Background: In a pilot study, the haemodynamic and gas exchange effects of acute hypercapoia during one-lung ventilation in thoracotomy patients were investigated. The effects of normocapnic one-lung ventilation (OLV-N) on haemodynamics and pulmonary gas exchange were compared with those of hypercapnic one-lung ventilation (OLV-H) in 14 patients undergoing pulmonary lobectomy.
Methods: Hypercapnia was induced by decreasing tidal volume until PaCO2 increased to 8-9 kPa. During OLV, minute ventilation was reduced from 8.8+/-1.7 to 4.2+/-0.7 l min(-1).
Results: Cardiac index (from 3.3+/-0.6 to 3.9+/-0.6 l min(-1), P<0.01) and pulmonary vascular resistance index (from 245+/-96 to 347+/-125 dyn s cm(-5) m(-2), P<0.05) increased during OLV-H, whereas systemic vascular resistance index decreased from 1952+/-403 to 1636+/-361 dyn s cm(-5) m(-2) (P<0.01). Pulmonary oxygenation remained unchanged.
Conclusions: All patients had an uneventful course during OLV-H. The determinants of pulmonary oxygenation during hypercapnic one-lung ventilation remain to be further elucidated.