Volume-targeted noninvasive ventilation (VT-NIV), a hybrid mode that targets a preseted tidal volume (VT) by automated adjustment of pressure support, could guarantee the delivered VT over pressure-limited noninvasive ventilation (PL-NIV) with fixed level pressure support. Whether VT-NIV is more effective in improving gas exchange in patients with acute hypercapnic respiratory failure (AHRF) as compared with PL-NIV remains unclear. Our aim was to verify whether in comparison with PL-NIV, use of VT-NIV was more effective in correcting hypercapnia, hence reducing the need for intubation and improving survival in patients with AHRF.

Inclusion Criteria:

• acute hypercapnic respiratory failure (AHRF)
• arterial pH <7.35 and ≥7.25
• PaCO2 >45 mmHg

Exclusion Criteria:

• age <18 years
• excessive amount of respiratory secretions or weak cough
• upper airway obstruction
• recent oral, facial or cranial trauma or surgery
• recent gastric or esophageal surgery
• severe metabolic acidosis; severe abdominal distension
• cardiac or respiratory arrest
• PaO2/FiO2 <150 mmHg
• pneumothorax
• severe ventricular arrhythmia or myocardial ischemia
• severe hemodynamic instability despite fluid repletion and use of vasoactive agents
• active upper gastrointestinal bleeding
• lack of cooperation
• refusal to receive NIV