[Comparison of changes in plasma concentrations of ACTH and beta-endorphin in cholecystectomy under general anesthesia and general plus epidural anesthesia].

OBJECTIVE

To study neuroendocrine response during cholecystectomy under general anesthesia with fentanyl and under general anesthesia with nitrous oxide plus thoracic epidural block, by determining plasma levels of ACTH and beta-endorphin.

PATIENTS AND METHODS

This was a prospective study of 2 randomly chosen groups of 7 patients each who were undergoing cholecystectomy. One group received general anesthesia with fentanyl at initial doses of 10 micrograms/kg-1 followed by perfusion of 5 micrograms.kg-1.h-1. The other group received general anesthesia with 60% nitrous oxide in oxygen combined with bupivacaine 0.5% for thoracic epidural blockade. Plasma levels of ACTH and beta-endorphin were determined at the following moments: A, upon arrival in the operating theater; B, after anesthetic induction and intubation; C, after incision; D, 30 minutes after start of surgery; E, after surgery but before extubation, and F, after arrival in the recovery room. Also recorded were mean arterial pressure and heart rate.

RESULTS

In both groups we found significantly higher levels of beta-endorphin throughout surgery. The increase was greater, however, in the group receiving combined anesthesia at moments D (p = 0.008) and E (p = 0.008). ACTH levels rose significantly during surgery (p = 0.004) in the combined anesthesia group, whereas there was only a slight increase in the group receiving only general anesthesia (p = NS). beta-endorphin levels increased proportionally more than ACTH levels during combined anesthesia. Hemodynamic stability was acceptable in both groups.

CONCLUSION

General anesthesia with fentanyl at the dose used in this study was more effective that combined anesthesia in mitigating the release of ACTH and beta-endorphin during cholecystectomy.