Noninvasive Ventilation Facemasks Favoring Carbon Dioxide Washout

Inclusion Criteria:

Acute respiratory failure with

• PaCO2 ≥ 45 mmHg;

• Arterial pH < 7.35;

• Signed written informed consent

Exclusion Criteria:

• Respiratory rate < 12 bpm;

• Immediate need for intubation;

• Haemodynamic instability (Systolic blood pressure <90 mmHg or mean arterial pressure <65 mmHg) and/or lactic acidosis (lactate >5 mmol/L) and/or clinically diagnosedshock;

• Metabolic Acidosis;

• Recent head surgery or anatomy that prevent the application of facemasks;

• Any contraindications to oesophageal balloon insertion and/or electrical impedancetomography (EIT) belt placement.

• Any contraindications to facemask noninvasive ventilation.