The Impact of Blood Gas Sample Waiting Time on Laboratory Parameters in Intensive Care Patients.

Objectives

This study aimed to investigate the impact of blood gas sample waiting time on laboratory parameters in intensive care patients, focusing on pH-related changes.

Methods

This prospective longitudinal observational study was conducted in the pulmonary diseases intensive care unit of a training and research hospital in Turkey between July 1 and November 30, 2023. A total of 81 patients were included in the study. Blood gas samples were categorized into three groups based on initial pH levels: acidosis, normal, and alkalosis. The samples were stored at 22 °C and analyzed at 0, 30, and 60 minutes after collection. Statistical analyses were conducted using ANOVA and the Friedman test, and effect sizes were evaluated with Eta squared and Kendall's W.

Results

Significant time-dependent changes were observed in PaO2 and SaO2 levels in the acidosis group. In the normal pH group, significant changes occurred in pH, PaCO2, PaO2, SaO2, glucose, and lactate levels. Similarly, in the alkalosis group, significant changes were detected in pH, PaCO2, SaO2, HCO3, glucose, and lactate levels. These findings suggested that slower metabolic activity in acidosis samples led to limited changes, whereas earlier changes were observed in normal and alkalosis samples.

Conclusions

To ensure accuracy in laboratory parameters, blood gas samples should be analyzed immediately after collection. Future studies with larger sample sizes and diverse methodologies are required to validate these findings and address the study's limitations, if unavoidable, aim for ≤30 min and document delay for interpretation.