The feasibility of patient-controlled paravertebral analgesia for major breast cancer surgery: a prospective, randomized, double-blind comparison of two regimens.

BACKGROUND Paravertebral analgesia is useful for breast surgery. Patient controlled analgesia by IV or epidural routes is well established for delivering postoperative analgesia. Our objective was to apply patient control to paravertebral analgesia and evaluate the efficacy and tolerability of two distinct dosing regimens. METHODS Patients undergoing major breast cancer surgery were recruited for this prospective, double-blind, randomized trial of two patient-controlled paravertebral analgesia regimens: 19 patients received levobupivacaine 0.2% at 8 mL/h with 3-mL bolus and 15-min lockout (15-min lockout group); 18 received levobupivacaine 0.2% at 4 mL/h with 8-mL bolus and 30-min lockout (30-min lockout group). Our primary outcome was dynamic pain scores (visual analog scale) at 4-hourly intervals for 36 h. Secondary outcomes were resting pain scores, rescue analgesia requirements, volume of levobupivacaine administered, demands for levobupivacaine, levobupivacaine boluses received, and patient satisfaction. RESULTS Resting and dynamic pain scores were comparable in the groups. Two 15-min lockout patients and five 30-min lockout patients required rescue analgesia (P = 0.23). Patients received 400 +/- 95 mL and 330 +/- 130 mL levobupivacaine in 15-min and 30-min lockout groups, respectively (P = 0.012). The 15-min lockout group requested a bolus 75 +/- 16 times; the 30-min lockout group requested it 69 +/- 14 times (P = 0.40). However, the 15-min lockout group received 39 +/- 22 boluses and the 30-min lockout group only 24 +/- 16 (P = 0.02). Systolic pressure, heart rate, respiratory rate, sedation scores, nausea, antiemetic requirement, and satisfaction scores were similar in each group. CONCLUSIONS Patient-controlled paravertebral analgesia for breast cancer surgery, with either regimen, provided satisfactory analgesia and was well tolerated.