A simulation study of common propofol and propofol-opioid dosing regimens for upper endoscopy: implications on the time course of recovery.

BACKGROUND Using models of respiratory compromise, loss of response to esophageal instrumentation, and loss of responsiveness, the authors explored through simulation published dosing schemes for endoscopy using propofol alone and in combination with selected opioids. They hypothesized that models would predict adequate conditions for esophageal instrumentation and once drug administration is terminated, rapid return of responsiveness and minimal respiratory compromise. METHODS Four published dosing regimens of propofol alone or in combination with opioids were used to predict the probability of loss of response to esophageal instrumentation for a 10-min procedure and the probability of respiratory compromise and return of responsiveness once the procedure had ended. RESULTS Propofol alone provided a low probability (9-20%) and propofol-opioid techniques provided a moderate probability (15-58%) of loss of response to esophageal instrumentation. Once the procedure ended, all techniques provided a high likelihood of rapid return of responsiveness (less than 3 min). Propofol-opioid techniques required more time than propofol alone to achieve a high probability of no respiratory compromise (7 vs. 4 min). CONCLUSIONS Propofol alone would likely lead to inadequate conditions for esophageal instrumentation but would provide a rapid return to responsiveness and low probability of respiratory compromise once the procedure ended. The addition of remifentanil or fentanyl improved conditions for esophageal instrumentation and had an equally rapid return to responsiveness. The time required to achieve a low probability of respiratory compromise was briefly prolonged; this is likely inconsequential given that patients are responsive and can be prompted to breathe.