Although we know that these numbers are underestimated, Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease that affects between 8 and 12% of adults. According to a 2020 WHO report, it is the third most common cause of mortality in developed countries. This disease is punctuated by exacerbations associated with an 8% mortality of hospitalized patients, increased to 24% when the patient is admitted to intensive care unit. Early detection and treatment of these exacerbations appears to be essential to improve patient survival. End-tidal carbon dioxide (EtCO2) is used to assess a patient's respiratory and hemodynamic status. Indeed, EtCO2 is a non-invasive measure that could allow the estimation of arterial carbon dioxide (PaCO2) without performing blood gases, an arterial blood sampling, classically at the radial artery. This study aimed to find an EtCO2 value which at the time of the initial management, would be predictive of a severe COPD exacerbation, as well as PaCO2.

The study will be conducted in the emergency departments of Grenoble and Lyon University Hospitals.

Patients will be recruited by the dispatch nurse at the emergency department reception according to the inclusion and non-inclusion criteria. The EtCO2 will be measured at the emergency reception during assessment of vital signs by the same nurse with the help of a mask or oxygen glasses measuring EtCO2. The patient will then be treated conventionally according to current international recommendations. The physician in charge of the patient will be blinded to this measurement. Once the patient is discharged from the emergency department, the primary and secondary endpoints will be collected by a clinical research associate 24 hours after admission from medical record.

Inclusion Criteria:

• All patient presenting to the emergency department with acute dyspnea and with a history of COPD documented or reported by the patient and/or family
• Male or female≥18 years old who did not oppose to participating in the study

Exclusion Criteria:

• Hypotension (SBP < 90 mmHg or MBP < 65 mmHg)
• Patient already included in the study during a previous visit to the emergency department
• Patient already ventilated with invasive or NIV during admission to the emergency department
• COPD exacerbation rejected after medical and additional examinations
• Non-communicative or non-French speaking patients, or with impaired comprehension, or with impaired consciousness
• Protected persons referred to in articles L1121-6 and L1121-8 of French public health code (deprived of liberty, tutorship or curatorship)

Patients admitted to emergency department for acute exacerbation of chronic obstructive pulmonary disease

The international writing and publication rules (The Uniform Requirements for Manuscripts of the ICMJE, April 2010) will be followed. The minimum anonymized source data for performing the statistical analysis will be made public at the time of publication, with the article, or deposited in an appropriate public database. Other anonymized data may be available from the principal investigator upon reasonable request and with the consent of the sponsor.

In accordance with the French law n ° 2002-303 of March 4th, 2002, the subjects can be informed, at their request, of the overall results of the research. In this study, the investigators commit to individually communicating the overall results to each subject participating in the research by a short (popularized) summary and associated with a copy of the scientific article.

at the time of publication

The international writing and publication rules (The Uniform Requirements for Manuscripts of the ICMJE, April 2010) will be followed. Moreover, In accordance with the French law n ° 2002-303 of March 4th, 2002