Journal: Br J Anaesth 101(2):250-254, 2008. 19 References
Reprint: Dept of Anesthesiology, University of Pittsburgh Medical Center, UPMC Shadyside Hospital, Ste M104 (Posner Pain Center), 5230 Centre Ave, Pittsburgh, PA 15232 (JE Chelly, MD)
Faculty Disclosure: Abstracted by L. Easley, who has nothing to disclose.
The use of warfarin in patients receiving continuous nerve block for postoperative analgesia represents an interesting setting to determine the coagulation status at the time of the removal of a deep perineural catheter. This retrospective study was designed to establish the coagulation status using international normalized ratio (INR) and prothrombin time (PT) at the time of removal of lumbar plexus perineural catheters in patients receiving warfarin after total hip replacement.
The authors collected data on INR and PT, bleeding, and nerve injury complications from patients undergoing total hip replacement between August 2002 and June 2007 who received warfarin thromboprophylaxis and in whom continuous lumbar plexus nerve block was performed to provide postoperative analgesia. The dose of warfarin administered was varied according to the patient's weight and prior history of thromboembolism and was administered on the day of surgery. The removal of each lumbar plexus catheter was scheduled on postoperative day 2 without any consideration of the INR value. Before discharge, each patient underwent a lower extremity ultrasound to possibly detect the presence of a deep venous thrombosis (DVT). Patients with suspected pulmonary embolism underwent a diagnostic CT scan.
Included in this study were 670 patients. Most lumbar plexus catheters were removed on postoperative day 2. The median dose of warfarin was 7.5 mg on the day of surgery, 1 mg on postoperative day 1, and 3 mg on the day when the lumbar plexus catheter was removed. INR and PT increased significantly between the values obtained before surgery and postoperative day 1 and between postoperative day 1 and the day of the lumbar plexus catheter removal. The only reported bleeding complication was that of bleeding at the catheter site after removal, where the INR was 3.0 at the time of removal.
This study provides original data concerning the INR at the time of the removal of the lumbar plexus catheter after total hip replacement or hip fracture fixation. The data indicate that at the time of removal of the lumbar plexus catheter, more than one third of the patients had an INR >1.4, which represents the highest recommended limit for performing a regional block according to the most recent consensus. For hip arthroplasty and hip fracture, current guidance on the use of an adjusted-dose vitamin K antagonist recommends maintaining the INR at 2.5.
These data indicate that only 12% achieved the recommended therapeutic end-point 2 days after surgery at the time of the removal of the lumbar plexus catheter. The data suggest that little protection was provided in most patients with the present warfarin dosing protocol. Epidural analgesia has been shown to be an effective alternative to PCA opioid, but the increased risks of epidural hematoma in patients receiving anticoagulation have limited its use beyond the recovery period.
Recently the comparison of continuous femoral and continuous lumbar plexus blocks demonstrated that the use of a continuous lumbar plexus technique provided better analgesia and less motor block than a continuous femoral block. In this study, a number of lumbar plexus catheters were removed with an INR ≥1.5 without any serious adverse outcomes in patients receiving warfarin after surgery. |
