The pharmacokinetic evaluation of the analgesic component of general intravenous anaesthesia. Is the intermittent administration of opioids adequate?

Abstract

The aim of the study was to determine the accuracy of the delivery and the availability of maintaining in time the effect - site concentration (Ces) values of fentanyl, adapted for the performed surgical intervention by bolus administration of the drug, as compared with data recommended in the literature. The study included a group of 18 female patients operated under total intravenous anaesthesia (TIVA) using intermitent, manual, administration of the anaesthetic drugs. The doses of fentanyl, the intervals between the administration and the age, sex, weight and height of the patient were introduced into Stangraf TM soft (Microsoft® & Greenleaf® Inc., Stanford, USA), where the perianaesthetic dynamics and the postanaesthetic decrease of the drug’s Ces were configurated. The results showed that the fentanyl Ces which were inadequately for surgical needs represented 40-70% of the anaesthesia time. Also, when extubation was performed, the level of fentanyl Ces was in the range to produce a recurrent respiratory depression. In conclusion, the manual, intermitent administration of fentanyl during TIVA is inadequate and the target controlled infusion should be preferred.