Excluding Pulmonary Embolism with End-tidal Carbon Dioxide: Accuracy, Cost, and Harm Avoidance

A non-randomized single center prospective, descriptive, correlational design was used to determine what end-tidal carbon dioxide (EtCO₂) level provided the best sensitivity, specificity, and negative predictive value to exclude pulmonary embolism (PE) diagnosis in hemodynamically stable hospitalized adults (n = 111). The financial impact and harm avoidance of adding EtCO₂ to the PE diagnostic process also were examined. PE diagnosis was determined by computed tomography pulmonary angiography (CTPA). PE prevalence was 18.9%. Mean±SD EtCO₂ was lower for PE positive than negative participants (28 ± 7.8 to 33 ± 8.1 mmHg respectively 95% CI: 1.22-8.96; P = .01). For PE exclusion, an EtCO₂ cutoff ≥42 mmHg yielded 100% sensitivity, 12.2% specificity, and 100% negative predictive value. For every six inpatients assessed with EtCO₂, one could be saved from unnecessary CTPA. Eliminating unnecessary CTPA removes the potential harm associated with radiation and intravenous contrast exposure. Additionally, an EtCO₂ cutoff ≥42 mmHg could eliminate ~$88,000/year in healthcare waste at this institution.