Delayed retroperitoneal haematoma after failed lumbar plexus block

E-mail: dthsu{at}msn.com

The case report of Aveline and Bonnet1 brings out an important potential clinical complication occurring after repeated attempts of a deep plexus block and the concomitant need for anticoagulation. Their patient had been maintained preoperatively, uneventfully, on prophylactic phenylindanedione (international normalized ratio (INR) between 2 and 3) which was stopped 5 days before surgery, restarted on day 3 after surgery and continued daily during hospitalization and at home. Enoxaparin 60 mg twice daily was given for 4 days before surgery and withheld for 24 h preceding surgery. It was restarted at 40 mg day 1 after surgery and then continued at 60 mg daily up to and including day 7. The dosing was fixed and not weight adjusted.

Low molecular weight heparins (LWMH) vary in their molecular weight, plasma half-life, pharmacological and anti-IIa, anti-Xa effects.2 INR and activated partial thromboplastin are insensitive measures of LMWH anticoagulant effect. Measure of anti-Xa level gives a better reflection of the quantitative anticoagulant effect.2 Enoxaprin has a half-life of 129–180 min and anti-factor Xa/IIa ratio 2.7:1.3

The patient's INR was maintained at the desirable values appropriate for prophylaxis and surgery, respectively. However, additional measurement of anti-factor Xa level would have given a clearer picture of her coagulation profile, allowing the phenylindanedione dose to be adjusted. According to Horlocker and Heit, peak anti-Xa levels of 0.1–0.2 U ml–1 provide sage and effective venous thromboembolism after hip and knee replacement surgery.2 4 5 The patient received a fixed dosing (not weight adjusted) of enoxaparin for a total of 11 days. The clinical significance of this is not known. The slow release of the LMWH from the subcutaneous depot cannot be ruled out even though treatment was stopped 7 days after surgery. If this is the case, the anticoagulation profile will be much altered. This raises the justification of monitoring INR and anti-Xa levels on selected patients who require complex perioperative anticoagulation treatment plan.

D. T. Hsu

Torrance, CA, USA


 
E-mail: caveline{at}club-internet.fr

Editor—We thank Dr Hsu for her interest in our case report describing a delayed postoperative retroperitoneal hematoma after lumbar plexus block.1 She suggests the necessity of monitoring the anti-Xa activity to obtain the real profile of anticoagulation during venous thromboprophylaxis after total hip replacement. In our case, enoxaparin 40 mg once a day was initiated postoperatively 14 h after the block and then 60 mg once a day from 2 days after surgery until INR was between 2 and 3. Total duration of enoxaparin treatment was 7 days. Phenylindanedione was reintroduced 3 days after surgery to achieve the range require in the prophylactic management of her thrombophilia. Preoperative renal function was normal (creatinine clearance 81 ml min–1) and did not change significantly during the postoperative period. In the same way, preoperative haemostasis tests and time of first injection of enoxaparin were in agreement with recommendation of management of plexus blockade and thromboprophylaxis.7 Dr Hsu suggests that monitoring of anti-Xa level could have given clear information about the haemostatic state in this case, in agreement with previous guidelines.24 However, more recently, relationships between anti-Xa activity, efficacy, and adverse effects have not been definitively established when renal function is not impaired and LMWH prescribed in once daily prophylactic fixed-dose.2 6 The monitoring of this test is not predictive and not recommended.7 Our patient did not receive any non-steroidal anti-inflammatory drugs or other antiplatelet medication and was discharged without any neurological symptom or defect. The retroperitoneal hematoma was diagnosed 7 days after her discharge (10 days after interruption of enoxaparin) with an INR at 3.5, which was higher than the INR expected for long-term prophylaxis. Lumbar plexus block was not achieved and several attempts were performed which suggest that, even without evidence of vessel trauma, oral anticoagulation must be delayed and their use justified. At present, there is no evidence that the anti-Xa level can be affected by body weight during prophylactic treatment with enoxaparin when renal function is in the normal value. The BMI of this patient was 31 kg m–2 and did not affect the metabolism of enoxaparin.8 LMWH are routinely used in Europe for venous thromboprophylaxis in hip surgery and are as effective as oral anticoagulants with less major hemorrhagic side-effects.9 This case report highlights the problems in the management of chronic anticoagulation in patients with thrombophilia requiring a plexus block. The reintroduction of oral anticoagulants, after a plexus block in which difficulties were noted at any time of the procedure, must be delayed and LMWH preferred during the first weeks.

C. Aveline

Cesson-Sévigné, France

References

1 Aveline C, Bonnet F. Delayed retroperitoneal haematoma after failed lumbar plexus block. Br J Anaesth 2004; 93: 589–91[Abstract/Free Full Text]

2 Horlocker TT, Heit JA. Low molecular weight heparin: biochemistry, pharmacology, perioperative prophylaxis regimens, and guidelines for regional anesthetic management. Anesth Analg 1997; 85: 74–85

3 Cosmi B, Hirsh J. Low molecular weight heparins. Curr Opin Cardiol 1994; 9: 612–18[ISI][Medline]

4 Levine MN, Planes A, Hirsh J, Goodyear M, Vochelle N, Gent M. The relationship between anti-factor Xa level and clinical outcome in patients receiving enoxaparine low molecular weight heparin to prevent deep vein thrombosis after hip replacement. Thromb Haemost 1989; 62: 940–4[ISI][Medline]

5 Kessler CM, Esparraguerra IM, Jacobs HM, et al. Monitoring the anticoagulant effects of a low molecular weight heparin preparation: correlation assays in orthopedic surgery patients receiving ardeparin sodium for prophylaxis of deep venous thrombosis. Am J Clin Pathol 1995; 103: 642–8[ISI][Medline]

6 Kruse MW, Lee JJ. Retrospective evaluation of a pharmacokinetic program for adjusting enoxaparin in renal impairment. Am Heart J 2004; 148: 582–9[CrossRef][ISI][Medline]

7 Horlocker TT, Wedel DJ, Benzon H, et al. Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation). Reg Anesth Pain Med 2003; 28: 172–97[CrossRef][ISI][Medline]

8 Hulot JS, Vantelon C, Urien S, et al. Effect of renal function on the pharmacokinetics of enoxaparin and consequences on dose adjustment. Ther Drug Monit 2004; 26: 305–10[CrossRef][ISI][Medline]

9 Samama CM, Vray M, Barre J, et al. SACRE Study Investigators. Extended venous thromboembolism prophylaxis after total hip replacement: a comparison of low-molecular-weight heparin with oral anticoagulant. Arch Intern Med 2002; 162: 2191–6[Abstract/Free Full Text]





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