Neurally adjusted ventilatory assist and proportional assist ventilation both improve patient-ventilator interaction

Introduction The objective was to compare the impact of three assistance levels of different modes of mechanical ventilation; neurally adjusted ventilatory assist (NAVA), proportional assist ventilation (PAV), and pressure support ventilation (PSV) on major features of patient-ventilator interaction. Methods PSV, NAVA, and PAV were set to obtain a tidal volume (V T ) of 6 to 8 ml/kg (PSV 100 , NAVA 100 , and PAV 100 ) in 16 intubated patients. Assistance was further decreased by 50% (PSV 50 , NAVA 50 , and PAV 50 ) and then increased by 50% (PSV 150 , NAVA 150 , and PAV 150 ) with all modes. The three modes were randomly applied. Airway flow and pressure, electrical activity of the diaphragm (EAdi), and blood gases were measured. V T , peak EAdi, coefficient of variation of V T and EAdi, and the prevalence of the main patient-ventilator asynchronies were calculated. Results PAV and NAVA prevented the increase of V T with high levels of assistance (median 7.4 (interquartile range (IQR) 5.7 to 10.1) ml/kg and 7.4 (IQR, 5.9 to 10.5) ml/kg with PAV 150 and NAVA 150 versus 10.9 (IQR, 8.9 to 12.0) ml/kg with PSV 150 , P <0.05). EAdi was higher with PAV than with PSV at level 100 and level 150 . The coefficient of variation of V T was higher with NAVA and PAV (19 (IQR, 14 to 31)% and 21 (IQR 16 to 29)% with NAVA 100 and PAV 100 versus 13 (IQR 11 to 18)% with PSV 100 , P <0.05). The prevalence of ineffective triggering was lower with PAV and NAVA than with PSV ( P <0.05), but the prevalence of double triggering was higher with NAVA than with PAV and PSV ( P <0.05). Conclusions PAV and NAVA both prevent overdistention, improve neuromechanical coupling, restore the variability of the breathing pattern, and decrease patient-ventilator asynchrony in fairly similar ways compared with PSV. Further studies are needed to evaluate the possible clinical benefits of NAVA and PAV on clinical outcomes. Trial registration Clinicaltrials.gov NCT02056093 . Registered 18 December 2013.