Comparison of the inhibitory effect of propofol, thiopentone and midazolam on neutrophil polarization in vitro in the presence or absence of human serum albumin.

Anaesthetic agents inhibit some aspects of immune function and this may be clinically important when prolonged infusions are used in an intensive care unit. We have studied the effects of propofol, thiopentone and midazolam on neutrophil polarization in vitro. At concentrations seen in plasma during anaesthesia, propofol and thiopentone produced significant (approximately 50%) and comparable degrees of inhibition. Inhibition was complete with greater concentrations of these drugs. When compared with equivalent concentrations of midazolam, propofol produced more inhibition (P less than 0.01) at all concentrations investigated, except the smallest. Midazolam produced no effect at clinically relevant concentrations. The effect of propofol was not attributable to its lipid carrier vehicle, as 10% Intralipid alone augmented neutrophil polarization. Human serum albumin conferred some degree of protection against the inhibition produced by clinically relevant concentrations of propofol and thiopentone, but not that produced by greater concentrations of these drugs.