Haemorrhage decreases the anaesthetic requirement for ketamine and thiopentone in the pig.

The anaesthetic requirements of ketamine and thiopentone were studied in eight pig littermates during normovolaemia and after haemorrhage (30% blood loss). Four animals received ketamine and four thiopentone, and the minimal anaesthetic doses of both drugs were determined. Moderate hypovolaemia decreased the anaesthetic requirements significantly and similarly: thiopentone 33 +/- 5%; ketamine 40 +/- 5% (mean +/- SEM).