STABILITY OF WHOLE BLOOD LACTATE SPECIMENS AT ROOM TEMPERATURE VS SLUSHED ICE CONDITIONS

Abstract

SESSION TITLE: Pulmonary Physiology Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: The purpose of this study is to define the rate of lactate accumulation on samples over time, and to determine the time a specimen of whole blood lactate can be kept under room temperature conditions before a clinically meaningful change (i.e., increase) in lactate of ≥ 0.4 mmol/L occurs. METHODS: This was an observational, prospective cohort study. Blood samples were obtained from 202 patients hospitalized for various pathophysiological conditions. Whole blood lactate concentration was measured over five different time-points spanning 80-90 minutes (approximately time 0, 20 40, 60, and 80 minutes after collection) in a blood-gas lab at a major hospital center. Samples were either stored at room temperature (22-24°C, ) or under slushed ice conditions (0.1-0.2°C) before analysis. An equal number of arterial and venous samples were analyzed. RESULTS: The mean increase in lactate concentration was 0.001 mmol/L per minute in samples on slushed ice over 90 minutes. However, under room temperature conditions, the mean increase in lactate concentration was 0.008 mmol/L per minute. Linear regression demonstrated that an increase in whole blood lactate concentration of ≥ 0.4 mmol/L was evident after 45 minutes at room temperature, with 5% of all whole blood specimens demonstrating a meaningful change at ≤ 20 minutes. The ≥0.4 mmol/L change in whole blood lactate is considered significant based on the College of American Pathologists (CAP) instrument peer group standards. It did not matter whether the sample type was arterial or venous since the increases were similar. The sample type was not a significant predictor in the linear regression model. CONCLUSIONS: Considering that a change in whole blood lactate concentration of ≥ 0.4 mmol/L is unacceptable instrument peer-group variation as defined by CAP, ice is no longer needed to stabilize whole blood lactate specimens when the draw time to analyze time is less than 45 minutes. Samples remain stable even at 90 minutes when left on ice. CLINICAL IMPLICATIONS: By omitting ice as a mandatory requirement during storage and transport, several positive outcomes can be observed: less water waste, less syringe waste, less blood waste and less staff time. These are all positive aspects of a more sustainable environment. As well, there could be less infection risk to the patient as the arterial or intravenous lines are accessed less frequently. DISCLOSURES: No relevant relationships by Rebecca Brooks, source=Web Response No relevant relationships by Samuel Gasparyan, source=Web Response No relevant relationships by Gerald Zavorsky, source=Web Response