Thoracic Anaesthesia

Quick Answer

Thoracic anaesthesia requires one-lung ventilation (OLV) for most intrathoracic procedures to provide surgical exposure and protect the dependent lung from contamination. Indications for OLV: Thoracotomy (lobectomy, pneumonectomy, oesophagectomy), VATS procedures, bronchopleural fistula, lung abscess, significant bleeding from one lung, asymmetric lung disease. Double-lumen endobronchial tubes (DLT): Left-sided preferred (less risk of right upper lobe obstruction), sizes 41, 39, 37, 35 Fr (adult), 32, 28 Fr (paediatric); bronchoscopic confirmation of position required. Bronchial blockers: Arndt, Cohen, Uniblocker devices for patients with difficult airway or requiring postoperative ventilation (easier to switch to single lumen tube). One-lung ventilation strategy: Volume control, tidal volume 4-6 mL/kg (predicted body weight), respiratory rate to maintain PaCO₂ 35-45 mmHg, PEEP 5 cm H₂O to dependent lung, FiO₂ 1.0 initially (can titrate down), inspiratory:expiratory ratio 1:2 or longer to prevent gas trapping. Hypoxaemia during OLV: Occurs in 5-10% despite 100% FiO₂; mechanisms include shunt through non-ventilated lung (20-30% of cardiac output perfuses non-ventilated lung) and V/Q mismatch in dependent lung; management includes suction non-ventilated lung, CPAP 5-10 cm H₂O to non-ventilated lung (opens alveoli, improves oxygenation but may compromise surgical exposure), PEEP to dependent lung, intermittent two-lung ventilation, check DLT position. Thoracotomy pain: Most severe postoperative pain; multimodal approach mandatory: thoracic epidural (T5-T8 level, infusion 4-10 mL/hour bupivacaine 0.125% + fentanyl 2-5 μg/mL), paravertebral block (pre-incision or post-op, catheter infusion 0.2% ropivacaine 8-10 mL/hour), systemic multimodal analgesia (paracetamol, NSAIDs, gabapentinoids, opioids). Post-thoracotomy complications: Atelectasis (20-30%), pneumonia (5-10%), respiratory failure requiring re-intubation (5-10%), chronic post-thoracotomy pain (20-40% at 3 months). Positioning: Lateral decubitus with flexion of operating table (opens intercostal spaces), padding of pressure points, securing patient to prevent falls. Monitoring: Arterial line (continuous BP, frequent ABG), central venous access, urine output, temperature; consider cardiac output monitoring for pneumonectomy or extensive resections. Pneumonectomy considerations: Perform fluid restriction (1-1.5 mL/kg/hour) post-op to prevent pulmonary oedema in remaining lung; no CPAP to non-ventilated side (no lung to reinflate); careful bronchial stump closure to prevent BPF. Indigenous patients: Higher smoking rates increase risk of COPD and hypoxaemia during OLV; thorough preoperative assessment and optimization essential. [1-10]