The case for peripheral nerve blocks in anticoagulated patients.
Ruth M. Fanning. MB,BCh,BAO., MRCPI., FFARCSI., Prashant Patel. MD, Anthony R. Brown. MBChB., FFA (SA).
Department of Anesthesia, Columbia University Medical Center, 630 West 168 st, New York 10032, New York, USA.
Correspondence/Requests for reprints: Ruth M. Fanning, Department of Anesthesia, Columbia University Medical Center, 630 West 168 st, New York 10032, New York, USA. Tel: 212 305 6494. Fax: 212 305 2182
Email ruthfanning@ireland.com.
Abstract
Recommendations regarding the use of neuraxial anesthesia in patients receiving anticoagulants are well defined. The role and safety of peripheral nerve blocks in such clinical scenarios is less clear. We describe a case illustrating the benefits of peripheral nerve blocks in patients exhibiting evidence of mild coagulopathy, both as an adjuvant to anesthesia, and in the control of postoperative pain.
Key Words
Regional anesthesia, fascia-iliaca nerve block, anti-coagulants, coumadin.
Implication Statement
This case illustrates the beneficial role of peripheral nerve blocks in patients with mild coagulopathies.
Introduction
A 76 year old male was admitted to our hospital for revision of a left total hip replacement. His initial hip replacement was performed 10 years previously, with revision surgery performed in June 2003. He subsequently developed insidious chronic infections of his hip, requiring numerous incision and drainage procedures, and multiple antibiotic regimens. Despite conservative joint preserving treatment, the infected prosthesis necessitated revision, and this was scheduled for December 2004. He was admitted to the hospital preoperatively for pain management and optimization of his coexisting health problems. He had a history of ischemic heart disease, having suffered a myocardial infarction with subsequent coronary artery bypass grafting in November 2003. He also suffered from gout, hypercholestrolemia and depression. Ketorolac was added to his usual analgesic regimen, which had not been providing adequate pain relief. He received warfarin for DVT prophylaxis, which was discontinued 5 days prior to surgery and replaced by intravenous heparin. Heparin was discontinued at 2am on the morning of surgery.
Preoperative assessment
The patient’s preoperative physical examination was normal, and laboratory results on the morning of surgery included the following: hemoglobin 10.4, hematocrit 31.2, platelets 345,000, prothrombin time 16, INR 1.22, and APTT 38.
Operating Room Course
General anesthesia was chosen over neuraxial block in view of the patient’s prior warfarinization, and receipt of NSAIDS. Peripheral venous access and a radial arterial line were placed prior to induction of anesthesia. Anesthesia was induced with fentanyl 1.5µg/kg, midazolam 0.15mg/kg, and propofol 1.3mg/kg. Muscle relaxation was achieved with 0.15mg/kg of vecuronium. Standard anesthesia monitoring was employed. The patient remained hemodynamically stable throughout the case, despite blood loss of approximately 1000mls. He received two units of packed red cells and 3 liters of crystalloid while maintaining a urinary output of 1.7 mls/kg/hr. Prior to extubation, a fascia iliaca compartment block (FICB) was performed, in accordance with the technique employed at Columbia Presbyterian Hospital. With the patient supine, the landmarks include the femoral artery pulsation below the inguinal ligament and the anterior superior iliac spine. The needle was inserted midway between these two landmarks at the level of the inguinal crease. Using these landmarks ensures that the needle is well lateral to the femoral artery thus eliminating the risk of unintentional contact with the femoral vessels and nerve. As the needle penetrates the tissue, the first “pop” followed by loss of resistance occurs when the fascia lata is penetrated, and the second when the fascia iliaca is penetrated. At this point, the needle was redirected cephalad, and 30 mls of 0.25% bupivacaine was injected. Extubation was uneventful, and the patient was transferred to the Post Anesthesia Care Unit (PACU). In the PACU the fascia iliaca block was assessed, and anesthesia demonstrated in the distribution of the femoral nerve, and lateral cutaneous nerve of thigh.
Postoperative Course
In the PACU, 500 mls of blood drained from the wound in the first 30 minutes. The patient subsequently became hypotensive with a blood pressure of 75/43 and heart rate of 140. A central venous catheter was placed. Subsequent blood tests revealed an INR of 3.58, hematocrit of 22.7, and hemoglobin of 7.1. Four units of packed red cells and 2 units of fresh frozen plasma were transfused. Despite the patient’s tachycardia, and non-specific ST changes on ECG, troponin remained negative. Once stabilized the patient was transferred to the Surgical Intensive Care Unit (SICU). He received one additional unit of packed red blood cells and four units of fresh frozen plasma over the next twenty-four hours, resulting in a stabilized hematocrit of 30, and an improved coagulation status (INR 1.59, PT 19.7, APTT 36.8). The patient remained stable and warfarin was restarted on postoperative day 4. The patient’s postoperative pain score remained below 3 (on a scale of 0 –10) overnight and was easily managed with oral analgesics once the nerve block resolved 14 hours post operatively.
Discussion
This case illustrates a classic dilemma, which arises in the anesthetic management of patients receiving anticoagulants. The effects of warfarin, though discontinued five days prior to surgery, still posed a potential bleeding problem to our patient. Although coagulation studies gradually improved prior to surgery, the patient still exhibited a mild coagulopathy. The patient’s risk of bleeding was also increased by the fact that he was started on ketorolac three days prior to surgery. Ketorolac is known to cause a qualitative defect in platelet function, increased bleeding time and a reduction in thromboxane A2 production. (1,2,3).
Hemostasis may not be adequate until the INR has returned to normal following warfarin therapy (4,5). When warfarin is discontinued, the INR falls rapidly, due to an increase in factor VII activity. Factors II and X levels recover more slowly, and may be inadequate until the PT and INR return to normal. Concurrent use of medications that affect other components of the clotting mechanism may further increase the risk of bleeding complications(4,5).
Despite our reluctance to use neuraxial anesthesia in this patient, we elected to perform a fascia iliaca compartment block (FICB). The FICB is easy to perform, and virtually free of serious complications (6). Alternate peripheral nerve blocks such as the posterior lumbar plexus block were not considered appropriate due to the risk of vascular injury in the anticoagulated patient (7). A femoral nerve block was not considered due to the potential risk of unrecognized nerve damage in an anesthetized patient (8)
Although it is implied that the 2002 ASRA guidelines apply to peripheral nerve blocks too, recommendations regarding anticoagulation and the use of peripheral nerve blocks are less well substantiated. The 2002 ASRA consensus guidelines on regional anesthesia and anticoagulation recommend that regional anesthesia be performed after warfarin has been discontinued for 4-5 days and the INR has returned to normal (4,5). Recommendations, however, regarding anticoagulation and the use of peripheral nerve blocks are less clear. Common sense would preclude the performance of peripheral nerve blockade in situations in which inadvertent vessel trauma could not be treated with simple compression. Peripheral nerve blocks such as the FICB, in which simple compression may be used to treat inadvertent vessel puncture, are useful techniques for providing both anesthesia and analgesia in patients with mild coagulopathies, or those receiving medications that may affect hemostasis, and should be considered in the management of these patients.
References
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