Cuskelly, James W., and McDonald, Craig A. (2025) Optimising the frequency of routine arterial blood gas testing in the intensive care unit: An observational study. Australian Critical Care, 38 (6). 101317.

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Abstract

Background: Arterial blood gas (ABG) testing is a broadly utilised tool in intensive care units (ICUs), though there is an acceptance that an excessive number are performed routinely. Reducing collection frequency has previously demonstrated no impact on benchmarked outcomes. This observational study assessed the impact of reducing routine ABG testing frequency on critical value detection, routine bedside interventions, and patient outcomes. Objective: The objective of this study was to evaluate the safety and clinical utility of routine ABG collection by reviewing test frequency, critical value detection, bedside interventions (including respiratory support and electrolyte supplementation), and patient outcomes. Methods: This observational study compared three time periods (preintervention, postintervention, and 1-year follow-up) between 2019 and 2021, following implementation of an ABG testing protocol in February 2020. ABG testing frequency and associated critical values were recorded alongside routine bedside interventions (system support changes). Setting: The study was conducted in Cairns Hospital ICU, a regional mixed ICU in Australia with approximately 1200 annual admissions. Participants: Adult patients admitted for over 24 h without an established need for high-frequency ABG collection participated in the study. Results: ABG use decreased significantly from 4.93 to 3.06 tests per patient per day (p < 0.001), sustained at 1-year follow-up. The proportion of patients with at least one critical value detected did not differ significantly (57% vs. 49%, p = 0.06), though the number of critical values per patient per day declined (3.89 vs. 2.99, p < 0.001). Rates of respiratory support changes—including adjustments in fraction of inspired oxygen, type of respiratory support, and amount of positive end-expiratory pressure—were not significantly reduced. Potassium supplementation remained similar (27.10 mEq/day vs. 26.20 mEq/day, p = 0.288). Mortality was unchanged (6.5% vs. 11.5%, p = 0.074). Conclusion: Routine ABG analysis is associated with overtesting. A routine ABG collection protocol supported by staff education significantly reduces their collection frequency without compromising day-to-day care or overall patient outcomes.

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