ABA Anesthesiology cheat sheet

MAC is the alveolar concentration at 1 atm that prevents movement to surgical stimulus in 50% of patients; MAC values are additive and reduced by hypothermia, pregnancy, sepsis, and opioids.

Oxygen content: CaO2 (mL O2/dL) = 1.34 × Hb (g/dL) × SaO2 + 0.003 × PaO2 (mm Hg); oxygen delivery DO2 = cardiac output × CaO2 × 10.

For a weak acid, fraction ionized = 1/(1 + 10^(pKa − pH)); for a weak base, fraction ionized = 1/(1 + 10^(pH − pKa)); only uncharged drug crosses lipid membranes.

Henderson–Hasselbalch: pH = pKa + log([A−]/[HA]) for acids; bicarbonate buffer pH = 6.1 + log([HCO3−]/(0.03 × PaCO2)).

Clearance = dose/AUC; volume of distribution = dose/Cp0; elimination half-life = 0.693 × Vd/Cl; context-sensitive half-time rises with infusion duration for lipophilic drugs but not remifentanil.

Poiseuille resistance R = 8ηL/(πr^4), so halving radius raises resistance 16-fold; turbulent flow is favored by high Reynolds number, low viscosity, and branching.

Alveolar Laplace law P = 2T/r predicts small alveoli require higher pressure to remain open; surfactant lowers surface tension and reduces collapse.

Nernst potential E = (61.5/z) × log([ion]out/[ion]in) at 37°C; hypokalemia hyperpolarizes resting membrane potential and can potentiate nondepolarizing blockade.

Preoxygenation with 3 minutes of tidal-volume breathing or 4 vital-capacity breaths raises alveolar oxygen and prolongs safe apnea; efficacy is reduced by obesity, pregnancy, and shunt.

Rapid-sequence induction commonly uses succinylcholine 1–1.5 mg/kg or rocuronium 1.2 mg/kg; adequate intubating conditions with rocuronium require about 60–90 seconds.

Macintosh is a curved laryngoscope blade that fits the vallecula; Miller is a straight blade that lifts the epiglottis; optimal laryngeal view requires alignment of oral, pharyngeal, and laryngeal axes.

Spinal anesthesia with hyperbaric bupivacaine produces sympathectomy, hypotension, and bradycardia; treatment includes vasopressors, fluids, and atropine for high block with bradycardia.

Epidural test dose commonly is 3 mL lidocaine 1.5% with epinephrine 1:200,000; a positive test shows heart-rate rise or systolic pressure rise within 60–120 seconds.

Malignant hyperthermia: stop volatile agents and succinylcholine, give dantrolene 2.5 mg/kg IV, hyperventilate with 100% oxygen, cool, and treat hyperkalemia/acidosis.

Lung-protective one-lung ventilation uses tidal volume 4–6 mL/kg predicted body weight, PEEP, and plateau pressure <30 cm H2O; permissive hypercapnia is often acceptable.

Difficult airway management prioritizes oxygen delivery; awake fiberoptic intubation is preferred when mask ventilation and supraglottic rescue are likely to fail.

Revised cardiac risk index predictors: ischemic heart disease, heart failure, cerebrovascular disease, insulin-requiring diabetes, creatinine >2 mg/dL, and high-risk surgery.

Perioperative myocardial injury is diagnosed by troponin elevation above the 99th percentile with or without symptoms; routine troponin screening is used in high-risk patients.

Aortic stenosis increases afterload; anesthetic goals include maintaining sinus rhythm, preload, and systemic vascular resistance while avoiding tachycardia and profound vasodilation.

Chronic kidney disease: cisatracurium undergoes organ-independent Hofmann elimination; succinylcholine is avoided when potassium is elevated or renal failure causes hyperkalemia.

Diabetes: target perioperative glucose commonly 140–180 mg/dL; avoid hypoglycemia; insulin infusion is preferred for prolonged fasting or poorly controlled diabetes.

Obstructive sleep apnea: STOP-BANG scores ≥3 indicate increased risk; postoperative monitoring is needed for opioid-induced respiratory depression and airway obstruction.

Liver disease: Child–Pugh and MELD predict perioperative risk; coagulopathy, hypoalbuminemia, ascites, and encephalopathy alter drug binding and clearance.

Pulmonary hypertension: avoid hypoxia, hypercapnia, acidosis, and systemic hypotension; maintain right ventricular perfusion and consider inhaled nitric oxide or prostacyclin for crisis.

ARDS Berlin criteria: acute onset within 1 week, bilateral opacities, PaO2/FiO2 ≤300 with PEEP ≥5 cm H2O, and respiratory failure not fully explained by cardiac failure.

Lung-protective ventilation in ARDS: tidal volume 6 mL/kg predicted body weight, plateau pressure ≤30 cm H2O, and driving pressure ≤15 cm H2O.

Septic shock: give broad-spectrum antibiotics within 1 hour, obtain cultures, measure lactate, and give 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L.

Norepinephrine is first-line vasopressor for septic shock; target MAP ≥65 mm Hg; add vasopressin or epinephrine for refractory shock.

KDIGO acute kidney injury: creatinine rise ≥0.3 mg/dL in 48 hours or ≥1.5 times baseline in 7 days, or urine output <0.5 mL/kg/h for 6 hours.

Hyperkalemia with ECG changes: give IV calcium first, then insulin with glucose, albuterol, and bicarbonate as needed; dialysis removes potassium.

Hyponatremia correction should not exceed 8–10 mmol/L in 24 hours to reduce osmotic demyelination risk; symptomatic severe hyponatremia may require hypertonic saline.

Restrictive transfusion threshold is hemoglobin 7 g/dL for most critically ill patients; 8 g/dL is considered for active cardiac ischemia or cardiac surgery.

Local anesthetic maximum doses commonly cited: lidocaine 4.5 mg/kg without epinephrine and 7 mg/kg with epinephrine; bupivacaine 2.5 mg/kg; ropivacaine 3 mg/kg.

LAST treatment: stop injection, call for help, secure airway with 100% oxygen, give 20% lipid emulsion 1.5 mL/kg bolus, then infusion 0.25 mL/kg/min.

Neuraxial anticoagulation: hold prophylactic enoxaparin 12 hours and therapeutic enoxaparin 24 hours before puncture; apixaban and rivaroxaban are typically held 72 hours.

Post-dural puncture headache is positional, worse upright, and relieved supine; conservative therapy includes caffeine, fluids, and analgesics; epidural blood patch is definitive.

Epidural hematoma presents with progressive motor weakness, sensory loss, and bowel/bladder dysfunction after neuraxial blockade; urgent MRI and decompression are indicated.

Opioid equianalgesia: oral morphine 30 mg ≈ parenteral morphine 10 mg ≈ oral oxycodone 20 mg; incomplete cross-tolerance requires dose reduction when switching.

Neuropathic pain responds to gabapentinoids, tricyclic antidepressants, and serotonin-norepinephrine reuptake inhibitors more than to NSAIDs or pure opioids.

Interscalene brachial plexus block frequently causes ipsilateral phrenic nerve palsy; avoid in severe pulmonary disease; supraclavicular block risks pneumothorax.

ASA physical status: 1 healthy; 2 mild systemic disease; 3 severe systemic disease; 4 severe disease with constant threat to life; 5 moribund; 6 brain-dead organ donor.

WHO surgical safety checklist includes sign-in, time-out, and sign-out; time-out confirms patient, site, procedure, consent, allergies, airway, and antibiotic prophylaxis.

Wrong-site surgery is a never event; prevention includes preoperative marking, site verification, and a structured time-out with the full team.

Capnography detects esophageal intubation, disconnection, obstruction, and malignant hyperthermia; persistent waveform is the standard confirmation of tracheal tube placement.

Root cause analysis examines system failures after serious events; PDSA cycles test small changes; both aim to reduce recurrence rather than assign individual blame.

Informed consent requires capacity, disclosure of risks/benefits/alternatives, understanding, and voluntariness; emergency treatment may proceed without consent when life-threatening.

Crisis resource management: closed-loop communication, role clarity, mutual monitoring, and call for help early improve team performance during critical events.

Hand hygiene and central line bundles reduce CLABSI; ventilator bundles reduce VAP; surgical bundles reduce SSI.