HYPOTHERMIC CARDIOPULMONARY BYPASS INFLUENCES THE CONCENTRATION-RESPONSE RELATIONSHIP AND THE BIODISPOSITION OF ROCURONIUM

In 10 patients scheduled for elective coronary artery bypass grafting under midazolam-sufentanil anaesthesia, the influence of hypothermia o n the plasma concentration-response and biodisposition of rocuronium w ere investigated. Neuromuscular function was monitored mechanomyograph ically. plasma and urine concentrations of rocuronium were determined by high performance liquid chromatography. Hypothermic cardiopulmonary bypass prolonged the duration of action of maintenance doses and alte red the plasma concentration-response relationship. The elimination an d distribution half-lives, following the last maintenance dose after r ewarming, and the urinary excretion of rocuronium were similar to valu es obtained during normothermia. A diminished hepatic uptake and stora ge in the liver of rocuronium during hypothermia may explain the more pronounced prolongation of the duration compared to that of other ster oidal neuromuscular blocking agents.