Potential preanalytical errors in whole-blood analysis: effect of syringe sample volume on blood gas, electrolyte and lactate values.

Background: Arterial blood samples are sensitive to bias because of the physiological properties of blood. Several errors can occur in the preanalytical phase leading to incorrect diagnosis and improper treatment of patients. Collection of a blood specimen, as well as its handling and transport, belong to the key factors to affect the accuracy and good quality of clinical laboratory analysis.

Methods: The aim of this study was to validate the effect of different sample volumes on the blood gas, electrolyte and lactate values using 3 mL Rapidlyte plastic syringes with filter cap and Rapidlab 865 blood gas analyser. Also, the stability of blood gas analyser parameters with different sample volume was studied.

Results: No substantial change in blood gas, electrolyte and lactate parameters was found when the results of 3 mL, 1.8 mL sample volumes in the 3 mL syringes were compared. The sample volume of 1.0 mL or 1.5 mL in the 3 mL syringe is not suitable for the measurement of oxygen tension, especially when accurate results of pO(2) and arterial blood is needed for patient's diagnosis.

Conclusions: The minimum sample volume when blood gases, electrolytes and lactate are all measured with the Rapidlab system should be 1.8 mL using 3 mL Rapidlyte plastic syringe with filtercap. According to this study <1.8 mL sample volumes can provide inaccurate results and can impose biases on measurements.