EDAIC cheat sheet

Oxygen delivery: DO2 = CO × CaO2, where CaO2 (mL/dL) = 1.34 × Hb × SaO2 + 0.003 × PaO2; at Hb 15 g/dL and SaO2 100%, dissolved O2 contributes only ~0.3 mL/dL.

Henderson–Hasselbalch: pH = 6.1 + log([HCO3-]/0.03 × PaCO2); respiratory acidosis raises PaCO2 10 mmHg for a pH fall of ~0.08 acutely, ~0.03 with renal compensation.

Clearance and half-life: t½ = 0.693 × Vd/CL; context-sensitive half-time rises with prolonged infusion for lipophilic drugs (thiopentone, fentanyl) but stays near constant for remifentanil and propofol.

Nernst equation: E = (61.5/z) × log([ion]out/[ion]in) mV at 37 °C; the resting membrane potential of −90 mV sits near the K+ equilibrium potential.

Starling equation: Jv = Kf[(Pc − Pi) − σ(πc − πi)]; a fall in plasma oncotic pressure or rise in capillary permeability increases filtered fluid and interstitial oedema.

Local anaesthetic block requires the uncharged base to cross the membrane; inflammation lowers pH, increases the charged fraction, and reduces efficacy of infiltration anaesthesia.

Oxygen–haemoglobin curve shifts right (reduced affinity) with increased 2,3-DPG, H+, CO2 and temperature; fetal haemoglobin and carboxyhaemoglobin shift it left.

Neuromuscular junction: acetylcholine binds nicotinic receptors, depolarisation opens voltage-gated Na+ channels; non-depolarising blockers are competitive antagonists, suxamethonium is a partial agonist causing fasciculations.

Malignant hyperthermia: triggered by volatile agents and suxamethonium; treat with dantrolene 2.5 mg/kg IV repeated to a total of 10 mg/kg, stop trigger, hyperventilate with 100% O2, active cooling, treat hyperkalaemia and arrhythmias.

Anaphylaxis: adrenaline 50 micrograms IV (0.5 mL of 1:10,000) in adults, repeated every 5 minutes as needed; remove trigger, give fluids, and consider a mast cell tryptase sample after resuscitation.

Difficult airway: plan A–D of the DAS algorithm - laryngoscopy, supraglottic airway, face-mask ventilation, then front-of-neck access; declare a CICO emergency and perform scalpel–bougie–tube cricothyroidotomy.

Local anaesthetic systemic toxicity: stop injection, secure airway with 100% O2, give 20% lipid emulsion 1.5 mL/kg bolus then 15 mL/kg/h infusion; avoid vasopressin, calcium channel blockers and beta-blockers.

Sepsis: give broad-spectrum antibiotics within 1 hour, 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L, and start vasopressors (noradrenaline first line) to keep MAP ≥65 mmHg.

Postoperative nausea and vomiting: Apfel risk factors are female sex, non-smoker, history of PONV/motion sickness, and postoperative opioids; each adds ~20% risk, so 3–4 factors warrant multimodal prophylaxis.

Acute coronary syndrome: perioperative troponin rise with ischaemic symptoms or ECG change defines myocardial injury/infarction; management includes aspirin, anticoagulation, and avoiding tachycardia and anaemia.

Chronic obstructive pulmonary disease: optimise bronchodilators and steroids preoperatively, use regional anaesthesia where possible, and target lung-protective ventilation with low tidal volumes and permissive hypercapnia.

Acute kidney injury: KDIGO stages by creatinine rise (1.5–1.9×, 2.0–2.9×, ≥3× or RRT) or urine output (<0.5 mL/kg/h for 6, 12, 24 h); maintain perfusion and avoid nephrotoxins.