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NEW Added to close a syllabus gap — "complications of anaesthesia" and "management of complications and incidents in perioperative care" are both named.

Complications & positioning

Awareness, aspiration, laryngospasm, PONV and nerve injury — the complications that appear in vivas and in incident questions.

Awareness

Incidence roughly 1:20 000 overall, but far higher in obstetric, cardiac and major trauma surgery, and with rapid sequence induction and TIVA with neuromuscular blockade.
Risk factors: paralysis, light anaesthesia by necessity, female sex, younger age, obesity, previous awareness, chronic opioid or alcohol use, and equipment failure or drug error.
Autonomic signs are unreliable — normal heart rate and blood pressure do not exclude awareness, particularly with beta blockade.
Reduce risk: benzodiazepine premedication, end-tidal agent monitoring with alarms, depth monitoring (BIS 40–60) where relaxants are used with TIVA, and a checked machine.
NAP5 found the majority of reports occurred at induction or emergence, and that distress and later PTSD were common — so follow up, apologise, explain and refer.

Airway complications

Aspiration

Risk factors: emergency surgery, full stomach, obstruction, pregnancy, obesity, reflux, diabetic gastroparesis, opioids, raised ICP, and an unprotected airway.
Classical thresholds (contested): gastric volume >25 ml and pH <2.5.
Management: head-down and lateral, suction, intubate and suction the trachea before ventilating where possible, 100% oxygen, PEEP. Antibiotics and steroids are not routine; bronchoscopy only for particulate matter.

Laryngospasm

Reflex glottic closure — most common in children, light anaesthesia, and after airway irritation or secretions.
Management ladder: remove the stimulus → 100% oxygen with CPAP and jaw thrust (Larson's point pressure) → deepen with propofol → suxamethonium (including IM or intraosseous if no IV access) → intubate.
Negative pressure pulmonary oedema can follow — forced inspiration against a closed glottis generates markedly negative intrathoracic pressure and alveolar transudation.

PONV

Apfel score — four factors, each adding roughly 20% risk: female sex · non-smoker · previous PONV or motion sickness · postoperative opioids.
Receptors and drugs: 5-HT₃ (ondansetron) · D₂ (metoclopramide, droperidol) · H₁ (cyclizine) · muscarinic (hyoscine) · NK₁ (aprepitant) · dexamethasone (mechanism uncertain).
Multimodal prophylaxis works best — combine agents from different receptor classes. Propofol TIVA reduces PONV; nitrous oxide and volatiles increase it.
Watch QT prolongation with ondansetron and droperidol, and extrapyramidal effects with metoclopramide.

Positioning & nerve injury

Nerve	Mechanism	Deficit
Ulnar	Compression at the elbow — commonest perioperative neuropathy	Claw hand, sensory loss in the little and ring fingers
Common peroneal	Compression at the fibular head — lithotomy poles	Foot drop, loss of eversion
Brachial plexus	Arm abduction >90°, shoulder braces in Trendelenburg, sternal retraction	Variable upper limb weakness
Radial	Compression against the arm board or spiral groove	Wrist drop
Lateral femoral cutaneous	Excessive hip flexion in lithotomy	Numb lateral thigh (meralgia paraesthetica)
Saphenous	Compression against the lithotomy pole medially	Numb medial calf

Position-specific problems

Lithotomy + Trendelenburg: foot drop, meralgia paraesthetica, pudendal injury, compartment syndrome with prolonged elevation, and reduced FRC with raised airway pressures.
Prone: eye injury and ischaemic optic neuropathy — check eyes regularly; also facial and airway oedema, and pressure necrosis.
Sitting: venous air embolism, hypotension, and quadriplegia from excessive neck flexion.
Lateral: dependent arm and axillary compression — use an axillary roll, and consider brachial plexus stretch on the upper side.
Most perioperative neuropathies are positional or surgical, not caused by regional blockade — an important distinction when a deficit appears after a block.