Effects of desflurane and propofol on arterial oxygenation during one-lung ventilation in the pig

Background: Desflurane depresses hypoxic pulmonary vasoconstriction (HPV) in vitro. During one-lung ventilation (OLV), HPV may reduce venous admixture and ameliorate the decrease in arterial O-2 tension by diverting blood from the non-ventilated to the ventilated lung. Accordingly this study compares the effects of desflurane with those of propofol on oxygenation during two-lung (TLV) and OLV in vivo. Methods: Ten pigs (25-30 kg) were premedicated (flunitrazepam 0.4 mg/kg im), anaesthetized (induction: propofol 2 mg/kg iv; maintenance: N2O/O-2 50%/50%, desflurane 3% propofol 50 mu g kg(-1) min(-1), and vecuronium 0.2 mg kg(-1) h(-1) iv), orally intubated and mechanically ventilated. Femoral arterial and thermodilution pulmonary artery catheters were placed, and the orotracheal tube was replaced by a left-sided 28-Ch double-lumen tube (DLT) via tracheotomy. After DLT placement, N2O and propofol were discontinued, FiO(2) was increased to 0.85, and anaesthesia continued randomly with either desflurane (1 MAC) or propofol 200 mu g kg(-1) min(-1). Using a cross-over design, in each animal the effects of a), changing from TLV to OLV (left lung) during both desflurane and propofol and b), the effects of changing between Be two anaesthetics during OLV were studied. Results:When changing from TLV to OLV, PaO2, decreased more (P<0.05) during desflurane (mean 75%) than during propofol (mean 60%). Changing between desflurane and propofol during OLV resulted in small but consistent (P<0.05) increases in PaO2 (mean 15%) during propofol. Conclusion: Consistent with in vitro results on HPV, 1 MAC desflurane impaired in vivo oxygenation during OLV more than did propofol.