A "new" automated bolus technique for continuous popliteal block: a prospective, randomized comparison with a continuous infusion technique.

BACKGROUND: We designed the present, prospective, randomized, double-blind study to compare the administration of an automated intermittent bolus dose with a conventional technique of continuous infusion of local anesthetic for postoperative analgesia in continuous popliteal sciatic nerve blockade.

METHODS: Forty-four patients undergoing hallux valgus repair were randomly assigned to receive either a continuous infusion of 0.125% levobupivacaine with an infusion rate of 5 mL/h (continuous infusion group, n=22) or automated bolus doses of 5 mL every hour of the same local anesthetic (automated bolus group, n=22) for 24 h. Postoperative pain scores were assessed using a verbal rating pain score. The amount of rescue tramadol medication for pain was also recorded.

RESULTS: In patients of the automated bolus group there was a reduction in pain scores (P<0.05) during the postoperative period, when compared to patients of the continuous infusion group. Five patients in the automated bolus group (24%) and 11 patients of the continuous group (52%) required rescue tramadol analgesia (P=0.055).

CONCLUSION: The present investigation demonstrated that local anesthetic administered by an automated bolus technique provided better postoperative pain relief than a continuous infusion technique for continuous popliteal nerve block after foot surgery.