Key result
An end-tidal CO2 threshold of 32.5 mmHg demonstrated a sensitivity of 98.6% and a negative predictive value of 98.8% for excluding pulmonary embolism.
Why the study?
Pulmonary embolism diagnosis remains challenging with low confirmation rates despite clinical suspicion, leading to a significant rise in unnecessary computed tomography pulmonary angiograms.
Does end-tidal CO2 measurement accurately exclude pulmonary embolism in patients with suspected PE?
Observational (n=479)
Single-blind
No
Does end-tidal CO2 measurement accurately exclude pulmonary embolism in patients with suspected PE?
Effect estimate: NPV 98.8%
ETCO2 measurement is a highly sensitive, non-invasive bedside screening tool that can reliably exclude pulmonary embolism and potentially reduce unnecessary CTPA scans.
May support EtCO2 for PE exclusion in select patients; hypothesis-generating and requires prospective validation.
Pulmonary Embolism (PE) is a global problem and a leading cause of cardiovascular death in the western world and a major public health problem The diagnosis of PE remains a challenge because of the high variability in clinical presentation complex interplay between different organs. Patients can present with chest pain, dyspnoea, haemoptysis, syncope and hypoxaemia Diagnosis of a PE is confirmed in <25% of patients that are clinically suspicious and the radiological investigations are essential Despite the low relative incidence of the disease, there is a significant rise in the number of patients undergoing unnecessary computed tomography pulmonary angiograms (CTPA) to exclude a PE. Moreover, the CTPA is the most robust predictive evidence base for adverse clinical outcomes in patients with acute PE
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A 2021 study conducted an observational in Suspected Pulmonary Embolism (n=479). End-tidal CO2 (ETCO2) measurement vs. Computed tomography pulmonary angiogram (CTPA) was evaluated on Diagnostic accuracy (sensitivity and negative predictive value) of ETCO2 at a threshold of 32.5 mmHg to exclude pulmonary embolism (NPV 98.8%). An end-tidal CO2 threshold of 32.5 mmHg demonstrated a sensitivity of 98.6% and a negative predictive value of 98.8% for excluding pulmonary embolism.
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