OBJECTIVETo investigate the effects of different ventilation modes for one lung ventilation anesthesia on arterial blood-gas, airway pressure, intrapulmonary shunt, and F(A)/F(I) changes in patients receiving sevoflurane inhalation.

METHODSThirty ASA class II-III patients with lung cancer undergoing pulmonary lobectomy were randomized into 3 equal groups. The patients in group A received volume-controlled ventilation (VCV) without positive end-expiratory pressure (PEEP) (VT=8 ml/kg, Rf=12/min), and those in group B, after a preceding VCV stabilize the airway pressure, had pressure-controlled ventilation with maintenance of an identical peak pressure (Ppeak) (Rf=12/min, PEEP=0). In group C, the patients received small tidal volume ventilation with PEEP (VT=6 ml/kg, Rf=16/min, PEEP=5 cm H(2)O). Blood gas analysis was carried out at 10 min after TLV and at 20, 45 and 70 min after one lung ventilation (OLV); the heart rate (HR), mean arterial pressure (MAP), SpO(2) and Ppeak were also recorded and blood samples collected from the artery and jugular vein at these time points. Inhalation of 1.5% sevoflurane for 20 min started at 20 min of OLV.

RESULTSCompared with those in TLV, the Ppeak increased, lung compliance decreased, arterial oxygenation (PaO(2)) decreased and intrapulmonary shunt (Qs/Qt) increased during OLV. Group B showed the fastest increase of F(A)/F(I) in the initial 8 min, followed by groups A and C, but the curves became similar with the passage of time.

CONCLUSIONSDuring OLV, the 3 ventilation modes result in similar F(A)/F(I) changes during sevoflurane inhalation but PCV can increase pulmonary compliance.