The effects of preemptive intravenous versus preemptive epidural morphine on postoperative analgesia and surgical stress response after orthopaedic procedures.

BACKGROUND

The purpose of this study was to evaluate the effect of pre-emptive intravenous versus pre-emptive epidural morphine on both postoperative analgesic consumption and surgical stress response.

METHODS

Sixty patients, ASA I or II, aged 18-85, undergoing total hip or knee replacement were randomly assigned to three groups of 20 patients. In group pre-emptive epidural, patients were administered an epidural injection of 75 micrograms.kg-1 morphine about 45 minute before dermal incision. In group pre-emptive intravenous, patients were administered 0.15 mg.kg-1 of intravenous morphine following induction before dermal incision. In group control, patients were administered intravenous saline following induction before dermal incision.

RESULTS

The pre-i.v. group used significantly less morphine than the pre-epi group (p < 0.0003). In all groups, plasma cortisol levels increased as compared to pre-op values, but plasma cortisol increased more significantly in the pre-i.v. and control groups within 4 hrs of surgery and was still significantly elevated at 7 am of the first postoperative morning compared to the pre-epi group (p < 0.001) and the increase persisted to the next morning in patients pre-i.v. and control groups.

CONCLUSIONS

Although pre-emptive epidural morphine has failed to decrease postoperative analgesic consumption, it has been able to suppress the surgical stress more significantly than intravenous morphine and a saline control.