Measurement of the Activated Partial Thromboplastin Time from a Capillary (fingerstick) Sample of Whole Blood: A New Method for Monitoring Heparin Therapy
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The monitoring of heparin anticoagulation is fraught with difficulties because of the need for repetitive venipunctures and the vagaries of sample handling and processing. The authors evaluated a new aPTT monitoring system with the potential to eliminate many of these difficulties. The Ciba Corning Diagnostics 512 Coagulation Monitor (CCD monitor) is a hand-held portable instrument that can measure an aPTT from a fingerstick sample of capillary whole blood. Fingerstick aPTTs from 319 subjects (including controls and individuals on heparin and/or warfarin) were compared to venipuncture-derived standard laboratory plasma aPTTs using different aPTT reagents on conventional instruments. The correlation coefficients between fingerstick and standard aPTTs (0.79-0.83) were the same as the correlation coefficient between standard laboratory aPTTs using different reagents (0.79). When venipuncture-derived whole blood was compared to fingerstick samples on the new instrument, the correlation coefficient was excellent (0.93). A high degree of precision, as demonstrated by low coefficients of variations, was shown for within-day and between-day testing using the CCD monitor and normal controls. This capillary whole blood, aPTT system is the first to provide the clinician with a means of rapidly and reliably assessing the anticoagulant response to heparin therapy at the bedside, and its use may ultimately lead to more efficient and effective therapy overall.
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