ITE Questions Flashcards
What are the 7 conditions approved for hyperbaric oxygen therapy treatment?
- Gas-bubble disease (air embolism/decompression sickness)
- Carbon monoxide poisoning
- Infections (soft tissue necrotizing infections)
- Acute/Chronic tissue ischemia
- Acute hypoxia (blood-loss anemia when transfusion unable to be given)
- Acute thermal burn injury
- Idiopathic sudden sensorineural hearing loss
What are transient neurological symptoms (TNS)? What are the risk factors for the development of TNS (4)?
- Characterized by pain in the butt or legs following spinal anesthesia (usually sef-limiting to 72 hours)
1. Lithotomy position
2. Lidocaine use
3. Addition of phenylephrine to 0.5% tetracaine
4. Pts. who undergo outpatient procedures
How much does oxygen consumption increase during the 1st and 2nd stage of labor?
- Oxygen demand increases by 40% in the 1st stage, and 75% in the 2nd stage
- These demands can be reduced w/ analgesics, especially neuraxial anesthesia
Neurological monitoring (BIS or Entropy) does not correspond to which 3 anesthetic agents?
- Nitrous oxide
- Ketamine (N2O and ketamine can induce anesthesia w/ a high BIS/Entropy value)
- Dexmedetomidine (can produce a low BIS/Entropy value w/o inducing general anesthesia)
What is the treatment for organophosphate poisoning? What can be taken for prophylaxis?
- Atropine (to reduce muscarinic-mediated side effects), pralidoxime chloride (removes organophosphate compound from acetylcholinesterase), decontamination, and supportive therapy if necessary
- Pyridostigmine is effective for prophylaxis, if taken greater than 30 minutes before exposure
What 3 diagnostic tests can help differentiate ATN from acute kidney injury?
- Urinalysis
- Fractional excretion of sodium (FENa)
- Response to fluid challenge
In what age group is emergence delirium most common? What medications can decrease incidence of ED?
- It is most common in children between the ages of 2-5 who undergo a painful procedure under general inhalational anesthesia
- Prophylactic administration of clonidine, dexmedetomidine, fentanyl, ketamine, nalbuphine, or propofol can decrease incidence
What are the 3 diseases that are closely associated w/ malignant hyperthermia? What is the earliest sign of MH? Treatment?
- Central Core Disease
- Multi-Minicore Disease
- King-Denborough Syndrome
-The earliest sign of MH is a rapid rise of end-tidal CO2. Treatment is 2.5 mg/kg of dantrolene
What are the 2 most common risks of using TPN?
-Infection is the most common risk, and thrombophlebitis is the next most common risk, esp. w/ peripherally-delivered TPN
What are values for extracellular/intracellular body weight percentages in neonates? When to the compartments reach adult levels?
- Neonates have an extracellular compartment of 40% and intracellular compartment of 20% of their body weight. The compartments reach adult levels at 1 year of age (Adult levels are reversed: Extra: 20%, Intra: 40%)
- Preterm infants have a higher total body water compared to term infants
What factors decrease FRC? When does the greatest decrease occur?
- It is reduced by obesity, in females (10% less than males), and when moving from upright to supine/prone/Trendelenburg position
- FRC is highest when in an upright position. The greatest decrease occurs when going from 60 degrees to totally supine at 0 degrees. Beyond Trendelenburg of -30 degrees, the drop in FRC is considerable
What is the treatment of choice for pts. w/ Von Willebrands Disease?
- Desmopressin (DDAVP) is the treatment of choice for surgical bleeding in pts. w/ type-1 vWD
- Factor 8-vWF concentrate is useful in pts. w/ type 1 vWD who fail to respond to desmopressin, are undergoing major surgery, or in the setting of severe bleeding
In pts. w/ glaucoma, what medications should be avoided?
- Medications that cause mydriasis (anti-cholinergics and anti-histamines)
- Corticosteroids should be used cautiously in pts. w/ glaucoma
- Atropine and glycopyrrolate are considered safe to use in pts. w/ open or closed-angle glaucoma
What echocardiographic study provides a measure of right ventricular systolic function? What other studies (2) can provide this information?
- The tricuspid annular plane systolic excursion (TAPSE) can be used w/ TTE or TEE. A normal TAPSE is between 1.5-2 cm
- Cardiac MRI or MUGA scans can be used to calculate right ventricular EF also
What are considerations when using carboprost, methylergonovine, misoprostol, and oxytocin?
- Carboprost: venoconstriction, bronchospasm
- Methylergonovine: (alpha-receptor stimulation) alpha-mediated hypertension. Should not be used in pre-eclamptic pts.
- Misoprostol: uterine rupture is possible when used in pts. w/ history of c-section
- Oxytocin: vasodilation/hypotension. Can cause ADH-responses in large doses (water retention, hyponatremia)
What nerve root is affected by a far lateral/paracentral disc herniation?
- A far lateral herniation will affect the exiting nerve root at the level of the disc herniation
- A paracentral herniation will affect the nerve root at the level BELOW the disc herniation
Which cranial nerves have parasympathetic components? Where are they located?
- Cranial nerves 3, 7, 9, and 10 have parasympathetic components
- The component for cranial nerve 3 lies in the midbrain. The others lie within the medulla
What is the most common cause of pregnancy-related maternal mortality in the U.S.?
Maternal cardiovascular conditions (cardiomyopathy, congenital heart disease, CHF, hypertensive/ischemic/valvular disease)
What lung-related parameters are similar between neonates and adults?
- Tidal volume is comparable to an adult on a volume/kg basis
- Closing volume, respiratory rate, and minute ventilation are increased in neonates
What is 1st-line therapy for organophosphate poisoning/nerve agent exposure?
Atropine. It will antagonize muscarinic receptors causing a decrease in secretions and bronchospasm, and an increase in heart rate which will improve hemodynamics
What is the leading cause of perioperative mortality in morbidly obese pts.?
Deep vein thrombosis leading to PE
What kind of response can an IgA-deficient pt. have from a blood transfusion?
They are at risk for an anaphylactic response to IgA antibodies in donor blood. To avoid this reaction, these pts. should receive washed RBCs or blood from IgA-deficient donors
When should epinephrine be given in non-shockable rhythms during cardiac arrest?
As soon as possible
This does not apply for shockable rhythms
How does somatostatin affect other hormones?
It is an inhibitory hormone that suppresses the release of insulin, glucagon, growth hormone, and TSH
What electrolyte changes occur w/ loop diuretics?
- HYPOnatremia/kalemia/magnesemia
- HYPERuricemia
What are goals of management in a pt. w/ hypertrophic obstructive cardiomyopathy (HOCM)?
- The goal is to keep the left ventricle full!
- Increased preload, increased afterload, depressed myocardial contractility, normal to low heart rate, and maintain sinus rhythm
Should SSRI’s, SNRI’s, and MAOI’s be continued perioperatively? What medications can induce a hyper-pyretic response in these pts.?
- SSRI’s and SNRI’s should be continued on the day of surgery. MAOI’s should be held on the day of surgery.
- Many opioids have been implicated in causing a hyper-pyretic response (esp. meperidine), morphine and hydromorphone have also been linked.
- *Fentanyl is safe to use**
What are the 2 most common causes of postoperative jaundice?
- Hemolysis and breakdown of extravasated blood or hematoma
- It is helpful to categorize postoperative jaundice into pre/intra/post-hepatic categories
What factors cause FRC to increase/decrease?
- FRC is Increased: w/ age due to loss of elastic lung tissue, in COPD
- FRC is Decreased: in obesity, fibrosis (restrictive lung disease), pregnancy
What drug interactions can occur in pts. taking SSRI’s? What are signs/symptoms of serotonin syndrome?
- They may cause serotonin syndrome when used w/ other drugs that increase serotonin levels (ondansetron, metoclopramide, meperidine, etc)
- They inhibit cytochrome P450 enzymes (CYP2D6- converts codeine, oxycodone, tramadol)
-Altered mental status, autonomic hyperactivity (flushing, sweating, tachycardia, hyperthermia), tremor, muscle rigidity
What physiologic changes (4) occur in morbidly obese pts.?
Increase in:
- Fat mass
- Lean body weight
- Extracellular fluid volume
- Cardiac output
*Give benzodiazepines/opioids w/ extreme caution!!**
How do vasodilating agents affect cerebral vasculature?
- Most vasodilating agents will also cause cerebral vasodilation- this may result in flushing and a headache.
- Cerebral perfusion pressure is the difference between mean arterial pressure minus the central venous pressure or ICP (whichever is higher)
What can potentiate digitalis toxicity?
- HYPOkalemia/hypomagnesemia
- HYPERcalcemia
-Hyperkalemia can be a sign of acute digitalis toxicity
How does digitalis work?
-It inhibits the Na/K-ATPase which creates an increase in intracellular calcium, increasing myocardial contractility
What is a normal A-a gradient? What does a value >15 indicate? What is the formula for PAO2?
- A normal A-a gradient is 5-15 mm Hg. A normal gradient indicates that the problem is outside of the lungs (gas exchange across the alveoli into the capillaries is not affected)
- A difference >15 indicates there is a problem w/ gas exchange, suggesting lung pathology.
Formula: PAO2= 150 - (PaCO2/0.8)
What lung volume remains unchanged in the elderly?
Total lung capacity remains the same
What are the 2 components of plasma?
- Total blood volume is composed of an intracellular part (blood cells) and an extracellular part
- The extracellular part (plasma) has 2 components: plasma and subglycocalyx compartments
- The glycocalyx layer acts as a semipermeable membrane that keeps intravascular proteins from moving to the interstitial fluid
What will happen if a vaporizer is mistakenly filled w/ the wrong volatile anesthetic that has a higher saturated vapor pressure?
-The volume percentage of volatile anesthetic will be HIGHER than the concentration set on the dial
(DHIES)
- Des (669)
- Halothane (243)
- Iso (238)
- Enflurane (172)
- Sevo (157)
If a pt. aspirates while supine, where will the fluid go (most likely)?
The posterior segment of the right lower lobe
What cardiovascular changes (4) occur in the elderly?
- Decreased left ventricular compliance
- Decreased vascular compliance
- Decreased inotropy
- Decreased sensitivity of beta-adrenergic receptors
What are 5 physiologic considerations in the neonatal/pediatric patient?
- Neonates have reduced GFR/immature nephrons predisposing to sodium loss
- Higher metabolic requirements predisposing to hypoglycemia
- Large evaporative losses due to large relative body surface area
- Larger total body water percentage
- Immature sympathetic nervous system w/ a non-compliant myocardium
Electrolyte findings in pyloric stenosis?
HYPOnatremic/kalemic/chloremic metabolic alkalosis
How do opioids reduce pain signal transmission?
-They activate G-protein coupled opioid receptors at both pre- and post-synaptic sites in the dorsal horn of the spinal cord
What malformation is commonly seen in pts. w/ meningomyelocele?
Chiari II malformation (herniation of the cerebellar vermis through the foramen magnum)
What is the strongest single predictor for risk of complications/mortality following lung resection?
Predicted post-operative carbon monoxide diffusing capacity < 40% (DLCO <40%)
How is etomidate metabolized/excreted? Does it have low or high protein-binding?
- It is primarily metabolized by hepatic ester hydrolysis to inactive metabolites. It is then excreted by the kidneys (85%) and in bile (13%)
- Etomidate is HIGHLY protein-bound (dose can be reduced in pts. w/ disease processes that decrease plasma protein concentration)
What is the formula for oxygen delivery?
DO2= CO x CaO2 x 10
CaO2= arterial O2 content
What is the advantage of regional anesthesia for orthopedic/urologic procedures?
Neuraxial anesthesia can reduce the incidence of DVT (assoc. w/ TURP, total hip/knee replacements) compared to general anesthesia
Exam findings of compartment syndrome? When is an emergent fasciotomy indicated?
- Pain out of proportion to injury, persistent deep aching pain, pain w/ passive stretching of affected compartment
- A compartment pressure over 40 mm Hg is an indication for emergent fasciotomy
How does propofol cause hypotension?
It decreases preload/afterload and cardiac function. It also impairs the baroreceptor reflex
What are independent risk factors (5) for difficult mask ventilation?
- Presence of beard/facial hair
- BMI >26
- Lack of teeth
- Age > 55
- History of snoring
What nerve is spared w/ brachial plexus blockade (interscalene/supra/infraclavicular)? What areas does it innervate?
The intercostobrachial nerve (ICB). It provides innervation to the skin of the axilla and medial aspect of the proximal arm
How do volatile anesthetics affect cerebral autoregulation?
They attenuate autoregulation. At high doses, autoregulation is abolished and cerebral perfusion becomes pressure-passive
How much rocuronium is renally excreted?
- Up to 30%
- Metabolism of rocuronium does not produce active metabolites (unlike vecuronium and pancuronium)
How do pts. w/ severe anemia compensate?
Cardiovascular compensation for pts. w/ chronic and severe anemia is primarily mediated through an increase in cardiac output secondary to decreased blood viscosity
The concentration of what molecules can increase after dialysis?
Large molecules such as proteins are unable to pass through the HD semi-permeable membranes. Serum proteins usually increase following HD due to a concentrating effect
What electrolyte abnormalities can make digoxin toxicity more likely?
- Toxicity is more likely to occur in the setting of hypokalemia (digoxin competes w/ K for the same binding site on Na/K ATPase)
- Digoxin use in pts. w/ hypomagnesemia or HYPERcalcemia may result in toxic increase of intracellular calcium which can cause ventricular arrhythmias
What kind of cardiac pacing results in higher cardiac output, ventricular or atrioventricular pacing?
AV sequential pacing results in a 10-50% improvement in cardiac output compared w/ ventricular pacing alone
What pts. require fructosamine testing? What HbA1C level is diagnostic for DM?
- Fructosamine testing is used for pts. who have reduced RBC lifespans (hemolytic anemia, sickle cell disease)
- A HbA1C level of 6.5% or higher, is diagnostic for DM
What roles do pKa/concentration/lipid solubility play when administering local anesthetics?
- pKa and concentration determine the SPEED of onset
- Lipid solubility determines potency, duration of action, and degree of protein-binding
What information is transmitted through the posterior columns/spinothalamic tract/corticospinal tract?
- Posterior Columns: carry touch/vibratory sensation
- Spinothalamic Tract: transmits pain/temperature signals
- Corticospinal Tract: descending motor information
What anesthetic drugs are affected by anti-retroviral (HAART) medications?
- Benzodiazepines and opioids are the most commonly affected (usually prolonged half-life). Protease inhibitors tend to have the most drug interactions.
- Neuromuscular blocking drugs are usually NOT affected
What is the most common side effect of NSAIDs in the elderly?
10-20% of elderly pts. will experience dyspepsia
-There is an increased risk of A-fib, CHF, renal toxicity, and GI bleeding; although these risks are all lower than development of dyspepsia
What are the potential uses for FFP (6)? What are the least stable factors in FFP?
- Treatment of specific factor deficiencies, coagulopathy related to hepatic insufficiency, TTP, dilution coagulopathy after massive RBC transfusion, anti-thrombin 3 deficiency, reversal of warfarin therapy
- Factors 5 and 8 are the least stable factors in FFP and can degrade above 4 degrees Celsius
What agents are contraindicated in MI w/ cardiogenic shock? What agents should be used?
- Vasodilators (nitroglycerin/morphine) are contraindicated in the setting of MI w/ cardiogenic shock
- Positive inotropic agents should be used (dopamine, dobutamine)
What is the best type of anesthetic to use for combined somatosensory/motor evoked potential monitoring?
An intravenous technique w/ either no neuromuscular blockade, or a stable blockade of 1-2 twitches to allow for accuracy of monitoring
What is the most common reaction that occurs in pts. receiving a blood transfusion? Who does it occur in most commonly?
- Non-hemolytic febrile reaction is the most common reaction. It is defined as a temperature increase of greater than 1 degree Celsius w/o concurrent hemolysis
- This occurs b/c recipient antibodies cause lysis of donor leukocytes
- Febrile reactions are relatively common in multi-transfused and multiparous pts.
What is the mechanism for cardiac toxicity from local anesthetics? What are presenting signs of LAST?
- Toxicity involves delayed repolarization via action potential inhibition w/ the binding of voltage-gated Na channels
- Local anesthetic toxicity can present w/: perioral numbness, metallic taste, confusion, seizures, and ventricular tachycardia/fibrillation, or asystole
What are risk factors for development of heparin resistance (5)? What is the treatment?
- Anti-thrombin levels <60% of normal
- Platelet count 300,000 or greater
- Preoperative heparin therapy
- Use of low molecular weight heparin
- Age 65 or greater
-Treatment includes supplemental heparin, anti-thrombin 3, or FFP
What nerves are involved in an ankle block?
- 5 nerves must be blocked:
1. Sural
2. Saphenous
3. Superficial peroneal (first 3 are purely SENSORY)
- Tibial
- Deep peroneal (these last 2 are motor AND sensory)
What is the most common type of nerve injury postoperatively? What are the risk factors?
- Ulnar nerve injury. Males are more likely than females to develop ulnar neuropathy
- The brachial plexus is also highly vulnerable
- Risk factors: male gender, BMI >38, prolonged postoperative bed rest
What is the current theory for how malignant hyperthermia is transmitted?
-The genetic inheritance patterns are not completely understood- autosomal dominant inheritance w/ variable penetrance is currently how it is thought to be transmitted
Differences between gastroschisis and omphalocele?
- Gastroschisis: occurs to the right of the umbilicus. Has a higher incidence of heat loss, rapid dehydration, infection and postoperative bowel hypo-motility than omphalocele
- Omphalocele: central defect of the umbilical ring. Typically larger defect than gastroschisis (stomach and liver are often involved). Often assoc. w/ other physical/chromosomal anomalies.
Pectus carinatum is more commonly seen in males or females? When do pts. present for surgery?
- It is more common in males. Pts. typically present in their adolescent years
- The postoperative course is complicated by high analgesic requirements and respiratory complications (i.e. flail chest)
In a spontAneously breathing pt. using a Mapleson A circuit, how much fresh gas flow should be used to prevent rebreathing of CO2?
- The FGF must be equal to the minute ventilation to prevent rebreathing of exhaled gas
- The FGF must be equal to 1-2 times minute ventilation in the Mapleson D, E, and F circuits in order to prevent rebreathing of exhaled gas during CONTROLLED ventilation
What is a complication following parathyroidectomy? What are the symptoms?
- Hypocalcemia
- Signs/symptoms: distal paresthesias, tetany, and in severe cases, seizures and laryngospasm
How can perioperative median nerve injury occur?
- It can occur from forced elbow extension (after neuromuscular blockers have been given), or by iatrogenic trauma during i.v. placement in the antecubital fossa
- Presents as decreased sensation over the lateral 3.5 fingers, or loss of ability to oppose the 1st and 5th digits
How is massive transfusion defined? When is platelet transfusion indicated?
- It is defined as receiving more than 10 units of blood products in a 24 hour period
- In a massive transfusion, platelet transfusion is indicated if less than 75,000 and in pts. w/ ongoing bleeding if less than 50,000
Anesthetic considerations in pts. w/ Down syndrome/rheumatoid arthritis?
- Cervical spine instability
- The transverse and alar ligaments provide support for the atlantoaxial joint
What are differences between volume control and pressure control ventilation?
- Volume control uses a constant flow rate to deliver a breath
- Pressure control delivers the breath as a deceleration, which improves pt. comfort
What lesions are assoc. w/ hypoplastic left heart syndrome (5)?
- Atrial septal defects
- Stenotic/atretic mitral/aortic valves
- Hypoplastic left ventricle
- Hypoplastic ascending aorta
- Patent ductus arteriosus
What are physiologic changes that occur in obese pts.? How should doses be given for propofol, succinylcholine, rocuronium?
- They have increased butyrylcholinesterase activity and extracellular fluid volume
- Total body weight: maintenance infusion of propofol, succinylcholine
- Lean body weight: induction dose of propofol, fentanyl, thiopental
- Ideal body weight: rocuronium, vecuronium
What are potential obstetric nerve injuries during childbirth and/or obstetric surgery?
-Lesions to the lumbosacral trunk, common peroneal nerve, meralgia paresthetica (lateral femoral cutaneous nerve), femoral nerve, and obturator nerve
What are physiologic goals for brain-dead donors (organ procurement)?
- MAP of 60 or greater
- Urinary output of 1 mL/kg/hr or greater
- Left ventricular EF of 45% or greater
-A 3-drug protocol is often used: thyroid replacement therapy, steroids, vasopressin
What is the triad of TURP syndrome? What is the treatment?
- Elevated systolic and diastolic pressures
- Bradycardia (may be due to HTN or increased ICP)
- Mental status changes
-Symptomatic pts. w/ NA <120 should have the serum osmolality corrected w/ 3% hypertonic saline and loop diuretics
What is amniocentesis used for? What technique should be used for sampling if the fetus is less than 15 weeks old?
- Amniocentesis is used for diagnosis and treatment of fetal disorders
- Chorionic villus sampling should be performed if the fetus is <15 weeks old
What should be done after cardiac arrest and ROSC?
- A 12-lead EKG should be obtained ASAP to determine whether acute ST-segment elevation is present
- Goals: O2 sat 94-99%, avoidance of hyperthermia, treat hypotension if systolic is <90 or MAP is less than 65
What are considerations in pts. w/ transplanted lungs?
- Transplanted lungs are denervated and cough reflex/mucociliary function will likely be impaired
- Lymphatic drainage is also absent and predisposes pts. to pulmonary edema w/ over-zealous fluid administration
How does thiopental affect the cerebral flow-metabolism relationship and cerebral autoregulation?
- They remain intact w/ use of thiopental
- Thiopental decreases cerebral blood flow and CMRO2 by 30% w/ induction doses, and by 50% upon achievement of an isoelectric EEG
What changes are seen in the renal function of pregnant pts.?
Increased GFR (by about 50%) w/ decreases in urea, uric acid, and creatinine. An increase in glycosuria is also seen
What is seen in pts. w/ hepatopulmonary syndrome?
- Intrapulmonary vascular dilatations
- Increased A-a gradient
- Hepatic failure
- Excessive levels of circulating nitric oxide cause V/Q mismatching
- A positive contrast-enhanced ECHO supports the diagnosis in a pt. w/o underlying cardiopulmonary disease**
What can be done when a pt. has a decreasing mixed venous saturation?
- Focus on increasing cardiac output and arterial saturation. If it remains low, consider giving a RBC transfusion
- In cases of sepsis or high catabolic states, treating the underlying reason for increased O2 consumption can also improve mixed venous saturation
What lung values increase w/ aging? What values decrease?
Increase:
- Closing capacity
- FRC
- Residual volume
Decrease:
- Vital capacity
- Diffusion capacity
Where are M2 and M3 receptors found? How do opioids cause miosis?
- M2: heart, lungs
- M3: smooth muscle (vascular, airway, ocular)
*Opioids cause miosis by binding to opioid receptors on the parasympathetic Edinger-Westphal nucleus in the brainstem. This nucleus then stimulates M3 muscarinic receptors, causing pupil constriction
What are the 5 criteria that may predict need for postoperative mechanical ventilation for pts. w/ myasthenia gravis?
- Duration of disease 6+ years
- Presence of pulmonary disease(s) unrelated to MG (i.e. COPD)
- Vital capacity of <2.9 L
- Negative inspiratory force <20 cm H2O
- Daily pyridostigmine dose >750 mg
-The leading predictor for postop respiratory failure is the inability to clear secretions and produce a strong cough
During closure of gastroschisis, what 2 factors suggest a staged-procedure should be performed?
-Increases in central venous pressure above 4 mm Hg, and intragastric pressure above 20 is assoc. w/ increased ischemia of the bowel
What agent should be used for uterine relaxation in a pt. w/ a retained placenta?
-Nitroglycerin. Volatile anesthetics are a potential 2nd option if nitro is ineffective
What is the difference between type 1 and 2 hepatorenal syndrome?
- Type I: ACUTE renal failure caused by an inciting event in pts. w/ liver cirrhosis
- Type II: gradual onset of renal failure not assoc. w/ an inciting event
*Unlike type 2, type 1 improves w/ treatment and stabilizes. Vasoconstrictors and volume expanders are the mainstay of treatment. Liver transplant is the definitive treatment for type 1/2 HRS
Which molecule is more active, T3 or T4?
Triiodothyronine is 3-4 times more active than thyroxine and directly affects the myocardium, causing lymphocytic and eosinophilic infiltration. T3 also causes fibrotic/fatty changes within the myocardium
Does magnesium prolong or shorten neuromuscular blockade? What about calcium?
- It prolongs neuromuscular blockade w/ non-depolarizing agents
- Calcium shortens neuromuscular blockade w/ non-depolarizing agents (it increases release of ACh)
What pts. have increased production of acetone during use of a closed circuit technique?
- Alcoholics, pts. w/ cirrhosis, malnutrition, or ketoacidosis. Acetone is removed by the lungs during exhalation
- Rebreathing of acetone can lead to nausea/vomiting/slow emergence
What factors attenuate hypoxic pulmonary vasoconstriction? How is HPV modulated?
- HYPOcapnia and alkalosis attenuate HPV
- HPV is triggered locally in the hypoxic alveolus by PAO2 and PvO2 and modulated in a paracrine fashion by local vasodilators and vasoconstrictors (i.e. nitric oxide/endothelin). It is NOT modulated by the autonomic nervous system
What determines duration of action for opioids? Why does fentanyl have faster onset than morphine?
- Lipid solubility determines the duration of action for opioids
- Lipophillic compounds (fentanyl) have faster onset and decreased duration of action compared to HYDROphillic compounds (morphine).
- Faster onset is due to penetration across the blood-brain barrier and decreased duration of action is due to redistribution into peripheral tissues
What are the premedication doses for midazolam/ketamine in pediatric pts.?
- Midazolam dose increases w/ decreasing age. Total oral dose should not exceed 15-20 mg. It is effective within 10-15 minutes.
- Oral ketamine dose is 5-6 mg/kg. IM dose is 2-5 mg/kg and is effective within 5 minutes
What are the management goals for pts. w/ cardiac tamponade?
-To keep the heart ‘full, fast, and tight’
Maintain preload w/ volume resuscitation, keep heart rate up, and maintain SVR w/ pressors
What is the standard therapy for hemophilia A?
- Factor 8 concentrate. Mild cases of hemophilia may respond to desmopressin.
- A factor 8 level of 30% for mild hemorrhages and at least 50% for severe hemorrhages is advisable
Where does dexmedetomidine act to produce its sedative-hypnotic effect?
It involves endogenous sleep pathways through alpha-2 receptors in the locus ceruleus
What is responsible for ‘fade’ during non-depolarizing neuromuscular blockade?
- Nondepolarizing neuromuscular blocking drugs bind to presynaptic and post-synaptic receptors. They prevent re-uptake of ACh at presynaptic receptors.
- As a result, ACh becomes depleted w/ each TOF stimulation, causing a ‘fade’
What facet block location has the highest chance of intravascular injection?
Cervical facet injections carry a higher risk of intravascular complications. This is due to the vertebral artery lying just lateral to the cervical facet joint
What are potential causes for a unilateral epidural block?
- An epidural catheter that is located laterally in the epidural space
- Inadequate local anesthetic
- Presence of the plica mediana dorsalis (midline fold on the dura mater that extends to the ligamentum flavum)
What are risk factors for cauda equina syndrome after insertion of intrathecal catheters?
- Use of a MICROcatheter
- High local anesthetic concentration
- Directing the tip in the dependent direction
- Slow and low-pressure injection of local anesthetic
*Factors that contribute to maldistribution of local anesthetic (such as spine tumors) have been reported in cases of CES
What is the only modality which consistently shows a reduction in post-thoracotomy respiratory complications?
Thoracic epidural catheter placement
What can happen when a bilateral carotid endarterectomy is performed?
Billateral carotid body denervation can occur- it can impair the ventilatory response to mild hypoxemia. This is much more likely to occur and cause significant respiratory depression when opioids are given
Up to what age should neonates be monitored after general anesthesia?
- Up until 60 weeks post-conceptual age (to avoid episodes of apnea and bradycardia)
- Post-conceptual age is calculated by subtracting the # of weeks born before 40 weeks from the chronological age
What effect do volatile anesthetics have on cerebral blood flow at low and high concentrations?
- They tend to decrease CBF by decreasing cerebral metabolic rate of O2 consumption (at 0.5-1.0 MAC)
- At higher concentrations, they tend to increase CBF by causing cerebral vasodilation (at 1.5-2.0 MAC)
*Nitrous oxide does NOT cause a decrease in CMRO2**
What are the most common causes of post-partum hemorrhage?
- Uterine atony
- Retained placenta
- Genital-tract trauma
- Coagulation disorders
What are absolute contraindications for shock wave lithotripsy?
- Pregnancy
- Bleeding disorders/anticoagulation therapy
What is the recommended initial treatment for a hyperoxic seizure during hyperbaric oxygen therapy?
- Immediate reduction in the inspired PO2. The chamber should not be decompressed until after the seizure has stopped (due to risk of pulmonary barotrauma if the pt. is unable to exhale)
- Pts. receiving bleomycin are at increased risk for developing fatal pulmonary oxygen toxicity from supplemental oxygen administration**
What is the 1st-line pharmacological treatment of symptomatic bradycardia in adults?
I.V. atropine (this should not delay pacing if needed)
Where is the stellate ganglion located? What are potential complications of doing a stellate ganglion block?
- The ganglion is the fusion of the C7 and T1 cervical sympathetic ganglion. It lies on the anterior surface of the C7 vertebral body. The approach is at C6 b/c the vertebral artery lies anterior to the C7 transverse process
- Complications: hoarseness (unilateral paralysis of recurrent laryngeal nerve), paralysis of phrenic nerve, hematoma, pneumothorax, etc
What changes occur w/ tourniquet inflation/deflation?
- Inflation: causes HTN and increased HR
- Deflation: causes HYPOtension (due to ischemic mediator-induced vasodilation). After deflation, increased lactate/K/End-tidal CO2 occur. Metabolic acidosis is often seen
What things can lead to degradation of the endothelial glycocalyx layer?
- Hypervolemia, hypoxia/ischemia, inflammatory factors, and atrial natriuretic peptide
- Injury can lead to development of edema
How long should nitrous oxide be avoided after injection of A.) Air, and B.) sulfur hexafluoride injection intraocularly?
- If air is used, 5 days
- If SF6 is used, 10 days (will create bubble expansion if used)
Does the placenta consume oxygen? What promotes O2 transfer from mother to fetus?
- Yes. The O2 consumed by the placenta decreases O2 available for transfer to the fetus
- Mechanisms which promote O2 transfer from mother to fetus: higher fetal Hb concentration, the Bohr effect, and the double Bohr effect
What are the 4 components of thromboelastography (TEG)?
- “R” (Reaction Time): from time 0 to initial clot formation. Normal range is 1-3 minutes
- “K” (Coagulation Time): measures speed of clot formation and strengthening. It relies on fibrinogen. Equal to the time from amplitude of 2mm to 20 mm
- “MA” (Maximum Amplitude): measures the strength of the fully formed clot. It reflects platelet # and function (primarily), as well as fibrin cross-linking. Normal is 50-60 mm
- Alpha-Angle: speed of clot formation. This relies on fibrinogen. Normal angle is 45-55 degrees.
What does a P50 value indicate (for hemoglobin)?
- Normal value is 27
- It corresponds to the partial pressure of O2 at which 50% of the Hb is saturated at normal pH and temperature
What current range is associated w/ high risk for intraneural injection during peripheral blocks?
Motor stimulation w/ < 0.2 mA is associated w/ intraneural injection
What is a contraindication for use of droperidol?
It is contraindicated in any pt. w/ a documented prolonged QT, or in pts. w/ electrolyte disturbances (at risk for development of prolonged QT- i.e. hypomagnesemia)
What are the 3 main components of therapy in pts. w/ DKA?
- Intravenous fluids
- Insulin
- Electrolyte replacement
What local anesthetics can be used for intravenous regional anesthesia (3)?
- Lidocaine (0.5-2%)
- Prilocaine (0.5%)
- Levobupivicaine (0.125%)
What are symptoms of congenital muscular dystrophy?
- They present in infancy w/ hypotonia, feeding difficulty, respiratory dysfunction
- They are NOT assoc. w/ increased risk for MH, but can lead to rhabdomyolysis or cardiac arrest after general anesthesia
What pts. are at risk for developing metformin-associated lactic acidosis? Should it be taken perioperatively?
-Metformin is excreted 90% unchanged by the kidneys. It should be continued perioperatively except in cases of acute renal failure, or in situations where the risk of renal insufficiency is high (i.e. contrast administration)
Pts. w/ myasthenia gravis have increased sensitivity to which kind of muscle relaxants?
- They are very sensitive to NON-DEPOLARIZING neuromuscular blocking drugs (regardless of their treatment status)
- Pts. being treated w/ cholinesterase inhibitors (pyridostigmine) have reduced metabolism of succinylcholine- depolarizing relaxants are therefore more likely to cause prolonged phase I blockade
What are possible complications of a stellate ganglion block?
- Vasovagal reactions
- Intravascular/spinal injection
- Horner syndrome (ptosis, anhidrosis, miosis) may also have enopthalmos and hyperemia of the eye
What does the standard error of the mean describe?
It describes the PRECISION of the population mean
How do spinal cord stimulators work?
They activate the larger A-alpha and A-beta fibers to a greater degree than the smaller nociceptive A-delta and C fibers. This closes the ‘gate’ and impedes conduction of pain sensation past the substantia gelatinosa of the dorsal horn of the spinal cord
A latex allergy is caused by what type of immune reaction?
Type I IgE-mediated antibody response
What should be done in pts. w/ pre-operative acute viral hepatitis?
Surgery should not proceed unless deemed an emergency; the risk of morbidity and mortality is significantly elevated in these pts.
In most pts., greatest amount of heat loss during general anesthesia is due to what mechanism?
- Radiation
- This is followed by: convection, evaporation, and conduction
What are the respiratory changes in the pregnant pt. (4)?
- Cephalad movement of the diaphragm
- Increase in anteroposterior/transverse diameter of thoracic rib cage
- Decrease in FRC (decreased expiratory reserve volume/residual volume)
- Increase in INSPIRATORY reserve volume
Considerations for SSEPs/MEPs? What agent enhances MEP amplitude?
- SSEPs and MEPs are sensitive to volatile anesthetics, but MEPs are, to a greater degree
- Paralytic agents cannot be used w/ MEPs
- Ketamine will enhance MEP amplitude
Mallampati definitions?
- MP I: full view of soft palate/uvula/tonsillar pillars
- MP II: upper portion of uvula/soft palate/fauces
- MP III: hard palate/soft palate/base of uvula
- MP IV: hard palate only
Common cause of post-operative hypoxemia? Treatment?
Atelectasis (w/ resultant decreased FRC). This produces a (usually small) right-to-left shunt which is more responsive to increasing mean airway pressures/PEEP (vs. increasing FiO2)
How can cerebral salt-wasting syndrome vs. diabetes insipidus be distinguished? What is the treatment for DI?
- Cerebral salt-wasting syndrome causes LOW Na concentrations within the blood (low serum osmolality) w/ dehydration.
- DI causes polyuria, HYPERnatremia (HIGH plasma osmolality), low urine osmolality
- *Desmopressin is the treatment for DI**
1st-line treatment for symptomatic bradycardia?
Atropine (0.5 mg repeated every 3-5 minutes to a maximum of 3 mg)
Absorption of glycine-containing irrigation solution during TURP may lead to what symptoms?
It may lead to hyper-ammonemia, causing neurological complications (encephalopathy and coma)
What happens to closing capacity in obese pts.?
Obese pts. have severely reduced FRC, which narrows the gap between closing capacity and tidal volume, predisposing these pts. to rapid desaturation w/ periods of apnea
What does a z-score mean if it is outside the range of the critical value?
In a test of proportions, if the z-score is outside the range of the critical value (higher than the critical value), the populations are unlikely to be similar (i.e. one group has greater effect w/ the intervention, etc)
What does the hepatic extraction ratio refer to? What are drugs w/ LOW hepatic extraction ratios (4)?
- Hepatic extraction ratio is the fraction of drug removed from blood passing through the liver
- Drugs w/ LOW hepatic extraction ratios: diazepam, methadone, rocuronium, and thiopental
What reaction can pts. w/ myotonic dystrophy have when succinylcholine is given?
-Excessive fasciculations/contractures may occur which can impair ability to ventilate and intubate
(Myotonic dystrophy is a disease of impaired muscle relaxation)
What are concerns w/ burn pts.?
- Large burns can cause hypothermia leading to coagulopathy (also impaired fibrinogen production)
- Succinylcholine should be avoided 48 hours after burn injury
Causes of prolonged PT?
- Liver disease
- Cystic fibrosis (deficient vitamin K)
- Warfarin
Lupus anticoagulant causes prolonged PTT (these pts. are actually PROthrombotic)
What 4 things increase statistical power?
- Increasing sample size
- Increasing effect size
- Increasing alpha (e.g. p-value)
- Reducing population variability (e.g. standard deviation)
What are the risks for repeat c-section vs. TOLAC?
- Repeat c-section: higher risk of maternal mortality
- TOLAC: higher risk of perinatal mortality
Characteristics of Cushing syndrome?
- Cushing syndrome results from prolonged exposure to excess cortisol
- Symptoms: fatty deposits in face/neck, abdominal weight gain, thinning of extremities, hirsutism, elevated blood glucose, mood changes
What drugs are metabolized/not metabolized in the lung?
- Metabolized: NE, Serotonin, Bradykinin, Angiotensin-1
- Not Metabolized: Epinephrine, Etomidate, Neuromuscular blocking drugs
What is a t-test used for?
- To compare 2 different MEANS
- It can be from paired or unpaired data (unpaired: 2 groups that aren’t associated. Paired: mean glucose value before and after a new medication for subjects). i.e. the means are ‘paired’ to the study subject
Most likely organisms responsible for ventilator-associated pneumonia within the first 48 hours after endotracheal intubation?
- Antibiotic-sensitive flora (methicillin-sensitive Staph aureus, H. influenzae, S. pneumoniae, Proteus, Klebsiella, Enterobacter)
- Early onset VAP has a negligible chance of causing any effect on morbidity/mortality
EKG changes w/ hyperkalemia?
-Earliest feature: peaked T-waves. This is followed by prolongation of PR segment, P-wave flattening, QRS prolongation, AV nodal block, bradycardia, asystole
What are the 5 lab findings in SIADH?
- Urine osmolality >100 mOsm (often >200-300)
- FENa >1 % (prevents diuresis but still permits natriuresis)
- Urine Na >20 mEq/L
- Low serum uric acid/BUN
- Dilutional, euvolemic HYPOnatremia (serum Na <135)
Symptoms of intravascular/intrathecal injection after a test dose of a local anesthetic/epinephrine?
- Intravascular: perioral numbness/metallic taste in mouth, tinnitus, tachycardia/HTN, lightheadedness
- Intrathecal: profound lower extremity motor blockade/hypotension
What are positive/negative effects from adding epinephrine into local anesthetic/opioid solutions for epidural labor analgesia?
-Positive:
More rapid onset/longer duration of analgesia, enhanced analgesia (due to alpha-1 receptor stimulation), decreased local anesthetic/opioid requirements
-Negative:
Increased intensity of motor blockade, cost, increased risk of drug error
What is the treatment for coronary artery vasospasm?
Nitrates or calcium channel blockers (Nicardipine is the most effective CCB)
What are findings in pts. w/ Morquio syndrome? (Type IV mucopolysaccharidosis)
- It is an autosomal recessive lysosomal storage disorder (inability to metabolize keratan sulfate)
- Short-trunk dwarfism, corneal deposits, normal intellegence, genus valgus, odontoid hypoplasia w/ atlantoaxial instability
How many total lung segements are there? Postoperative FEV/DLCO values associated w/ greater postoperative complications?
- There are 42 total lung segments (10 in left upper/lower lobe, 6 in right upper, 4 in right middle, 12 in right lower lobe)
- Pts. w/ postoperative predicted FEV1 <40% are at risk for respiratory complications after surgery
- *DLCO <40%: also at risk for cardiac complications postoperatively**
After severe spinal cord injury, what is the goal value for MAP?
To maintain adequate spinal cord perfusion, MAP should be kepts at 85 mm Hg or higher for the first 7 days following injury
Pediatric pre-procedure anxiety is highest for what age range?
6 months-6 years
Describe the 2nd gas effect?
When nitrous oxide rapidly diffuses into the blood; this concentrates the additional inhalational agent within the alveoli
What are common side effects of flumazenil?
- Nausea/vomiting
- Seizures are unlikely to occur w/ small doses
Methods for management of hypoxemia during 1-lung ventilation?
- PEEP to the dependent lung
- CPAP to the non-dependent lung
- Suctioning/ensuring proper tube/bronchial blocker positioning, muscle relaxation, intermittent 2-lung ventillation, clamping of the pulmonary artery
What blood produce has the lowest risk of TRALI?
- PRBCs have a lower risk of TRALI b/c the plasma fraction is removed during processing
- Plasma-containing blood products have higher risk for development of TRALI. FFP and platelets have the highest incidence of TRALI
What agents do transplanted hearts respond to?
- Direct acting agents (isoproterenol)
- They don’t respond to vagal stimulation
What are the components of a fetal biophysical profile (5)?
- A non-stress test (HR acceleration of 15 for 15 minutes, etc)
- Fetal breathing
- Fetal movement
- Fetal tone
- Amniotic fluid volume
Does neuraxial labor analgesia cause prolongation of labor?
Yes. It causes a slight prolongation (15 minutes) of the 2nd stage of labor
Double lumen sizing for males/females?
Males: if less than 5 7’: 39F, if greater: 41F
Females: if less than 5 3’: 35F, if greater: 37F
What are the characteristic features of the infant airway (5)?
- A proportionally larger tongue
- More cephalad larynx
- Short omega-shaped epiglottis
- Angled vocal cords
- Relatively larger head
What colors of nail polish cause falsely low oxygen saturations w/ pulse oximeters?
-Blue, green, and to a lesser extent, black nail polish
What are major complications of rheumatoid arthritis?
- TMJ motion restriction
- Atlantoaxial subluxation
- Cardiac involvement (aortic/mitral regurg, pericardial effusion)
- Pulmonary fibrosis/effusion
Treatment for intraoperative thyroid storm?
- First, remove the offending stimulus/event
- A thyrostatic medication must be given first (propylthiouracil), then thyroid hormone release can be blocked by sodium/potassium iodide
- Supportive therapies: IV fluids, hydrocortisone, beta-blockers, anti-arrhythmics, temp. control
What Cobb angle defines scoliosis? What Cobb angle is an indication for surgical intervention?
- A Cobb angle of 10 degrees or more defines scoliosis
- A Cobb angle of >40 degrees is an indication for surgical intervention
What is the vaporizer output equation? What are the saturated vapor pressures for Sevo, Iso, Halo, Des?
VO= (Gas Flow x Saturated Vapor Pressure/ (Barometric Pressure - SVP)
- Sevo: 157 (mm/Hg)
- Iso: 238
- Halo: 243
- Des: 669
What defines a ‘sentinel event’?
It must first reach the patient (a ‘good catch’ is not a sentinel event) and cause severe harm (an error causing no harm is NOT a sentinel event)
What 7 things are premature infants at risk for?
- Intraventricular hemorrhage
- Retinopathy of prematurity
- Respiratory distress syndrome
- Necrotizing enterocolitis
- Metabolic derangements of glucose
- Hypothermia
- Persistent fetal circulation
How does furosemide improve symptoms of CHF acutely?
It dilates venous capacitance beds and reduces systemic venous resistance (thereby decreasing LVEDV and LVEDP)
How does protein-binding affect drug metabolism? Who has higher amounts of plasma proteins?
- The degree to which a drug is protein-bound correlates w/ decreased hepatic metabolism
- Plasma proteins are relatively higher in ‘BOP’ (Burn pts., Obesity, Pregnancy)
- Plasma proteins are relatively decreased w/ hepatic and renal disease, and extremes of age
What regional technique is most associated w/ anterior spinal artery syndrome?
Transforaminal cervical epidural injections are most commonly assoc. w/ this complication
What is the best study to diagnose cerebral vasospasm? What is the best treatment?
- Cerebral angiography
- ‘Triple H’ therapy (hypervolemia/HTN/hemodilution), nimodipine
Management of constrictive pericarditis?
Midline sternotomy to remove the parietal and epicardial pericardium from the heart
Treatment for CNS depression caused by anti-cholinergic medication?
- Physostigmine (can cross the blood-brain barrier)
- PYRIDostigmine cannot (pyramids are large, large things can’t cross the BBB!!)
Anesthetic considerations for pts. w/ Down syndrome?
- Atlantoaxial instability
- Macroglossia/Subglottic stenosis
- ASD/VSD/Endocardial cushion defects
- GI malformations which may promote aspiration
- Extremes of cardiac chronotropy
- Difficult peripheral IV access/severe separation anxiety from caregiver
What can decrease the risk of pre-eclampsia?
- Smoking can decrease the risk by 30-40%
- Low-dose aspirin can be used in pts. w/ history of pre-eclampsia (causes 10-20% reduced risk)
What type of heparin causes HIT more often? What are the tests w/ highest sensitivity/specificity for HIT?
- Unfractionated heparin causes HIT 10 times more often than LMWH
- Antiplatelet factor 4 antibodies are commonly used to diagnose HIT (high sensitivity)
- The serotonin release assay has high specificity for HIT
What agents should be avoided in pts. w/ carcinoid tumors? What is the mneumonic for neuromuscular drugs that release histamine?
- Agents that release histamine should be avoided to prevent precipitating carcinoid crisis (morphine, thiopental, succinylcholine)
- Mneumonic: “MAST” (mast cells release histamine)
- Mivacurium
- Atracurium
- Succinylcholine
- d-Tubocurarine
What is the formula for volume of anesthetic vapor delivered by a vaporizer?
Volume of anesthetic vapor = (volume percent of anesthetic vapor x fresh gas volume)/(1- volume percent of anesthetic vapor)
*1 mL of liquid anesthetic is equal to approx. 200 mL vapor at room temperature**
What is the classic x-ray finding for anthrax toxicity?
A widened mediastinum
What are the differences between alpha-stat and pH-stat management during CPB for acid-base management?
(pH-stat management adds CO2 to the circuit so that the pH remains neutral- hypothermia causes increased pH, remember?)
-Alpha Stat: couples cerebral blood flow w/ cerebral metabolic rate. Autoregulation is maintained and embolic load to the brain is minimized
-pH Stat: increased speed of cerebral cooling through cerebral vasodilation, reduced cerebral metabolic rate, increased CBF and improved O2 delivery to tissue
Disadvantages: increased embolic load to the brain and loss of cerebral autoregulation
What can be used as an initial intervention in a monitored pt. w/ witnessed v-tach?
A ‘precordial thump’ (Hit middle of sternum w/ ulnar part of fist!)
What are 2 phases of amniotic fluid embolism?
- 1st Stage: pulmonary vasospasm and right heart dysfunction/failure
- 2nd Stage: pulmonary edema and left heart dysfunction/failure
- Maternal coagulopathy (consumptive) occurs in the majority of cases
- Emergency C-section is required if uterine hypertonus leads to fetal bradycardia/distress
What are 2 end-points to monitor during CPR?
- Chest compressions should be improved if:
1. End-tidal CO2 is <10 OR
2. Diastolic BP is <20
What compound is citrate metabolized into?
Bicarbonate. It may therefore cause metabolic alkalosis/hypocalcemia
Treatment for post-herpetic neuralgia?
1st-Line Agents: TCAs, opioids, gabapentin, or pregabalin. There is synergy between each class and they should be used in combination if tolerated
What are the 2 ways in which lithium potentiates non-depolarizing neuromuscular blocking drugs?
- It activates K channels in pre-junctional neurons (interferes w/ action potential transmission to nerve terminal)
- It activates K channels on post-synaptic myocytes which inhibits muscle contraction
- Overall dose of non-depolarizing neuromuscular blocking drugs should be reduced for pts. on Li
Methylene blue is contraindicated in pts. taking what kind of medications?
- SSRIs/SNRIs/MAOIs
- Methylene blue is a MAO-A inhibitor and may cause serotonin syndrome in pts. taking these medications
- Treatment is mostly supportive, although cyproheptadine can be attempted (serotonin receptor antagonist)
What are the 5 goals for management of hypertrophic obstructive cardiomyopathy?
- Reduced myocardial contractility
- Maintenance (or increase) of SVR
- Increased preload and CO
- Maintaining a low-normal heart rate
- Avoidance/treatment of arrhythmias
What are the values (normal, mild, moderate, severe) for the apnea-hypopnea index (AHI)?
- Normal: 0-4 (i.e. no OSA)
- Mild: 5-15
- Moderate: 15-30
- Severe: 30 or greater
What kinds of autonomic changes do elderly pts. have?
- Elderly pts. have a decrease in parasympathetic tone and increase in sympathetic tone at rest
- They also have worsening diastolic dysfunction w/ increased left atrial pressures
How does phenytoin use affect non-depolarizing NMBDs?
- Acute administration (of phenytoin) augments neuromuscular block
- Chronic administration results in shorter duration of action of non-depolarizing NMBDs
What are values for prolonged QT interval in males and females? What anesthetic technique is safest in these pts.?
- Males: QTc >450
- Females: QTc >470
- The safest option for maintenance is TIVA w/ propofol and opioids (except methadone). Etomidate, lidocaine, and non-depolarizing NMBs are also safe
Intravenous regional anesthesia technique?
- A double tourniquet is used; the proximal cuff is inflated 150 mm Hg above the systolic pressure
- Prilocaine or lidocaine can be given w/ inflation of the distal cuff and deflation of the proximal cuff when the pt. experiences tourniquet pain
Initial treatment for atrial flutter (in hemodynamically stable pts.)?
An agent that decreases AV conduction (beta-blockers, Ca-channel blockers, or ibutilide)
What are the most important factors influencing block height during spinal injection?
- Density of solution
- Patient positioning (esp. w/ hyper/hypobaric injectate)
- Site of injection (esp. w/ isobaric)
What are the 5 things that can decrease evoked potential amplitude during neuromonitoring?
- Volatile anesthetics
- Nitrous oxide
- Anemia
- Ischemia
- Hypoxia
What are the 4 most accurate sites for measurement of core temperature?
- Tympanic membrane
- Nasopharynx
- Distal esophagus
- Pulmonary artery
What are the 3 drugs approved for fibromyalgia?
‘ePMD’
- Pregabalin
- Milnacipran
- Duloxetine
After receiving naloxone, how long should pts. be monitored?
- Pts. should be monitored for 2 hours for sedation and respiratory depression
- The elderly and obese are particularly prone to re-sedation following naloxone use
- Naloxone has a duration of action of 60-90 minutes
What are the 3 muscle diseases that are assoc. w/ increased susceptibility for MH? What kind of inheritance pattern is seen w/ MH?
- Central Core Disease
- Multi-Minicore Disease
- King-Denborough Syndrome
-MH is inherited as an autosomal dominant condition w/ incomplete penetrance. Triggering agents: succinylcholine and volatile agents (not nitrous oxide)
Why does desflurane require a heated vaporizer?
Desflurane has an extremely high vapor pressure; it vaporizes significantly at room temperature. It requires a heated vaporizer to prevent changes in VAPOR PRESSURE. (vapor pressure would otherwise decrease significantly from evaporative cooling)
What electrolyte abnormalities are seen w/ hyperparathyroidism?
Hyperchloremia and increased renal bicarbonate loss which may result in a normal anion gap metabolic acidosis
What are the 5 standard monitors for a general anesthetic?
- EKG
- Blood pressure
- Oxygenation (pulse oximeter)
- Ventilation (CO2)
- Temperature
How is sepsis diagnosed? How is septic shock diagnosed?
- When a pts. has a suspected infxn, if they have at least 2 of the following, they have sepsis:
- RR 22/min or higher, altered mental status, or systolic BP 100 or less
-If the pt. is then fluid resuscitated and continues to require pressors to maintain MAP of 65 or higher and has a lactate of >2 mmol/L, they are in SEPTIC SHOCK!
What antifungals are the 1st-line treatment for candidemia?
The echinocandins (caspofungin, micafungin), they inhibit 1, 3 beta-D glucan synthase and cell wall synthesis
What value of pulse pressure variation is assoc. w/ responsiveness to fluids?
- If the PPV is > 13% the pt. should be responsive to fluids
- PPV is most accurate in the setting of controlled positive pressure mechanical ventilation w/ tidal volumes 7-8 mL/kg and NO PEEP
What can create a respiratory quotient greater than 1? How is it calculated?
- A RQ >1 can result from lipogenesis. Excess carbs can lead to lipogenesis and a RQ >1
- RQ= CO2/O2 (the ratio of CO2 produced to O2 consumed)
When does a post-dural puncture headache usually present? What is the incidence when the dura is punctured w/ the epidural needle?
- It usually presents 6-72 hours after dural puncture, commonly accompanied by nausea/neck stiffness and ocular/auditory manifestations
- Incidence is 50% when the dura is accidentally punctured w/ the epidural needle
What are the best treatment options for neuraxial opioid-induced pruritis?
- 5 HT3 receptor antagonists
- Opioid antagonists (full and partial, i.e. nalbuphine)
- NSAIDS
- Droperidol/propofol
*Antihistamines don’t work, they only cause sedation**
What are 2 concerns w/ pts. who have placenta previa?
- It confers increased risk of intraoperative blood loss
- There is a high risk of placenta accreta in pts. w/ previa who have had previous c-sections
Who develops myalgias more often after succinylcholine administration?
- Risk of myalgias is higher in females and ambulatory pts.
- Pts. who are in good shape w/ increased muscle tone/bulk have lower risk. Elderly and children also have lower risk
What happens to plasma volume and total blood volume in the pregnant pt.?
- Plasma volume and total blood volume are increased, but red cell volume is not increased to the same degree, which results in an anemia of pregnancy (Hb: 11-12)
- A greater mineralocorticoid activity increases total body water content
4 medications that can trigger carcinoid crisis?
- Atracurium
- Ketamine
- Morphine
- Meperidine
What is the drug of choice to treat myasthenic pts. who are pregnant?
- Pyridostigmine is the agent of choice for treatment
- Myasthenia graves in pregnant pts. is assoc. w/ preterm labor and increased maternal mortality
3 causes of increased beta-1 and beta-2 receptor density in the cardiac sarcolemma?
- Beta-blocker use
- Myocardial ischemia
- Hyperthyroidism
What is seen in pts. w/ potassium-aggravated myotonia?
- It is not associated w/ weakness
- Succinylcholine should be avoided b/c of risk of spasms/stiffness
Does helium have decreased density, or viscosity, compared to O2?
He has decreased gas DENSITY compared to O2
“He is not dense”
How long will it take for a pneumothorax to double and triple in size w/ 75% nitrous oxide?
It will double in size by 10 minutes, and triple in 30 minutes
What are 6 common physiological changes seen after brain death?
- Myocardial dysfunction
- Catecholamine storm
- Hemodynamic instability/hypovolemia
- Pulmonary edema
- HYPERglycemia
- Polyuria (from diabetes insipidus)
What are 9 risk factors for difficult bag-mask ventilation?
- Beard
- BMI >26
- Edentulous
- Age >55
- Hx of snoring
- Mallampati 3 or 4
- Limited mandibular protrusion
- Mouth opening < 3 cm
- Thyromental distance < 6 cm
What is the most common type of tracheoesophageal fistula? 50% of TEFs are associated w/ VACTERL abnormalities- what is VACTERL?
- Type C (esophageal atresia w/ distal TEF)
- Vertebral defects
- imperforate Anus
- Cardiac anomalies
- TEF
- Renal dysplasia
- Limb anomalies
When can phase-2 blocks develop w/ use of succinylcholine?
Phase 2 blocks (train of 4 fade/post-tetanic potentiation) can develop when sux is given to pts. w/ butyrylcholinesterase deficiency, or when given in high cumulative doses (i.e. 5 mg/kg)
How do increased altitudes affect variable-bypass vaporizers (sevo, iso) and desflurane vaporizers?
- Variable bypass vaporizers deliver constant partial-pressures of anesthetic. At high altitudes, the vaporizers have to increase the output so that the delivered concentration increases (i.e. delivered concentration of isoflurane at sea level: 1%, which is equal to 7.6 mm Hg partial pressure. At high altitude: delivered concentration is 2%, which still equals 7.6)
- Des vaporizers deliver fixed % concentrations. The dialed inspired concentration must be increased at higher altitudes to maintain appropriate partial pressure of des
What effects do ketamine and etomidate have on somatosensory evoked potentials?
They enhance the quality of the signals
What does a dibucaine number signify? What is a normal/abnormal number range?
- The dibucaine test measures the amount of pseudocholinesterase inhibition caused by the addition of dibucaine to a sample of the pt.’s blood
- Dibucaine inhibits NORMAL pseudocholinesterase by 70-80% (dibucaine # of 70-80) and only minimally inhibits abnormal pseudocholinesterase
- A small dibucaine # indicates ABNORMAL pseudo activity (heterozygous: 50-60, homozygous 20-30)
What receptors does ipratropium antagonize?
The M3 muscarinic receptor. It causes bronchial smooth muscle relaxation
When should a bronchial blocker be used vs. a double lumen tube?
- Bronchial blockers are useful in difficult airways, pts. who are already intubated (or will remain intubated), pts. w/ a tracheostomy
- DLTs are more likely to cause airway injury
What 3 medications can reduce pulmonary HTN in children?
- Inhaled nitric oxide
- Epoprostenol
- Sildenafil
What is the drug of choice in paroxysmal supraventricular tachycardia (in a hemodynamically stable pt)?
- Adenosine
- It is contraindicated in pts. w/ asthma (can cause bronchospasm)
What electrolyte abnormalities are seen in pts. w/ hypothyroidism?
Hyponatremia and hypoglycemia
What nasal structures increase the surface area of the nasal cavity?
The nasal turbinates (AKA concha) moisten and warm inspired air
What are normal values for pulmonary artery occlusion pressure and pulmonary artery diastolic pressure?
From 4-12 mm Hg
What nerve distribution does a transversus abdominus plane block affect?
- T7-L1 (Anesthetic is injected between the transversus abdominis and internal oblique)
- It can provide unilateral analgesia to skin, muscle, and the parietal peritoneum of the abdominal wall
CNS alterations in the elderly (related to neruaxial anesthesia)?
- Decrease in myelinated nerves within ventral/dorsal nerve roots
- Reduction in the epidural space
- Decreased CSF volume
- Increased permeability of the dura
What type of induction should be used in pts. w/ acute epiglottitis?
Inhalational induction in the sitting position w/ maintenance of CPAP during spontaneous ventilation to prevent inspiratory laryngeal airway collapse/irritation
What is the venous admixture equation?
Qs/Qt= (pulmonary capillary blood O2 content - arterial blood O2 content)/(PCB O2 content - mixed venous blood O2 content)
-This equation measures the venous admixture
Criteria for chronic bronchitis Dx?
- It is a type of COPD characterized by a productive cough during most days for 3 consecutive months out of the past 2 years
- An elderly, long-term smoker w/ excessive secretions has chronic bronchitis until proven otherwise**
What causes epiglottitis in kids?
- Haemophilus influenzae (bacterial). It causes sore throat, dysphagia, stridor, drooling, chest retractions
- It usually occurs in kids 2-6 years old
What factor modulates hepatic arterial vasoconstriction/vasodilation in response to portal venous flow?
Adenosine
Should IV hydrocortisone be given to pts. in septic shock?
- It can be given ONLY if hypotension is refractory to volume replacement and vasopressor therapy
- Hydrocortisone inhibits nitric oxide synthesis**
What is one of the earliest signs of diabetic autonomic neuropathy?
- Decreased heart rate variability w/ breathing, followed by resting tachycardia
- Other symptoms include gastroparesis, urinary retention, and erectile dysfunction
What can occur w/ glucose-loading during TPN administration?
HYPOphosphatemia. It is most commonly caused by an increase in intracellular movement of phosphate
What test can be used in pts. w/ liver disease to differentiate DIC from end-stage liver disease?
- Factor 8 can be used
- In DIC, factor 8 will be decreased
- Coagulopathy due to end-stage liver disease will show a normal or elevated factor 8 level
Can opioids reduce the seizure threshold?
Yes!!
Does glucagon increase or decrease hepatic artery blood flow?
Increase!!
What is the reduction in cerebral metabolic rate for every degree Celsius decrease in temperature?
There is a 6-7% reduction in cerebral metabolic rate per degree-Celsius decrease in temp.
What is a concern during use of inhaled NITRIC oxide?
It can cause methemoglobinemia. It results in Hb that is unable to release O2, and causes a left-shift in the oxyhemoglobin dissociation curve
How does a peripheral arterial waveform differ from a central arterial waveform?
A more peripheral arterial waveform will have a higher systolic pressure, a wider pulse pressure, a more delayed and slurred dicrotic notch, and a more pronounced diastolic wave
Where are the 2 most important sites of action for spinal and epidural anesthesia?
- Dorsal root ganglia
2. Spinal nerve roots
Treatment of thyroid storm?
- Symptom control w/ propranolol
- Inhibiting thyroid hormone synthesis/secretion (propylthiouracil/methimazole)
- Avoid aspirin!! (competes w/ T3 and T4 for binding to thyroid binding globulin)
What causes acute mountain sickness? What is the treatment?
- It occurs at high altitudes as a result of hypoxia
- Acetazolamide provides both prophylaxis and treatment by causing an acidosis that shifts the C02-response curve leftward
- Descent, and dexamethasone are other treatments
What defines refractory angina pectoris?
- It is chest discomfort due to ischemia that persists despite optimized medical therapy in pts. who can’t be treated w/ percutaneous or surgical revascularization.
- Treatment: lifestyle modification, enhanced external counter-pulsation, spinal cord stimulation, transmyocardial revascularization, and thoracic epidural
What is the major disadvantage of doing a paracervical nerve block during labor?
A high frequency of fetal bradycardia (assoc. w/ decreased fetal oxygenation and fetal acidosis)
What are the anatomic boundaries for the triangle of Petit?
- Anterior: External oblique
- Posterior: Latissimus dorsi
- Inferior: Iliac crest
(For TAP blocks)
Management for acute mitral regurgitation (in a normotensive pt)?
Temporizing measures to decrease regurgitant flows: arterial vasodilators (sodium nitroprusside) and inotropic agents when contractility is impaired (milrinone)
What age group does croup occur in most commonly?
- Laryngotracheobronchitis (croup) is a viral sub-glottic syndrome that occurs most commonly in pts. 6 months-6 years of age
- Pts. have inspiratory stridor, a ‘barking’ cough, hoarseness, and low-grade fever
*Chest X-ray shows the ‘steeple sign’**
What 3 additives can be used to prolong anesthesia during peripheral nerve blocks?
- Epinephrine
- Steroids (dexamethasone)
- Alpha-2 agonists (clonidine)
*Epinephrine doesn’t significantly prolong ropivicaine/bupivicaine epidural/peripheral blockade**
What effects does propofol have on hypoxic pulmonary vasoconstriction and in pts. w/ COPD?
- It can potentiate HPV
- It causes bronchodilation in pts. w/ COPD
What is seen in pts. w/ polycythemia vera?
- Primary and secondary PV are assoc. w/ a microcytic erythrocytosis
- In primary PV the platelet count and leukocyte count are increased (in secondary, only RBCs are increased)
*Primary PV is assoc. w/ mutation of the JAK2 gene**
What electrolyte abnormalities can loop/thiazide diuretics cause?
They can cause a HYPOchloremic metabolic alkalosis
How is multifocal atrial tachycardia diagnosed? What diseases is it assoc. with?
- It is defined by a HR greater than 100, and 3 or more distinct morphologies of the P-wave on an EKG
- It is seen in pts. w/ pulmonary/cardiac disease, esp. those causing atrial distention and pulmonary HTN
*COPD exacerbation is the most common cause**
What are the 3 categories of Von Willebrand Disease? What are the treatments for each?
- Type 1: Partial quantitative deficiency
- Type 2: Qualitative deficiency
- Type 3: Total deficiency
Treatment:
- Type 1: trial of desmopressin
- Type 2: trial of desmopressin, avoid if known type IIB
- Type 3: vWF concentrate (desmopressin has no effect)
*Desmopressin should be given prior to surgery in pts. w/ type 1 vWD**
What can citrate intoxication lead to (after multiple transfused units of PRBCs?)
It can cause metabolic alkalosis. (Citrate is metabolized in the liver to bicarbonate)
What is the difference between pharmacodynamics and pharmacokinetics?
- Pharmacodynamics: interactions w/ receptors, type of effect it has (agonist, antagonist, etc)
- Pharmacokinetics: route of adminstration, bioavailability, metabolism, etc
'KADE' (for pharmacoKinetics) Kinetics Absorption Distribution Elimination
What is the revised guideline regarding elective surgery and drug-eluting stents?
Elective non-cardiac surgery should be delayed 180 days (vs. 365 in old guidelines)
What is the formula to estimate amount of bicarbonate to give to a pt.?
The amount that will normalize blood pH can be approximated w/ this formula:
Bicarbonate (mEq)= 0.2 x pt. weight (kg) x base deficit
What lung volumes increase in pregnancy?
- Inspiratory capacity increases (increased inspiratory reserve volume and increased tidal volume)
- Everything else is decreased (FRC -i.e. expiratory reserve volume and residual volume)
What drugs/electrolyte antagonize non-depolarizing neuromuscular blocking drugs?
“ACC”
- Anticonvulsants (carbamazepine, phenytoin)
- Corticosteroids
- Calcium
What are the 3 rules that must be followed to prevent re-breathing of CO2 in a circle system?
- A unidirectional valve must be positioned between the pt. and the reservoir bag on the inspiratory and expiratory limbs of the circuit
- Fresh gas inflow cannot enter the circuit between the pt. and the expiratory valve
- The APL valve cannot be positioned between the inspiratory valve and the pt.
What changes occur in the heart w/ advancing age?
- Impaired diastolic filling (decreased ventricular compliance)
- LV hypertrophy
- Impaired beta-receptor sensitivity
- This results in impaired ability to increase CO w/ stress or exercise (poor tolerance of increased HR)
What are the last muscles recruited during impending respiratory failure?
The large back and paravertebral muscles
What are risk factors for desaturation during 1-lung ventilation? (4)
- High percentage of V/Q to the operative lung (as evidenced on V/Q scan)
- Poor PaO2 during 2-lung ventilation (esp. when in the lateral position)
- Right-sided thoracotomy (b/c the right side has 10% more volume than the left)
- Supine position during surgery
What causes bronchopulmonary dysplasia?
- It results from respiratory distress syndrome
- It is most often seen in preterm infants <32 weeks gestation and is a chronic disease of the airways and lung parenchyma
Respiratory considerations in the neonate? What is the most important respiratory muscle?
- They have a pliable rib cage which causes retractions, making gas exchange less efficient
- They have increased chest wall compliance but lower lung compliance
- The diaphragm is the most important muscle of respiration in the neonate- the intercostal muscles are not fully developed
What is the most common presenting sign of high or total spinal anesthesia in infants/children under 5 years of age?
Respiratory depression/apnea
What symptoms are seen w/ ‘bone-cement implantation syndrome’?
- It can happen during hip/knee arthoplasties
- Pts. can develop hypoxia, hypotension, cardiac dysrhythmias, and increased pulmonary vascular resistance (substance: methyl methacrylate)
What trimester is best for non-obstetric surgeries in pregnant pts.?
The 2nd trimester (for procedures that are time-sensitive)
What ingredients does propofol have? What are contraindications for propofol use?
- It contains soybean oil, glycerol, and lethicin
- Any hypersensitivity reactions to any of these ingredients is an absolute contraindication for propofol use
When the same group undergoes more than 2 repeated measurements, what statistical test is used?
Repeated measures ANOVA
At what age does physiological anemia of the newborn occur?
At 8-12 weeks of age (drops down to 11). It does not require treatment
What happens w/ a complete recurrent laryngeal nerve injury vs. a partial nerve injury?
- A complete unilateral recurrent laryngeal nerve injury would cause the ipsilateral cord to take a paramedian position
- A partial injury (affecting abductor fibers primarily) would place the cord(s) in a ADDucted position
- *A bilateral parital injury= potential airway emergency**
Redistribution of most anesthetic drugs moves into what area?
Skeletal muscle (to terminate drug action) (i.e. propofol)
What is a unique consideration for pts. who have had the Fontan procedure?
- They have passive pulmonary blood flow; preload must be maintained
- Minimizing increases in pulmonary vascular resistance is crucial (avoid hypercarbia/acidosis, hypothermia, hypoxia)
Do high-density gases have a tendency for laminar or turbulent flow?
‘TD in LV’
- Gases w/ higher densities (i.e. nitrous oxide) have a greater tendency for TURBULENT flow
- Increasing viscosity will INCREASE laminar flow
What is the most common agent causing anaphylactic reactions in adults? In children?
- Adults: neuromuscular blocking drugs
- Children: latex
Which toxin enters the CNS, botulinum toxin or tetanus toxin?
- Tetanus toxin travels via retrograde axonal transport from peripheral to central neurons. It also causes autonomic dysfunction
- Botulinum only affects peripheral motor neurons (prevents release of Ach)
What are coagulation changes in pregnant pts.?
- Impaired fibrinolysis
- A decrease of anti-coagulants (protein S, resistance to protein C)
- Increased pro-coagulants (D-dimer, thrombin-antithrombin complexes)
- Decreased platelet count from dilution/increased consumption
What kind of needles should be used for peripheral nerve blocks?
Short-beveled insulated needles should be used for more accurate needle placement and for avoidance of nerve penetration
What are the general platelet levels required for major surgery/neurosurgery?
- Major surgery: greater than 50,000
- Neurosurgery: greater than 100,000
What will decrease diffusing capacity for carbon monoxide?
Diseases or physiologic states which reduce pulmonary blood flow or alveolar mass will decrease DLCO (restrictive lung disease, anemia)
How long does a scopolamine patch take to work? What is a contraindication to using scopolamine?
- The patch requires 4 hours to take effect; it can help prevent/treat PONV for up to 72 hours
- It is contraindicated in pts. w/ glaucoma (causes mydriasis and cycloplegia which can raise IOP)
How much suppression is there after 1, 2, 3, and 4 twitches during TOF stimulation?
1 Twitch: >90% suppression
2 Twitches: 80-90%
3 Twitches: 70-80%
4 Twitches: 65-75%
What is amiodarone used for? What is a consideration for pts. taking amiodarone in the OR?
- It can be used for atrial fibrillation and v-fib/v-tach
- Pulmonary fibrosis resulting from amiodarone can become worse when exposed to high FiO2
- Bleomycin and methotrexate can also cause pulmonary toxicity/fibrosis**
What is the 1st-line therapy for atrial fibrillation w/ rapid ventricular response?
- Beta-blockers or calcium channel blockers (in hemodynamically-stable pts.)
- Amiodarone is another option for a-fib that is difficult to control
After appropriate reversal w/ protamine, pts. w/ persistent bleeding after CPB should receive what blood product?
They should receive a platelet transfusion first
A preoperative 12-lead EKG is recommended in which pts. undergoing elevated-risk surgery?
Pts. w/:
- Coronary artery disease/significant structural heart disease
- Significant arrhythmia
- Peripheral arterial disease
- Cerebrovascular disease
What should be done during MRI to prevent burns/injury w/ EKG leads?
To minimize burns, make sure monitoring cables do not have loops or coils
Recommendations for pregnant pts. taking warfarin?
- Warfarin use during the first 6-12 weeks of pregnancy can be assoc. w/ fetal complications
- It is recommended to d/c warfarin when doses are greater than 5 mg daily during the 1st trimester (can be resumed in the 2nd and 3rd trimesters!)
What happens to minute ventilation and PaO2 during pregnancy?
- Increased minute ventilation causes a respiratory alkalosis w/ a compensatory metabolic acidosis (pH may be normal or slightly elevated)
- Increased alveolar ventilation also causes an increase in PaO2 (103-107)
What are 3 things that can improve asthma during pregnancy? What is 1 thing that can worsen it?
- Progesterone-induced relaxation of airway smooth muscle
- Increased production of bronchodilating prostaglandins
- Higher cortisol level
-Decreased sensitivity to beta-agonists can worsen symptoms
Is the metabolism of remifentanil different in neonates vs. children/adults?
- YES!
- It is the ONLY opioid medication w/ increased clearance in neonates compared to children/adults
Is the decrease in concentration of volatile anesthetics context-sensitive?
- YES!
- The 90% decrement time for sevoflurane is very similar to that of des for the first 90 minutes of anesthesia
What are the 4 main functions of glucagon?
- Glycogenolysis
- Gluconeogenesis
- Lipolysis
- Increased uptake of amino acids by the liver
*These things all serve to increase the amount of glucose within the blood**
What is the mechanism for ischemia-reperfusion injury during liver transplantation?
Thought to be caused by disruption of the Na-K pumps secondary to decreased ATP and glycogen
Can an adductor canal block affect motor function of the leg?
- Although the saphenous nerve is purely sensory, adductor canal blocks often affect the nerve to the vastus medialis b/c of its location within the adductor canal.
- Motor weakness may occur, and pts. should be closely monitored as they begin to ambulate
What is the pathway for catecholamine production?
“TDNE” (touchdown New England!)
Tyrosine–>DOPA–>Dopamine–>NE–>Epinephrine
During infrared spectrophotometry, is the amount of light detected proportional or inversely proportional to the amount of gas in the sample?
- INVERSELY proportional!
- Infrared spectrophotometry is used to analyze polar, asymmetric gases (CO2, volatile agents, N2O)
How is enoxaparin activity measured? How is unfractionated heparin activity measured?
- Enoxaparin is monitored by factor Xa activity
- Unfractionated heparin is monitored using either aPTT or ACT, depending on the clinical situation
For a 1st-order kinetics elimination reaction, how much does the drug amount decrease by after 1, 2, and 3 time constants?
-After 1 time constant: 63%
“ “ 2 time constants: 86%
“ “ 3 time constants: 95%
(After 3 time constants, a little less than 5% of the original concentration remains)
How is Becker muscular dystrophy different from Duchenne muscular dystrophy? What is it assoc. with?
- It is x-linked recessive w/ mutations in the dystrophin gene. Unlike Duchenne, dystrophin is present, but there is a decrease in QUANTITY
- Cardiac involvement is common and occurs more often than w/ Duchenne. Also assoc. w/ epilepsy, color blindness, and macroglossia
What is the value for mixed-venous oxygen tension in resting adults?
- In a resting adult breathing room air: 40 mm Hg
- Increasing FiO2 to 100% will only slightly increase mixed venous O2 content (45-50 mm Hg)
What is gantacurium? How can it be reversed?
- It is an ultra-short acting non-depolarizing NMB drug belonging to the ‘fumarate’ class
- It undergoes non-enzymatic metabolism and it can be rapidly reversed w/ L-cysteine (an amino acid)
The odds ratio estimates the risk ratio (relative risk) in what type of study? What type of study can be used to calculate relative risk?
- Cohort studies w/ a low incidence of disease
- Relative risk can only be calculated for cohort studies (not case-control)
What should happen for sickle cell pts. prior to elective surgeries?
They should typically have a hematology consult prior to any elective surgery
What are the 4 symptoms of hypercalcemia?
“Stones, bones, abdominal groans, psychiatric moans”
What is the management for neonates w/ congenital diaphragmatic hernias?
- Bag-mask ventilation should be avoided (risk of gastric insufflation)
- The pt. should be intubated; ventilation type must minimize airway pressures to avoid barotrauma/pneumothorax (high frequency oscillatory ventilation)
- Pts. will usually have respiratory distress/scaphoid abdomen**
What is the standard initial therapy for TCA overdose?
Sodium bicarbonate
What are the 5 risk factors for perioperative cardiac events?
- Type of surgery
- Dependent functional status
- Abnormal creatinine
- ASA class
- Increased age
What are the metabolic changes seen w/ TPN?
- HYPERglycemia/carbia/insulinemia
- HYPOphosphatemia/kalemia/magnesemia
- TPN can also cause thrombophlebitis and hepatic steatosis**
Anaphylactic reactions to blood transfusions are likely due to what situation?
- IgA-containing blood being transfused to a deficient recipient
- Future PRBCs should be washed to remove all traces of IgA from the blood
What is the most important factor in the closure of the ductus arteriosus?
- Oxygen tension
- Preterm neonates are less responsive to O2 and may have a persistent patent ductus arteriosus which needs medical/surgical closure**
During an interscalene block, where is the phrenic nerve in relation to the brachial plexus?
It is anterior to the brachial plexus
What is the treatment for SVT in pts. w/ Wolff-Parkinson-White?
Procainamide (AV-blocking agents should be avoided b/c they increase conduction through the accessory pathway)
What is Goldenhar syndrome?
- Goldenhar a.k.a. oculoauriculovertebral spectrum (OAVS) is characterized by hemifacial microsomia, mandibular hypoplasia, cleft lip/palate and possible cervical spine instability
- These pts. have high likelihood of being a difficult airway
What is the single best predictor of a difficult intubation?
The upper-lip bite test
Symptoms/treatment of organophosphate poisoning?
- Organophosphates inhibit acetylcholinesterase and butyrylcholinesterase, increasing ACh in both the nicotinic and muscarinic synapse (heart rate is variable; not necessarily bradycardic). Cholinergic signs predominate (miosis, salivation, etc)
- Treatment is primarily w/ atropine, w/ or w/o pralidoxime
Side effects of carbamazepine?
- Toxic epidermal necrolysis, agranulocytosis, aplastic anemia
- It is a Na-channel blocker used to treat trigeminal neuralgia
- It induces CYP3A4 and has multiple interactions w/ other medications (oxcarbazepine is a better option b/c it has less side effects)
Can pts. w/ a PCN allergy be given cephalosporins?
- Pts. w/ a Hx of a delayed reaction to PCN can be given cephalosporins
- An immediate reaction to PCN w/ concerning features (flushing, hives, pruritus, angioedema, bronchospasm, hypotension) means an alternate drug should be given!
Symptoms of myxedema coma? Treatment?
- Hypotension/bradycardia, altered mental status
- Hypothermia occurs in 80% of pts.
- Immediate treatment w/ thyroid hormone replacement (T3/T4); *it should not wait for a definitive diagnosis**
Calculation for SVR?
(MAP-CVP/CO) x 80
Side effects of gabapentin?
Sedation, nausea, dizziness, nystagmus, ataxia, peripheral edema
What symptoms can result in pts. w/ multiple myeloma?
‘CRABi’
- hyperCalcemia
- Renal failure
- Anemia
- Bone pain/osteolytic destruction
- immunosuppression (leading to recurrent infections)
What clotting factors do obese pts. have an excess of?
- Obese pts. have higher levels of:
- Factor 7, 8, von Willebrand factor, and plasminogen activator-inhibitor-1
- This leads to a HYPERcoagulable state**
What are contraindications (5) to performing acute normovolemic hemodilution?
- Preoperative anemia
- Cardiac disease
- Recent CVA
- Clinically significant renal/liver disease
- Active infection
What can be given to help prevent neonatal apena? Why does bradycardia occur during apnea in neonates?
- Caffeine can be given to decrease the incidence of postoperative apnea
- Bradycardia during apnea is thought to be caused by stimulation of the carotid body chemoreceptors
Definition of TRALI?
- Development of acute lung injury within 6 hours of blood transfusion
- Leads to non-cariogenic pulmonary edema (PCWP <18)
- TACO can be differentiated from TRALI by sending BNP (Elevated BNP is seen in TACO)
What are the 3 conditions that require a patent ductus arteriosus?
- Hypoplastic heart
- Transposition of the great vessels
- Pulmonary atresia
What is the most common cause of death from liposuction? What can happen after a tumescent liposuction procedure?
- PE due to fat emboli (most common cause of death from liposuction)
- Tumescent liposuction involves injection of very large volumes of saline solutions which can cause volume overload/pulmonary edema
- Recommendation is 35-55 mg/kg (max dose of lidocaine)
What types of pediatric pts. should spinal anesthesia be considered for?
- Neonates/infants less than 60 weeks post-conceptual age
* This decreases the risk for postoperative apnea**
What are the 7 conditions that increase risk for digitalis toxicity?
1-4: HYPOkalemia/thyroidism/glycemia/magnesemia
- HYPERcalcemia
- Hypoxemia
- Renal insufficiency
What can exacerbate HYPERkalemic periodic paralysis?
-HYPOthermia/glycemia
-Metabolic acidosis
-Rest after exercise
-K infusions
*Caused by a sodium channel defect- treatment: thiazide diuretics, restriction of K**
*HYPOkalemic periodic paralysis is caused by a calcium channel defect**
(“HYPER kids say Na, Na, Na”)
What 2 non-depolarizing NMBDs can cause hypotension?
Rapid administration of mivacurium or atracurium can cause transient hypotension due to histamine release
Treatment for diabetes insipidus? Vasopressin should be used w/ caution in what kind of pts.?
- Either vasopressin or desmopressin (DDAVP) can be used. DDAVP is usually preferred b/c it does not cause systemic HTN
- Vasopressin can cause myocardial ischemia in pts. w/ coronary artery disease (vasoconstriction of stenotic coronary arteries)
Difference between restrictive and obstructive lung disease?
- Restrictive: characterized by proportional decreases in ALL lung volumes
- Obstructive: characterized by decreases in expiratory flows
How long should someone stop smoking prior to surgery to reduce post-operative pulmonary complications?
Pts. should ideally stop smoking 4-8 weeks prior to surgery
What perioperative finding is assoc. w/ high risk of post-operative mortality in pts. undergoing liver transplant?
A perioperative PaO2 of 50 or less on room air (Hepatopulmonary syndrome causes hypoxemia and pulmonary vasodilation)
What is required for diagnosis of abdominal compartment syndrome?
Sustained intra-abdominal (intravesical) pressure readings >20 mm Hg that is assoc. w/ development of new organ dysfunction or failure
When does hypocalcemia occur following thyroid surgery (if it happens)?
It usually occurs 24-48 hours after surgery
What fluids should be avoided in intracranial aneurysm surgery?
Any hypotonic fluid or those that contain glucose (unless the pt. is hypoglycemic)
What is the anatomy from medial to lateral in the popliteal fossa?
From medial to lateral:
Popliteal artery–>Popliteal Vein–>Tibial nerve–>Common peroneal nerve
*The sciatic nerve lies behind and LATERAL to the vessels of the popliteal fossa at the apex**
General effects of nitroprusside (4) ?
- Reduced preload/afterload
- Inhibition of hypoxic pulmonary vasoconstriction
- Causes coronary steal
- Impairs platelet aggregation
What drug is contraindicated in neuraxial obstetrical anesthesia by the FDA?
Clonidine
What kind of fluid should be used in pts. w/ traumatic brain injury?
- Normal saline or hypertonic saline can be used
- Some studies suggest better outcomes w/ hypertonic saline
4 Consequences of CPAP? It is commonly used for which pts.?
- Decreases cardiac output
- Decreases surfactant depletion
- Increases total lung volume (increases FRC)
- Increases minute ventilation
-Commonly used in pts. w/ obstructive diseases, neuromuscular pathology, hypoventilation, severe kyphoscoliosis
If blood flow decreases through the portal vein, what happens within the liver?
It causes increased adenosine concentration in the liver, local arteriole dilation, and increased hepatic artery blood flow
What is the limitation when using jugular-bulb venous oxygen saturation (SjVO2)?
- It measures GLOBAL cerebral O2 supply/demand balance. (It cannot assess focal ischemia/neuronal death)
- This is used to measure O2 extraction of brain tissue; values are usually kept between 55-75%
When viewed on a CXR, where should the tip of a central venous catheter (placed in the right IJ) be located?
- It should be above the level of the carina
- If the carina is not visible, it should be above the pericardial reflection or approximately the 3rd anterior intercostal space
Risk factors for postoperative vision changes/blindness (9)?
- Direct eye injury/pressure
- Prone spine procedures
- Long surgical time
- Extracorporeal circuit use
- Obesity
- Male Gender
- High blood loss
- Hypotension
- Glycine toxicity (after TURP)
What should be done for a newborn w/ continued apnea/cyanosis, bradycardia, and poor muscle tone during the 1st minute of life?
Positive pressure ventilation w/ room air should be initiated
What 4 things will increase turbulent flow?
- Increased mean velocity
- Increased gas density
- Increased flow length
- Decreased viscosity
Basic pathway of an SSEP from stimulus to terminal recording?
Peripheral nerve–>Dorsal root ganglia–>Posterior spinal cord–>Brainstem–>Thalamus–>Cortex
Autonomic hyper-reflexia occurs most commonly in pts. w/ spinal cord lesions at what level?
- It occurs most commonly in pts. w/ lesions above T5, and those having surgery below the level of injury
- The best treatment is prevention. If it does occur, deepening anesthetic and using vasodilators/beta/Ca-channel blockers can decrease risk of complications
Waht anti-emetic medication is contraindicated in pts. w/ pheochromocytoma?
Metoclopramide (b/c it is assoc. w/ catecholamine release)
Mechanism of local anesthetic action on peripheral nerves?
They reversibly bind to the iNtracellular portion of voltage-gated sodium (Na) channels. This inhibits iNflux of sodium (interrupts action potential along nerve fibers)
Electrolyte abnormalities in pts. w/ protracted pyloric stenosis?
HYPOnatremia/kalemia/chloremia
-Metabolic alkalosis
Difference in lab values for pts. w/ primary vs. secondary adrenal insufficiency?
Pts. w/ secondary AI usually ONLY have a glucocorticoid deficiency. Since mineralocorticoid production is usually intact, these pts. usually only have mild electrolyte abnormalities
What can happen to pets. w/ prolonged exposure to corticosteroids?
Chronic or high-dose steroid use can lead to myopathy. It often presents w/ proximal muscle weakness and normal levels of creatine kinase
