Comparison of Arterial and Capillary Blood Gas Analyses in Patients With Respiratory Distress Due to COPD or APE

The assessment of gas exchange is crucial for the management of patients suffering from respiratory distress due to an exacerbation of chronic obstructive pulmonary disease (COPD) or cardiogenic acute pulmonary edema (APE). These measurements are used by physicians to determine the need for noninvasive ventilation (NIV) as well as to evaluate its effectiveness and to decide whether to continue the treatment. Arterial blood gas analysis is currently the gold standard for the measurement of these gas exchanges, though invasive, painful and risky (failure risks and possible local complications). Capillary blood gas analysis, which consists in collecting a blood drop from the ear or the finger by capillarity after punction, could represent a less invasive alternative. However, data comparing the performances of arterial and capillary blood gas analysis in the context of respiratory distress requiring a NIV remain limited. This study is based on the hypothesis that capillary blood gas analysis can perform as well as arterial blood gas analysis. It is aimed at comparing values obtained from arterial and capillary blood gas analyses from patients with respiratory distress and requiring a NIV due to an exacerbation of COPD or cardiogenic APE.

Inclusion Criteria: * Patients older than 18 years old * Patients admitted in the emergency care unit with an exacerbation of COPD or a cardiogenic APE requiring a non-invasive ventilation (i.e. for COPD patients pH\< 7.35, for APE patients: PCO2 \> 45 mmHg) * Patients affiliated to a social security system Exclusion Criteria: * Patients for which a non-invasive ventilation was initiated upon pre-hospital care * Contraindication for non-invasive ventilation * Patients for which non-invasive ventilation is not indicated * Patients for which capillary or arterial blood gas analyses are impossible * Adults subject to legal guardianship (guardianship, conservatorship) * Pregnant women * Patients with a congenital heart disease