CO2 measurement for the early differential diagnosis of pulmonary embolism-related shock at the emergency department: A case series

OBJECTIVE: An early differential diagnosis is mandatory when facing a patient with clinical shock of unclear aetiology, in order to guide proper treatment. We assessed if the expired CO(2) measurement and alveolar-arterial CO(2) calculation could improve the differential diagnosis of shock during its initial presentation, particularly in separating pulmonary embolism from other causes of shock. METHODS: We analysed the charts of 12 patients who presented with clinical shock and had end-tidal CO(2) (EtCO(2)) and arterial CO(2) partial pressure (PaCO(2)) measurements. RESULTS: In cases with pulmonary embolism-related shock (n = 3), the gradient between PaCO(2) and EtCO(2) was increased (37 vs 0.2 mmHg). There was a similar trend for a higher PaCO(2) value (60 vs 32.2 mmHg) and a lower EtCO(2) value (23 vs 32 mmHg). CONCLUSION: An initial CO(2) measurement might be an easily available tool for the early diagnostic work-up of clinical shock.