Postoperative epidural analgesia: trials of bupivacaine combined with fentanyl or morphine after spinal fusion surgery

Background: major spinal fusion surgery causes severe postoperative pain, which persists for at least 3 days. Efficient and safe methods for postoperative analgesia after spinal fusion surgery are, therefore, mandatory. This study aimed to compare the analgesic effect of different epidural analgesia combinations and their effects on blood level of Beta-endorphin. We also studied the impact of these analgesic regimens on defined postoperative mobilization maneuvers and on patient satisfaction

Methods: This study was registered in clinical trials number NCT01838707. Sixty patients scheduled for elective posterior lumbar fusion surgery for correction of Spondylolisthesis were enrolled in this study. Patients were randomly allocated into three equal groups [20 each] according to analgesic drugs combinations administered through epidural catheter inserted intraoperatively. All patients received standard general anesthesia. Al the end of posterior instrumentation, the surgeon inserted the epidural catheter under direct vision in the midline. All patients in this study were nursed in a high dependency intensive care facility and received analgesics according to the following protocol. Continuous drug flow will be maintained with a syringe pump. The syringe pump was connected to the epidural catheter [with the reservoir contain either: 0.125% Bupivacaine HCI at flow rate of 4 5 ml/h [5-6.25mg/h bupivacaine]. 0.125% Bupivacaine HCI fentanyl 100 microg at flow rate of 3 5 ml/h [3.75-6.24 mg/h bupivacaine I 6-10 microg /h fentanyl] 0.125% Bupivacaine HCI morphine sulphate 3 mg at flow rate of 3 5 ml/h [3.75-6.24 mg/h bupivacaine 0.18-0.3 mg/h morphine]. Infusion was continued until the third postoperative day. The rate was increased if pain VAS >3 [visual analogue scale] at rest or VAS >6 with movement. The rate was decreased when patients have intolerable relevant motor block [Bromage score >0] or sensory disturbances [numbness], or hypotension [systolic blood pressure <90 mm Hg]. IV rescue analgesia will be Ketrolactromethamine 30 mg. Epidural catheters were removed on the third postoperative day. Pain was assessed using the VAS ranging from "0" [no pain] to "10" [worst imaginable pain]. Pain was evaluated at rest and during mobilization. Maneuvers of particular clinical importance for postoperative mobilization [alone and with help] were chosen: Turning in bed. Standing in front of the bed and walking, and using the toilet without help. The time needed until the patient can first successfully perform these maneuvers was documented. Three venous samples to measure serum B-endorphin level first one preoperative base line, second at first time VAS more three at rest and third sample when VAS less than three at rest. For assessment of patients satisfaction with postoperative pain management a verbal rating score was used. Motor block was quantified with the Bromage scale. Patients will be asked about sensory deficits. Verbal rating scores was used for sedation. Nausea and vomiting and the incidence of pruritus were recorded

Results: There were no significant differences observed between the studied groups regarding patient characteristics [age, sex, ASA status, anesthesia time, surgery duration and number of segments fused]. There were no significant differences in all hemodynamic variables between the three groups, the results of this study showed less pain scores as recorded by VAS all over the study time for group 3 [bupivacaine+ morphine]. Pain scores were lowest for group Ill [bupivacaine + morphine] all over the study time when testing pain during movement. The mean times to turn in bed with and without assistance were lowest in group Ill [bupivacaine morphine]. B-endorphin level, there was no significant differences between means of B-endorphin samples between the groups or within each group. Patients were more satisfied in group 3 all over the study period. The incidence of nausea, vomiting or itching within the observation period was significantly different between the three groups. It was more common in the bupivacaine morphine group

In Conclusion: Epidural analgesia after spine surgery improve pain control and enhance functional recovery, but potential cost issues related to maintenance of the epidural infusion and ICU slay versus potential cost savings in hospital stay and effect on long term outcome must be considered. Also the cost of use B-endorphin as a biomarker of pain severity needs to be revised against the subjective assessment of pain

Effect of midazolam/fentanyl infusion on haemodynamic and metabolic responses during short surgical procedures

Midazolam was used in combination with fentanyl as total intravenous anesthesia for twenty patients undergoing short surgical procedures; fentanyl [1.5 ug/kg] was given intravenously. Three minutes later, midazolam was administered started by bolus dose of 0.3 mg/kg, followed by drip infusion of 0.25 mg/kg/h. Patients were oxygenated by 100% O2 face mask during the procedures. The hemodynamics and metabolic responses [serum cortisol, lactate, pyruvate and blood glucose changes] were followed preoperatively, intra and postoperatively. Although the hemodynamic parameters [systolic, diastolic and mean blood pressure, heart rate and rate pressure product] showed significant changes, they were not of apparent importance. Insignificant increase in blood glucose concentration was seen following incision; but maximum significant concentration was measured after two hours. From induction in the early postoperative period, serum cortisol concentration significantly increased after induction and during surgery then after 24 hours serum cortisol and glucose returned to pre-induction values. Serum lactate significantly decreased until 24 hours after induction, but serum pyruvate increased significantly at skin incision and during operation; but after 24 hours it returned to pre-induction values. In all patients, good operating conditions were produced and patient's acceptance was high. It was concluded that midazolam infusion in combination with fentanyl may be useful technique in short procedures without inhibiting adrenal steroid release or producing cardiorespiratory instability