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Effect of Phlebotomy Technique on Serum Bicarbonate Values
Author(s) -
Berns Scott D.,
Matchett Jessica L.
Publication year - 1998
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/j.1553-2712.1998.tb02573.x
Subject(s) - vacutainer , medicine , phlebotomy , bicarbonate , tourniquet , serum concentration , anesthesia
Objectives: To determine whether the following phlebotomy technique factors result in spuriously low serum bicarbonate values: 1) small needle size, 2) prolonged tourniquet time, and 3) underfilling of Vacutainer tubes. Methods: Thirty‐eight healthy young adult student volunteers from Brown University (mean age = 22 years) were randomly assigned to 1 of 2 (24‐ga or 20‐ga) IV needle size groups. With a tourniquet applied, the subjects had blood sampled initially and then at 3 intervals 1 minute apart. In addition, the initial blood sample was separated into four 4‐mL Vacutainer tubes in blood volumes of 0.5, 1, 2, and 3 mL. Serum bicarbonate values (mmol/L) were compared using these techniques. Results: 1) Small needle size did not affect serum bicarbonate values (p > 0.60); 2) prolonged tourniquet time resulted in a statistically significant serum bicarbonate elevation (32.0, 32.5, 33.8, and 33.6, respectively; p < 0.01); and 3) underfilling of Vacutainer tubes resulted in significantly lower serum bicarbonate values for all 4 Vacutainer blood volume groups (21.4, 23.0, 25.0, and 26.2, respectively; p < 0.001). Conclusions: Small needle size does not affect serum bicarbonate values. Prolonged tourniquet time results in a statistically significant elevation of serum bicarbonate, although this elevation may not be clinically meaningful. Underfilling of Vacutainer tubes significantly influences the accuracy of serum bicarbonate values.