Abstract ID: A2

Abstract Title: Prospective Comparison of Continuous Femoral Nerve Block with Nonstimulating Catheter Placement vs. Stimulating Catheter-Guided Placement in Volunteers

Poster Type: Either


ABSTRACT BODY

Introduction: Studies have revealed that the course of continuous femoral catheters is unpredictable, and that neither ease of insertion nor advancement are predictive of successful continuous femoral nerve block. Stimulating catheter-guided perineural placement may potentially increase the success rate and overall quality of continuous femoral nerve block as compared with a nonstimulating catheter. This hypothesis has not yet been rigorously tested.

Materials and Methods: 20 volunteers underwent placement of bilateral femoral nerve catheters in this prospective randomized double-blind study. For both sides, a stimulating needle was advanced until quadriceps contraction was obtained at ≤ 0.5 mA. On one side, a stimulating catheter was advanced 4-5 cm beyond the needle tip while eliciting quadriceps contraction via the catheter. If quadriceps contractions either decreased or disappeared, the stimulating catheter position was adjusted until quadriceps contraction could be elicited at ≤ 0.5mA. On the contra-lateral side, the identical catheter was advanced 4-5 cm beyond the needle tip without attempts to elicit quadriceps contraction via the catheter. Ropivacaine 0.2% at 10 ml/hr was continuously infused through both catheters for 4 hours. Success of continuous femoral block was assessed by loss of sensation to pinprick and cold stimuli. Tolerance to transcutaneous electrical stimulation (cutaneous analgesia), and force dynamometry of quadriceps strength (motor block) were assessed to quantitatively evaluate overall depth of continuous femoral nerve block between the two techniques.

Results: Block success was 100% via the stimulating catheters vs. 85% via the nonstimulating catheters (P = 0.07). There was a significant difference in peak TES tolerance (Figure 1) between the SC technique and NSC technique (49 mA vs. 25 mA, P = 0.0004). Overall tolerance to transcutaneous electrical stimulation (P = 0.009), (Figure 2) and overall depth of motor block (P = 0.04), (Figure 3) were significantly higher in the stimulating catheter-guided femoral nerve blocks.

Discussion: The use of a stimulating catheter-guided technique for continuous femoral nerve block resulted in a lower incidence of failed blocks, and also provided a greater deoth of neural blockade of both the anterior and posterior divisions of the femoral nerve. This may result not only in an improved quality of continuous femoral analgesia, but also lower anesthetic infusion requirements. The results of this volunteer study warrant prospective randomized clinical trials to asess the potential clinical advantage of stimulating catheters.

References:
1. Salinas FV. Location, location, location. Continuous peripheral nerve blocks and stimulating catheters. Reg Anesth Pain Med. 2003;28:79-82.

2. Capdevila X, Biboulet PH, Morau D, et al. Continuous three-in-one block foe postoperative pain after lower limb orthopedic surgery: where do catheters go? Anesth Analg 2002;94:1001-1006.

3. Ganapathy S, Wasserman RA, Watson JT, et al. Modified continuous femoral three-in one-block for postoperative pain after total knee arthroplasty. Anesth Analg 1999;89:1197-1202.








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Reg Anesth Pain Med 2004; 29(2):A2