Elevation of Activated Partial Thromboplastin Time After Low-Dose Unfractionated Heparin.

SESSION TYPE: DVT/PE/Pulmonary Hypertension Posters IPRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PMPURPOSE: Low dose unfractionated heparin (LDUH) is used for thrombophylaxis world-wide. Elevation of activated partial thromboplastin time (APTT) and hemorrhagic complications are not expected, and APTT monitoring is not advised. Anecdotal experience at our institution suggests that in some patients LDUH may significantly raise APTT. A small number of reports in the literature are consistent with our experience. We present data on 10 patients with prolonged APTT after LDUH identified by chance at our hospital.METHODS: From 7/11 - 3/12 we identified 10 patients with elevated APTT after LDUH encountered by members of the Pulmonary Division during consultation, in the ICU, or RCU. Clinical and demographic data were culled from patients' charts focusing on previously reported risk factors associated with increased APTT after LDUH. These included older age, low BMI, decreased renal function, and low serum albumin.RESULTS: Baseline APTT was less than 40 seconds in all 10 patients. Six received LDUH 5000 q12hr, and 3 q8hr. Mean APTT on LDUH was 98.8 (41.1-185). In 4, APTT exceeded 90 sec. Mean age was 68.8 (42-99) and exceeded 70 in 5. Seven were women, Mean BMI was 21.6 (17.6-29.6) and was below 19 in 5. Mean GFR was 53.4 (5.1-123.6), and was below 50 in 5. Mean albumin was 2.8 (1-4.2) and was below 3 in 5. Three had malignancies, 2 HIV, 2 liver disease. In 1 patient copious bloody secretions/clots caused lobar atelectasis. In 1 patient, removal of a ventricular drain was delayed due to increased APTT. In 9 patients APTT normalized with discontinuation or dose reduction of LDUH. One expired prior to reduction of LDUH dosage.CONCLUSIONS: LDUH caused elevation of APTT in 10 randomly identified patients. Older age, female gender, lower BMI, renal insufficiency and hypoalbuminemia were frequent in these patients.CLINICAL IMPLICATIONS: LDUH may require APTT monitoring in some patients. We are presently conducting an observational study in hospitalized patients to determine the frequency of and risk factors for APTT elevation after LDUH.DISCLOSURE: The following authors have nothing to disclose: Sadaf Mir, Peter Smith, Taiyo Nishimoto, Phani Surapaneni, Louis Gerolemou, Michael Elias, Elpidio Jimenez, Patricia O'NeillNo Product/Research Disclosure InformationSUNY Downstate Medical Center at Long Island College Hospital, Brooklyn, NY.