nadir >30 seconds after the onset of uterine contraction) are concerning for uteroplacental insufficiency and fetal distress.
Sinusoidal FHR pattern is indicative of severe fetal anemia and associated with high rates of fetal morbidity and mortality
Respiratory alkalosis, such as from hyperventilation, can cause electrolyte abnormalities, such as hypocalcemia, hypokalemia, and hypophosphatemia. Hypocalcemia is caused by increased calcium binding to negatively charged plasma proteins as the proteins release hydrogen ions to restore physiologic pH
Lorazepam premedication can prolong extubation times and does not improve patient satisfaction. Clonidine decreases MAC but can increase the risk of hypotension and bradycardia. Fentanyl premedication may actually sensitize patients to pain postoperatively. Scopolamine is more likely than atropine to cause central anticholinergic syndrome.
Respiratory depression as a result of over-sedation is the most common mechanism of injury during monitored anesthesia cases.
The shunt fraction (Qs/Qt) can be calculated by using the venous admixture equation Qs/Qt = (CcO2 − CaO2) / (CcO2 − CvO2), where CcO2 is the oxygen content in pulmonary capillary blood, CaO2 is the oxygen content in arterial blood, and CvO2 is the oxygen content in mixed venous blood. The shunt fraction is the percentage of total cardiac output (Qt) that bypasses oxygenation from the lungs due to a right-to-left shunt.
Etomidate is an induction agent that increases the seizure duration of electroconvulsive therapy (ECT). Etomidate (0.15-0.3 mg/kg)
The physiological response to ECT is an initial parasympathetic response that includes transient bradycardia, followed by a sympathetic response including tachycardia and hypertension.
Enteral nutrition should be initiated within 48 hours of a critically ill patient’s admission without contraindications to enteral feeding. Enteral nutritional support should not be initiated in patients with intractable vomiting and diarrhea, bowel obstruction, gastrointestinal ischemia or bleeding, hemodynamic instability, severe and protracted ileus, or high-output fistulas
The early initiation of enteral nutrition should be avoided in critically ill patients who are hemodynamically unstable and have not had their intravascular volume fully resuscitated because such patients may be predisposed to bowel ischemia
Two types of postoperative liver injuries have been reported to be associated with halogenated anesthetic administration. The first type is a mild injury characterized by nausea, lethargy, and fever. The second type, mediated by the patient’s immune system, is severe acute hepatitis with histological findings of widespread hepatic necrosis. This is rare. Isoflurane & halothane have similar mechanisms
Desflurane, as a consequence of trifluoroacetic acid (TFA) reactive intermediates, has been implicated in the formation of dangerous immunogenic compounds.
Sevoflurane metabolism has not resulted in the formation of TFA intermediates and the potential for hepatic toxicity is low. Instead, sevoflurane metabolism yields a compound hexafluoroisopropanol (HFIP), which does not accumulate and rapidly undergoes phase II biotransformation.
Abdominal compartment syndrome can lead to multiorgan dysfunction within and beyond the abdomen because hypertension in the abdominal compartment produces widespread physiological consequences. Important cardiovascular complications include an increase in central venous pressure and pulmonary capillary wedge pressure, ultimately resulting in a decrease in cardiac output.
Pulmonary manifestations could include ventilation/perfusion mismatching, atelectasis, hypoxia, hypercarbia, increase in plateau and peak pressures, and an increased work of breathing. Urgent identification of this syndrome is imperative, and abdominal compartment syndrome can be diagnosed by measuring intra-abdominal pressures >20 mmHg. After abdominal compartment syndrome has been diagnosed, management includes immediate paracentesis and opening the abdomen for urgent decompression.
Down syndrome patients frequently have cardiovascular defects. The most common of these is endocardial cushion defects.
Down syndrome is associated with atlantoaxial instability, hypotonia, and gastrointestinal, genitourinary, respiratory, vascular, and metabolic defects
Down syndrome is associated with decreased muscle relaxant requirement
In a pneumonectomy, adequate vascular access should be obtained with an arterial line, central venous catheter, and another large-bore venous catheter to permit close monitoring and to allow for targeted resuscitation with vasoactive agents and judicious fluid therapy as needed.
Other best practices include restrictive fluid administration, and ventilation with low tidal volumes <5 ml/kg and low pressures.
Lower extremity complex regional pain syndrome can be treated with serial lumbar plexus sympathetic blocks, which can be complicated by ejaculatory problems in men, particularly when bilateral blocks are performed. Back pain from needle trauma is common after the procedure and usually resolves in a few days; it may be treated with heat, ice, and rest.
For lumbar plexus sympathetic blocks, a Blockade of the genitofemoral nerve or lumbar plexus within the psoas muscle may result in numbness in the groin, thigh, or quadriceps and cause prolonged neuralgia and burning pain, especially in the groin, if a neurolytic agent is injected. Other adverse effects include renal or urethral trauma, hematoma, infection, abscess, intravascular injection, perforation of a disk, diskitis, somatic nerve injury, and chronic back pain
Difficult airway algoritim
Anesthetic partial pressures most quickly equilibrate between alveoli and the VRG and most slowly equilibrate between alveoli and fat. This difference is primarily due to differences in the fraction of cardiac output received and is represented by the k.
Increased cardiac output increases the k for all three compartments, allowing faster equilibration between compartments. A result of this is the persistent draining of volatile anesthetics from the alveoli compartment to the large fat compartment, slowing the rise in alveoli partial pressure, which leads to a slowed induction speed and FA:FI rise.
In the initial distribution phase immediately after an inhaled anesthetic is discontinued, the anesthetic agent diffuses from the alveoli and VRG to the muscle and fat groups (in addition to being exhaled). In the terminal phase, long after an inhaled anesthetic has been discontinued, the anesthetic agent diffuses from the fat group to the alveoli group, which then gets exhaled.
Chemical stimuli that mediate the activation of peripheral nociceptors include prostaglandins, substance P, calcitonin gene-related peptide, glutamate, bradykinin, protons, adenosine triphosphate, and proinflammatory cytokines, whereas spinal cord inhibition is mediated by opioids, γ-aminobutyric acid, and/or glycine.
Doxapram, a pharmacologic respiratory stimulant, may be beneficial in select cases of hypercapnic respiratory failure due to exacerbations of chronic obstructive pulmonary disease, particularly when supplemental oxygen is administered. However, its approved indications are otherwise restricted to the temporary amelioration of drug-induced and postanesthetic respiratory depression, and alternative therapies are often preferred
Intraoperative blood glucose levels should be <180 mg/dL.
Closing capacity (CC), defined as the volume at which small airways begin to collapse during exhalation, increases with age.
In the elderly, Total respiratory system and chest wall compliance decrease while lung compliance increases. Lung volume changes include a decrease in alveolar surface area, diffusion capacity, forced expiratory volume in the first second, forced vital capacity, and vital capacity
In the elderly theres an increase in FRC, closing capacity, dead space, and residual volume. Total lung capacity is relatively unchanged in the elderly.
Hypoxic pulmonary vasoconstriction is blunted in the elderly (> 65 years) population, and this can cause difficulty with one-lung ventilation.
Warming mattresses are a good option to prevent hypothermia since these gel-filled mattresses do not need a power supply once activated and are ideal for transport.
Forced-air convection warmers are the most common due to their effectiveness at preventing and treating hypothermia, cost-effectiveness, disposable component, and ease of use.
water warming garments (WWGs)
These garments are based on the technology used by astronauts’ space suits. The patient is wrapped in a garment that covers well while allowing surgical exposure. Warm water is then circulated next to the patient’s skin and the temperature is adjusted via feedback mechanisms
Radiant heaters
These heaters are used during the induction of anesthesia in vulnerable patients such as neonates and premature infants
In order to avoid excessive heating, a built-in measuring tape can be used to mark a safe distance from the patient
Another disadvantage of these heaters is inadvertent warming of personnel between the patient and the heater
Reflective blankets
These are aluminized plastic foils designed to contain 80% of body heat
Limited data in the pediatric population exist, however, some reports indicate that at least 60% of the body surface area must be covered in order to maintain normothermia
These devices are hence more useful in the out-of-hospital setting where other alternatives may be bulky or require electrical outlets
It is important to reduce heat loss during anesthesia, which most commonly occurs via radiation (heat lost due to the temperature gradient of the patient and the surrounding environment) and convection (heat loss via currents of air moving across exposed areas of the patient). Radiation losses can be prevented by warming the operating room. This is particularly important for newborns.
Convection heat loss is reduced by keeping the patient covered and shielded from the constant flow of air in the operating room environment. Evaporative losses from the respiratory tract and any exposed mucous membranes as well as moist skin surfaces (surgical preparation), however, these tend to be minimally effective for the most part. Conductive heat loss is due to direct contact with objects and this is less common during surgery.
For Cleft palate and lip repairs, Oral and nasal airways should be avoided in cases of postoperative obstruction; instead positioning changes should be attempted (e.g., prone positioning). Patients with isolated cleft palate without cleft lip are more likely to have an associated syndrome.
Causes of Nicotinic AChR Upregulation
- Nerve Injuries
o Stroke
o Spinal cord injury
- Burns (24 hours up to 1-2 years after burn injury)
- Prolonged immobility (risk greatest after 16 days)
- Prolonged exposure to neuromuscular blockers
- Myopathies
o Duchenne muscular dystrophy
- Denervation Disorders
o Multiple sclerosis
o Guillain-Barré syndrome
o Amyotrophic lateral sclerosis
Alterations of medication dosing in morbidly obese patients must take into account the physiologic changes that accompany the disease. Most important are an increase in the fat mass, lean body weight, extracellular fluid volume, and cardiac output.
Fatty acids from triglycerides are converted to acetyl-coenzyme A prior to metabolism into ATP. The respiratory quotient of lipid metabolism is 0.7.
Parathyroid hormone inhibits renal bicarbonate reabsorption. Increased renal bicarbonate loss leads to a metabolic acidosis. Furthermore, PTH has been shown to inhibit the sodium chloride cotransporter in the distal convoluted tubule of the nephron leading to hyperchloremia.
Intraoperative electroencephalogram (EEG) monitoring is used to monitor cerebral oxygenation. The main frequencies captured during intraoperative EEG are between 1 to 30 Hz.
BIS is considered simplified and processed EEG.
Delta Waves: 0.5Hz - 4 Hz = surgically anesthetized = BIS of 40-65
In the neonate, the spinal cord (conus medullaris) ends at L3 (L1 in adults), and the dural sac ends at S3-4 (S2-3 in adults)
Placental abruption typically presents with painful vaginal bleeding, uterine tenderness, and nonreassuring fetal heart rate patterns. Risk factors include hypertension, cocaine and/or tobacco abuse, trauma, and advanced maternal age and parity
A SAH is defined by bleeding into the subarachnoid space, which makes about 5% of all strokes. The most common cause of a SAH is a ruptured cerebral aneurysm. Risk factors for aneurysms include hypertension, polycystic kidney disease, fibromuscular dysplasia, and cerebral aneurysm in a first-degree relative. Symptoms of a SAH can be wide-ranging.
One way to grade SAH is to use the Hunt-Hess scale. This scale uses clinical features to approximate prognosis and mortality.
Major independent preoperative risk factors for postoperative acute kidney injury following noncardiac surgery in patients with normal renal function include age ≥59, body mass index (BMI) ≥32, chronic liver disease, chronic obstructive pulmonary disease requiring chronic bronchodilator use, peripheral vascular occlusive disease, high-risk surgery, and emergency surgery.
The ganglion impar block is performed for cancer-related pain originating in the perineal area, typically caused by malignancies of the vulva, rectum, and anus. Ganglion impar can also be used to treat intractable sacral and coccygeal pain
The superior hypogastric block is performed for pain from the pelvic area secondary to cancer and chronic pelvic conditions (endometriosis) causing pain. The superior hypogastric plexus can be found in the retroperitoneum anterior to the L5-S1 vertebral body junction, with the common and internal iliac arteries/veins lateral to the plexus.
The superior hypogastric plexus innervates the descending and sigmoid colon, proximal rectum, uterus, ovaries, testes, seminal vesicles, prostate, and urinary bladder.
Ammonia is the primary byproduct of protein metabolism and must be converted to urea to be excreted. This occurs primarily in the liver, and therefore, shunting blood away from the liver is likely to worsen hyperammonemia by reducing the hepatic conversion of ammonia to urea. Therefore, hepatic encephalopathy is a relative contraindication to a transjugular intrahepatic portosystemic shunt procedure
Patients with dental Implants are safe for MRI
acute Tubular necrosis
Destruction of the tubular and epithelial cells in ATN impairs the kidney’s ability to concentrate the urine and retain sodium. As a result, the urine is typically diluted with a high Na content. Lab findings suggestive of ATN include: muddy brown casts, FENa > 1%, Uosm < 350 mOsm/kg, UNa > 40 mEq , low specific gravity, and BUN:Cr 10:1 – 15:1.
Loop 1- fixed
Loop 2 - extrathoracic
Loop 3 - intrathoracic
Loop 4- obstructive pattern, such as COPD
A fixed airway obstruction, whether intrathoracic or extrathoracic, will cause a reduction in flow in both the inspiratory and expiratory limbs of the flow-volume loop. A variable intrathoracic obstruction has relatively normal inspiration pattern, but reduced flow on expiration. A variable extrathoracic obstruction has a relatively normal expiration pattern, but reduced flow on inspiration.
Diagnostic blocks using local anesthetic help identify if a neurolytic block will provide benefit to a patient and are often required prior to insurance coverage of a neurolytic block.
The duration of benefit is expected to be hours to days for local anesthetics and days to months for local anesthetics with steroids and a 30-80% relief of pain (depending on the source and insurance provider) is required for the block to be considered successful.
To establish a medical malpractice lawsuit, 4 elements must be proven:
Causation
Duty to the patient
Negligence or breach of duty
Damages
Causation asks whether the act of care or omission of care caused the poor outcome. Duty to the patient refers to the provider’s responsibility to the patient to provide care. Negligence or breach of duty means that the standard of care in the community was not met. The alleged damages, which can be physical, psychological, or financial, must be foreseeable by the average and reasonably minded practitione
T3 hormone decreases during stress or s
Plasma heparin concentration, when it is used alone, may greatly overestimate anticoagulation during cardiopulmonary bypass due to varying patient heparin sensitivity. Plasma heparin concentration may be a useful adjunct to the most commonly used assay, activated clotting time (ACT), when conditions such as hypothermia or hemodilution result in less accurate ACT testing.
For most intravenously administered drugs, combining drugs with different mechanisms of action causes a synergistic effect. The exception to this rule is ketamine, which may cause additive, infra-additive, or synergistic effects depending on the drug combination.
side effects of the fospropofol are paresthesias (typically perianal or genital) and genital pruritus. Due to its slower onset of action, the incidences of respiratory depression, apnea, and hypotension are lower with fospropofol compared to propofol
Isopropofol is metabolized to propofol in the liver.
Acute use of phenytoin classically potentiates the response to rocuronium, while chronic use of phenytoin shortens the duration of rocuronium
Steroids will antagonize the effects of rocuronium & nondepolarizing neuromuscular blocking agents
Pulmonary vascular resistance equation
PAOP= pulmonary artery occlusion pressure
systemic vascular resistance equation
central venous pressure is commonly substituted for Right Atrial Pressure
Transcranial Doppler is used during surgery for CEA procedures to measure blood flow velocities, detect embolization to the brain, identify shunt function or malfunction, and detect asymptomatic carotid artery occlusion and/or hyperperfusion syndrome. The technique involves assessment of the middle cerebral artery.
Flow velocities of the middle cerebral artery are typically evaluated by TCD via the temporal isonation window. Isonation windows are areas of the skull where the bone is less dense, and thus more amenable to ultrasound penetration.
Flexible bronchoscopy is appropriate during certain procedures such as whole lung lavage, transbronchial biopsies, and the evaluation of areas that the rigid bronchoscope cannot reach such as small airways. Rigid bronchoscopy is preferred for airway foreign body removal, laser procedures, and assessment of the posterior larynx.
EEG wave from with different anesthetic drugs
Correct placement of a left-sided double-lumen tube should reliably produce only left-sided breath sounds while ventilating only the bronchial lumen and produce only right-sided breath sounds while ventilating the tracheal lumen (assuming both cuffs are inflated and the opposite lumen is clamped). If both lumens are unclamped and both cuffs are inflated, bilateral breath sounds should be auscultated
Pic summary of cardiac disorders
Evidence of adequate gas exchange as demonstrated by an PaO2 > 150 to 200 mmHg while on minimal ventilator settings (fraction of inspired oxygen [FiO2] ≤ 50% with PEEP ≤ 8 cm H2O) is predictive of a successful wean
Nitrous oxide does not cause suppression of respiratory drive in spontaneously breathing patients. Nitrous oxide has significant analgesic effects.
Antibiotics, such as aminoglycosides, clindamycin, polymyxins, and tetracyclines can potentiate the neuromuscular blockade by nondepolarizing neuromuscular blocking agents.
Type I or α error = incorrectly rejecting the null hypothesis (false positive)
Type II or β error = incorrectly accepting the null hypothesis (false negative)
The saphenous nerve is a terminal branch of the femoral nerve and is blocked in an ankle block. It provides sensory innervation to the medial aspect of the leg, ankle, and foot. The saphenous nerve can be blocked 2-3 cm proximal and 1-2 cm anterior to the medial malleolus.
The sural nerve is purely sensory and forms from branches of the common peroneal nerve and tibial nerve. It provides sensation to the foot’s dorsolateral aspect, including the fourth and fifth toes. The sural nerve lies 1-2 cm distal to the tip of the lateral malleolus within the subcutaneous tissues.
Antiretroviral therapy (HAART) can significantly alter the metabolism and clearance of many anesthetic drugs, including benzodiazepines and opioids.
Radiant infrared heat lamps provide heat newborns who are otherwise unable to properly regulate their body temperature. The advantage of this heating modality compared to a convection incubator is the ease of access to the patient while they are under heat lamps compared to shut within an incubator. There is a very real risk of thermal burns when using infrared heat lamps, however, and skin temperature monitoring specifically is essential in order to monitor for excessive skin temperatures.
The main peripheral chemoreceptor is the carotid body located at the bifurcation of the common carotid artery. It detects changes in the PaO2, PaCO2, and pH, with PaO2 being the most significant driver. When PaO2 is < 60 mmHg, signals are sent via the glossopharyngeal nerve to the medulla to increase respiration by tidal volume and respiratory rate, increasing minute ventilation
Bilateral carotid endarterectomy carries a relatively high complication rate for bilateral carotid body denervation. One complication of bilateral endarterectomy is damage to the carotid body, in which the glossopharyngeal nerve carries afferent signals. Bilateral damage can result in a complete loss of ventilatory response to acute hypoxia.
Patients with myotonic dystrophy have an increased risk of pulmonary aspiration due to gastric atony and delayed emptying, intestinal hypomotility, and pharyngeal muscle weakness.
Lingual nerve, recurrent laryngeal nerve, and hypoglossal nerve injuries have been reported after laryngeal mask airway use. Risk factors include overinflation of a small-fitting cuff, prolonged operative time (>2-4 hours), lidocaine lubrication, difficult insertion, use of nitrous oxide, and cervical joint disease.
Adenine maintains a pool of ATP preventing the membrane from disintegrating by powering enzymatic reactions that function as antioxidants and keeping the Na+/K+-ATPase pump functioning properly.
Citrate is used to chelate calcium in the solution, preventing coagulation from occurring; phosphate acts as a buffer to maintain the pH of the storage solution
The respiratory quotient (RQ) is the volume of CO2 released over the volume of oxygen consumed during respiration or when a substance is metabolized.
RQ = VCO2/VO2
The RQ is 0.7 for fats, 0.8 for proteins, and 1.0 for carbohydrates.
When it is administered at a dose of 0.5 minimum alveolar concentration (MAC), Cerebral metabolic rate suppression-induced reduction in CBF predominates, and CBF decreases. At 1 MAC, CBF remains unchanged. At concentrations above 1 MAC, vasodilatory activity predominates, and CBF significantly increases.
Vasodilation with increasing doses of volatile agents leads to an attenuation of cerebral autoregulation. With high concentrations (>1 MAC) autoregulation is significantly blunted and cerebral perfusion becomes pressure passive. The order of vasodilating potency of volatile agents is, from greatest to least, halothane > enflurane > desflurane = isoflurane > sevoflurane.
Sevoflurane has the lowest vapor pressure at 157 mm Hg, followed by isoflurane at 238 mm Hg and desflurane at 669 mm Hg.
The boiling point of desflurane at 24ºC is near room temperature (20ºC) and, thus, requires a closed storage container and a pressurized and heated vaporizer to prevent boiling and unpredictable vapor concentrations.
Characteristic anatomic features of the infant airway, relative to adults, include: a proportionally larger tongue, more cephalad larynx, short omega-shaped epiglottis, angled vocal cords, as well as a relatively larger head.
Echothiophate inhibits pseudocholinesterase, thereby potentiating the effects of succinylcholine.
Echothiophate is an anticholinesterase used to treat refractory glaucoma by causing miosis.
ASA PS 1 - A patient without a history of any medical condition
ASA PS 2 - A patient with at least one controlled medical condition
ASA PS 3 - A patient with at least one severe systemic disease
ASA PS 4 - A patient with a severe systemic end stage disease of at least one organ system that is life threatening with or without surgery
ASA PS 5 - A patient who is moribund with a low chance of survival even with the surgery
ASA PS 6 - A declared brain-dead patient for organ donation
Tricyclic antidepressants (TCA) used for pain control. TCA mechanisms for its analgesic effects, including an enhancement of serotonin, antagonism of central α-receptors, the release of endogenous opioids, blockade of the NMDA complex, inhibition of the uptake of adenosine, and blockade of sodium channels. The side effect profile of TCAs limits their use in clinical practice.
For a TAP block, The Triangle of Petit is outlined by the iliac crest inferiorly, the latissimus dorsi muscle posteriorly, and the external oblique muscle anteriorly.
The most common clinical manifestation of hyperparathyroidism is nephrolithiasis, which occurs in 60-70% of patients
Endotracheal intubation is generally contraindicated in the setting of laryngeal cartilage disruption or laryngotracheal separation. Awake surgical tracheostomy is the preferred method for airway control
The laser wavelength can also be modified to target specific tissues. When the laser vaporizes the tissues that contain water and interstitial proteins, the laser is termed ablative, whereas when the laser targets pigment proteins (eg, hemoglobin), it does not cause tissue destruction directly and is termed nonablative.
Ablative lasers include carbon dioxide (CO2) and erbium-doped yttrium-aluminum-garnet (Er:YAG) lasers, and non-ablative lasers include pulsed dye (PDL), potassium-titanyl-phosphate (KTP), and neodymium-doped yttrium-aluminum-garnet (Nd:YAG).
Pregnant patients are at an increased risk for the development of pruritus following intrathecal or epidural opioid administration. Lipophilic opioids have a shorter duration of pruritus, while hydrophilic opioids have a longer duration and more involvement of the head and neck. Coadministration of neuraxial local anesthetic with neuraxial opioids can decrease the incidence of pruritus compared to that with neuraxial opioids alone.
placenta previa and a history of multiple previous cesarean sections put an obstetric patient at a dramatically increased risk for placenta accreta and peripartum hemorrhage.
Mannitol is a sugar alcohol that acts as an osmotic diuretic as it is freely filtered at the glomerulus with poor reuptake back into the vasculature. Hyperglycemia may also act as an osmotic diuretic when glucose levels rise beyond the point of maximum transport through the glomerulus.
Tizanidine is often prescribed for musculoskeletal pain, but its mechanism of action is via alpha-2 receptor agonism.
The glycocalyx, an endothelial structure that plays a pivotal role in vascular permeability and fluid physiology, is a structure sensitive to damage by hypervolemia, ischemic-reperfusion injury, inflammation, oxidative stress, and massive hemorrhage.
In addition to functioning as a passive barrier, the glycocalyx regulates vascular permeability as a mechanotransducer of shear stress.
Transpulmonary pressures are highest in patients with restrictive lung disease due to a reduction in lung compliance.
Potassium-aggravated myotonias will present with a pure myotonia (muscle stiffness w/ no weakness), aggravated by potassium ingestion and variable responses to cold. They are inherited autosomal dominant. Don’t use succinycholine
Blood in the brain drains by the following path: superior sagittal sinus—>inferior sagittal sinus —> straight sinus → transverse sinus → sigmoid sinus → internal jugular vein.
Hypoxic-ischemic encephalopathy is common in victims who survive a drowning event regardless of the source of water in which the patient drowned. This injury can result in cerebral edema and potentially dangerously elevated intracranial pressures
Pregnancy is a state of hypercoagulability with a most notable increase in the levels of fibrinogen.
Factors that increase include I (fibrinogen), VII, VIII, IX, X, XII, and von Willebrand factor which peak at the time of parturition.
In Pregnancy, Factors that decrease include XI, XIII, antithrombin III, and tPa. Also, resistance to activated protein C occurs as well as a decline in the level of protein S.
Isovolumetric relaxation: this phase begins with the closure of the aortic valve and continues till the opening of the mitral valve. During this time, the left ventricle is relaxing, however there is no change in the ventricular volume (isovolumetric).
Early rapid filling: this phase begins with the opening of the mitral valve. The left ventricle begins to fill with blood from the left atrium. The flow of blood is driven by the transmitral pressure gradient. This phase contributes the largest volume of blood to the left ventricle during diastole.
Diastasis (slow filling): as the left ventricle fills, the pressure difference between the left ventricle and atrium decrease. This slows down the filling considerably, and contributes approximately 5% of the preload. This phase occurs mid-diastole.
Late rapid filling (atrial contraction): the left atrium contracts, ejecting additional blood into the left ventricle. This phase can contribute 15-20% of the preload. Atrial contraction is the last phase of diastole. The mitral valve closes after the atrial contraction.
Sodium thiosulfate would be an appropriate treatment for cyanide toxicity. Cyanide toxicity can be caused by fire exposure or sodium nitroprusside.
Both toxicities present with normal pulse oximetry and cherry-red facies.
Cyanide toxicity more often presents with hemodynamic instability, arrhythmia, and severe lactic acidosis (ie, lactate of 8-10 mmol/L) compared with carbon monoxide poisoning.
Cyanide toxicity results from the binding of ferric (Fe3+) ions on the mitochondrial cytochrome complex.
This causes functional hypoxia by inhibiting oxidative phosphorylation, resulting in profound lactic acidosis.
Treatment is with sodium thiosulfate, hydroxocobalamin, or amyl nitrate.
Complex regional pain syndrome is a chronic and multifactorial pain syndrome that occurs after trauma, with bone fractures being the most common precipitating factor. Complex regional pain syndrome can also occur after orthopedic surgeries of the extremities, immobilization, and strokes.
Complex regional pain syndrome is divided into types I and II. The key distinguishing feature between these two types is the presence of a definitive nerve injury with subsequent neuropathic pain in type II. In type I, there is no definite nerve injury, and the pain is nociceptive rather than neuropathic.
Resection of Arteriovenous malformations should have the use neuro monitoring to make sure cerebral motor and sensory functioning are intact 
Arteriovenous malformations (AVM) are surgically resected when they become large in size. A typical AVM consists of feeder arteries, a nidus, and draining veins. The high pressure from the arteries goes directly into the veins due to lack of arterioles and capillary beds. As a result, there is a high risk of bleeding and aneurysmal formations.
The sites at which core temperature can be measured are the pulmonary artery, distal aspect of the esophagus, tympanic membrane, and nasopharynx.
Acoustic impedance is the product of the density of a medium and the propagation speed of sound through that medium. Ultrasound reflections that occur at the interface of different mediums are due to the changes in acoustic impedance. Since propagation speed changes slightly between biological mediums, acoustic impedance is primarily dependent upon density.
Preoperative spirometry has not been shown to predict postoperative pulmonary outcomes in patients with COPD undergoing non-cardiothoracic surgery better than a routine clinical encounter with a history and physical examination. Preoperative arterial blood gas analysis should be considered in patients with a home supplemental oxygen requirement. Routine chest radiography is also not recommended unless suspicion for other clinical pathology, such as pneumonia, are present.
Transplanted lungs are denervated and cough reflex and mucociliary function will likely be impaired. Lymphatic drainage is also absent and may affect fluid clearance during subsequent anesthetics.
Midazolam has the potential to abolish microelectrode recordings during stereotactically guided brain surgery, eliminating any functional confirmation of needle placement. Most other IV agents are acceptable for use for sedation in these cases, including propofol, remifentanil, and dexmedetomidine.
Skeletal muscle contraction
When placing a femoral nerve block using a nerve stimulator, contraction of the sartorius muscle indicates that the needle needs to be moved deeper and more laterally.
The femoral nerve courses beneath the inguinal ligament where it sits atop the iliopsoas muscle. The femoral nerve lies just lateral to the femoral artery. The nerve travels beneath the fascia lata and the fascia iliaca.
Myasthenia gravis patients require increased succinylcholine dosage for intubating conditions.
Myasthenia gravis & Lambert Eaton patients would require decreased dosages of nondepolarizing neuromuscular blockers
Lambert-Eaton (myasthenic syndrome) patients typically require decreased succinylcholine dosage.
A Bier block is a form of intravenous regional anesthesia in which a tourniquet is inflated to prevent venous drainage in an extremity, and a local anesthetic is then injected into a distal IV in an extremity. Don’t use bupivicaine
A double-cuff tourniquet can be used to limit the discomfort caused by the tourniquet during a Bier block. When tourniquet pain begins to occur, the distal cuff is inflated over the area that had been previously anesthetized, followed by deflation of the proximal cuff to decrease the pain over the proximal cuff. Tourniquet pain often recurs at the distal cuff, which limits the duration of the Bier block.
If the screen from a type and antibody screen has a negative result for antibodies, the patient can be given ABO and Rh-compatible blood because the patient has no clinically significant antibodies against red blood cells (RBCs). If time permits, the blood should be crossmatched. If the antibody screen result is positive, the patient’s plasma is mixed with a panel of RBCs containing specific antigens to determine the antibody present.
Pneumonia is considered an intrinsic (parenchymal) restrictive lung disease because it is associated with reduced lung volumes and reduced respiratory system compliance
Restrictive processes can also be further subdivided into intrinsic, extrinsic, and neuromuscular disorders. Intrinsic defects, which most commonly involve filling of the airspaces (e.g. with fluid or exudate) or fibrosis of the pulmonary interstitium, typically reduce respiratory compliance by directly reducing intrinsic lung compliance and lowering all lung volumes. it is associated with hypoxemia partially as a result of diffusion defects, which may be quantified by a reduced diffusing capacity of the lung for carbon monoxide (DLCO).
By contrast, extrinsic restrictive lung defects such as kyphoscoliosis, morbid obesity, and large pleural effusions reduce chest wall or pleural compliance to decrease certain lung volumes and respiratory compliance.
Neuromuscular disorders such as amyotrophic lateral sclerosis, Guillain-Barré syndrome, and diaphragmatic paralysis impair respiratory muscle function and thus impede the mechanics of lung inflation and deflation.
Both extrinsic and neuromuscular restrictive defects do not necessarily reduce both FRC and TLC simultaneously, and these are not as commonly associated with reductions in DLCO.
When the testes are exposed to > 0.15 Gy of radiation in a brief period, it can result in temporary or permanent sterility.
the lens of the eye is the most sensitive to the biological effects of radiation. As a result of continued exposure to radiation, cataracts and opacities of the lens can develop. > 0.5 Gy
Lung abscesses usually occur due to primary infections, namely aspiration pneumonia, and are commonly caused by anaerobic bacteria such as Bacteroides, Peptostreptococcus. Lung isolation should be utilized if surgical intervention is necessary
the interscalene block (ISB) will almost always block the ipsilateral phrenic nerve, causing hemidiaphragmatic paralysis.
Rare or potential complications include dorsal scapular or long thoracic nerve injury (posterior approach), horner syndrome
Interscalene block is used to anesthetize the shoulder and proximal upper extremity and is not recommended for procedures of the forearm and hand because the ulnar nerve (C8-T1) is usually spared. The interscalene block primarily anesthetizes the ventral rami of C5-C7 and the supraclavicular branches of the cervical plexus (C1-C3).
A supraclavicular block (SCB) classically has been considered to carry a 1% to 6% risk of pneumothorax
Morbidly obese patients have both an increase in butyrylcholinesterase activity and extracellular fluid volume.
The interaction of barbiturates and propofol with specific membrane structures appears to decrease the rate of dissociation of GABA from its receptor, thereby increasing the duration of the GABA-activated opening of the chloride ion channel.
Simple face masks supply 35-50% FiO2 with flow rates >5 L/min.
Nasal cannulas provide an FiO2 of 25-40% with flow rates up to 6 L/min
The preganglionic fibers of both and the postganglionic of the parasympathetic fibers are cholinergic and release acetylcholine. The parasympathetic nervous system has long preganglionic fibers, short postganglionic fibers, and ganglia located on (intramural ganglia) or near (terminal ganglia) the visceral effector organs. The innervation of the parasympathetic nervous system is via cranial nerves III, VII, IX, and X and sacral nerves 2-4.
the postganglionic of the sympathetic fibers are adrenergic and release norepinephrine.
The sympathetic nervous system has short preganglionic fibers, long postganglionic fibers, and the ganglia located close to the spinal cord. The innervation of the sympathetic nervous system is from T1-L2.
The glossopharyngeal nerve block is performed by injecting local anesthetic commonly at the base of the anterior tonsillar pillar (perioral approach). This injection anesthetizes the posterior third of the tongue, the soft palate, and the region above the epiglottis, including the oropharynx. Typically done for awake intubation
A stellate ganglion block can be useful in the diagnosis and treatment of sympathetically mediated pain in the upper limb, head, and neck regions such as in complex regional pain syndrome. Although the ganglion lies on the anterior surface of the C7 transverse process, to best avoid complications such as vascular injury to the vertebral artery and pneumothorax, the block should be performed at the level of C6.
Several risk factors have been identified that predict the requirement for postoperative ventilation in patients with Myasthenia Gravis who are undergoing anesthesia, including
-Vital capacity of < 2L
-Pyridostigmine dose of >750 mg daily
-Disease duration > 6 years
-History of COPD
-Intraop blood loss of >1 L
-History of myasthenic crises
-Serum acetylcholine receptor antibody level >100 nM/mL
factors that increase MAC include hyperthermia, hypernatremia, chronic ethanol abuse, and increased central neurotransmitter levels (e.g., as caused by MAOIs, acute amphetamine use, cocaine, ephedrine, and levodopa).
Many factors decrease the MAC of anesthetic agents including acute ethanol ingestion, pregnancy, metabolic acidosis, and hyponatremia.
In general, factors that decrease CNS metabolic activity, neurotransmission, CNS neurotransmitter levels will decrease MAC.
The most reliable sign of uterine rupture during labor is non-reassuring fetal heart rate (FHR) patterns
Uterine rupture typically presents with vaginal bleeding, maternal tachycardia & hypotension, cessation of labor, abdominal pain, and non-reassuring FHR patterns.
Common risk factors include prior c-section, grand multiparity, and induction of labor with oxytocin or prostaglandin
Tracheoinnominate fistula is a rare but life-threatening complication after tracheostomies, describing an abnormal connection between the trachea and the innominate artery, also known as the brachiocephalic trunk or brachiocephalic artery.
dexmedetomidine has EEG patterns similar to those seen in normal human sleep, with increased slow wave activity and prominent sleep spindles.
Burst suppression cannot be produced even with high doses of dexmedetomidine.
Bispectral index values at comparable levels of sedation are lower with dexmedetomidine than with propofol.
Hepatopulmonary syndrome there is intrapulmonary shunting resulting in a ventilation-perfusion mismatch that increases the alveolar-arterial oxygen gradient. On pathology, patients will have gross dilatation of pulmonary precapillary and capillary vessels and an increase in the number of dilated vessels.
Patients will also present with platypnea and orthodeoxia. Platypnea is shortness of breath that worsens when sitting or standing up but improves by lying down.
Orthodeoxia is hypoxemia in the upright position that improves when lying down.
Potential benefits of parental presence during the induction of anesthesia in a pediatric patient include a decreased requirement for premedication, decreased anxiety in the child, and increased mask acceptance for the induction of anesthesia.
Parental presence is most effective when the pediatric patient is anxious and the parent is calm. Parental presence is less effective than premedication in reducing anxiety and increasing compliance in pediatric patients
Carbamazepine toxicity is associated with neurologic, cardiovascular, and anticholinergic symptoms.
These include mydriasis, nystagmus, QT prolongation, tachycardia, hypotension, flushing, dry mouth, and urinary retention.
Carbamazepine induces the hepatic cytochrome P-450 system
Blood products and fat emulsions are risk factors for catheter-related bloodstream infections and, if they are administered through a central line, the tubing set should be replaced within 24 hours.
In the Bohr effect, during areas of high CO2, the hemoglobin has less affinity for O2, which is more readily released for consumption by the tissues.
According to the Haldane effect, deoxygenated hemoglobin has a higher affinity for CO2. After the deoxygenated hemoglobin reaches the lungs, the high O2 concentration decreases this affinity, and the CO2 is released.
Wait at least 60 days after a myocardial infarction (MI) before noncardiac surgery is performed in the absence of any coronary intervention
Wait at least 14 days after balloon angiography before doing elective surgery
Transtracheal injection of local anesthetic through the cricothyroid membrane results in anesthesia of the recurrent laryngeal nerve and is used to anesthetize the vocal cords and trachea during awake intubation.
It is performed with the patient supine and the neck extended. Insertion of the needle through the cricothyroid membrane in a perpendicular plane with aspiration of air confirms intratracheal location, and then local anesthetic is injected. The patient will cough, but ultimately this reflex will be inhibited by the local anesthetic.
Most newborns after delivery should undergo the initial steps of newborn care: dry and warm under radiant warmer, stimulate, and suction oropharyngeal secretions with bulb syringe.
Meconium at birth is thick and can mechanically obstruct a newborn’s tracheobronchial system.
Drugs that have a higher unbound fraction will more readily cross the placenta. If a drug is protein-bound, drugs that bind to albumin have increased placental drug transfer compared to alpha-1-acid-glycoprotein (AAG) bound drugs.
Digoxin is a cardiac glycoside with a narrow therapeutic window. Digoxin toxicity can occur due to hypercalcemia, hypomagnesemia, hypokalemia, renal insufficiency, and hypothyroidism.
Treat with digoxin antibodies
A glucose test is appropriate to differentiate saline from cerebrospinal fluid. Additionally, glucose testing can be done as a point-of-care test with a test strip, giving near-immediate results. The reliability and speed of the point-of-care glucose strip make it the most appropriate test for differentiating dural puncture from loss-of-resistance saline return
Administration of heparin for more than 5 days may result in a decrease in platelet count in a subset of patients, and patients may be at risk for heparin-induced thrombocytopenia. Patients receiving intravenous or subcutaneous unfractionated heparin for more than 4 days should have a platelet count assessed
TPN should be continued in the perioperative period if at all possible. Close monitoring of electrolytes, specifically potassium, phosphate, and glucose should occur. Blood should not be administered through the same line as TPN using Y-site or piggyback connections. The use of the alternate lumen of a multi-lumen central catheter that is being used to actively infuse TPN is generally considered safe, though some providers will prefer to place and utilize an alternate peripheral intravenous line to avoid any potential increases in infectious risk
Diarrhea and orthostatic hypotension are common side effects of the celiac plexus block.
A celiac plexus block can be performed to help alleviate significant abdominal pain.
One of the major limitations of Anesthesia information management systems (AIMS) is the inadequate vertical integration between one phase of care to another and the standardization across vendors to allow communication between devices.
1) Patients experiencing a cardiac arrest with a shockable rhythm (pulseless ventricular tachycardia or ventricular fibrillation) should be treated with defibrillation via an immediate unsynchronized shock of 200 joules.
2) For shockable rhythms, 1 mg of IV/IO epinephrine should be administered after the second unsuccessful defibrillation attempt.
3) For shockable rhythms, 300 mg of IV/IO amiodarone should be administered after the third unsuccessful defibrillation attempt
Although rare, awareness under anesthesia is more likely during cardiac, obstetric, and trauma procedures.
Maintaining end-tidal volatile concentrations of 0.7 MAC or above can significantly reduce the risk of awareness.
Ceftaroline, tigecycline, and Bactrim have the broadest spectrum of activity effecting both Gram positives and some Gram negatives. Many of the other agents effective against MRSA like vancomycin, daptomycin, and linezolid are only effective against Gram-positive organisms.
The preoptic anterior hypothalamus plays a role in temperature homeostasis and thermoregulation.
Expressive or Broca aphasia results from damage to the Broca area in the frontal lobe. The Broca area is supplied by the middle cerebral artery
Post-thoracotomy pain is best-managed with a regional anesthetic technique. Though thoracic epidural is the preferred technique, the paravertebral approach is becoming more widely utilized with much success and is a good alternative to a thoracic epidural.
Volatile anesthetics are safe for nonobstetric surgery during pregnancy and for general anesthesia for C-section. These drugs rapidly cross the placenta and can lower APGAR scores. There is a 30% reduction of MAC for volatile anesthetics during pregnancy and the use of volatile anesthetics can cause decreased uterine smooth muscle tone which can increase blood loss during cesarean section
Hypoglycemia can be seen with acute stoppage of total parenteral nutrition (TPN) because the significant carbohydrate load in TPN causes the pancreas to secrete excess insulin. High Insulin level prevent hyperglycemia during infusion of TPN. However, with acute discontinuation of TPN the pancreas continues to secrete insulin even after TPN is stopped. This period of time prior to the pancreas adjusting to a lower glucose load can cause a patient to experience significant hypoglycemia
Cervical spine injuries should be suspected or ruled out with further investigation in patients the following risk factors
- high-speed (> 35 miles per hour) motor vehicle collision
-being at the scene of a motor vehicle collision where someone died,
-falling from a height > 10 feet,
- closed head injury of intracranial hemorrhage seen on imaging
- pelvic or multiple extremity fractures
-having neurologic symptoms
bypassing phase 1 recovery and proceeding straight to phase 2 recovery is shown in patients who dont require parenteral medications, experience minimal pain and PONV,TOF >0.9, and rapidly recover baseline hemodynamic and cognitive function following emergence
Autoregulation is responsible for maintaining cerebral blood flow (CBF) over a range of mean arterial pressure between 60 and 150 mmHg in which cerebral vascular resistance is adjusted to maintain a constant CBF. The arterial concentration of carbon dioxide (PaCO2) is directly proportional to CBF. An increase in the PaCO2 leads to an increase in hydrogen ions in the cerebrospinal fluid, which is responsible for the cerebral vasodilation seen in hypercapnia. With significant hypocapnia (less than 20-24 mmHg), the vasoconstriction response is blunted, and cerebral ischemia ensues.
as PaCO2 increases from 30 to 60 mmHg, CBF doubles.
Pathologic states, including trauma, ischemia, or tumors, decrease the response to PaCO2. Mild hypocapnia with PaCO2 levels between 30 and 34 mmHg is used to facilitate surgical access in patients with large space-occupying lesions undergoing craniotomies.
If a vaporizer meant for an inhaled anesthetic gas with a lower saturated vapor pressure (SVP) is misfilled with an inhaled anesthetic with a higher SVP, the output concentration will be much higher than what the actual dial indicates for the inhaled anesthetic with the lower SVP.
HI-Se, is a way to remember the order of vapor pressure of the volatile anesthetics. From highest to lowest saturated vapor pressure: halothane > isoflurane (243 mmHg) > sevoflurane (160 mmHg) > enflurane.
Commonly used conversion ratios for morphine are as shown below:
1 mg of intrathecal (IT) morphine = 10 mg of epidural (EP) morphine
1 mg of EP morphine = 10 mg of IV morphine
1 mg of IV morphine = 3 mg of PO morphine
Hyperglycemia in patients with diabetes who undergo surgery is associated with increased rates of surgical site infection, myocardial infarction, stroke, and death. Intraoperative hyperglycemia is an independent risk factor for perioperative complications in cardiac surgery patients.
Sodium bicarbonate administration is associated with transient increases in partial pressure of CO2, end-tidal CO2, and intracranial pressure, with transient decreases in serum calcium and potassium.
Myocardial infarction is the most common cardiovascular cause of death in noncardiac surgical cases and must be thoroughly evaluated preoperatively to reduce its incidence.
Revised Cardiac Risk Index (RCRI) can help identify patients at risk.
At high altitudes, the partial pressure of desflurane will decrease in proportion to the reduction in atmospheric pressure as it correlates to the calibration pressure, usually 760 mmHg (1 atm). This is described by the formula:
Required dial setting = Normal dial setting (volume %) * 760 mmHg / (Ambient pressure mmHg)
The normal response to hypoglycemia is an increase in sympathetic discharge, cortisol release, and glucagon release with symptoms of diaphoresis, tachycardia, hypertension, altered mental status, and possibly even seizures.
Chloroprocaine is an ester-type local anesthetic and is broken down in the blood by plasma cholinesterase, just as all ester local anesthetics are. The amide local anesthetics undergo hepatic metabolism. Chloroprocaine is the most rapidly metabolized of all of the local anesthetics. Safe to use for pregnancy
Bupivacaine crosses the placenta but to a lesser extent than lidocaine because of the high degree of protein binding of bupivacaine.
In general, the more protein-bound amide-type local anesthetics (eg, bupivacaine and ropivacaine) less readily cross the placenta compared with less protein-bound local anesthetics (eg, lidocaine). Amide anesthetics cross the placenta more than ester-type anesthetics
The earliest presenting signs of MH in pediatric patients are tachycardia and a rapid increase in end-tidal CO2 & hyperthermia. Dantrolene should be administered when MH is strongly suspected. Dantrolene is a muscle relaxant that works intracellularly to restore calcium homeostasis. Its most common side effect is muscle weakness, including dysarthria, diplopia, and respiratory weakness.
In Malignant Hyperthermia, Calcium channel blockers should be avoided in MH as they may interact with dantrolene to produce fatal hyperkalemia and cause cardiovascular collapse. Intravenous calcium should be administered to stabilize the myocardial membrane in the setting of life-threatening hyperkalemia.
drugs that contain N-methyl-D-aspartate (NMDA) antagonistic properties (ketamine, butorphanol, buprenorphine, and nitrous oxide) can either prevent or reduce opioid-induced hyperalgesia caused by remifentanil.
Prostaglandin E1 is used to maintain patency or reopen the ductus arteriosus in “ductal-dependent lesions” to improve blood flow to the lungs or systemic circulation, depending on the nature of the congenital lesion. Side effects include apnea, hypotension, fever, and central nervous system irritability.
Leukopenia can occur during TRALI due to sequestration of the neutrophils in the pulmonary vasculature.
Donor antibodies activating recipient neutrophils are the cause of TRALI. These neutrophils result in damage to the pulmonary vascular capillary bed, resulting in pulmonary edema.
When assessing the degree of neuromuscular blockade using TOF stimulation after nondepolarizing NMBD administration:
1 palpated twitch indicates >90% suppression.
2 palpated twitches indicate 80-90% suppression.
3 palpated twitches indicate 70-80% suppression.
4 palpated twitches indicate up to 65-75% suppression.
Neonates with congenital diaphragmatic hernia (CDH) should be intubated, and mechanical ventilation with a pressure-limited ventilation mode with permissive hypercapnia should be initiated.
If worsening acidosis or if CDH is severe, high-frequency ventilation (HFV) should be initiated. When HFV fails, ECMO should be initiated.
Gabapentin binds and inhibits the alpha2-delta subunit of the voltage-gated calcium channel. This results in a decreased release of the excitatory neurotransmitter glutamate.
Gabapentin side effects include nausea, sedation, dizziness, ataxia, nystagmus, peripheral edema, and weight gain.
Cerbral Palsy patients have an increased incidence of gastroesophageal reflux and esophageal dysmotility.
Pulmonary aspiration is increased in CP patients and places them at a greater risk for postoperative pulmonary complications. Succinycholine is safe to use.
Safe airway management of acute epiglottitis is founded on inhalational induction in the sitting position with maintenance of CPAP during spontaneous ventilation to prevent inspiratory laryngeal airway collapse or irritation.
Transdermal fentanyl is an excellent treatment option for chronic pain. Transdermal fentanyl is contraindicated for patients with acute pain. Can be given to patients who are taking high doses of morphine
VCV delivers a set volume breath at a set interval or frequency. With VCV airway pressure is a dependent variable of the breath. The volume of the breath being delivered will not change based on intrinsic factors of the lungs.
In PCV, the airway pressure for the breath is set, and the breath size or volume is variable. This means that the volume of each breath changes depending on chest wall compliance, airway resistance, and lung compliance.
Severity of postintubation croup can be measured by the Clinical Croup Score which can help dictate treatment. Mild postintubation croup can be treated with cool, humidified mist, while moderate-severe symptoms benefit from nebulized racemic epinephrine followed by 4-5 hours of monitoring to watch for rebound effects
Direct acting β-adrenergic agents (e.g. isoproterenol, epinephrine) should be administered in the setting of bradycardia in a patient with a transplanted heart.
Electrocardiographic analysis of a patient with a transplanted heart may demonstrate two P waves, especially during the first few weeks, since one technique involves the native right atrium being sutured to the transplanted right atrium
Sevoflurane undergoes the most extensive metabolism (5-8%) followed by isoflurane (0.2%) then desflurane (< 0.2%).
Despite demonstrated elevations in serum fluoride concentrations in long cases, it has not been shown to cause fluoride-induced nephrotoxicity.
Moderate to severe aortic insufficiency is an indication for the use of retrograde cardioplegia because antegrade cardioplegia delivered to the aortic root in the presence of a regurgitant lesion will not exclusively traverse the coronary arteries but, instead, be partially diverted into the left ventricle. Other indications for the use of retrograde cardioplegia include severe coronary artery stenosis, previous coronary artery bypass graft with a patent internal mammary graft, and a prolonged anticipated pump run
The combination of arresting myocardial contractility combined with selective myocardial hypothermia can reduce the cardiac myocyte oxygen demand by up to 90% compared to physiologic conditions. The goals of cardioplegia are prompt, continuous arrest in all regions of the myocardium to facilitate surgical technique; early return of function after the aortic cross-clamp is removed; and minimal inotropic requirements for successful separation from cardiopulmonary bypass.
Moderate to severe aortic insufficiency is an indication for the use of retrograde cardioplegia because antegrade cardioplegia delivered to the aortic root in the presence of a regurgitant lesion will not exclusively traverse the coronary arteries but, instead, be partially diverted into the left ventricle. Other indications for the use of retrograde cardioplegia include severe coronary artery stenosis, previous coronary artery bypass graft with a patent internal mammary graft, and a prolonged anticipated pump run
Poor perioperative outcome following pneumonectomy include:
PaCO2 >45 mm Hg
PaO2 < 50 mm Hg on room air
FVC < 50%
FEV1 < 2 L
FEV1/FVC < 50%
Maximum voluntary ventilation < 50%
DLCO < 50
Antibiotic treatment of Gram-negative bacteria may result in worsening hypotension through the release of lipopolysaccharide
Lipopolysaccharides found in the outer membrane of Gram-negative bacteria act as endotoxins that can induce a significant immune response. This compound serves to further worsen the sepsis response by indirectly causing the release of multiple cytokines and factors, including nitric oxide
Hemodynamic goals for patients with single-ventricle Fontan physiology include maintenance of normal heart rate and avoiding tachycardia, ensuring adequate preload (eg, avoidance of prolonged periods of nothing consumed by mouth without intravenous hydration), avoiding rapid reductions in systemic venous return (which may be induced by a spinal anesthetic), and avoiding situations that would result in increased pulmonary vascular resistance (eg, hypercarbia, hypoxia, high airway pressure with positive-pressure ventilation, and positive-pressure ventilation when it is possible).
Fontan repairs of congenital heart defects result in single-ventricle physiology in which the single ventricle pumps blood systemically through the aorta and returning circulation returns passively to the right-sided circulation to the lungs without encountering the heart.
Enteral metal ions such as calcium, magnesium, aluminum, and iron commonly form complexes with antibiotics including tetracyclines and fluoroquinolones.
Iron will also readily bind with the catechol moiety in both levodopa and carbidopa. This drug-metal complex will reduce enteric absorption of the drug and decrease its clinical effectiveness.
For this reason, it is recommended that all metal-containing medications (antacids, laxatives, iron supplements) be given at least 2 hours from the time that these other drugs are given.
Opioid receptors couple to G proteins and agonist activation leads to membrane hyperpolarization. Acute opioid effects are mediated by inhibition of adenylyl and activation of phospholipase C.
Opioid receptor activation inhibits the excitatory response from nociceptive neurons primarily through blocking the release and response of excitatory neurotransmitters (acetylcholine, substance P). They block presynaptic release and postsynaptic response of these substances.
Pain stimuli are carried along afferent neurons to the dorsal horn of the spinal cord which results in activation of glutamate and other excitatory neurotransmitters within the secondary neuron. Opioids can disrupt this pain signal transmission at several points along the pathway. Pain stimuli can be attenuated in the periphery by opioids acting at μ-opioid receptors. The strength of action potentials reaching the dorsal horn can be blunted at the presynaptic ending by opioids. Opioids also inhibit the postsynaptic neuron pain signal transmission.
Sodium deficit = (140 – serum sodium) * total body water
Total body water = kilograms of bodyweight * 0.6
Symptomatic patients with serum Na+ < 120 mEq/L should have the serum osmolality corrected by 3% HS
Typically, 50% of the Na+ deficit is corrected during the first 24 hours, and the rate of hypertonic saline administration should never be higher than 100 mL/hr.
Transcutaneous pacers activate the right ventricle followed by the left ventricle
The atria may be activated by retrograde conduction however there is no association thus the atrial kick is lost resulting in up to a 20% decrease in cardiac output
The rate should be set 10 to 20 beats per minute higher than the spontaneous heart rate to capture 100% of the beats and avoid R-on-T phenomenon.
Pacing thresholds are significantly higher because it requires transmission of the electrical impulse through the chest tissue, which has large impedance
Caudal epidural anesthesia is a commonly used anesthetic technique in neonates and infants, especially for abdominal surgery. The caudal needle will enter the sacral hiatus which is a V-shaped defect located between the S4-5 vertebrae before entering the epidural space.
Nonobstetric surgery for the pregnant patient should be performed in the second trimester if possible to decrease the risk of miscarriage.
The function of modern pacemakers is generally designated using a 3 letter code. The first letter indicates the heart chamber(s) paced, the second is the chamber(s) for which intrinsic electrical activity is sensed, and the third is response to sensing. The presence of an R as a fourth letter means the pacemaker is rate-responsive and will increase its rate, for example, when it senses exercise.
When a patient’s intrinsic heart rate is greater than the set pacemaker rate along with a pacemaker in an asynchronous mode, an R-on-T phenomenon may occur leading to ventricular tachycardia or ventricular fibrillation.
The function of modern pacemakers is generally designated using a 3 letter code. The first letter indicates the heart chamber(s) paced, the second is the chamber(s) for which intrinsic electrical activity is sensed, and the third is response to sensing. The presence of an R as a fourth letter means the pacemaker is rate-responsive and will increase its rate, for example, when it senses exercise.
When a patient’s intrinsic heart rate is greater than the set pacemaker rate along with a pacemaker in an asynchronous mode, an R-on-T phenomenon may occur leading to ventricular tachycardia or ventricular fibrillation.
Asynchronous pacemaker modes (i.e., DOO, VOO, or AOO) are those in which the pacemaker neither senses nor inhibits. Regardless of the underlying rhythm or intrinsic heart rate, a pacemaker in an asynchronous mode will pace at whatever rate it is set. This mode is most commonly used perioperatively in pacemaker-dependent patients in order to decrease problems associated with electromagnetic interference (EMI) from an electrocautery unit (ECU).
For example, a patient with complete heart block (CHB) has a DDD pacemaker in place. The pacemaker detects the EMI from the ECU and interprets it as R waves. Since the pacemaker thinks the patient’s ventricle is therefore beating, the pacemaker inhibits itself. In a patient with CHB, no pacing can mean bradycardia (or even asystole) and hemodynamic instability. To prevent this complication, the pacemaker may be changed to DOO perioperatively. Then, the pacer will consistently pace at a set rate (commonly 80-100) and will not sense EMI.
Ground fault current interrupter (GFCI) electrical outlets are outlets with TEST and RESET buttons that allow the operator to test the plug to make sure the ground is correctly connected in order to avoid electrical injuries from improper grounding.
Spinal cord stimulator inhibiting transmission of painful stimuli through the spinothalamic tract via dorsal column stimulation
Coronary arteries
Aortic axis TEE view
Acetazolamide leads to hypokalemia.
Acetazolamide causes an increase in H+ and Cl- but a decrease in K+, Na+, and HCO3-.
The cause of hypokalemia is due to increased delivery of Na+ to the collecting ducts which is exchanged for K+ via the Na+/K+ ATPase causing efflux of K+
In adults, neuromuscular blocking agents are the most likely agents to induce an anaphylactic reaction in the perioperative period. In children, latex is the most likely causative agent.
Forced expiratory volume in one second (FEV1) is used to diagnose exercise-induced bronchoconstriction with an exercise challenge test.
Rexed lamina II: Substania Gelatinosa, where opioids work
For pain first order neuron is dorsal root ganglia, second order is Dorsal horn, Third order is cerebral cortex
Rexed lamina V: responsible for wind up phenomenom and sensitization for pain
Plavix inhibits the P2Y12 receptor. It is a prodrug. 40% people don’t have a response. Irreversible. Can cause Thrombotic thrombocytopenia purpuric
Cangrelor is an IV version of the active form of Plavix. Return of platelet function in 60-90min
Ketamine is one of the fastest acting anesthetic agents because there is no delay in equilibration between plasma concentrations and effect-site. Onset of action is 30 seconds and maximal effect occurs in 60 seconds. It is also rapidly redistributed leading to a short duration of action after bolus doses (anesthesia lasts for 10-15 minutes after an induction dose).
Other pharmacokinetic characteristics include high liposolubility, high volume of distribution, and high clearance. Unlike many other IV anesthetics, ketamine has low plasma protein binding
Hetastarches are traditionally associated with a higher risk of coagulopathies (platelet adhesion interference, reduced factor VIII:C and von Willebrand factor levels, and prolongation of partial thromboplastin time) compared with the newer, lower molecular weight tetrastarches.
Mean arterial pressure is the most accurate blood pressure measurement with oscillometric noninvasive blood pressure monitoring. It occurs at the peak amplitude of arterial pulsations. Systolic pressure is underestimated and diastolic pressure is overestimated with oscillometric noninvasive blood pressure monitoring.
In normal-weight adult males and females, total body water makes up approximately 60% and 50% of total body weight, respectively. Approximately 2/3 of total body water is intracellular while 1/3 is extracellular. About 75% of extracellular fluid is interstitial fluid and 25% is plasma. Obese individuals have a proportionally smaller TBW compared to their weight.
Neonates and infants have a proportionately higher TBW than adults which causes them to require higher doses of water-soluble drugs (succinylcholine, midazolam) to achieve the same effect.
law of LaPlace
As the pressure and radius of the ventricle increases, the wall tension increases.
However, as the thickness of ventricle increases, the wall tension will decrease.
Propofol increaseshepatic blood flow due to splanchnic vasodilation. It has not been shown in clinical practice to precipitate episodes of hepatic encephalopathy.
Abdominal compartment syndrome is diagnosed by observing a tense, distended abdomen and by obtaining bladder pressure readings > 20-25 mm Hg via a urinary catheter.
Brain glucose metabolism in the brain is approximately 5 mg/100 g/min. The brain is highly dependent upon glucose and oxygen for its energy supply under normal conditions but utilizes ketone bodies during starvation.
mid Esophageal Aortic valve, short axis view
Goldenhar syndrome is arare genetic disorder that has important consideration of airwaymanagement as there is potential for difficult mask ventilation and difficult laryngoscopic visualization.
Goldenhar syndrome pts have cardiac & renalm problems
Total cerebral blood flow (CBF) is 50 mL / 100 g / min in a healthy adult, while CBF in gray matter is 80 mL / 100 g / min, andCBF in white matter is 20 mL / 100 g / min.
Amiodarone is associated with pulmonary fibrosis that is further exacerbated when supplemental oxygen is used.
Due to the mitochondrial dysfunction in septic shock, tissues are unable to extract sufficient oxygen from the blood, which results in an elevated mixed venous oxygen saturation. As a result of the decrease in oxygen extraction, tissues switch to anaerobic metabolism for energy, ultimately resulting in lactic acidosis (levels of lactate >2 mmol/L).
In children, the BIS values paradoxically increase with values of expired sevoflurane greater than 3%. BIS values may also be inaccurate in infants and children with developmental delays.
The Bezold-Jarisch reflex is a recognized complication of interscalene nerve blockade, especially when the patient is placed in the seated position. It is caused by a decrease in preload causing activation of mechanoreceptors in the atria and ventricles in the heart.
The activation of these receptors results in profound bradycardia and hypotension due to an inhibition of sympathetic outflow to the heart, and an increase in parasympathetic tone.
Mapleson systems
Phantom pain following limb amputations is very prevalent and difficult to treat. Preoperative pain is a risk factor for phantom pain, but more studies are needed to determine whether pre-amputation analgesia will prevent the development of phantom pain.
Sodium bicarbonate amount that will normalize blood pH can be approximated with the formula:
Sodium bicarbonate (mEq) = 0.2 * patient weight (kg) * base deficit.
IABP tracings
Hexamethonium is an example of a ganglionic blocking drug which acts as an antagonist at the neuronal-type nicotinic receptors.
Factors that increase the risk of an acute exacerbation in patients with acute intermittent porphyria include stressful situations, prolonged fasting times, and certain medications(barbituates, sulfonamides)
adequate hydration to decrease the risk of dehydration and supplementation with glucose to avoid starvation states can decrease risk of an acute exacerbation in patients with acute intermittent porphyria
Diffusion hypoxia, also known as the Fink effect, occurs when the washout of large amounts of nitrous oxide exit the blood and enter the alveoli during the emergence from anesthesia after nitrous oxide has been discontinued.
The large amounts of nitrous oxide entering the alveoli result in a decrease of the partial pressure of oxygen, causing alveolar hypoxia. This hypoxia can be worsened by the rapid washout of carbon dioxide from a phenomenon similar to the second gas effect, leading to a relative hypocarbia and decreased respiratory drive.
Children with a witnessed aspiration event who do not develop pulmonary sequelae within two hours can be safely discharged home. The incidence of aspiration and the severity of pulmonary sequelae are lower in children than in adults.
Scheduled acetaminophen therapy (> 3 days) in patients on chronic warfarin therapy has been shown to increase INR to supratherapeutic levels in otherwise stable patients.
The different types of irrigationfluids used for TURP each have specific disadvantages. Glycine irrigating solution may causetransient blindness. Distilled water hasthe highest risk for intravascular hemolysis, hypervolemia, and dilutionalhyponatremia.
Balanced salt solutions(such as normal saline) cause electrical current dispersion during TURP butsignificantly reduce the risk of TURP syndrome. Sorbitol and mannitol solutions may lead to hyperglycemia (sorbitol),intravascular fluid expansion with absorption (mannitol) and an osmoticdiuresis (sorbitol and mannitol).
