One-Lung Ventilation, Maintenance & Fluids
🌫️ Maintenance
- < 1 MAC volatile (preserves hypoxic pulmonary vasoconstriction); N₂O avoided (it raises PVR and expands air spaces).
| OLV ventilator setting | Target |
|---|---|
| FiO₂ | Up to ~0.95 (titrate to SpO₂) |
| Tidal volume | 5–6 mL/kg (lung-protective) |
| Respiratory rate | 12–20/min, targeting EtCO₂ ~32–38 mmHg |
| Mode | Pressure-controlled; peak airway pressure <35, plateau <25 cmH₂O |
| PEEP | 5–10 cmH₂O to the ventilated lung; permissive hypercapnia accepted |
Timing & troubleshooting: OLV is started before insertion of the thoracotomy trocar/incision. If hypercarbia develops, increase minute ventilation. For hypoxaemia on OLV: confirm DLT position (FOB), ↑ FiO₂, apply PEEP to the dependent lung and CPAP to the operative lung, and — as a last resort — ask the surgeon to clamp the pulmonary artery.
💧 Fluid management
- Judicious fluids — crystalloids < 3 L in the first 24 h; do not replace "third-space" losses.
- Over-transfusion → oedema of the dependent lung and ↑ pulmonary shunting → post-pneumonectomy pulmonary oedema (often fatal).