Haemodynamic effects of propofol vs thiopental in infants:: an echocardiographic study

Rapid i.v. induction of general anaesthesia is indicated in infants at risk of vomiting or regurgitation to reduce the risk of aspiration of gastric contents. Propofol is an alternative to thiopental in infants, and we have compared cardiovascular changes when propofol or thiopental was used for induction of anaesthesia in infants. Twenty infants, ASA I or II, aged 1-11 months, undergoing elective surgery were allocated randomly to receive either thiopental or propofol for i.v. induction. Cardiovascular and echocardiographic data were recorded in both groups before, during and for 5 min after induction of anaesthesia. Doses required to induce anaesthesia in each group were mean 10.3 (sD 0.9) mg kg(-1) of thiopental and 6.1 (0.6) mg kg(-1) of propofol. Thiopental did not alter significantly systolic or mean arterial pressure, afterload indices, rate-corrected velocity of circumferential fibre shortening or cardiac index, but decreased shortening fraction at I and 5 min after induction compared with awake values. Propofol did not alter heart rate, shortening fraction, rate-corrected velocity of circumferential fibre shortening or cardiac index at 1 and 5 min after i.v. induction compared with awake values. After induction, systolic and mean arterial pressures and afterload indices decreased more after propofol than after thiopental. Myocardial contractility decreased significantly 5 min after induction with both agents, but did not become abnormal. Thus propofol decreased arterial pressure more than thiopental because of an effect on afterload. Cardiac output remained unchanged with both agents.