Petra Jilma-Stohlawetz1, Susanne Fritsche-Polanz2, Peter Quehenberger1, Christian Schörgenhofer2, Johann Bartko2, Robin Ristl3, Bernd Jilma2. 1. a Department of Laboratory Medicine, Division of Medical and Chemical Laboratory Diagnostics , Medical University of Vienna , Vienna , Austria. 2. b Department of Clinical Pharmacology , Medical University of Vienna , Vienna , Austria. 3. c Center for Medical Statistics, Informatics, and Intelligent Systems , Medical University of Vienna , Vienna , Austria.
Abstract
BACKGROUND AND AIMS: The aim of this study was to assess the circadian variation and the between- and within-subject variation in 10 healthy subjects over a period of 8 weeks by ROTEM®. We further evaluated the influence of elevated body mass index and the effect of low molecular weight heparin and antithrombin on clot formation. METHODS: Citrated blood samples were analysed in the NATEM® test system. The clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF) and the maximum lysis (ML) were assessed. RESULTS: Duplicate measurements showed that 23% of the CT and 31% of the CFT measurements had a coefficient of variation (CV) greater than 10%. The within-subject CV was 16% for the CT and 30% for the CFT. The MCF was fairly constant (6%), whereas ML showed more variation (18%). The between-subject CV was 6% for the CT and 20% for the CFT. Analytical variability was improved by summing up CT and CFT. Compared to morning values, CT, CFT and the sum of CT + CFT were shortened in the afternoon. High body mass index was associated with faster clotting. High concentrations of antithrombin had similar effects on clot formation as 0.2 IU/ml of enoxaparin. CONCLUSIONS: To overcome the influence of diurnal variation, we recommend obtaining blood samples at specified times in the morning. The within-subject variation should be taken into account, when serial measurements of drug effects are required.
BACKGROUND AND AIMS: The aim of this study was to assess the circadian variation and the between- and within-subject variation in 10 healthy subjects over a period of 8 weeks by ROTEM®. We further evaluated the influence of elevated body mass index and the effect of low molecular weight heparin and antithrombin on clot formation. METHODS: Citrated blood samples were analysed in the NATEM® test system. The clotting time (CT), clot formation time (CFT), maximum clot firmness (MCF) and the maximum lysis (ML) were assessed. RESULTS: Duplicate measurements showed that 23% of the CT and 31% of the CFT measurements had a coefficient of variation (CV) greater than 10%. The within-subject CV was 16% for the CT and 30% for the CFT. The MCF was fairly constant (6%), whereas ML showed more variation (18%). The between-subject CV was 6% for the CT and 20% for the CFT. Analytical variability was improved by summing up CT and CFT. Compared to morning values, CT, CFT and the sum of CT + CFT were shortened in the afternoon. High body mass index was associated with faster clotting. High concentrations of antithrombin had similar effects on clot formation as 0.2 IU/ml of enoxaparin. CONCLUSIONS: To overcome the influence of diurnal variation, we recommend obtaining blood samples at specified times in the morning. The within-subject variation should be taken into account, when serial measurements of drug effects are required.
Entities:
Keywords:
Point of care testing; biological variation; body mass index; human; reproducibility; rotational thromboelastometry
Authors: Nina Buchtele; Christian Schörgenhofer; Alexander O Spiel; Bernd Jilma; Michael Schwameis Journal: Crit Care Med Date: 2018-10 Impact factor: 7.598