Hypercapnia is a frequent clinical situation defined as an elevation of the partial pressure of carbon dioxide (PaCO2) above 45 mmHg. Several physiopathological parameters such as respiratory minute volume, dead space volume or CO2 production influence the PaCO2. Therefore, hypercapnia can affect the time of various diseases.

Available epidemiological data regarding hypercapnia are from studies investigating the efficacy of non-invasive ventilation (NIV), with different population cohorts. However, their interpretation must be cautious given the heterogeneity in patient case-mix and results.

Then, whether hypercapnia is a common reason for intensive care unit (ICU) admission, epidemiological data is scarce and heterogeneous. The aim of this study is to investigate the epidemiological, clinical determinants and outcomes of patients admitted to ICU with hypercapnic respiratory failure.

Inclusion Criteria:

• patients ≥18 years old presenting with at least of the following items :

  1. respiratory rate ≥ 25/min,
  2. paradoxical motion of the abdomen,
  3. intercostal retraction AND

• a PaCO2 > 45 cm H20 before ICU admission or within the 12 hours following ICU admission.

Exclusion Criteria:

• Refusal to give informed consent,
• pregnancy,
• < 18 years patient,
• dying patient

The aim of this study is to investigate the epidemiological, clinical determinants and outcomes of patients admitted to ICU with hypercapnic respiratory failure.