Effect on lipid, complete blood count and blood proteins of a standardizedpreparation for drawing blood: a randomized controlled trial

Objective: To compare a standardized recommended procedure for drawing bloo d to measure blood Lipid and lipoprotein levels with the procedure commonly used in clinical practice. The aim was to see if hemoconcentration and spu riously elevated lipid levels could be avoided. Design: An open randomized crossover clinical trial. Setting: The University of Calgary. Patients: Twenty-five patients with dyslipidemia. Interventions: Blood drawing using a standardized procedure in which the pa tient remained seated for 5 minutes before blood collection and tourniquet use was minimized or avoided. Main outcome measures: Differences in lipid l evels between the usual clinical procedure and the recommended procedure fo r drawing blood. Results: Prior to drawing blood, laboratories have sat patients for an aver age of 1.4 minutes (95% CI, 0.9 to 1.9) and used a tourniquet in every pati ent. In the standardized procedure, patients rested for an average of 5.6 m inutes (95% CI 5.0 to 6.2), and a tourniquet was used briefly in only 3 of 23 patients. There were no differences in lipid and lipoprotein values and no clinically significant difference in hemoglobin or albumin levels or in the calculation of hemoconcentration. Conclusions: Efforts to rest patients and avoid tourniquet use when drawing blood for assessment of lipid levels are unlikely to be useful.