Propofol induction: normalizing the dose in morbidly obese patients

Excerpt

The estimation of appropriate induction doses for obese patients remains controversial but is of considerable importance. Too low a dose risks awareness and sympathetic response and too high a dose risks hypotension and cardiovascular instability. The study by Subramani et al. in this issue of the Journal 1 reports induction doses of propofol that are clinically relevant for morbidly obese patients. Propofol was infused at a rate of 100 mg·kg⁻¹·hr⁻¹ lean body weight (LBW) until a target criterion was met. The target in the LBW group was a total dose of 2.6 mg·kg⁻¹ LBW, and the target in the bispectral index (BIS) group was a decrease in the BIS score to 50. When the target for each group was reached, adequacy of induction was assessed every 30 sec until no response was observed to trapezius squeeze. In the LBW group, 18 of 30 patients were still responsive after the initial dose of 2.6 mg·kg⁻¹ LBW. In the BIS group, all but one of 30 patients were unresponsive at the target BIS of 50, which corresponded to a mean value of 3.83 mg·kg⁻¹ LBW. Under the conditions of this study, 2.6 mg·kg⁻¹ LBW of propofol was not adequate for 60% of the patients, and 3.83 mg·kg⁻¹ LBW of propofol was enough for all but one patient. …