Factors Predicting CT Pulmonary Angiography Results in the Emergency Department

Area of Science:

• Emergency Medicine
• Radiology
• Pulmonology

Background:

• Pulmonary embolism (PE) is a significant cause of emergency department visits for respiratory symptoms.
• CT pulmonary angiography (CTPA) use is increasing, but diagnostic yields are often low.
• Investigating factors associated with PE can optimize CTPA utilization.

Purpose of the Study:

• To identify factors associated with pulmonary embolism (PE) on CT pulmonary angiography (CTPA).
• To reduce unnecessary CTPA requests in emergency patients.
• To evaluate the impact of pre-existing pulmonary conditions on PE diagnosis.

Main Methods:

• Retrospective analysis of 1555 CTPA reports from emergency patients in 2023.
• Evaluation of patient variables for association with PE presence/absence.
• Assessment of pre-CTPA pulmonary pathology and physiological variables.

Main Results:

• 17.9% of CTPA scans were positive for PE.
• Deep vein thrombosis (DVT) significantly increased PE odds (OR=40.9).
• Acute congestive heart failure (CHF), COPD exacerbation with hypercapnia, and cancer showed lower PE odds.
• Tachycardia and hypoxemia correlated with PE; hypercapnia correlated negatively.
• Elevated D-dimer cut-offs maintained 100% PE sensitivity in CHF, COPD, and pneumonia patients.

Conclusions:

• Implementing stricter CTPA criteria for patients with other pulmonary pathologies may decrease unnecessary scans.
• Higher D-dimer thresholds in specific conditions (CHF, COPD, pneumonia) can improve CTPA specificity without compromising sensitivity.