The effects of thiopentone, etomidate, ketamine and midazolam on several bactericidal functions of polymorphonuclear leucocytes in vitro.

Polymorphonuclear leucocytes (PMNL) are an essential component of the defence system against invading bacteria. There is evidence that some anaesthetics are able to suppress PMNL functions, promoting, perhaps, perioperative infection. We studied the effects of thiopentone, etomidate, ketamine, and midazolam on the generation of bactericidal agents (superoxide anion, hydrogen peroxide, and myeloperoxidase) by PMNL in vitro. Thiopentone inhibited superoxide anion (P < or = 0.01) as well as hydrogen peroxide production (P < or = 0.001). However, there was no statistically significant effect on myeloperoxidase release. Neither etomidate nor ketamine influenced the PMNL functions tested to any extent. Midazolam suppressed superoxide anion generation (P < or = 0.01) but only if a concentration far beyond clinical relevance was used.