Does the performance of lower limb peripheral nerve blocks differ among orthopedic sub-specialties? A single institution experience in 246 patients.

OBJECTIVES

Continuous peripheral nerve blocks (cPNBs) have shown promising results in pain management after orthopaedic surgeries. However, they can be associated with some risks and limitations. The purpose of this study is to describe our experience with the cPNBs regarding efficacy and adverse events in patients undergoing orthopedic surgeries on the lower extremity in different subspecialties.

METHODS

This is a prospective cohort study on collected data from perineural catheters for pain management after orthopedic surgeries in lower limbs. Catheters were placed by experienced anesthesiologists using sterile technique. After an initial bolus dose of 10-20 mL ropivacaine 0.5% (weight adjusted), the catheters were secured and connected to disposable mechanical infusion pumps with ropivacaine 0.2% (basal infusion rate = 6 mL/h; weight adjusted (0.2 mL/kg/h)). After catheterization, the patients were examined daily, by specially educated acute pain service nurses. Pro re nata (PRN) or fixed boluses (10 mL bupivacaine 0.25%; weight adjusted) with an upper limit of 4 times/day, were administered if indicated. Patients' demographic data, physiological status, and pre-op intake of opioids and other analgesics were registered. The severity of post-operative pain was assessed with 'Numeric Rating Scale' (NRS) and 'Face, legs, Activity, Cry, Consolability' (FLACC) scale for adults and children, respectively. The need for additional opioids and possible complications were registered.

RESULTS

We included 547 catheters of 246 patients (Range 1-10 catheters per patient). Overall, 115 (21%) femoral, 162 (30%) saphenous, 66 (12%) sciatic, and 204 (37%) popliteal sciatic nerve catheter were used. 452 (83%) catheters were inserted by a primary procedure, 61(11%) catheters employed as a replacement, and 34 catheters (6.2%) used as a supplement. For guiding the catheterization, ultrasound was applied in 451 catheters (82%), nerve stimulator in 90 catheters (16%), and both methods in 6 catheters (1.1%). The median duration a catheter remained in place was 3 days (IQR = 2-5). The proportion of catheters with a duration of two days was 81, 79, 73, and 71% for femoral, sciatic, saphenous, and popliteal nerve, respectively. In different subspecialties, 91% of catheters in wound and amputations, 89% in pediatric surgery, 76% in trauma, 64% in foot and ankle surgery, and 59% in limb reconstructive surgery remained more than two days. During first 10 days after catheterization, the proportion of pain-free patients were 77-95% at rest and 63-88% during mobilization, 79-92% of the patients did not require increased opioid doses, and 50-67% did not require opioid PRN doses. In addition to 416 catheters (76%), which were removed as planned, the reason for catheter removal was leaving the hospital in 27 (4.9%), loss of efficacy in 69 (13%), dislodgement in 23 (4.2%), leakage in 8 (1.5%), and erythema in 4 catheters (0.73%). No major complication occurred.

CONCLUSIONS

After orthopaedic procedures, cPNBs can be considered as an efficient method for improving pain control and minimizing the use of additional opioids. However, the catheters sometimes might need to be replaced to achieve the desired efficacy.