[Ketamine - a cardiovascular stimulating agent with direct cardiodepressant action (author's transl)]

Induction anaesthesia with 2 mg/kg of ketamine causes the well-known increases in heart rate and blood pressure. Simultaneous registration of the systolic-time-intervals (PEPI, LVETTI, PEP/LVET = Q), however, reveals a biphasic effect of ketamine on these contractility-parameters: an initial increase of PEPI and Q, representing a cardiac depressive effect of ketamine, is followed by a decrease of PEPI and Q, indicating a positive inotropic action of ketamine. Injecting the same dose of ketamine during the steady-state of a halothane-N2O:O2-anaesthesia, that causes a depression of the central and peripheral sympathetic activity, however, results in an increase of PEPI and Q, only. Thus, ketamine is a cardiac depressive agent, this effect, however, usually being overlapped by a centrally-induced cardiac stimulation.