ABPS Anesthesiology (BCA) cheat sheet

Poiseuille's law: Q = πΔPr⁴/(8ηL); flow rises with the fourth power of radius and falls with viscosity and length.

Laplace's law: wall tension T = P × r for a cylinder and T = (P × r)/2 for a sphere; smaller-radius vessels require less tension for the same pressure.

Henderson–Hasselbalch: pH = 6.1 + log([HCO3−]/(0.03 × PaCO2)).

Arterial oxygen content: CaO2 = 1.34 × Hb × SaO2 + 0.003 × PaO2.

Alveolar gas equation: PAO2 = FiO2 × (PB − 47) − PaCO2/R, with R ≈ 0.8.

MAC is the alveolar concentration at 1 atm that prevents movement in 50% of patients exposed to a standard noxious stimulus; MAC values are additive.

Potency increases with lipid solubility (Meyer–Overton), but nonimmobilizers and stereoisomers are exceptions.

Clearance = dose/AUC; context-sensitive half-time increases with infusion duration for highly lipophilic drugs.

Capnogram phases: I inspiratory baseline, II expiratory upstroke, III alveolar plateau, IV inspiratory downstroke; the end-tidal point is at the end of phase III.

Sudden ETCO2 loss suggests disconnection, esophageal intubation, circuit obstruction, cardiac arrest, or pulmonary embolism; a gradual rise suggests hypoventilation or increased metabolism.

A sloping phase III plateau suggests bronchospasm, obstructive lung disease, or sampling artifact.

Low-pressure leak test: close the APL valve, occlude the Y-piece, pressurize to 30 cm H2O, and confirm no pressure decay.

Oxygen fail-safe systems and proportioning devices prevent hypoxic mixtures; the oxygen analyzer and supply-pressure alarm are essential monitors.

Pulse oximetry uses 660-nm and 940-nm absorption; carboxyhemoglobin, methemoglobin, poor perfusion, motion, and nail polish reduce accuracy.

NIBP cuff width should be about 40% of arm circumference; a cuff that is too narrow falsely elevates readings.

Desflurane has a boiling point near 23.5°C and requires a heated, pressurized vaporizer; sevoflurane and isoflurane use variable-bypass vaporizers.

ASA physical status: I healthy, II mild systemic disease, III severe systemic disease, IV constant threat to life, V moribund, VI organ donor; suffix E denotes emergency.

Revised cardiac risk index: one point each for high-risk surgery, ischemic heart disease, heart failure, cerebrovascular disease, insulin-treated diabetes, and creatinine >2.0 mg/dL.

Fasting intervals: 2 h clear fluids, 4 h breast milk, 6 h light meal or infant formula, 8 h fatty or fried meal.

Continue chronic beta-blockers; starting a beta-blocker on the day of surgery is not recommended because it increases stroke and death in low-risk patients.

Smoking cessation for at least 4 weeks reduces pulmonary complications; longer abstinence further lowers risk.

STOP-BANG: snoring, tiredness, observed apnea, pressure (hypertension), BMI >35, age >50, neck circumference >40 cm, male gender; ≥3 indicates OSA risk.

Direct oral anticoagulants are held before neuraxial procedures based on renal function and drug half-life; bridging is individualized for high thrombotic risk.

Anemia is associated with increased perioperative morbidity; transfusion decisions use hemoglobin, symptoms, and bleeding rate rather than a single threshold.

Difficult mask ventilation predictors (MOANS): mask seal, obesity, age >55, no teeth, snoring or stiff lungs.

Difficult intubation predictors (LEMON): look externally, evaluate 3-3-2, Mallampati, obstruction, neck mobility.

Cricothyrotomy is the emergency front-of-neck access for cannot-intubate, cannot-oxygenate situations when supraglottic rescue fails.

Awake fiberoptic intubation is indicated when mask ventilation is predicted to fail, aspiration risk is high, or mouth opening is limited; spontaneous ventilation is preserved.

Supraglottic airway rescue is attempted before front-of-neck access in the cannot-intubate, cannot-oxygenate algorithm when feasible.

Video laryngoscopy improves glottic view in difficult airways; a failed attempt should prompt change of device, operator, or technique.

Extubation strategy includes assessing leak, neuromuscular recovery (TOF ratio >0.9), hemodynamic stability, and readiness for reintubation.

Sellick maneuver (cricoid pressure) may reduce gastric insufflation but can worsen laryngoscopic view and is not recommended for routine intubation.

Adult MAC values: halothane 0.75%, isoflurane 1.15%, sevoflurane 2.0%, desflurane 6.0%, nitrous oxide 105%.

Induction doses: propofol 1.5–2.5 mg/kg, etomidate 0.2–0.3 mg/kg, ketamine 1–2 mg/kg, thiopental 3–5 mg/kg.

Neuromuscular blockade: rocuronium 0.6 mg/kg for routine intubation, 1.2 mg/kg for rapid sequence; succinylcholine 1–1.5 mg/kg.

Reversal: neostigmine 0.04–0.07 mg/kg with glycopyrrolate; sugammadex 2 mg/kg at TOF count 2, 4 mg/kg at PTC 1–2, 16 mg/kg for immediate reversal.

Maintenance propofol TIVA 100–200 µg/kg/min; remifentanil 0.05–0.2 µg/kg/min; target-controlled infusions use effect-site concentrations.

Malignant hyperthermia: stop triggers, dantrolene 2.5 mg/kg, 100% oxygen, active cooling, treat hyperkalemia and acidosis.

Local anesthetic maximum doses: lidocaine 4.5 mg/kg plain and 7 mg/kg with epinephrine; bupivacaine 2.5–3 mg/kg; ropivacaine 3 mg/kg.

The 4-2-1 rule for hourly maintenance fluids: 4 mL/kg for first 10 kg, 2 mL/kg for next 10 kg, 1 mL/kg for each kg above 20.

LAST management: stop injection, call for help, secure airway with 100% oxygen, give 20% lipid emulsion 1.5 mL/kg bolus then 0.25 mL/kg/min, and continue CPR if arrested.

Spinal anesthesia for cesarean delivery usually uses hyperbaric bupivacaine 0.75% 1.5–2 mL to achieve a T4 sensory level; hypotension is treated with vasopressors and fluids.

Epidural test dose: 3 mL lidocaine 1.5% with epinephrine 1:200,000; heart rate increase >20 beats/min or systolic pressure rise suggests intravascular injection.

Interscalene block commonly causes phrenic nerve palsy and should be avoided or modified in severe pulmonary disease; it also risks Horner syndrome and recurrent laryngeal nerve block.

Supraclavicular block carries the highest risk of pneumothorax among brachial plexus approaches; ultrasound guidance reduces but does not eliminate the risk.

Adductor canal block provides knee analgesia while sparing quadriceps strength better than femoral nerve block.

ASRA neuraxial anticoagulation: LMWH prophylactic dose held 12 h, therapeutic 24 h; clopidogrel 5–7 days; warfarin until INR normalizes.

Femoral nerve block risks vascular puncture and quadriceps weakness; popliteal sciatic block spares the common peroneal and tibial divisions depending on approach.

Apfel PONV score: female sex, nonsmoker, history of PONV or motion sickness, postoperative opioids; each one point; ≥2 warrants prophylaxis.

PONV prophylaxis options: ondansetron 4 mg, dexamethasone 4–8 mg, droperidol 0.625–1.25 mg, scopolamine patch, aprepitant; combine drugs from different classes.

Aldrete score: activity, respiration, circulation, consciousness, oxygen saturation, each 0–2; score ≥9 is commonly required for PACU discharge.

Postoperative shivering raises oxygen consumption and intracardiac pressure; meperidine 12.5–25 mg, clonidine, or dexmedetomidine are effective after hypothermia is addressed.

Malignant hyperthermia can present in the PACU with hypercarbia, rigidity, hyperthermia, and rhabdomyolysis; dantrolene is the treatment.

Postoperative hypoxemia causes include atelectasis, hypoventilation from opioids, aspiration, pulmonary edema, and pulmonary embolism.

Multimodal analgesia combines acetaminophen, NSAIDs, regional blocks, and reduced opioids to lower opioid-related nausea, sedation, and respiratory depression.

Postoperative delirium risk factors include advanced age, cognitive impairment, frailty, sensory deprivation, pain, and polypharmacy.

Adult ACLS: compressions 100–120/min, depth 5–6 cm, ratio 30:2 without advanced airway; epinephrine 1 mg every 3–5 min; amiodarone 300 mg for refractory VF/pVT.

Defibrillation for VF/pVT uses biphasic 120–200 J; resume compressions immediately after shock.

Septic shock: lactate, cultures, antibiotics within 1 h, 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L, then norepinephrine for MAP <65 mmHg.

ARDS ventilation: tidal volume 6 mL/kg predicted body weight, plateau pressure <30 cm H2O, permissive hypercapnia.

Hyperkalemia treatment: calcium gluconate for membrane stabilization, insulin with glucose, albuterol, and bicarbonate when acidosis is present.

Severe hyponatremia correction should not exceed 8–10 mmol/L in 24 h to reduce osmotic demyelination risk.

Transfusion threshold in critically ill patients is commonly hemoglobin 7 g/dL; higher thresholds are used for active bleeding or myocardial ischemia.

Post-cardiac arrest care includes targeted temperature management, avoiding hyperthermia, maintaining normoxia and normocapnia, and treating the cause.

Pediatric uncuffed ETT size (mm ID) = age/4 + 4; cuffed tube = age/4 + 3.5; confirm depth by auscultation and capnography.

Pediatric fasting: 2 h clear fluids, 4 h breast milk, 6 h formula or light meal; neonates may require shorter intervals.

Obstetric patients: left uterine displacement after 20 weeks, aspiration prophylaxis, and cautious airway management because of edema and reduced functional residual capacity.

Magnesium sulfate toxicity: loss of deep tendon reflexes, respiratory depression, cardiac arrest; calcium gluconate is the antidote.

Geriatric patients have decreased MAC, reduced clearance of many drugs, and increased sensitivity to opioids and benzodiazepines.

Bariatric patients have increased risk of OSA, aspiration, and difficult airway; preoxygenation and positioning improve safety.

Neonatal MAC is lower than infant MAC; MAC peaks around 6 months of age and declines with age.

Pulmonary hypertension: avoid hypoxemia, hypercapnia, acidosis, and pain, which increase pulmonary vascular resistance.

ASA closed claims: respiratory events are the most common cause of anesthesia malpractice claims, followed by nerve injury and awareness.

WHO surgical safety checklist has sign-in before induction, time-out before incision, and sign-out before leaving the operating room.

Root cause analysis focuses on system factors rather than individual blame and produces recommendations to prevent recurrence.

Informed consent requires capacity, disclosure of diagnosis, treatment, risks, benefits, alternatives, and voluntary authorization.

Medication errors are reduced by barcode scanning, standardized concentrations, and separating look-alike/sound-alike drugs.

Hand hygiene is the single most effective measure for preventing healthcare-associated infection.

Quality measures in anesthesia include surgical site infection, unplanned reintubation, postoperative nausea and vomiting, and patient satisfaction.

A do-not-resuscitate order is reviewed before surgery; the anesthesiologist clarifies which interventions are permitted in the perioperative period.