Objective: To observe the effects of neurally adjusted ventilatory assist (NAVA) on subject-ventilator synchrony in rabbits with acute respiratory distress syndrome (ARDS).
Methods: The rabbit model of ARDS was induced by intratracheal infusion of hydrochloric acid. After sufficient recruitment, the rabbits were randomly divided into 2 groups: pressure support ventilation (PSV) group and NAVA group. The parameters of subject-ventilator synchrony such as ventilation trigger, ventilation switching and magnitude of assist were observed at 0, 1, 2, 3 h respectively.
Results: (1) Ventilation trigger: 1) trigger delay: the trigger delay in the NAVA group were markedly lower than the PSV group at 0, 1, 2, 3 h (P < 0.05); as ventilation time elapsed, the trigger delay changed neither in NAVA nor in PSV group (P > 0.05). 2) Ineffective trigger index: the ineffective trigger index was 17.7% ± 13.7% in the PSV group. While all neural efforts were trigger, there was no ineffective trigger observed in the NAVA group. (2) Off-cycle delay: the off-cycle delay were significantly lower in the PSV group than that in the NAVA group at 0, 1, 2, 3 h (P < 0.05); as the ventilation time elapsed, the off-cycle delay changed neither in the NAVA group nor in the PSV group (P > 0.05). (3) Magnitude of assist: in the NAVA group, peak EAdi and peak pressure were markedly correlated (determination coefficient 0.86 ± 0.07, P < 0.05). But pressure delivery during the PSV group was not correlated with EAdi (P > 0.05).
Conclusion: As compared with PSV, NAVA can improve subject-ventilator synchrony in rabbits with ARDS.