Comparison of Continuous Infusion versus Automated Bolus for Postoperative Patient-controlled Analgesia with Popliteal Sciatic Nerve Catheters

Background: This investigation was designed to compare a new methodology of automated regular bolus with a continuous infusion of local anesthetic for continuous popliteal sciatic block; both regimens were combined with patient-controlled analgesia (PCA). Methods: Fifty patients undergoing hallux valgus repair were randomly allocated to receive an infusion of 0.125% levobupivacaine administered through a popliteal catheter as an automated regular bolus (n = 25) or as a continuous infusion (n = 25), both combined with PCA. Postoperative pain scores, incremental doses delivered by the PCA, local anesthetic consumed per hour, and the need for rescue tramadol analgesia were recorded. Results: Both dosing regimens provided similar postoperative analgesia. Consumption of local anesthetic (5.14 ml/h, 5-5.75 ml/h) and dose request from the PCA (1, 0-5.4) was lower in the automated bolus group as compared to the continuous infusion group (5.9 ml/h, 5.05-7.8 ml/h; doses by PCA: 6.5, 0-20.5; P < 0.05). The need for rescue tramadol was similar in the two groups. Conclusion: In continuous popliteal sciatic block, local anesthetic administered as an automated regular bolus in conjunction with PCA provided similar pain relief as a continuous infusion technique combined with PCA; however, the new dosing regimen reduced the need for additional PCA and the overall consumption of local anesthetic.