title: CO2 measurement for the early differential diagnosis of pulmonary embolism-related shock at the emergency department: A case series.
abstract: 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 CO2 measurement and alveolar-arterial CO2 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 CO2 (EtCO2) and arterial CO2 partial pressure (PaCO2) measurements.
  
  
  RESULTS
  In cases with pulmonary embolism-related shock (n = 3), the gradient between PaCO2 and EtCO2 was increased (37 vs 0.2 mmHg). There was a similar trend for a higher PaCO2 value (60 vs 32.2 mmHg) and a lower EtCO2 value (23 vs 32 mmHg).
  
  
  CONCLUSIONS
  An initial CO2 measurement might be an easily available tool for the early diagnostic work-up of clinical shock.
authors.affiliation: Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Emergency Department, Brussels, Belgium.
authors.forename: Cédric
authors.initials: C
authors.lastname: Van Marcke
authors.affiliation: Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Emergency Department, Brussels, Belgium.
authors.forename: Anas
authors.initials: A
authors.lastname: Daoudia
authors.affiliation: Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Emergency Department, Brussels, Belgium.
authors.forename: Andrea
authors.initials: A
authors.lastname: Penaloza
authors.affiliation: Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Emergency Department, Brussels, Belgium.
authors.forename: Franck
authors.initials: F
authors.lastname: Verschuren
keywords: CO2; Pulmonary embolism; Shock