Peripheral Nerve Block Catheters and Low Molecular Weight Heparin

Abstract

To the Editor: Bickler et al. (1) recently described three cases of localized bleeding or extensive hematoma after femoral and sciatic continuous nerve blocks in conjunction with the use of low molecular weight heparin (LMWH). However, we doubt their conclusion regarding the importance of timing of catheter removal relative to LMWH dosing. It is ironic that the authors chose to (incorrectly) cite our case report (2) of sciatic nerve compression from hematoma after total hip replacement. In that case, the sciatic compression was due to surgical bleeding in the hip joint, not to bleeding at the site of the nerve block. Recognition of that distinction led to prompt diagnosis and intervention and full neurologic recovery. In the cases described by Bickler et al. the preoperative coagulation status (International Normalized Ratio, partial thromboplastin time, platelet count) was not reported for any of the patients. Moreover, no attempt was made to perform a computed tomography scan to establish the diagnosis of hematoma or the site of the bleeding. While in Case 1 there was obviously bleeding at the site of the peripheral nerve block catheters, it is not clear that the bulk of bleeding into the thigh did not derive from the surgical site. Specifically, in Figure 1, it appears that while there is ecchymosis in the inguinal area the majority of the swelling and ecchymosis extend up posteriorly from the knee. Furthermore the authors note that the bleeding at the site of the catheters had begun long before catheter removal. In Cases 2 and 3 there were only relatively minor bleeding complications at the nerve block sites. Again, the bleeding in these cases occurred before removal of the catheters and most likely was related to traumatic placement, not catheter removal. We believe, therefore. that this report has more to say about the technique of neural blockade and its implications for bleeding complications than it does about the removal of the catheters. In our experience of more than 10,000 continuous femoral, sciatic, and lumbar plexus blocks over the past 4 yr in patients receiving prophylactic warfarin, LMWH, and fondoparinux, not a single patient has experienced a bleeding complication upon catheter removal despite the fact that we do not schedule catheter removal with respect to anticoagulant administration. To reiterate, the critical point is one of the technique of placement, not of timing of removal. Rather than providing new objective evidence that special consideration should be given to the timing of peripheral nerve block catheter removal, this report does, however, nicely illustrate the relative safety of continuous peripheral nerve blocks in patients receiving anticoagulants and the lack of disastrous consequences even when bleeding does occur. Bruce Ben-David, MD Jacques E. Chelly, MD, PhD, MBA Department of Anesthesiology Presbyterian-Shadyside Hospital University of Pittsburgh Medical Centers Pittsburgh, PA [email protected]