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

Study Overview
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Brief Summary
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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.

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

Conditions
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Pulmonary Embolism

Intervention / Treatment
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* Diagnostic Test: Laboratory testing: D-dimeer and astrup


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient with suspected pulmonary embolism Emergency department D-dimer result available Arterial blood gas available Exclusion Criteria: Patients without documented oxygen suppletion durig blood gas measurement Patients without documented and insufficient data to calculate YEARS criteria Pregnancy
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Suspected PE<br>Patients with suspected pulmonary embolism | Diagnostic Test: Laboratory testing: D-dimeer and astrup<br>* Standard care: Laboratory result (D-dimer and astrup). CT scan for pulmonary embolism if indicated<br>* Other names: CT-scan for pulmonary embolism;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic accuracy of a combination of a normal Alveolar-Arterial Oxygen Gradient with negative YEARS criteria in patients with suspected pumonary embolism |  | At submission in the Emergency Department | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| How many CT-scans would have been avoided if the algorithm was used in normal practice |  | At submission in the Emergency Department | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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A-a gradient