[Two cases of intraoperative awareness during intravenous anesthesia with propofol in morbidly obese patients]

Abstract

We experienced two cases of intraoperative awareness during intravenous anesthesia with propofol and fentanyl in morbidly obese patients. The rates of propofol infusion were calculated according to the adjusted body weights, or reduced intentionally as obese patients are generally believed to require lower doses of propofol compared with non-obese patients. Our postoperative analysis by simulations using the anesthesia records showed that, when the simulation was based on real body weight, the blood/effect-site concentrations of propofol in both patients would have been below the necessary levels to keep the patients unconscious during the operation, but when the simulation was based on adjusted body weight, those concentrations might have been within the necessary range to maintain an adequate hypnotic level. We propose that the rate of propofol infusion should be the same in obese and non-obese patients and should be calculated according to the real body weight not to the adjusted body weight.