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Time to Therapeutic Levels: Comparison of the Anti Xa Assay vs PTT in Critical Care FREE TO VIEW

Amy Gearhart, BSN; Nikkol Dorman, RN; Danielle Scott, BSN; Omar Rahman, MD
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Geisinger Medical Center, Danville, PA

Chest. 2011;140(4_MeetingAbstracts):286A. doi:10.1378/chest.1118722
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PURPOSE: Reaching therapeutic heparin levels within 24 hours of initiating treatment is imperative to prevent complications or death in critically ill patients. We hypothesized that using the anti Xa assays would shorten time to therapeutic levels compared to using PTT values.

METHODS: A retrospective chart review of patients who received heparin in the Adult Intensive Care Unit at Geisinger Medical Center was performed. After locating heparin start time in the chart, corresponding anti Xa assays were tracked until therapeutic levels of 0.3 to 0.7 were achieved. A second retrospective chart review was performed on random AICU patients from 2009 who received heparin. The Heparin start time and baseline PTT were noted and considered within therapeutic range when levels of 66-92 were achieved. This correlates to an anti Xa assay value of 0.3-0.7. Hours to therapeutic levels for both arms of the study were calculated in 15 minute increments and compared using means and the independent T-test.

RESULTS: Ten critically ill patients were included in each part of the study. Fourteen patients from the Xa assay group and 12 patients from the PTT group were excluded due to discontinuation of the heparin or death prior to therapeutic levels being reached. The common indications for heparin infusion included DVT, PE, and AMI. Eighty percent of the Xa assay patients were within therapeutic range in less than 24 hours compared with 40% of the PTT patients. The mean time to therapeutic range was 18.08 hours in the Xa assay group versus 43.9 hours in the PTT group.

CONCLUSIONS: In this retrospective analysis, there was a decrease in the mean time to therapeutic level by 25.8 hours using the Xa assay. Patients reaching Xa assay therapeutic range were double the number of patients reaching PTT therapeutic range within 24 hours.

CLINICAL IMPLICATIONS: Anti Xa assay monitoring with heparin may be superior to PTT. Randomized trials are needed.

DISCLOSURE: The following authors have nothing to disclose: Amy Gearhart, Nikkol Dorman, Danielle Scott, Omar Rahman

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