Iraqi Board Anesthesia cheat sheet

Volume of distribution Vd = dose / plasma concentration; propofol Vd 2-10 L/kg is large because of high lipophilicity.

Clearance CL = elimination rate / plasma concentration; half-life t½ = 0.693 × Vd / CL, so t½ rises with both Vd and falling clearance.

Context-sensitive half-time is the time for 50% decline in plasma concentration after stopping an infusion; it is short for remifentanil (about 3-4 min) regardless of infusion duration.

Henderson-Hasselbalch: pH = pKa + log([base]/[acid]); a drug is 50% ionized when pH equals its pKa, and only uncharged drug crosses lipid membranes.

Laplace law for alveoli: P = 2T/r; small alveoli need surfactant to lower surface tension T and avoid collapse into larger units.

Oxygen content CaO2 = (1.34 × Hb × SaO2) + (0.003 × PaO2); the dissolved fraction is negligible at room air.

Poiseuille flow: resistance is proportional to length and inversely proportional to the fourth power of radius, so a 16% reduction in radius doubles resistance.

Nerve fibre block order: small unmyelinated C fibres (pain, temperature) block before A-delta, then A-beta touch, then motor A-alpha; sympathetic B fibres block first.

ASA Physical Status: I healthy; II mild systemic disease; III severe systemic disease; IV constant threat to life; V moribund; suffix E for emergency.

Revised Cardiac Risk Index (Lee) six predictors: ischaemic heart disease, heart failure, cerebrovascular disease, insulin-treated diabetes, creatinine >177 µmol/L, and high-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular).

Metabolic equivalents (METs): 4 METs (climbing a flight of stairs, heavy housework) is the threshold for acceptable functional capacity.

Stop smoking at least 4 weeks before surgery for meaningful reduction in pulmonary complications; shorter abstinence still improves carboxyhaemoglobin.

Dual antiplatelet therapy after coronary stenting: defer elective surgery 6 months after elective drug-eluting stent placement and 1 month after bare-metal stent unless risk of waiting exceeds bleeding risk.

HbA1c ≥ 8.5% or glucose > 10-12 mmol/L predicts poorer outcomes; aim for perioperative glucose 6-10 mmol/L.

STOP-BANG scores 1 point each for Snoring, Tiredness, Observed apnoea, Pressure (hypertension), BMI >35, Age >50, Neck circumference >40 cm, Gender male; ≥5 indicates high OSA risk.

Correct anaemia preoperatively: haemoglobin <130 g/L in both sexes is associated with increased 30-day morbidity and mortality.

Mallampati classes I-IV describe visible oropharyngeal structures with the patient seated, mouth open, tongue protruded, no phonation.

Difficult mask ventilation predictors (MOANS): Mask seal, Obesity/Obstruction, Age >55, No teeth, Snores/Stiff lungs.

Difficult laryngoscopy (LEMON): Look externally, Evaluate 3-3-2, Mallampati, Obstruction, Neck mobility.

3-3-2 rule: 3 fingerbreadths mouth opening, 3 fingerbreadths thyromental distance, 2 fingerbreadths hyoid-to-thyroid cartilage.

Cormack-Lehane grade: 1 full vocal cords, 2 partial cords, 3 epiglottis only, 4 epiglottis and soft palate not visible.

Failed intubation algorithm: declare failure, maintain oxygenation with supraglottic airway or mask, limit attempts to 3-4, call for help, and proceed to front-of-neck access if 'cannot intubate, cannot oxygenate'.

Rapid sequence induction: preoxygenation, cricoid pressure (10 N awake, 30 N after loss of consciousness), rapid-acting induction agent, then suxamethonium 1-1.5 mg/kg.

Suxamethonium is contraindicated in hyperkalaemia, burns or denervation beyond 24-48 h, malignant hyperthermia susceptibility, and known pseudocholinesterase deficiency.

MAC (minimum alveolar concentration) is the alveolar concentration at 1 atm that prevents movement in 50% of patients to a standard surgical stimulus; sevoflurane MAC ≈ 2%, isoflurane ≈ 1.15%, desflurane ≈ 6%.

MAC is reduced by ~25-50% with 70% nitrous oxide, opioids, hypothermia, pregnancy, and increasing age (about 6% per decade after 40).

Spinal anaesthesia block height depends on baricity, patient position, and dose; hyperbaric bupivacaine with sitting position produces a saddle block.

Epidural test dose: 3 mL lidocaine 1.5% with epinephrine 1:200,000; a rise in heart rate >20 bpm or systolic BP >15-20 mmHg suggests intravascular placement.

Local anaesthetic maximum doses: lidocaine 3 mg/kg plain, 7 mg/kg with adrenaline; bupivacaine 2 mg/kg; ropivacaine 3 mg/kg; levobupivacaine 2.5 mg/kg.

LAST management: stop injection, call for help, airway and 100% oxygen, benzodiazepine for seizures, and 20% lipid emulsion 1.5 mL/kg bolus then 0.25 mL/kg/min infusion.

TIVA with propofol: induction 1.5-2.5 mg/kg, maintenance 4-12 mg/kg/h; target-controlled infusion uses a pharmacokinetic model (Marsh or Schnider).

MAC (monitored anaesthesia care) requires continuous monitoring of oxygenation, ventilation, circulation and temperature, with a provider dedicated solely to the patient.

Pulse oximetry: SpO2 90% corresponds to PaO2 ≈ 60 mmHg on the oxyhaemoglobin dissociation curve.

Capnography waveform: a sudden drop to zero suggests disconnection, oesophageal intubation or circuit leak; a rising end-tidal CO2 suggests hypoventilation or CO2 absorption.

Bispectral index (BIS) ranges: 40-60 is the recommended depth for general anaesthesia; >60 increases risk of awareness.

Neuromuscular monitoring: train-of-four ratio ≥0.9 at the adductor pollicis indicates adequate recovery; post-tetanic count assesses deep block.

WHO Surgical Safety Checklist has three phases: sign-in before induction, time-out before incision, and sign-out before the patient leaves theatre.

Critical incident reporting is non-punitive; a just culture distinguishes human error from at-risk and reckless behaviour.

Capnography is mandatory for all intubations and is the most reliable confirmation of tracheal tube placement.

Nerve stimulator for regional blocks: 0.5 mA at 0.1 ms indicates proximity to a motor nerve; injection should not proceed if pressure >15 psi or pain on injection.

Caesarean section under spinal: hyperbaric bupivacaine 0.5% 2-2.5 mL with opioid; left uterine displacement and prophylactic phenylephrine infusion reduce hypotension.

Pulmonary hypertension: avoid hypoxia, hypercapnia, acidosis, hypothermia and pain, all of which raise pulmonary vascular resistance and precipitate crisis.

Aortic stenosis: maintain sinus rhythm, preload, and afterload; avoid tachycardia and sudden drops in systemic vascular resistance.

Pheochromocytoma: preoperative alpha blockade (phenoxybenzamine) for 10-14 days, then beta blockade; intraoperative sodium nitroprusside or phentolamine for hypertensive crisis.

Laparoscopic surgery: CO2 insufflation at 12-15 mmHg causes hypercapnia, raised intra-abdominal pressure, reduced venous return, and atelectasis; use PEEP and adjust ventilation.

Carcinoid syndrome: avoid histamine-releasing drugs (morphine, atracurium) and catecholamine release; octreotide 50-100 µg IV treats intraoperative crisis.

Neurosurgery: maintain cerebral perfusion pressure (MAP - ICP) 60-70 mmHg, normocapnia (PaCO2 35-40 mmHg), and head-up 15-30 degrees.

Obstructive sleep apnoea: use opioid-sparing technique, extubate awake, and monitor postoperatively with continuous pulse oximetry.

Sepsis-3: sepsis is life-threatening organ dysfunction from infection, defined by a SOFA score increase of ≥2; septic shock requires vasopressors to maintain MAP ≥65 mmHg with lactate >2 mmol/L despite fluids.

ARDS Berlin definition: acute onset within 1 week, bilateral opacities, not explained by cardiac failure, PaO2/FiO2 ≤300 mmHg on PEEP ≥5 cmH2O.

Lung-protective ventilation: tidal volume 6 mL/kg predicted body weight, plateau pressure ≤30 cmH2O, driving pressure ≤15 cmH2O.

Surviving Sepsis: 30 mL/kg crystalloid within 3 h for sepsis-induced hypoperfusion; norepinephrine is first-line vasopressor with MAP target 65 mmHg.

Acute kidney injury KDIGO: creatinine rise ≥26.5 µmol/L in 48 h, or ≥1.5× baseline in 7 days, or urine output <0.5 mL/kg/h for 6 h.

Hyperkalaemia with ECG changes: IV calcium gluconate 10 mL 10% for membrane stabilisation, then insulin-glucose, salbutamol, and dialysis if refractory.

Ventilator weaning: rapid shallow breathing index (respiratory rate / tidal volume in litres) <105 predicts successful extubation; perform spontaneous breathing trial for 30-120 min.

Propofol infusion syndrome: risk with >4 mg/kg/h for >48 h; presents with metabolic acidosis, rhabdomyolysis, hyperkalaemia and cardiac failure.

WHO analgesic ladder: step 1 non-opioid, step 2 weak opioid (codeine, tramadol), step 3 strong opioid (morphine, oxycodone), with adjuvants at every step.

Multimodal analgesia combines paracetamol, NSAIDs, local anaesthetics, opioids and adjuvants (ketamine, gabapentinoids) to reduce opioid consumption.

Opioid conversion: oral morphine 30 mg ≈ oral oxycodone 20 mg ≈ IV morphine 10 mg ≈ fentanyl 100 µg IV.

Patient-controlled analgesia: bolus dose, lockout interval, and background infusion; background infusion is generally avoided in opioid-naive patients.

Neuropathic pain: first-line gabapentin, pregabalin, amitriptyline, or duloxetine; tramadol is an alternative.

Ketamine for acute pain: subanaesthetic 0.1-0.3 mg/kg bolus then 0.1-0.2 mg/kg/h; monitor for psychotomimetic effects.

Epidural analgesia for thoracic surgery: local anaesthetic plus opioid improves pulmonary function and reduces respiratory complications.

Chronic pain biopsychosocial model: address nociception, psychological factors (catastrophising, depression), and social factors in a multidisciplinary programme.

Adult cardiac arrest: compressions 100-120/min, depth 5-6 cm, full recoil, minimise interruptions, ratio 30:2, and early defibrillation for shockable rhythms.

Advanced life support: adrenaline 1 mg IV every 3-5 min; amiodarone 300 mg after the third shock for refractory VF/VT.

Reversible causes (4 Hs and 4 Ts): Hypoxia, Hypovolaemia, Hypo/hyperkalaemia, Hypothermia; Tension pneumothorax, Tamponade, Toxins, Thromboembolism.

Trauma: catastrophic haemorrhage control (CABCDE); permissive hypotension to systolic 80-90 mmHg until haemorrhage control in penetrating trauma without head injury.

Massive transfusion: give balanced ratio (1:1:1 red cells:FFP:platelets), tranexamic acid 1 g within 3 h of injury, and calcium replacement.

Trauma airway: assume cervical spine injury, preoxygenate, and use manual in-line stabilisation or video laryngoscopy; avoid cricoid pressure if it impairs view.

Head injury: avoid hypoxia (SpO2 <94%) and hypotension (systolic <90 mmHg); maintain PaCO2 35-40 mmHg and head-up 30 degrees.

Anaphylaxis: adrenaline 0.5 mg IM (1:1000) into the anterolateral thigh, repeat every 5 min; IV fluids and airway support.

Postoperative nausea and vomiting (PONV) risk factors (Apfel): female sex, non-smoker, history of PONV or motion sickness, and postoperative opioids; each scores 1 point.

PONV prophylaxis: ondansetron 4 mg, dexamethasone 4-8 mg, droperidol 0.625-1.25 mg, or aprepitant; multimodal therapy for high-risk patients.

Malignant hyperthermia: dantrolene 2.5 mg/kg IV, then 1 mg/kg every 5-10 min to a maximum 10 mg/kg; stop volatile agents and suxamethonium, hyperventilate with 100% O2, and cool.

Postoperative hypoxia: consider atelectasis, opioid-induced respiratory depression, pulmonary embolism, aspiration, and laryngospasm.

Anaphylaxis in the operating theatre: common triggers are neuromuscular blockers (suxamethonium, rocuronium), antibiotics, chlorhexidine and latex.

Postoperative delirium: risk factors include age >65, cognitive impairment, hip fracture, and polypharmacy; use non-pharmacological prevention first.

Enhanced recovery after surgery (ERAS): carbohydrate loading, opioid-sparing multimodal analgesia, early mobilisation, and early enteral feeding.

Post-dural puncture headache: conservative therapy, caffeine, and epidural blood patch (15-20 mL autologous blood) if persistent.

Four principles of biomedical ethics: autonomy, beneficence, non-maleficence, and justice.

Informed consent requires capacity, adequate disclosure of material risks, comprehension, and voluntariness; document the discussion.

Capacity assessment: patient can understand, retain, weigh, and communicate a decision; if lacking, act in best interests with the least restrictive option.

Confidentiality: disclosure without consent is permitted where required by law, to prevent serious harm, or for public health reporting.

Do-not-attempt-resuscitation decisions are made with the patient or, if lacking capacity, in their best interests; they do not preclude other treatments.

Duty of candour: disclose harm to patients openly and apologise; a apology is not an admission of legal liability in many jurisdictions.

Root cause analysis: identify system failures rather than individual blame; recommendations should be measurable and followed up.

Resource allocation: triage decisions should be transparent, consistent, and based on clinical need and likelihood of benefit.