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 O2 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 i.m.), anaesthetized (induction: propofol 2 mg/kg i.v.; maintenance: N2O/O2 50%/50%, desflurane 3%, propofol 50 micrograms kg-1 min-1, and vecuronium 0.2 mg kg-1 h-1 i.v.), 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, FiO2 was increased to 0.85, and anaesthesia continued randomly with either desflurane (1 MAC) or propofol 200 micrograms 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 the 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.