Dr. Boezaart’s review article titled “Perineural Infusion of Local Anesthetics”1represents a commendable attempt to educate the reader on a complex and evolving topic. In reading this article, we were surprised by the author’s use of a study performed in volunteers to support the claim that the use of a stimulating catheter was associated with “around” 100% success compared with 65–85% for a nonstimulating technique. Studies conducted in patients certainly did not support this concept.2It is unfortunate that Dr. Boezaart did not acknowledge the value of continuous lumbar plexus blocks for hip primary replacement3and acetabular fracture,4especially when considering that some surgeons include the inguinal crease in their hip preparation, making impossible the preoperative placement of a femoral perineural catheter. Also, the recommended use of a posterior popliteal approach to the sciatic nerve for knee surgery or other procedures requiring a thigh tourniquet also deserves discussions. This practice has the potential for increasing the anesthesiologist’s liability in the case of nerve injury. Therefore, the choice of the sciatic approach should facilitate the differentiation between the nerve block, the tourniquet, and/or surgery itself. When the site of the block is very close to the tourniquet or surgical field, electromyographic and conduction nerve studies cannot allow such a differentiation, and by default, the anesthesiologists is usually blamed. In our practice, we favor the use of approaches away from the tourniquet and the site of the surgery.5 

The problem of continuous nerve blocks and anticoagulation is undoubtedly an important issue for regional anesthesiologists. In his article, the author referred to recommendations made by the American Society of Regional Anesthesiologists, but after going to the American Society of Regional Anesthesiologists Web site, we could not verify the source of these recommendations. Moreover, the authors of this letter have several thousand patient experiences with the combination of continuous lumbar plexus and thromboprophylaxis using various anticoagulants (aspirin, warfarin, low-molecular-weight heparin, and fondaparinux). As long as these anticoagulants are administered for the prevention of deep vein thrombosis and pulmonary embolism and not for their treatment, we found no reason to take any precaution when placing or removing the lumbar plexus catheter.6For total knee arthroplasty,5,7we also would like to stress the value of a continuous sciatic nerve block for postoperative analgesia. In our experience, 80% of patients undergoing total knee replacement report sciatic pain.7Finally, although the author recommended the use of 0.2% ropivacaine for perineural infusion, he also recommend the use of 0.5% bupivacaine for the initial injection. Bupivacaine is recognized to be more toxic than ropivacaine.8Therefore, it is surprising that the author would continue to recommend its use for the initial bolus injection. Certainly, in our practice, we have eliminated the use of bupivacaine.

*University of Pittsburgh Medical Center, UPMC Presbyterian-Shadyside Hospital, Pittsburgh, Pennsylvania. chelje@anes.upmc.edu

Boezaart A: Perineural infusion of local anesthetics. Anesthesiology 2006; 104:872–80
Casati A, Fanelli G, Koscielniak-Nielsen Z, Cappelleri G, Aldegheri G, Danelli G, Fuzier R, Singelyn F: Using stimulating catheters for continuous sciatic nerve block shortens onset time of surgical block and minimizes postoperative consumption of pain medication after hallux valgus repair as compared with conventional nonstimulating catheters. Anesth Analg 2005; 101:1192–7
Horlocker TT, Kopp SL, Pagnano MW, Hebl JR: Analgesia for total hip and knee arthroplasty: A multimodal pathway featuring peripheral nerve block. J Am Acad Orthop Surg 2006; 14:126–35
Chelly JE, Greger J, Casati A, Al-Samsam T, Coupe K, Criswell A, Tucker J: Continuous lumbar plexus block for acute postoperative pain management after open reduction and internal fixation of acetabular fractures. J Orthop Trauma 2003; 17:362–7
Ben-David B, Schmalenberger K, Chelly JE: Analgesia after total knee arthroplasty: Is continuous sciatic blockade needed in addition to continuous femoral blockade? Anesth Analg 2004; 98:747–9
Chelly JE, Joshi R, Kandel A, Merman R, Ben-David B: Continuous lumbar plexus blocks are safe for total hip replacement (abstract). Anesthesiology 2005; 103:A915
Pham Dang C, Gautheron E, Guilley J, Fernandez M, Waast D, Volteau C, Nguyen JM, Pinaud M: The value of adding sciatic block to continuous femoral block for analgesia after total knee replacement. Reg Anesth Pain Med 2005; 30:128–33
Graf BM, Abraham I, Eberbach N, Kunst G, Stowe DF, Martin E: Differences in cardiotoxicity of bupivacaine and ropivacaine are the result of physicochemical and stereoselective properties. Anesthesiology 2002; 96:1427–34