Effects of propofol vs sevoflurane on arterial oxygenation during one-lung ventilation

The inhibitory effect of anaesthetic agents on hypoxic pulmonary vasoconstriction may depend upon their dose, especially when using a volatile agent. The aim of this randomized open study was to compare the effects of sevoflurane and propofol, as primary anaesthetic agents, on oxygenation during one-lung ventilation (OLV), with their administration being adjusted to maintain bispectral index (BIS) values between 40 and 60.

Eighty patients scheduled for a lobectomy, receiving an epidural mixture of ropivacaine and sufentanil, were randomly assigned to Group S (maintenance with sevoflurane) or Group P (maintenance with propofol). After placement of a double-lumen tube, the lungs were ventilated at an inspiratory fraction of oxygen of 1.0, a tidal volume of 6 ml kg(-1), and 12 bpm. Arterial blood gas samples were taken as follows: during two-lung ventilation before OLV, and during the first 40 min of OLV.

Fifteen patients were excluded (incorrect placement of the tube or BIS outside the desired range). The two groups were comparable in terms of demographic variables, haemodynamic, and BIS levels during the operation. Four patients in each group had a Sp(O2)<90%. Mean of the lowest Pa(O2) was 16.3 (7.5) kPa in Group S and 17.7 (9.3) kPa in Group P (ns).

Sevoflurane and propofol had similar effect on Pa(O2) during OLV when their administration is titrated to maintain BIS between 40 and 60.