Saturday, February 06, 1999
"When warfarin is used for prophylaxis, some patients are overly sensitive and the prothrombin time elevates rapidly, increasing the risk of bleeding and hematoma formation," said Gregory J. Golladay, MD, University of Michigan Health System, Ann Arbor, Mich. "Traditional treatment protocols have used fresh frozen plasma or intravenous vitamin K to correct excessive anticoagulation in this situation. Fresh frozen plasma carries a risk of fluid overload and disease transmission, and most surgeons prefer to avoid treatment with large doses of vitamin K to allow further warfarin treatment if necessary,"
Dr. Golladay studied 20 warfarin sensitive patients who were managed with one milligram of vitamin K, when the PT was greater than 20 seconds. There were 15 females and five males with an average age of 61 (range: 19 to 81). Their diagnoses included osteoarthritis (13), rheumatoid arthritis (five), osteonecrosis (one) and post-infectious arthritis (one). All but one had normal preoperative coagulation profiles including plate-let count, prothrombin time and activated partial thromboplastin time (APTT). All patients were treated with warfarin and elastic compression stockings.
The elevated PTs ranged from 20.1 to 25.9 seconds (INR range: 2.0 to 2.6). Vitamin K was necessary on postoperative day one (four patients) or postoperative day two (16 patients). One day after the vitamin K treatment, the PT decreased on average 6.75 seconds (range: 2.5-11.3) to a mean of 15 seconds (INR 1.5). No patient's APTT was elevated above 40 seconds.
Patients were screened with color doppler venous ultrasound on postoperative day three. Three developed postoperative hematomas that did not require operation. "There was no excessive wound drainage or infection; no patient developed a DVT.
"The low-dose oral aqueous vitamin K is well-tolerated and still allows warfarin use for further prophylaxis or treatment for DVT, without having to use heparin," said Dr. Golladay.
Co-authors of the study with Dr. Golladay from the University of Michigan Health System are Andrew A. Freiberg, MD, assistant pro-fessor; Paula L. Bockenstedt, MD, clinical assistant professor; and Brian R. Hallstrom, MD, resident.