ABA ADVANCED Exam cheat sheet

Laminar flow resistance is R = 8ηL/(πr^4); doubling radius lowers resistance 16-fold, while turbulent flow appears when Reynolds number exceeds roughly 2000 and resistance rises with density and velocity squared.

Laplace law: spherical alveolus P = 2T/r and cylindrical vessel P = T/r; smaller alveoli have higher collapsing pressure, offset by surfactant lowering surface tension.

Bernoulli principle: an increase in fluid velocity lowers lateral pressure; Venturi meters, jet nebulizers, and flowmeters use this pressure-velocity relationship.

Gas laws: Boyle PV constant at fixed T, Charles V/T constant at fixed P, Gay-Lussac P/T constant at fixed V; Dalton adds partial pressures and Henry states dissolved gas is proportional to partial pressure.

Variable-bypass vaporizer output depends on saturated vapor pressure, carrier-gas flow, temperature, and back pressure; desflurane has high vapor pressure and requires a heated, pressurized vaporizer.

Pulse oximetry uses the ratio R = (AC660/DC660)/(AC940/DC940); carboxyhemoglobin falsely elevates SpO2, methemoglobin drives SpO2 toward 85 percent, and poor perfusion or motion creates artifact.

Capnogram phases: I anatomic dead space, II ascending transition, III alveolar plateau, IV inspiratory downstroke; end-tidal CO2 approximates PaCO2, while a sudden drop suggests disconnection or pulmonary embolism.

Oscillometric NIBP sets MAP at maximal cuff oscillation and derives systolic and diastolic pressures; readings are unreliable in arrhythmia, severe obesity, and arterial calcification.

Electrical safety thresholds: 1 mA perception, 10-20 mA let-go, 100 mA ventricular fibrillation; microshock as low as 100 µA through myocardium requires isolated intracardiac equipment and line isolation monitoring.

Inhaled anesthetic MAC at 1 atm: nitrous oxide about 104 percent, desflurane 6 percent, sevoflurane 2 percent, isoflurane 1.15 percent, halothane 0.75 percent; MAC values are additive.

MAC is reduced by hypothermia, pregnancy, opioids, sedatives, and advanced age; it is increased by hyperthermia, chronic alcohol use, and catecholamine excess.

Blood:gas solubility determines inhaled induction speed (low solubility is faster); oil:gas solubility correlates with potency; nitrous oxide causes second gas effect and diffusion hypoxia.

Intravenous induction doses: propofol 1.5-2.5 mg/kg, etomidate 0.2-0.3 mg/kg, ketamine 1-2 mg/kg; etomidate causes adrenal suppression and ketamine raises heart rate and blood pressure.

Opioid kinetics: fentanyl onset 3-5 minutes and duration 30-60 minutes; remifentanil is hydrolyzed by nonspecific esterases and has context-insensitive offset; meperidine metabolite normeperidine can cause seizures.

Neuromuscular blockade: succinylcholine 1-1.5 mg/kg is depolarizing and contraindicated after burns or denervation due to hyperkalemia; rocuronium 0.6-1.2 mg/kg is nondepolarizing; extubation requires train-of-four ratio above 0.9.

Reversal: neostigmine 0.03-0.07 mg/kg with glycopyrrolate 0.2 mg per mg; sugammadex 2 mg/kg for moderate block, 4 mg/kg for deep block, and 16 mg/kg for immediate reversal after rocuronium.

Local anesthetics are weak bases; ion trapping in acidic infected tissue reduces efficacy; maximum lidocaine is 4.5 mg/kg without epinephrine and 7 mg/kg with it; bupivacaine maximum is about 2-3 mg/kg.

Local anesthetic systemic toxicity presents with perioral numbness, tinnitus, seizures, then arrhythmias; treatment is airway support, benzodiazepines, and intravenous lipid emulsion.

Oxygen delivery DO2 = CO × CaO2 × 10; CaO2 = 1.34 × Hb × SaO2 + 0.003 × PaO2; normal DO2 is about 1000 mL/min and oxygen consumption is about 250 mL/min.

Shunt fraction = (CmvO2 - CaO2)/(CmvO2 - CcO2); physiologic dead space fraction = (PaCO2 - mixed expired PCO2)/PaCO2.

Respiratory compliance = ΔV/ΔP; airway resistance = (Pmouth - Palv)/flow; surfactant lowers alveolar surface tension and increases compliance, while obesity and pregnancy reduce functional residual capacity.

Cerebral perfusion pressure CPP = MAP - ICP; autoregulation keeps cerebral blood flow constant between MAP about 50 and 150 mmHg; PaCO2 changes cerebral flow about 3-5 percent per mmHg.

Coronary perfusion pressure = aortic diastolic pressure - left ventricular end-diastolic pressure; myocardial oxygen extraction is high, so increased demand is met mainly by increased coronary flow.

Renal blood flow is autoregulated between MAP about 80 and 180 mmHg; below this range glomerular filtration falls; antidiuretic hormone and the renin-angiotensin-aldosterone system regulate sodium and water balance.

Henderson-Hasselbalch: pH = 6.1 + log([HCO3-]/(0.03 × PaCO2)); anion gap = Na - (Cl + HCO3), normal 8-12 mEq/L, and hypoalbuminemia lowers the measured gap.

Frank-Starling relationship: increasing preload raises stroke volume until the ventricle reaches its optimal sarcomere length; beyond that, volume loading increases congestion without increasing output.

Hypothermia causes shivering, vasoconstriction, coagulopathy, and arrhythmias; the stress response raises cortisol, catecholamines, and antidiuretic hormone, increasing catabolism and fluid retention.

Preoperative airway assessment includes Mallampati class, mouth opening, thyromental distance, cervical spine mobility, and dentition; no single test reliably predicts difficult intubation.

Fasting intervals for elective anesthesia: clear liquids 2 hours, breast milk 4 hours, infant formula and nonhuman milk 6 hours, light meal 6 hours, fatty meal 8 hours.

Rapid-sequence induction is selected when aspiration risk is high; preoxygenate, give induction agent and neuromuscular blocker, apply cricoid pressure if indicated, and intubate without positive-pressure ventilation.

Difficult airway management prioritizes oxygenation; after failed intubation, limit attempts, use a supraglottic airway, and proceed to emergency invasive airway if ventilation cannot be maintained.

Malignant hyperthermia: stop volatile anesthetics and succinylcholine, give dantrolene 2.5 mg/kg IV and repeat as needed, hyperventilate with 100 percent oxygen, cool, and treat hyperkalemia and arrhythmias.

Local anesthetic systemic toxicity: stop injection, secure airway with 100 percent oxygen, control seizures with benzodiazepine, give lipid emulsion 1.5 mL/kg bolus then 0.25 mL/kg/min, and avoid vasopressin and calcium channel blockers.

Transfusion: one unit of packed red blood cells raises hemoglobin about 1 g/dL; restrictive threshold is hemoglobin 7 g/dL for stable adults, with 8 g/dL considered for myocardial ischemia or cardiac surgery.

Postoperative nausea and vomiting: Apfel factors are female sex, nonsmoking, motion sickness or prior postoperative nausea, and postoperative opioids; high-risk patients receive multimodal prophylaxis.

Enhanced recovery after surgery combines regional analgesia, acetaminophen, nonsteroidal anti-inflammatory drugs when safe, early feeding, and opioid-sparing analgesia to reduce surgical stress and length of stay.