Background and objective: The aim of this pilot study was to evaluate efficacy and safety of propofol 350 versus 200 mg for induction of anaesthesia in morbidly obese patients undergoing bariatric surgery.
Patients and methods: Twenty morbidly obese patients (BMI range 38-60 kg m) were randomized to receive propofol 350 or 200 mg over 60 s for induction of anaesthesia. Bispectral index (BIS) values, induction characteristics and haemodynamic parameters were compared.
Results: At the time of intubation, in the 200 mg group, mean BIS values were more variable and significantly higher [53 (range 27-86) versus 31 (range 18-52), 200 versus 350 mg group (P = 0.01)]. In 20% of the 200 mg group, an additional propofol dose was needed, whereas no additional doses were judged necessary in the 350 mg group. At the time of intubation, six patients in the 200 mg group had systolic arterial pressures above 160 mmHg [mean 162 (range 100-210)], whereas mean pressures in the first 10 min were more in the target range in the 350 mg group [mean 122 (range 90-170)] (P = 0.01). One patient in the 350 mg group experienced a serious decrease in systolic arterial pressure (below 60 mmHg), immediately upon starting the maintenance dose. There were no significant differences in heart rate.
Conclusion: Although propofol 200 mg proved to be an inadequate induction dose for morbidly obese patients, the 350 mg induction dose deserves further study, provided the maintenance dose is not started within 5 min, thereby preventing temporary cardiovascular instability.