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LETTER TO THE EDITOR

Prolonged Activated Partial Thromboplastin Time in Patients with Antiphospholipid Antibody Syndrome

Department of Anesthesia, Perioperative and Pain Medicine; Brigham and Women’s Hospital; Boston, Massachusetts; ltsen{at}zeus.bwh.harvard.edu

In Response:

We concur with Drs. Dyer and Raj (1) that lupus anticoagulant may interfere with phospholipid-dependent clotting tests and result in a prolonged activated partial thromboplastin time (aPTT). However, in our case (2), the lupus anticoagulant most likely had limited or no effect in prolonging the aPTT, because the patient had normal values, 26.7 and 28.6 s, before pregnancy and heparin use, and after pregnancy when anticoagulant medications had been discontinued. Moreover, despite receiving her last heparin dose 9 h before admission, our patient’s serial aPTT measurements remained elevated, but they continued to decrease from 48.2 s on admission, to 40.5 s after 4 h, and to 38.4 s after an additional 5 h. A similar trend with lupus anticoagulant has yet to be reported.

Drs. Dyer and Raj agree that coagulation tests, particularly the aPTT, are difficult to interpret in patients with antiphospholipid syndrome treated with anticoagulant medications. Recently, however, Jacobsen et al. (3) reported that the heparin neutralizing agent, hexadimethrinebromide, allowed health care providers to detect and quantify lupus anticoagulants in the plasma from heparin-treated patients. These drugs may someday help determine the independent effect of lupus anticoagulants on coagulation profiles in heparinized patients. Although thromboelastography (TEG®) and many other "bed-side" hematologic monitors have yet to be validated against routine coagulation parameters and ultimately adverse clinical outcomes, TEG® may guide difficult clinical decisions. We recently reported TEG® values in two patients in active labor who requested epidural analgesia (4). They were receiving heparin therapy with increased aPTTs. Because TEG® revealed parameters within the normal range for pregnancy, we administered epidural analgesia to each patient, with uneventful anesthetic and obstetric outcomes. While these cases do not conclusively defend using TEG® data as a basis for deciding the safety of administering neuraxial techniques, they do add to the body of literature that may ultimately assist clinicians and their patients.

REFERENCES

1. James RD, Tilak R. Prolonged activated partial thromboplastin time in patients with antiphospholipid antibody syndrome. Anesth Analg 2006;103:1586–8.[Free Full Text]
2. Harnett MJ, Walsh ME, McElrath TF, Tsen LC. The use of central neuraxial techniques in parturients with factor V Leiden mutation. Anesth Analg 2005;101:1821–3.[Abstract/Free Full Text]
3. Jacobsen EM, Trettenes EJ, Wisloff F, Abildgaard U. Detection and quantification of lupus anticoagulants in plasma from heparin treated patients, using addition of polybrene. Thromb J 2006;4:3.[Medline]
4. Harnett MJ, Bhavani-Shankar K. Thromboelastography® assessment of coagulation status in parturients with lupus anticoagulant receiving heparin therapy. Int J Obstet Anesth 2006;15:177, 178.

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