Regional versus General Anaesthesia
The principle
- Regional anaesthesia, wherever feasible, is preferred — it eliminates airway manipulation, avoids the pressor response and polypharmacy, gives profound analgesia and reduces DVT & blood loss. GA carries increased respiratory morbidity in COPD.
Regional — advantages
- No airway manipulation; avoids pressor response
- Profound analgesia; avoids polypharmacy & systemic opioids
- Less blood loss, ↓ DVT, faster ambulation & recovery
Regional — cautions
- A sensory block above T6 impairs the accessory/abdominal muscles → ↓ ERV, PEFR & MVV
- Inadequate cough → retained secretions
- Titrate the level; high blocks are poorly tolerated
Premedication & Drug Selection for GA
Premedication
- Cautious sedatives — blunted hypoxic/hypercapnic drive; but anxiolysis helps (anxiety → hyperventilation, CO₂ wash-out, dynamic hyperinflation)
- Avoid long-acting benzodiazepines & excess opioids
- Continue bronchodilators (nebs/inhalers), steroids & nicotine-replacement; anticholinergic to dry secretions
- Optimise pre-oxygenation — CPAP may help in severe disease
Induction & maintenance
- Consider supraglottic device over ETT — minimise airway manipulation
- Induction: propofol or ketamine; avoid morphine & barbiturates (may provoke bronchospasm)
- Blunt airway reflexes: IV/laryngotracheal lignocaine, fentanyl
- Maintenance: sevoflurane (bronchodilator); avoid desflurane (airway irritant) and N₂O (expands bullae)
- Relaxants: non-histamine-releasing (vecuronium, rocuronium); ensure full reversal
The Laparoscopy Problem — Pneumoperitoneum & Trendelenburg
Why laparoscopic surgery is a "double hit" in COPD
Pneumoperitoneum (CO₂)↑ intra-abdominal pressure → ↓ FRC & ↓ compliance; CO₂ absorption → hypercarbia → may need ↑ minute ventilation, which COPD tolerates poorly → risk of respiratory acidosis
Trendelenburg positionFurther ↓ lung volumes, ↑ airway pressures, ↑ atelectasis
Practical response: keep insufflation pressure as low as the surgeon allows, watch EtCO₂ and airway pressures, do serial ABGs in prolonged cases, accept permissive hypercapnia, and optimise the ventilator strategy (next tab).