A prospective evaluation of anesthesia for posterior lumbar spine fusion: the effectiveness of preoperative epidural anesthesia with morphine.

Study Design: A prospective, randomized, single-blinded study.

Objectives: To prospectively compare the anesthesia for posterior lumbar spinal fusion between the age- and gender-matched groups with and without preoperative epidural anesthesia with morphine.

Summary Of Background Data: To reduce the blood loss, hypotensive anesthesia is frequently used in the spinal fusion. However, in spite of administration of the hypotensive agents, inadequate analgesia during operation often causes unfavorable and unexpected elevation of blood pressure resulting in excessive bleeding. As well, intractable wound pain sometimes occurs after spinal fusion due to inadequate analgesia during surgery.

Methods: Forty cases of posterior lumbar spinal fusion were investigated prospectively. Twenty patients underwent preoperative epidural anesthesia with morphine and sedation by continuous intravenous administration of propofol but without administration of any kind of anesthetics, including intraoperative and/or postoperative epidural anesthesia (Group E). Another 20 patients underwent inhalation general anesthesia with sevoflurane and intermittent intravenous administration of fentanyl without any regional block (Group F). In these groups, dynamics and average mean blood pressure during surgery, blood loss during surgery, postoperative requirement of analgesics, the visual analogue scale, and accuracy of neurologic evaluation immediately after surgery were analyzed.

Results: The average mean blood pressure during surgery was significantly lower in Group E than Group F: 57.1 mm Hg and 72.8 mm Hg, respectively. In addition, the dynamics of blood pressure were more stable in Group E than Group F. The blood loss during surgery was significantly less in Group E than in Group F: 546 g and 631 g, respectively. The patients of Group E required analgesics after surgery less frequently, and the rating on the visual analogue scale was significantly lower in Group F on the first, second, and third days after surgery. It was difficult to evaluate the neurologic status accurately in 5 patients of Group F because of the inadequate emergence immediately after surgery. There were no patients in Group E whose neurologic status was unclear because of the paralysis caused by epidural anesthesia.

Conclusions: To combine preoperative epidural anesthesia with other anesthetic procedure for spinal fusion contributes to maintain more stable hypotension during surgery. As a result, it will be possible to lessen the bleeding during surgery. In addition, the postoperative pain was easily controlled with administration of fewer analgesic agents in patients who underwent the epidural anesthesia. The effectiveness of pre-emptive analgesia should be emphasized to diminish the postoperative pain.