La riduzione della pressione di aspirazione diminuisce l’emolisi nei prelievi da catetere intravenoso

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ABSTRACT

Reducing stress shear may decrease hemolysis associated to intravenous catheter blood collection

Blood collection through intravenous (IV) catheter is one of the most frequent causes of hemolysis and stress shear is reported to have an important role in that. Aim of this work was to determine whether the hemolysis rate of blood samples drawn through IV catheter may decrease by using 2.5 mL vacuum collection tubes instead of 5 mL tubes, currently in use. Consecutive samples collected at the emergency department to measure potassium using a 18 gauge IV catheter were evaluated for the presence of hemolysis in the 5 mL lithium heparin with separator gel tubes. The same samples were retested in a similar tube with 2.5 mL aspiration volume, collected at the same time. Hemolysis was evaluated spectrophotometrically on Siemens Advia 2400 analyzer as hemolysis index (HI) in the same run on the two types of tubes for the potassium array. Using a 150 HI cut-off, 48 (6%) of the 798 5 mL specimens were hemolysed, with median HI of 278 (95% confidence interval: 228÷362, range 153÷1146). Using the 2.5 mL tubes, only 6 samples of these 48 had an HI >150 (P <0.0001). On average, the percentage of reduction of HI values was 86% (range, 44÷98). These data confirm that shear stress due to the strength of aspiration is an important cofactor of the hemolysis induced by IV catheter. Last generation analyzers require few microliters of sample to perform a lot of tests. The use of tubes with lower filling volume and consequently lower negative pressure could reduce the rate of samples to be rejected for hemolysis that can delay patient care in overcrowded emergency departments.

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