Reducing inappropriate arterial blood gas testing in a level III intensive care unit: a before-and-after observational study

Background: Arterial blood gas (ABG) analysis is the most frequently performed test in intensive care units (ICUs), often without a specific clinical indication. This is costly and contributes to iatrogenic anaemia. Objectives: To reduce the number of ABG tests performed and the proportion that are inappropriate. Design, setting and participants: The indications for ABG analysis were surveyed at a 58-bed level III ICU during fortnightly periods before and after a multifaceted educational intervention which included the introduction of a clinical guideline. The number of ABG tests performed during the period July-December 2017 was compared with that for the period July-December 2018. Tests were predefined as inappropriate if performed at regular time intervals, at change of shift, concurrently with other blood tests or after a treatment was ceased on a stable patient or after ventilatory support or oxygen delivery was decreased in an otherwise stable patient. The study was enrolled on the Quality Improvement Projects Register and ethics approval was waived by the local ethics committee. Results: There was a 31.3% bed-day adjusted decrease in number of ABG tests performed (33 005 v 22 408; P < 0.001), representing an annual saving of A$770 000 and 100 litres of blood. The proportion of inappropriate ABG tests decreased by 47.3% (54.2% v 28.6%; P < 0.001) and the number of inappropriate ABG tests per bed-day decreased by 71% (2.8 v 0.8; P < 0.001). Patient outcomes before and after the intervention did not differ (standardised mortality ratio, 0.65 v 0.63; P = 0.22). Conclusion: Staff education and implementation of a clinical guideline resulted in substantial decreases in the number of ABG tests performed and the proportion of inappropriate ABG tests.