Point-of-care peripheral venous blood gas in the elderly demographic in the emergency department; a pilot study

Abstract

Background: The peripheral venous blood gas (PVBG) has gained popularity over the arterial blood gas and electrolytes- urea-creatinine panel in non-critical situations in the emergency department (ED). Despite its convenience and rapid result return, it is costly and potentially over-utilized.

Aim: To assess the utility of point of care (POC) PVBG samples in predicting re-presentation of elderly patients (over the age of 65) to the ED within 72 hours, who were discharged without inpatient admission directly from ED.

Method: A retrospective audit was performed on patients of the above demographic, who presented to three Monash Health EDs between January 2011 and October 2015 and had a single POCPVBG sample taken. The individual POCPVBG values were compared between those who re-presented within 72 hours to those who did not, as were demographic data.

Results: In the 723 eligible cases in the study period, 127 (18%) re-presented within 72 hours whilst 596 (82%) did not. The median ages were similar 76 [70;82] and 77 [71;83] as was proportion of males (50%, 51%). The most common presenting complaints in both groups were shortness of breath and abdominal pain. Categorical analysis showed a statistically significant (p < 0.05) association between low base excess (Odd Ratio: 2.5; 95% Confidence Interval 1.2-4.9) and low potassium (OR: 2.5; 95% CI: 1.2-3.8) with re-presentation. However, these results had unclear clinical significance; the sensitivity and likelihood ratios for each were 16% and 2.2 and 15% and 1.9.

Conclusion: The PVBG may have some utility as a predictor of re-presentation in non-critical presentations of elderly patients to the ED. However, the role of a single POCPVBG sample in assessment of such patients remains unclear, and further research and guidelines need to be established to avoid over-utilization.