Positive effects of ketamine v. metomidate anesthesia on cardiovascular function, oxygen delivery and survival. Studies with a porcine endotoxin model

Pulmonary and cardiovascular function, oxygen delivery and mortality were compared in endotoxemic pigs spontaneously breathing air and with continuous i.v. infusion of ketamine anesthesia (n = 10) or the equianesthetic dose of metomidate (n = 10). Continuous 6-hour i.v. infusion of endotoxin caused profound pulmonary and cardiovascular derangement in both groups. Cardiac output, mean arterial blood pressure, oxygen delivery and base excess were significantly higher and pulmonary vascular resistance significantly lower from 2-3 hours onwards in the ketamine than in the metomidate group. Six-hour survival was 6/10 and 1/10 in the respective groups. Death was presumably due to insufficient oxygen delivery in relation to tissue demand, reflected in the metomidate group's low base excess values. Control, non-stressed pigs showed no notable physiologic changes with either anesthetic regimen. The study demonstrated the importance of the type of anesthesia in stressful endotoxemic animal models. Although extrapolation of animal data requires great caution, the results may favor use of ketamine over etomidate (the clinical analogue of metomidate) in septic shock states requiring surgical intervention.