Difficulty of inclusion

In COPD patients with chronic hypercapnic respiratory failure, the prognosis is poor and the treatment with non invasive ventilation is actually well established. However the best mode of ventilation is not well known.

In severe COPD patients various disorders of respiratory mechanics result in insufficient ventilation, which can be life-threatening or create NIV discomfort. The main characteristic of these disorders is a cyclical closing of small airways that can limit an expiratory flow and provoked some fluctuations in flow curve. To our knowledge, the management of dynamic hyperinflation seems to play an important role in explaining the effect of the NIV. Few studies have examined the effects of the machine's adjustments on dynamic hyperinflation.

The main objective of this study is to analyze the impact of specific ventilatory modes supposed to reduce the dynamic hyperinflation on the hematosis, by studying transcutaneous pressure of carbon dioxide, in severe hypercapnic COPD patients ventilated by NIV. Two modes of ventilation will be compared. First one is an algorithmic mode developed by the company Löwenstein (AirTrap Control, Trigger Lockout and the Expiratory Pressure Ramp). The second one is a standard algorithmic mode, used in the same ventilator. These two ventilatory modes will be evaluated in each patient, during two consecutive nights in current living conditions at home.

Inclusion Criteria:

• Diagnosis of COPD using Gold 2017 criterion
• Optimal medical treatment of COPD, ie. inhaled steroids, long-acting β2-agonist, long-acting anticholinergic, according to GOLD 2017 guidelines.
• At least one acute exacerbation of COPD with hypercapnic respiratory failure
• Introduction of NIV distant to acute exacerbation of COPD with persisting hypercapnia (> 7kPa) on arterial blood gas at rest.
• NIV equipment from the service provider "Don Du Souffle (DDS)".
• Patient able to give their consent

Exclusion Criteria:

• Contraindication to NIV (consensus conference of SFAR-SPLF-SRLF)
• Obstructive sleep apnea with apnea/hypopnea index > to 20/h
• BMI > 35 kg/m2
• Low compliance with NIV treatment (<3h per day)
• Acute exacerbation COPD during inclusion or pH <7.30 in routine blood gas arterial
• Severe heart failure (New York Heart Association stage IV/IV)
• Unstable angina
• Severe arrhythmias
• Severe renal insufficiency stage > 4
• Other conditions than COPD resulting in hypercapnia
• Pregnancy
• Patient without health insurance
• Patient excluded by another study

Patients followed in the pneumology department of the Besançon university hospital.