Role of neurally adjusted ventilatory assist in lung-protective ventilation in patients with acute respiratory distress syndrome
Objective To observe the influence of neurally adjusted ventilatory assist(NAVA)on mechanical power in different lung regions of patients with acute respiratory distress syndrome(ARDS),and to explore its role in improving patient-ventilator synchrony.Methods Sixty patients with mild to moderate ARDS were treated in Henan Provincial People's Hospital from January 2016 to January 2019,among whom 30 patients received NAVA ventilation(observation group),and the other 30 patients received synchronized intermittent mandatory ventilation(SIMV)+pressure support ventilation(control group).Both two groups received conventional treatment including anti-infection,treatment of primary diseases,and airway management to ensure the hemodynamic and internal environmental stability.Lung electrical impedance tomography was used to monitor the total mechanical power and mechanical power in non-gravitational dependent and gravitational dependent lung regions 12 and 24 h after mechanical ventilation in both groups.The clinical data such as the etiology,degree of ADRS,and Acute Physiology and Chronic Health Evaluation Ⅱ(APACHE Ⅱ)score on admission were compared between two groups.The pa(O2),pa(CO2),oxygenation index,inspiratory trigger delay time,inspiratory-expiratory phase transition delay time,maximal expiratory pressure,maximal inspiratory pressure,and rapid shallow breathing index were recorded 12 and 24 h after mechanical ventilation.Results(1)There were no significant differences in the gender ratio,proportion of moderate ARDS,age,etiology,and admission APACHE Ⅱ score between two groups(P＞0.05).(2)After mechanical ventilation for 12 and 24 h,the values of pa(CO2),rapid shallow breathing indexes,total mechanical power values,and mechanical power values in non-gravitational dependent lung region were lower in observation group[(44.38±3.00),(42.10±2.88)mmHg;(89.55±5.56),(78.05±5.42)breaths/(min·L);(10.43±1.12),(11.28±1.26)mJ;(7.21±0.57),(7.90±0.58)mJ]than those in control group[(49.55±2.57),(48.43±2.53)mmHg;(92.23±3.83),(91.20±3.51)breaths/(min·L);(11.22±1.11),(13.88±1.69)mJ;(7.98±0.75),(9.17±1.03)mJ](P＜0.05),the maximal expiratory pressures and maximal inspiratory pressures were higher in observation group[(88.14±5.98),(95.64±2.71)mmH2O;(44.79±7.59),(61.19±4.57)mmH2O]than those in control group[(84.66±6.13),(86.67±2.70)mmH2O;(41.73±2.48),(41.80±2.99)mmH2O](P＜0.05),the inspiratory trigger delay time and inspiratory-expiratory phase transition delay time were shorter in observation group[(90.77±2.48),(70.65±1.33)ms;(85.98±0.97),(80.64±1.35)ms]than those in control group[(92.61±4.12),(74.51±1.85)ms;(96.74±1.06),(84.33±1.42)ms](P＜0.05),and there were no significant differences in the pa(O2)values,oxygenation indexes,and mechanical power values in gravitational dependent lung region between two groups(P＞0.05).And the above indexes were more obviously improved 24 h after ventilation than those 12 h after ventilation(P＜0.05).Conclusion NAVA mode for mechanical ventilation can improve patient-ventilator synchrony,reduce respiratory drive,alleviate over-inflation and respiratory load in the non-gravitational dependent lung region,and contribute to lung-protective ventilation in ARDS patients.
acute respiratory distress syndromeneurally adjusted ventilatory assistelectrical impedance tomographymechanical power
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