Non invasive spontaneous dual ventilation in critically ill patients with chronic obstructive pulmonary disease

AbstractBackgroundEffective non-invasive ventilation (NIV) is dependent on optimal ventilator settings for alveolar ventilation. Volume-assured pressure support (VAPS) is a mode of servoventilation, providing constant automatic adjustment of pressure support (PS) to achieve a target ventilation. Our aim is to evaluate the effectiveness of the new dual spontaneous mode of ventilation named intelligent volume assured pressure support (iVAPS) in comparison with conventional pressure support using S/T mode in-patients with acute hypercapnic respiratory failure due to acute exacerbation of COPD.Patients and methodsForty patients with hypercapnic respiratory failure and respiratory acidosis due to acute exacerbation of COPD after failure of conventional medical treatment including oxygen therapy were recruited into the study. Patients were categorized into two groups, Group I ventilated with S/T mode and Group II ventilated with iVAPS mode. Patients were fitted with an oronasal mask (Ultramirage, ResMed) connected to VPAP ST(ResMed).ResultsBoth groups were comparable on admission. The successful outcome was achieved in 15 patients (75%) in the PS group vs 16 patients (80%) in the iVAPS group. Both groups show significant (p<0.01) improvement after 1h NIV compared with preventilatory level in respiratory rate (25.7±1.6 vs 34.5±1.8 for PS and 27.9±4.8 vs 34.6±1.3 for iVAPS) without significant difference between the two groups. In the iVAPS group, there were a significantly (p<0.01) higher pH (7.34±0.02 vs 7.31±0.02 for PS group) and significantly (p<0.001) lower PaCO2 (74.00±2.3 vs 79.00±3.7 for PS group) after 1h NIV. There was a significant (p<0.01) higher minute ventilation and significant (p