• I Rundshagen, T Standl, E Kochs, M Müller, and J Schulte am Esch.
• Department of Anesthesiology, University Hospital Eppendorf, Hamburg, Germany.
• Reg Anesth. 1997 Mar 1;22(2):150-6.

Background And ObjectivesAdequate postoperative pain relief has been achieved in orthopedic patients by subarachnoid bolus administration of plain bupivacaine. This prospective randomized study compares bolus injections of bupivacaine with a patient controlled infusion via subarachnoid 28-gauge microcatheters for postoperative analgesia after elective hip replacement.MethodsForty-two patients (mean age, 69 +/- 11 years) were randomly allocated to one of two groups. Group. 1 patients received a constant subarachnoid infusion of 0.6 mg/h of bupivacaine by a patient-controlled device and were allowed to self-administer 0.6 mg every 30 minutes Group 2 patients received a nurse-administered bolus of 3.75 mg of plain bupivacaine on request. Pain was assessed by patients and nurses by a visual analog scale (VAS) every hour. The degree of motor block and the level of analgesia were documented every 4 hours. Hemodynamic and respiratory parameters were recorded hourly. Differences between groups were tested by analysis of variance for repeated measurement.ResultsTechnical problems occurred in six patients were more frequent in group 1 but none in group 2. Patient-controlled analgesia resulted in lower pain scores than bolus application during 18 postoperative hours (VAS score 19 +/- 19 mm in group 1 and 39 +/- 30 mm in group 2; P < .01). Lower total doses of bupivacaine were required in group 1 (17.6 +/- 4 mg) than in group 2 (22.3 +/- 7 mg; P < .05). The groups did not differ with respect to the degree of motor block (Bromage score 3.5 +/- 0.5), the sensory level (L1-2 +/- 1), or hemodynamic or respiratory parameters.ConclusionIn spite of a higher incidence of technical problems, patient-controlled analgesia with a continuous background infusion via microspinal catheters provides more effective postoperative analgesia, without hemodynamic or respiratory side effects, than bolus administration.

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