Continuous subgluteus sciatic nerve block after orthopedic foot and ankle surgery: comparison of two infusion...

To compare continuous infusion or a patient-controlled technique for postoperative analgesia after foot surgery, using a new subgluteus approach for continuous sciatic nerve block.

Fifty healthy patients, undergoing orthopedic foot surgery, received a continuous sciatic nerve block using a new subgluteus approach. All blocks were placed with the aid of a nerve stimulator using a 10-cm, 18-gauge insulated Tuohy needle. After either plantar flexion or dorsiflexion of the operated foot was elicited at < or = 0.5 mA, 20 mL of 0.75% ropivacaine was injected incrementally using repeated aspiration tests, then followed by the introduction of a 20-gauge epidural catheter. Postoperatively, 0.2% ropivacaine was infused with either a 10 mL/h continuous infusion (group Continuous, n = 25) or with a 5 mL/h basal rate with 5 mL bolus every 60 minutes (group patient-controlled analgesia [PCA], n = 25). Intraoperative analgesic supplementation, as well as postoperative pain relief, morphine consumption, incidence of complication, and patient satisfaction were recorded by an observer unaware of group assignment.

The sciatic catheter was successfully placed in all patients. Intravenous fentanyl supplementation (dose range, 50 to 150 microg) was required in 4 patients in each group, but no patient required general anesthesia. Catheter dislocation was reported in 2 patients (4%). The quality of pain relief was good in both groups, and none experienced complications. Nine patients of the Continuous group (37%) and 7 patients of the PCA group (29%) required rescue morphine analgesia because of pain in the femoral dermatomes (P =.76). Ropivacaine consumption was 240 mL in the Continuous group (range, 200 to 240 mL) and 140 mL in the PCA group (range, 120 to 290 mL) (P =.0005). Patient acceptance was good in both groups.

The continuous subgluteus sciatic nerve block represents an easy and reliable option for postoperative analgesia after foot surgery; using a patient controlled rather than a continuous infusion technique reduces the consumption of local anesthetic solution without affecting the quality of pain relief.