Comparison of a single injection of morphine versus ketamine or neostigmine into the epidural space on postoperative analgesia and hormonal stress response after spinal anesthesia

Background In patients undergoing lower extremity orthopedic procedures who receive spinal anesthesia, an epidural injection of morphine, ketamine, or neostigmine has an effect on postoperative analgesia duration and hormonal stress response. Patients and methods We carried out a prospective, randomized study comparing the effects of addition of 0.6 mg morphine versus 50 mg ketamine versus 60 μg neostigmine into the epidural space in patients who received spinal anesthesia in terms of postoperative analgesia duration and hormonal stress response. Results There was marked prolongation in the postoperative analgesia (428 ± 257) and attenuation of the hormonal stress response in the morphine group compared with the other groups. Also, neostigmine led to prolongation of postoperative analgesia and attenuation of stress response but less than morphine (363 ± 119). Conclusion The preemptive morphine injection into the epidural space could attenuate hormonal stress response and led to prolongation in the postoperative analgesia period.