Prevention of hemolysis in blood samples collected from intravenous catheters

Objectives: Samples drawn through intravenous catheters are frequently hemolyzed. We planned a prospective, randomized study to establish whether hemolysis in samples drawn from intravenous catheters may be reduced using S-Monovette (R) tubes collected by manual aspiration as compared with standard vacuum tubes. Design and Methods: We studied 52 consecutive patients admitted to the ED. Blood was drawn through a 20-gauge intravenous catheter. A 5.0 mL, Becton Dickinson Vacutainer (R) SST II Plus serum tube was collected and discarded. In the odd group of patients (i.e., n. 1, 3, 5, etc.), a second SST II tube was drawn with vacuum ("BD-V"), followed by a 5.5 mL 5-Monovette (R) serum tube collected with manual aspiration ("SD-A") and an identical S-Monovette collected by vacuum ("SD-V"). In the pair group of patients (i.e., n. 2, 4, 6, etc.), the sequence was modified to "SD-A", "SD-V" and "BD-V". Serum was separated and tested for lactate dehydrogenase (LDH), potassium and cell-free hemoglobin. Results: The mean concentration of potassium (+2.7% in BD-V and + 1.7% in SD-V, respectively), LDH (+15% in BD-V and + 7% in SD-V, respectively) and cell-free hemoglobin was significantly increased when samples were collected with vacuum tubes as compared with manual aspiration. No significant differences were observed between SD-V and BD-V. The frequency of hemolyzed samples was higher when blood was collected with the vacuum as compared with SD-A (i.e., 2%), but did not differ between BD-V and SD-V (i.e., 29 versus 31%; p = 0.70). Conclusion: S-Monovette can be used with vacuum or aspiration collection. This latter approach allows blood drawing with limited shear stress and less likelihood of generating spuriously hemolysis. (C) 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.