In vitro, halogenated agents reduce the pulmonary vasoconstrictor response
to alveolar hypoxia in isolated perfused lungs. However, studies in intact
animals have been less convincing. The aim of the present study was to asse
ss the effect of sevoflurane on hypoxic pulmonary vasoconstriction (HPV) in
anaesthetized piglets using the pressure/cardiac index relationship (P/Q).
Ten large white piglets were anaesthetized and mechanically ventilated, al
ternately in hyperoxia (FIO2 = 0.4) and hypoxia (FIO2= 0.12). Multipoint pl
ots of pulmonary arterial pressure (PAP) or differences between PAP and lef
t atrial pressure (LAP) against Q were generated by gradual inflation of a
balloon introduced into the inferior vena cava. P/Q relationships were esta
blished in hyperoxia and hypoxia at baseline, and then with sevoflurane. In
hypoxia, pressure gradients (PAP - LAP) increased at every level of Q, thu
s demonstrating active pulmonary vasoconstriction. Sevoflurane at 1 MAC did
not affect these P/Q relationships in hyperoxia or hypoxia as compared wit
h baseline. Sevoflurane at a clinically relevant concentration (1 MAC) has
no significant effect on HPV in anaesthetized piglets.