Truelearn Questions 2 Flashcards
Identify this block
- Performed at what level?
- What are the landmarks
- Indications
- Key Complications
Supraclavicular Block
- Trunks
- First Rib Inferior, Middle Scalene Muscle (Lateral), Anterior Scalene Muscle (Medial), Subclavian artery
- Any surgery below mid-humerous level
- Pneumothorax (most serious, most common), Subclavian artery puncture, spread to stellate ganglion, phrenic nerve blockade, recurrent laryngeal nerve blockade.
Identify this Block
- At what level Is block performed
- Landmarks
- Key Complications
Infraclavicular Block
- Cords
- Pectoralis major, Pectoralis minor, Axillary Artery, Axillary Vein
- Axillary Artery Puncture and Pectoral discomfort d/t transgressing pectoral fascia
At what part of the brachial plexus are each of these blocks perfromed
- Interscalene Block
- Supraclavicular Block
- Infraclavicular Block
- Axillary Block
- Roots
- Trunks
- Cords
- Nerve Branches
What is the pathology of this CVP waveform?
How would you take someone through anesthesia?
Cardiac tamponade
Notice the Exaggerated X decent and Attenuated Y
- Low-dose ketamine bolus with maintenance of spontaneous ventilation and then infiltration of pre-existing sternotomy wound followed by surgical drainage.
- Cardiac depression, vasodilation, and slowing of the heart rate should be avoided. Acute loss of preload, contractility, and heart rate can cause catastrophic circulatory collapse in the setting of cardiac tamponade. Epinephrine, therefore, is a useful medication in the management of cardiac tamponade and an infusion should be considered prior to induction of anesthesia
What is the difference between high peak inspiratory pressures in setting of normal plateau pressures vs increased plateau pressures.
Describe some common causes of each.
- High PiP w/ Normal plateau
- d/t AIRWAY RESISTANCE
- ie airway compression, Bronchospasm, mucus plug, foreign body, mucus plug, kinked ETT.
- High PiP w/ High Plateaue
- d/t PULMONARY COMPLIANCE
- ie: Abdominal insufflation, Ascites, Intrinsic lung disease, OBESITY, Pulm edema, Trendelenberg, Tension Ptx.
Ballon analogy: Takes more force to initially inflate balloon, less to maintain plateau.
Mechanism of Cyanide Toxicity
- Cyanide primarily causes toxicity by impairing cellular aerobic respiration.The cyanide ion (CN-) binds to the ferric ion (Fe3+) in mitochondrial cytochrome-c oxidase, inhibiting the final stage of the electron transport chain. Depletion of cellular ATP and the lactic acid produced by anaerobic metabolism can lead to profound acidosis.
What is the starting landmark for proper placement of lateral femoral cutaneous nerve block?
Anterior Superior Iliac Spine
5 indications for Hyperbaric Oxygen
- Burns
- Air Embolism
- Brown Recluse Spider bite
- necrotizing infection
- acute hypoxia
Identify the process that correlates to the following letters
A. Diuretics, reduce EDV thus reduce cardiac filling pressures
B. Ionotropy + Vasodilation + Diuresis
C. Vasodilators; hydralazine and nicardipine, result in improved ventricular function while reducing cardiac filling pressures.
D. Ionotropy + Vasodilation; Milrinone
E. Pure ionotrope improves contractility; norepi, epi
Ionotrope: Increases force of contraction of cardiac muscle (Epinephrine, Dobutamine, Milrionone)
Chronotrope: Increases Heart Rate; Atropine, Isopryl, Dobutamine, Epi
Describe the following Cormack and Lehane Views
- Grade I
- Grade II
- Grade IIa
- Grade IIb
- Grade III
- Grade IIIa
- Grade IIIb
- Grade IV
Grade I: visualization of the entire laryngeal aperture.
Grade II: posterior third of glottis visible.
Grade IIa: arytenoids and posterior cords visible.
Grade IIb: only epiglottic edge and arytenoids visible.
Grade III: no cords visible, only epiglottis visible.
Grade IIIa: only epiglottic edge visible (epiglottis raised).
Grade IIIb: downfolded or floppy epiglottis is visible.
Grade IV: no view of any airway structure (including epiglottis).
When is autonomic hyperreflexia observed?
What spinal level can it occur?
Describe the Pathophysiology
2 weeks to 6 months after spinal transection ABOVE T12.
Spinal cord reflexes from the above stimuli trigger sympathetic activity (preganglionic sympathetic nerves) along the splanchnic outflow tract, but because of the SCI, inhibitory impulses from higher CNS centers (e.g. cerebral cortex, cerebellum, and brain stem) cannot reach below the level of SCI. Accordingly, intense generalized vasoconstriction occurs below the level of SCI while reflex cutaneous vasodilation occurs above the level of SCI (usually in proportion to the magnitude of the inciting stimulation).
Signs and symptoms of AH reflect the imbalance above. The intense sympathetic response below the level of injury can cause acute hypertension (at least 20-40 mm Hg above baseline), reflex bradycardia, cardiac arrhythmias (e.g., premature ventricular contractions or atrial-ventricular conduction abnormalities), and myocardial infarction. The hypertension can further lead to headaches, blurred vision, retinal hemorrhage, intracranial hemorrhage, stroke, seizure, and/or cerebral edema. Additionally, the intense vasoconstriction leads to cool, dry, pale skin below the level of SCI. The reflex cutaneous vasodilation above the level of the SCI leads to nasal congestion; sweating; and warm, flushed skin on the upper extremities, shoulders, neck, and face.
Describe Afferent and Efferent pathway of Oculocardiac Reflex
Afferent: Increase eye pressure ►Ciliary nerves ►Gasserian Ganglion ►Trigeminal Nucleus
Efferent: Vagus
What is the Mechanism of Action of Magnesium?
- Magnesium Antagonizes Voltage Gated Calcium Channels causing vasodilation and reduced systemic vascular resistance.
Identify the Block and Structure at the Arrow.
What are the Landmarks?
Supraclavicular Block; Subclavian Artery
Between anterior and middle scalene muscles
Seen as “Bundle of Grapes”
Identify these Dermatomes
What is a Blalock-Taussig Shunt?
- Used in the surgical treatment of Tetralogy of Fallot
- A graft from the left or right subclavian artery to the ipsilateral pulmonary artery, depending on the medical condition of the neonate.
- Will improve blood flow (blue arrows) through the pulmonary circulation and also improve oxygenation - BYPASSESS PULMONARY STENOSIS
Biggest Risk Factor for Pneumonitis in the Setting of Aspiration
- VOLUME of aspiration > 0.4 mL/kr
- pH <2.5
- Particulates in Aspirate
What is Klippel-Feil Syndrome?
- Congenital condition associated with Fusion of Cervical Spine
Fill in the Following Parameters Correlating to Each Shock State
Hemodynamic Goals in idiopathic Hypertrophic Subaortic Stenosis/Hypertrophic Obstructive Cardiomyopathy
Hemodynamics goals in IHSS/HOCM are:
- Preload should be kept up.
- Afterload should be kept up.
- Heart rate should be kept down.
- Myocardial contractility should be kept down.
- Sinus rhythm should be maintained.
Risk Factors For Transient Neurologic Syndrome
Key Symptoms
-
Use of Lidocaine in Spinal Anesthesia
- High concentrations ► Directly Neurotoxic ► irreversible conduction block and complete loss of resting potential.
- Lidocaine causes an excessive release of glutamate leading to an increase in intraneuronal calcium
- Positioning of patient (specifically lithotomy)
- Same Day Surgery
- Early Ambulation after Surgery
-
Key Symptoms
- exclusively pain in buttocks, thighs, legs, no dysfunction
Key Point: BARICITY NOT ASSOCIATED W/ TNS
What is Precurarization Dose?
Pre-curarization dose of the Non-depolarizing Neuromuscular Blocking Drugs
- Rocuronium
- Vecuronium
- Cisatracurium
- Pancuronium
10% of ED 95
What is Strong Ion Difference?
- The difference between the positively and negatively charged strong ions in plasma.
- SID (Strong Ion Difference) = [strong cations] - [strong anions] = [Na+ + K+ + Ca2+ + Mg2+] - [Cl- + lactate-]
- Disturbances that increase the SID increase the blood pH (alkalosis) while disorders that decrease the SID lower the plasma pH (acidosis). So, low pH or SID is associated with acidosis and high pH or SID is associated with alkalosis.
Which one represents Guillian Barre Syndrome? What do the other patterns represent?
- Patient A: Obstructive Lung Pattern - COPD, Emphysema; Conditions are considered obstructive when the FEV1/FVC ratio falls below 70% of predicted. DLCO decreased d/t intrinsic lung damage
- Patient B: Restrictive Lung Pattern; Guillian Barre Syndrome; demonstrate decreases in the FEV1 and FVC. However, the FEV1/FVC proportions remain normal. The FEV1/FVC ratio remains normal in restrictive lung conditions, and the TLC is decreased
- Patient C: Normal PFT
- Patient D: Obstructive Pattern such as Asthma. DLCO is normal or increased. TLC increases during asthma.
Brachial Artery Cannulation is Most likely to injure what nerve?
Median Nerve
Drugs that do not cross the placenta
Hint: “tHINGS”
Heparin, Insulin, Nondepolarizing muscle relaxants, Glycopyrrolate, and Succinylcholine. Additionally phenylephrine does not cross the placental barrier.
What are the contents of cryoprecipitate?
What are some indications?
- Cryoprecipitate contains von Willebrand factor (vWF), fibrinogen, fibronectin, factor VIII, and factor XIII.
Hemodynamic effects aortic cross clamping
1)
2)
3)
4)
5)
6)
7)
8)
- *Hemodynamic effects of aortic cross clamping include:**
1) Increased arterial blood pressure above the level of the clamp
2) Increased coronary artery blood flow
3) Increased left ventricular wall stress
4) Increased central venous pressure
5) Increased pulmonary artery wedge pressure
6) Decreased arterial blood pressure below the clamp
7) Decreased cardiac output
8) Decreased renal blood flow
What Protective Lenses Are Needed for the Following Lasers?
1) CO2
2) Argon
3) Krypton
4) Nd:YAG
5) KTP-Nd:YAG
What is the difference between Acute tubular necorsis and Pre-renal Azotemia?
- Acute Tubular Necrosis: “muddy brown casts”; Excretion of sodium FENA >1%; Uosm <350
- Pre renal: hypovolemia issue, urine is concentrated, osmolarity HIGH Uosm >500. BUN:Cr >20
What is the minimum tourniquet pressures required for upper extremity and lower extremity surgery?
- 50 mm Hg above the systolic pressure of upper extremity surgery
- 100 mm Hg above systolic pressure of lower extremity surgery.
Aortic Cross Clamp Metabolic Changes
- Decreased total-body oxygen consumption
- Decreased total-body carbon dioxide production
- Increased mixed venous oxygen saturation
- Decreased total-body oxygen extraction
- Increased epinephrine and norepinephrine
- Respiratory alkalosis
- Metabolic acidosis
What is shown in the following image
Pericardial Effusion
Pericardial tamponade can be differentiated from myocardial failure by the presence of pulsus paradoxus (a drop of at least 10 mm Hg (or >9%) in systolic arterial blood pressure on inspiration)
Best treatment of Nausea/Vomiting after high spinal blockade?
Atropine
Associated with High T5 Spinal Blockade
The difference between Type 1 vs Type 2 MI
Which is more common?
- Type 1: Acute Thrombus
- d/t plaque rupture, stress on atheroma etc.
- Type 2: Demand ischemia
- MOST Common type of MI to occur in OR
- Myocardial oxygen demand exceeds oxygen supply d/t factors such as tachycardia, anemia, hypoxemia, hypotension
- Manage w/ rapid revascularization, aspirin, heparin.
Troponin vs CK-MB; Which has greater sensitivity in the diagnosis of Myocardial Ischemia?
Troponin
- Serum troponin levels are elevated in 80% of patients within 2 to 3 hours of MI.
- CK-MB may be elevated after only 2-3 hours but often does not peak for several hours after ischemia.
- The sensitivity of troponins is nearly 50% within 3 hours, 75% by 6 hours, and nearly 100% by 12 hours.
- Troponin may also be elevated in other disease states like renal failure, sepsis, and congestive heart failure. Elevated troponin from any cause is a sign of poor prognosis and should be considered equivalent to cardiac injury until proven otherwise.
What is the most common porphyria?
Acute intermittent porphyria
- An autosomal dominant condition that results from an error in porphobilinogen deaminase, an enzyme involved in heme synthesis
- Symptoms are vague and include: abdominal pain, diarrhea, constipation
- Attacks a precipitated b conditions that increase amnolevulinic acid (ALA)
- Ie Inducers of P450 system: alcohol, benzodiazepines, nifedipine, glucocorticoids.
- Important to maintain normothermia and hydration.
Estimated blood volume in mL/Kg for the following
- Premature infant
- Full term newborn
- Infant (3 mo - 1 year)
- Child ( 1 - 12 year)
- Adult Male
- Adult Female
Think “60, 70. 80, 90”
60 ml/kg- adult female
70 ml/kg - anyone after age 3 months
80 ml/kg - full term newborn
90 ml/kg - premature infant
Metabolic Derangements seen in Addison’s Disease
- Hyponatremia
- Hyperkalemia
- Hyperchloremia
- Hypercalcemia
What are the values of a thromboelastogram and how do you interpret them?
- MA value decreased -> platelets. (“Ma Platelets)
- K value prolonged -> cryoprecipitate. (“Kryoprecipitate)
- R value prolonged -> FFP. (“RLASMA” - theres a P in the R)
- Teardrop configuration -> antifibrinolytics.
What is the difference between roller and cetrifugal pumps used in cardiopulmonary bypass?
- Both are pumps used to circulate blood between the CPB machine and the patient.
- Both can deliver pulsatile flow
- Key Difference: Centrifugal require flowmeters on the arterial portion of the CPB circuit since flow can vary from alterations in pump preload and afterload
- Roller pump flow is essentially only dependent on the speed of the rollers
- Due to compressive forces, roller pumps have higher incidence of blood element destruction, creation of plastic microemboli, inflow/outflow obstruction.
- Centrifugal pumps rotate about a magnetically controlled impeller associated with an electric motor. Centrifugal pumps are often favored over roller pumps due to less blood element destruction, lower line pressures, lower risk of air emboli, and elimination of tubing wear and spallation.
What happens to the following parameters during pregnancy?
What values affected the least?
- Inspiratory reserve volume
- Tidal Volume
- Expiratory Reserve Volume
- Residual Volume
- Inspiratory Capacity
- Functional residual capacity
- Vital Capacity
- Total Lung Capctiy
- Dead Space
- Resipratory Rate
- Minute Ventilation
Vital Capacity is Unchanged
Characteristics of Gilbert Syndrome
- Most common cause of jaundice in the adult population in the USA caused be decreased activity of enzyme bilirubin glucuronyltransferase.
- Autosomal dominant; Decreased ability to uptake unconjugated bilirubin
- A large unconjugated bilirubin load, such as from multiple packed red blood cell (PRBC) transfusions, overwhelms the limited enzyme activity resulting in clinically evident jaundice. Jaundice is typically noticeable with serum bilirubin levels above 2-2.5 mg/dL
Characteristics of Lumbar Plexus
Hint: “I (twice) get laid on fridays”
“2 from 1; 2 from 2; 2 from 3”
- Forms inside PSOAS MAJOR MUSCLE from Anterior Rami of L1 to L4
- 6 MAIN NERVES; mnemonic: “I (twice) Get Laid On Fridays”
- iliohypogastric
- ilioinguinal
- Genitofemoral
- Lateral Femoral Cutaneous
- Obturator
- Femoral
- All the nerves except Genitofemoral and Obturator emerge lateral to psoas major; “they GO anterior and medial”
Characteristics of Sciatic Nerve
- Arises from anterior and posterior divisions of spinal nerves of L4 to S3; Supplies posterior compartment of thigh, leg and foot
- Courses beneath piriformis muscle and exits through greater sciatic foramen, travels deep to gluteus maximus and into posterior compartment of thigh where it innervates Semimembranosus, Semitendonosus, Biceps femoris
- Branches at popliteal fossa to become tibial nerve and common peroneal nerve
Why is sodium bicarbonate contraindicated in cardiac arrest?
What circumstances would you give bicarbonate during CPR?
- It can worsen respiratory acidosis
- Causes extracellular alkalosis, which will shift the oxygen-hemoglobin dissociation curve to the left making unloading of oxygen more difficult.
- Produces hypernatremia and hyperosmolarity.
- May inactivate administered catecholamines such as epinephrine by exacerbating venous acidosis. Bicarbonate may compromise cerebral perfusion pressure (CPP) by reducing systemic vascular resistance.
-
2 Circumstances where giving Bicarbonate may be appropriate
- Known Hyperkalemia
- Known TCA overdose
True or false: High dose glucocorticoids have been shown to increase mortality in patients with traumatic brain injury
TRUE
Specific cytokines released in septic shock
- TNF alpha
- Interferon Gamma
- IL-1
- IL-2
- IL-6
- IL-8
- IL-10
Patient who was previously on heparin drip for MI presents for CABG and you administer bolus of heparin prior to bypass, ACT comes back at 200. You administer additional bolus and resultant ACT minimally changed (230)
Etiology and Management?
Iatrogenic Antithrombin 3 Deficiency
Administer FFP or AT 3 concentrates
What is the best way to determine acute kidney injury?
Measure Creatinine Clearance
- Creatinine Clearance = (Urine creatinine x Urine volume)/Plasma Creatinine
What is FeNa?
What is the equation and how do you interpret the results?
Fractional excretion of sodium
- Used to determine cause of an established AKI; can identify wheather injury is caused by prerenal, intrinsic, or postrenal etiology’
-
FENa = (Urine sodium * Plasma creatinine) / (Urine creatinine * Plasma sodium)
- FENa < 1% = Prerenal
- FENa > 1% = Intrinsic (e.g. acute tubular necrosis)
- FENa > 4% = Postrenal
Characteristics of Glasgow Coma Scale
mnemonic: “EVM, 456”
- Eyes; 4
- Verbal; 5
- Motor; 6
Identify the following nerves and their nerve roots
Hint: Cheerleading song
Musculocutaneous nerve
- Musculocutaneous nerve (C5,6,7)
- Axillary nerve (C5,6)
- Radial nerve (C5,6,7,8,T1)
- Median nerve (C5,6,7,8,T1)
- Ulnar nerve (C7,8,T1)
What are the risk factors for development of Post dural puncture headache?
1)
2)
3)
4)
5)
6)
- Age <40 years
- Prior PDPH
- BMI <30
- History of air travel
- Multiple dural attempts
- Quincke needle (only cutting needle)
Key point: midline vs paramedian approach & air vs saline LOR technique do not alter PDPH incidence.
16 year old presents to ER with mother after she reportedly swallowed large amount of unknown over the counter medication. Patient complains of nausea, dizziness, headache, ringing in ears.
Most likely diagnosis?
What is most likely seen on an arterial blood gas?
Acetylsalicylic acid toxicity
ABG shows Mixed Respiratory acidosis and metabolic acidosis
- Acute overdoses cause harm by interfering with the Krebs cycle and causing uncoupling of oxidative phosphorylation. This leads to a build up of organic acids such as lactate and ketoacids, causing an anion gap metabolic acidosis. Salicylate also acts directly on the respiratory center to increase the respiratory drive leading to a respiratory alkalosis
Arterial Blood Gas
-
Classic ABG
- pH: 7.43/PaCO2: 25/ PO2: 81/ HCO3 16/ SpO2 99%
At what age is MAC highest?
6 months of age then begins to decline
Diagram the course of the sciatic nerve in the popliteal fossa. What muscle is medial? Which is lateral?
Another name for Eaton Syndrome
Compare to Myasthetnia gravis in regards to
1) Pathophysiology
2) Clinical manifestations
3) Gender propensity
4) Coexisting diseases
5) Response to neuromuscular blocking drugs (hint: “lambs are sensitive animals”)
Identify the Following Structure
Mid Esophageal Aortic Valve Short Axis View
Patient undergoing endoscopic sinus surgery and turbinate reduction is an indication for what type of nerve block?
- Sphenopalatine ganglion block
Should you perform neuraxial anesthesia on patients with ALS?
Use of neuraxial anesthesia is generally not recommended because it can exacerbate disease. The exact mechanism is not clear, and it may be secondary to local trauma from the needle or local anesthetic effects near the nerves.
What is Cushing’s Triad
Hypertension
Bradycardia
Irregular Respirations
Pathophysiology of amniotic fluid embolism
CVP waveform shows what
Atrial Fibrillation
Fill in the table
Helpful mnemonic: “Syndrome of INAPPropriate ADH: Increased Na (sodium) in PP (urine).”
Which of the following describes ACUTE respiratory acidosis?
What do the others resemble?
SET D
a) Prolonged emesis or excessive diuretic therapy can cause a metabolic alkalosis. Respiratory compensation for metabolic events occurs more quickly than renal metabolic compensations for respiratory events. Therefore, patients with metabolic alkalosis decrease their respiratory drive to achieve a PaCO2 increase of 0.5-0.6 mm Hg per 1 mEq/L increase in bicarbonate.
b) Patients with chronic respiratory acidosis, such as those with chronic hypercarbia from chronic obstructive pulmonary disease (COPD), have a relatively normal pH, an elevated PaCO2, and a serum bicarbonate level that reflects a 4-5 mEq/L increase per 10 mm Hg increase in PaCO2.
c) Patients with metabolic acidosis compensate by increasing respiration to remove carbon dioxide. The Winter formula is used to determine the appropriate PaCO2 response for a metabolic acidosis: PaCO2 ≈ [HCO3-] * 1.5 + 8 ± 2. Therefore, an acidemic patient with a serum bicarbonate level of 14 mEq/L would be expected to increase ventilatory drive to achieve a PaCO2 of 29 ± 2 mm Hg
e) Although unusual, it is also possible to have a concurrent metabolic and respiratory acidosis (or concurrent alkalosis). For example, a patient may have diabetic ketoacidosis, uremia, or diarrhea resulting in a metabolic acidosis coupled with a respiratory acidosis from COPD or hypopnea due to postoperative pain. These patients can experience severe, life-threatening acidemia if not promptly treated
What nerves are affected by TAP block?
- Intercostal
- Subcostal
- Iliohypogastric
- Ilioinguinal
What is the triangle of petit?
mnemonic: where the TAP block “LIE”s
Landmarks for TAP block
The lumbar triangle of Petit - its inferior edge the iliac crest, the posterior edge the latissimus dorsi, and the anterior edge the external oblique. The tip of the triangle of Petit is the rib cage.
Between what layers of muscle do you inject into for a TAP Block?
- Internal Oblique and Transverse Abdominis
Describe the different types of Tracheoesophageal fistulas
Which is most common?
Type A
Type B
Type C
Type D
Type E
Type F
The most common being type C (occurs about 84% of the time)
Transcranial doppler measures flow velocities in what blood vessel?
Middle Cerebral Artery
Characteristics of Arterial line in setting of
1) Aortic Stenosis
2) Aortic Regurgitation
3) Low SVR
4) High SVR
What is the qSOFA score?
The quick sequential organ failure assessment (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 may also be used in adult out-of-hospital, emergency room, and general ward patients with suspected infection to identify those that are more likely to have poor outcomes typical of sepsis.
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.
What are the differences between Omphalocele and Gastrochisis
Etiology?
Location?
Covering?
Associated conditions?
- The incidence of gastroschisis is 0.4-3 per 10,000 births, compared to the more common omphalocele, occurring in 1.5-3 per 10,000 births.
- Gastroschisis lesions are comprised of an abdominal wall defect, typically to the right of the umbilical cord, through which small and large bowel are exposed outside of the body.
- A omphalocele lesion is a central defect of the umbilical ring and the abdominal contents (stomach, loops of bowel, and possibly the liver) are protruded outside the abdomen, yet enclosed in an amniotic membrane sac externally and peritoneal membrane internally.
- Gastroschisis tends to be an isolated lesion while omphalocele is often associated with other anomalies and/or chromosomal abnormalities including Beckwith-Wiedemann, Reiger, and prune belly syndromes and trisomy 13, 18, and 21
Bernoulli Equation?
Continuity equation?
- Transvalvular pressure = 4 x Peak velocity2
- Using the Doppler function on the echocardiography, one is able to measure the velocity of blood flow. Peak velocity refers to the highest value measured, while the mean velocity refers to the average of all the values measured. Velocity is related to pressure and this principle was first described by the physicist Bernoulli. The Bernoulli equation is based on the principle of conservation of energy, which states that energy is neither created nor destroyed. In a given system, the total energy (sum of potential and kinetic energy) must remain the same. The potential energy is manifested as pressure, while the kinetic energy is manifested as velocity.
Based on this principle, the Bernoulli’s equation states: P1*V1 = P2*V2
When blood flows through a narrow orifice, the velocity increases, but the pressure decreases (to maintain equal energy). By measuring the velocity across a region (e.g. aortic valve), one can calculate the change in pressure. The pressure gradient correlates with the degree of narrowing.
The Bernoulli equation that is used in echocardiography is a simplified version: Pressure Gradient (P2 - P1) = 4 \* (Velocity)^2
What is the parkland formula?
The Parkland formula for the total fluid requirement in 24 hours is as follows: 4ml x TBSA (%) x body weight (kg); 50% given in first eight hours; 50% given in next 16 hours.
Hypoplastic left heart syndrome is associated with what septal defect?
ATRIAL SEPTAL DEFECT, NOT Ventricular septal defect.
TURP Syndrome is commonly seen with what type of irrigation solution?
Distilled water
What is the difference between perimembranous and muscular ventricular septal defects?
- Perimembranous VSD:
Perimembranous VSDs occur in the upper ventricular septum, close to the aortic and/or mitral valve. They account for 70-80% of all VSDs and are the most common congenital anomaly recognized at birth. Perimembranous VSDs shunt blood across the left ventricle outflow tract into the right ventricle at the level of the tricuspid valve.
- Muscular VSD:
Muscular VSDs occur lower in the ventricular septum in the more muscular portion of the septum, closer to the apex of the heart. They account for 20-30% of all VSDs.
Fill in the following table regarding PACEMAKER NOMENCLATURE.
What happens when you place magnet over pacemaker?
How do you manage patients with pacemakers (long explanation)
- A magnet over a permanent pacemaker with an asynchronous magnet setting will induce one of the following modes: AOO, VOO, or DOO. Which of these settings is activated depends on the patient’s original programming for their underlying pathology.
Pacemakers are inserted for several reasons including symptomatic sinus or atrioventricular nodal disease, long QT syndrome, hypertrophic obstructive cardiomyopathy, and dilated cardiomyopathy. There are multiple ways to provide pacemaker capabilities and hundreds of possible devices. When a patient with a pacemaker presents for surgery, evaluation should occur first to determine the reason for pacemaker placement and to determine the patient’s other comorbid conditions. Determining if the patient is pacemaker dependent is vital and can usually be ascertained from history or documentation. If not, an electrocardiogram should be obtained to see if every P-wave or QRS complex is preceded by a pacemaker spike. If possible, device interrogation should occur as this gives the best evaluation of pacemaker settings, function, battery life, lead integrity, and device history. Often, programmers (pacemaker technicians) can help guide perioperative management of the pacemaker. In addition, checking serum electrolytes (especially serum potassium) should occur because alterations can make capturing of the pacemaker easier (hyperkalemia) or more difficult (hypokalemia).
A pacemaker set in DDD mode will ensure that each spontaneous atrial depolarization is followed by a ventricular depolarization. This will allow AV sequential pacing or “physiologic pacing” because the ventricular rate tracks the atrial rate. These pacemakers usually have a lead in the right atrium and the right ventricle – occasionally in severe disease, there will be three pacemaker wires (one in the right atrium and biventricular leads). The atrial lead fires leading to atrial contraction, followed by a preset interval and then the ventricular lead will follow causing ventricular contraction, resulting in “normal” atrioventricular contraction sequence. It allows sensing and pacing of both chambers along with inhibition of pacing in both chambers. This is important in patients who rely on the atrial kick contribution to cardiac output. It is a versatile mode that is commonly used, however, the development of pacemaker-mediated tachycardia can occur.
A major concern in the intraoperative period with pacemakers is electrocautery interference, also known as electromagnetic interference (EMI). EMI may result in oversensing by the pacer causing inappropriate inhibition on the pacing function. If electrocautery is required, a bipolar cautery device should be used if possible else the grounding pad should be placed as far away from the pacemaker as possible without the electrical pathway going through the pacemaker. If feasible, bursts should be limited to less than 10 seconds. Reprogramming of the device may be the best way to avoid intraoperative problems if monopolar electrocautery is planned. Most clinicians will place the patient into an asynchronous mode (AOO, VOO, DOO), this causes the pacemaker to fire at a fixed preset rate, independent of the patient’s underlying cardiac activity.The rate will need to be higher than the patients underlying rhythm to try to ensure that an R-on-T phenomenon does not occur, protecting the patient from arrhythmias.This is crucial for patients that are not pacemaker dependent.Setting the patient in asynchronous mode can result in competition with the patient’s intrinsic rhythm and may result in the development of a malignant arrhythmia, thus appropriate means to treat this should be available (namely a defibrillator and appropriate antiarrhythmic and blood pressure support medications).In addition,if the patient has an automated implantable cardioverter defibrillator (AICD), this needs to be deactivated if electrocautery is planned under certain circumstances.Tachyarrhythmia therapies, such as overdrive pacing, also need to be disabled. This may also be completed with a magnet in modern devices. Of note,a magnet does not affect pacemaker function for modern AICDs. Rather, magnets inhibit defibrillation in those devices.
In the perioperative period, placement of a magnet over the pacemaker may have variable results. Nearly all modern pacemakers will switch to a continuous asynchronous mode at a preset heart rate – the exact mode is variable (and maybe unknown without interrogation). Generally, DDD pacemakers switch to DOO, VVI switches to VOO, and AAI switches to AOO. If switched to asynchronous mode, the pacemaker will shut down the demand (inhibition) function allowing protection of pacemaker-dependent patients during electrocautery. Placing a magnet is not without risk since asynchronous pacing may trigger ventricular asynchrony in patients with hypoxia, electrolyte imbalances, and myocardial ischemia. It is useful to know the pacemaker model and what will happen when a magnet is placed (if an electrophysiologist or device specialist is unavailable, calling the manufacturer can be invaluable in helping to determine this).
Stage 1 of labor dermatome levels that should be covered?
Stage 2?
- Stage I of labor analgesia requires sensory blockade of uterine contractions (T10-L1 alone).
- The T12-L1 and S2-4 dermatomes need to be covered during the second stage of labor for a patient to remain comfortable.
Fill in the following table that describes features of dehydration in new born
What are the landmarks for infragluteal sciatic nerve block?
- The ischial tuberosity, greater trochanter of the femur, and sciatic groove are all anatomic landmarks for an infra-gluteal sciatic nerve block.
What happens to strong ion difference after several liters of normal saline?
It is reduced
- Key point: In the setting of hyperchloremia (from large saline infusion) the plasma Cl- concentration increases which results in a decrease in HCO3- to maintain net neutrality. The decrease in HCO3- reduces the SID.
Which pacemaker setting below poses the greatest risk to a patient?
Why?
Scenario C
- 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.
- As long as the patient’s intrinsic heart rate is less than the pacemaker rate setting, complications are unlikely. However, if the patient’s intrinsic heart rate increases above the pacemaker rate, the pacemaker will still continue to pace and the potential for an R-on-T phenomenon develops. This is where a ventricular depolarization (represented by the R wave) initiated by the pacemaker occurs during the relative refractory period of the cardiac conduction cycle (represented by the T wave). An R-on-T phenomenon can lead to life-threatening ventricular tachycardia and/or ventricular fibrillation. Accordingly, if a patient’s pacemaker is changed to an asynchronous mode perioperatively, it should be changed back to its original setting as soon as possible after the surgery is complete.
What is the peak time of the following biomarkers in the setting of myocardial infarction
1) Myoglobin
2) Total CK
3) CK-MB
4) Troponin I and T
5) Lactate Dehydrogenase
There is a clear correlation between CK-MB and 6-month mortality rates, with values ≥20 ng/ml corresponding to 20.2% mortality. Troponins have also been used to monitor post-cardiac surgery myocardial injury, with increased troponin I (>3.5 ng/ml) having predictive and prognostic value for cardiac-associated death and major postoperative complications such as malignant ventricular arrhythmia, myocardial infarction, congestive heart failure, and the need for myocardial revascularization within 1 year following CABG.
Troponin is integral to cardiac and skeletal muscle contraction. It acts by binding to the protein tropomyosin. Tropomyosin is an inhibitory molecule that prevents the actin-myosin fiber cross-bridge. After calcium binds to troponin, troponin inhibits tropomyosin via reversible conformational change. This allows actin and myosin to bind and muscle contraction to occur. Troponin is not found in smooth muscle.
Fill in the following Table
What is wrong with this circle system
- The fresh gas inlet should not be positioned between the patient and the inspiratory or expiratory valves in a traditional circle system.
