Choice of blood gas syringe – does it matter?

The preanalytical phase of laboratory testing has long been recognized as a stage for potential error, and blood gas analysis is a test that is well-recognized as being particularly vulnerable in this regard. Much research has been directed at devising procedures that minimize variability of measured blood gas parameters during sample collection and handling. 

One potential source of variability examined in a recently published study is the syringe used to collect arterial blood samples. The object of the study was to determine if blood gas syringe is a source of variability by comparing results obtained using four brands/types of heparin-coated syringe. 

Arterial blood was sampled from 100 volunteer patients and collected directly into the four brands/types of syringe. All samples were analyzed using the same blood gas analyzer within 5 minutes of sample collection. The blood gas analyzer used has the capacity to measure or calculate 16 parameters, including: those for assessing acid/base and oxygenation status, sodium, potassium, lactate, calcium, glucose and total hemoglobin. 

So for each of 100 study participants there were four results to be compared for each of the 16 parameters. Analysis of this database revealed statistical differences between syringe samples for all parameters, but these differences were not necessarily clinically significant. 

Parameters that were associated with clinically significant differences between syringe sample results were pCO₂, sodium, potassium, calcium, glucose and lactate. The results of this study suggest that differences in syringe manufacture can represent a source of variability in blood gas analyzer derived patient results.