Diagnostic Accuracy of Arterial-alveolar Oxygen Gradient in Low Risk Patients With Suspected Pulmonary Embolism

Introduction:

The diagnosis of pulmonary embolism (PE) is a challenge in the Emergency Department. D-dimer based diagnostic algorithms for PE have a very high sensitivity, but rely upon a vast amount of CT angiography and potentially unnecessary exposure to radiation. An accurate diagnostic algorithm that does not involve d-dimer testing might reduce this burden.

An abnormal Alveolar-arterial oxygen gradient (A-a gradient) seems to increase the chance of PE. However, a normal A-a gradient on its own does not exclude the diagnosis. In this paper, the accuracy of A-a gradient testing and a combination of Years criteria with A-a gradient testing will be assessed.

Methods:

This is a prospective, single center, observational study. All patients that present at our emergency department from September 2022 until September 2023 with a suspicion of pulmonary embolism will be analyzed for eligibility and included in the study after informed consent. The aim is to include at least 230 patients in the study.

Analysis: The primary outcome is the diagnostic accuracy of a YEARS and A-a gradient based algorithm for pulmonary embolism. The secondary outcome is the potential decrease in performed imaging in order to exclude pulmonary embolism.

Valorisation An accurate A-a gradient-based algorithm for pulmonary embolism in low risk patients will be a step towards an improved clinical risk score. We aim to reduce the amount of diagnostic imaging, i.e. CT-angiography. Meaning less, potentially unnecessary, exposure to radiation for the patient. Furthermore, it could lower healthcare costs by reducing expensive diagnostic imaging.