EDAIC Part I cheat sheet

Inhalational agent potency: MAC is the alveolar concentration at 1 atm abolishing movement to a standard stimulus in 50% of subjects; MAC is inversely related to lipid solubility and potency, and MAC-awake is roughly one-third of MAC.

Oxygen delivery: DO2 = cardiac output × arterial oxygen content; CaO2 (mL/dL) = 1.34 × Hb (g/dL) × SaO2 + 0.003 × PaO2. Each gram of haemoglobin carries about 1.34 mL O2, so anaemia limits DO2 even with normal SaO2.

Neuromuscular blockade monitoring: train-of-four ratio >0.9 at the adductor pollicis indicates adequate recovery; a ratio of 0.7 corresponds to marked pharyngeal dysfunction and aspiration risk.

Local anaesthetic maximum doses (adult, healthy): lidocaine 3 mg/kg plain, 7 mg/kg with adrenaline; bupivacaine 2 mg/kg; ropivacaine 3 mg/kg. Intravascular bupivacaine causes refractory ventricular arrhythmias treated with 20% lipid emulsion 1.5 mL/kg bolus.

Malignant hyperthermia: triggered by volatile agents and suxamethonium; earliest signs are rising end-tidal CO2 despite hyperventilation, masseter spasm, tachycardia, and hyperthermia. Treatment is dantrolene 2.5 mg/kg IV repeated to 10 mg/kg, stop trigger, hyperventilate with 100% O2, active cooling.

Laryngospasm management sequence: remove stimulus, 100% O2 with CPAP, deepen anaesthesia with propofol 0.5–1 mg/kg, then suxamethonium 0.5–1 mg/kg (or 4 mg/kg IM) if obstruction persists; hypoxaemia and negative-pressure pulmonary oedema are the main complications.

Acute respiratory distress syndrome (Berlin definition): onset within 1 week of a known insult, bilateral opacities not fully explained by effusion/collapse/nodule, and PaO2/FiO2 ≤300 mmHg with PEEP ≥5 cmH2O; severity is mild 200–300, moderate 100–200, severe <100.

Sepsis-3: life-threatening organ dysfunction from dysregulated host response to infection, defined operationally by a SOFA increase of ≥2 points; qSOFA (RR ≥22, altered mentation, SBP ≤100) flags risk but is not diagnostic.

Ventilator-induced lung injury targets: plateau pressure ≤30 cmH2O, tidal volume 6 mL/kg predicted body weight, driving pressure ≤15 cmH2O, and permissive hypercapnia; prone positioning ≥16 h/day reduces mortality in severe ARDS (PaO2/FiO2 <150).

Starling equation: Jv = Kf[(Pc − Pi) − σ(πc − πi)]. In sepsis, glycocalyx breakdown raises Kf and lowers σ, producing oedema despite normal hydrostatic pressures; fluid resuscitation alone may worsen it.

Oxygen-haemoglobin dissociation: right shift (↑2,3-DPG, ↑CO2, acidosis, pyrexia) reduces affinity and improves tissue unloading; fetal Hb and carboxyhaemoglobin shift left. P50 normally ~26.6 mmHg.

Induction agent dosing: propofol 1.5–2.5 mg/kg IV causes dose-dependent hypotension via venodilation and myocardial depression; reduce dose by 30–50% in hypovolaemia, elderly, or ASA III–IV patients. Ketamine 1–2 mg/kg preserves airway tone and sympathetic drive, useful in shock.

Suxamethonium: depolarising blocker metabolised by plasma cholinesterase; causes hyperkalaemia (dangerous in burns >24 h, denervation, prolonged immobility), bradycardia on repeat dosing, and raised intraocular pressure.

Opioid pharmacology: morphine is metabolised to morphine-6-glucuronide (active, accumulates in renal failure); fentanyl is 100 times more potent than morphine and causes chest wall rigidity at high IV doses; naloxone reverses with a short half-life requiring re-dosing.

Difficult airway algorithm (DAS): declare CICO (cannot intubate, cannot oxygenate) and proceed to emergency front-of-neck access - scalpel-bougie-tube or cannula techniques - rather than repeating failed intubation attempts.

Anaphylaxis under anaesthesia: commonest triggers are neuromuscular blockers, antibiotics, and chlorhexidine/latex. Adrenaline 50 µg IV boluses titrated, fluid bolus 20 mL/kg, stop the trigger, and send mast cell tryptase within 1 h and at 24 h.

Postoperative nausea and vomiting: Apfel score (female, non-smoker, history of PONV/motion sickness, postoperative opioids) predicts risk; each factor adds ~20%. Multimodal prophylaxis combines dexamethasone 4–8 mg, ondansetron 4 mg, and droperidol or cyclizine.

Perioperative cardiac risk: revised cardiac risk index factors are ischaemic heart disease, heart failure, cerebrovascular disease, insulin-treated diabetes, creatinine >177 µmol/L, and high-risk surgery. Functional capacity ≥4 METs allows most surgery without further testing.