New developments in neonatal respiratory management

Respiratory distress syndrome (RDS) is the major cause of respiratory failure in preterm infants due to immature lung development and surfactant deficiency. Although the concepts and methods of managing respiratory problems in neonates have changed continuously, determining appropriate respiratory treatment with minimal ventilation-induced lung injury and complications is crucially important. This review summarizes neonatal respiratory therapy's advances and available strategies (i.e., exogenous surfactant therapy, noninvasive ventilation, and different ventilation modes), focusing on RDS management.     

NAVA对早产儿呼吸窘迫征血指标及呼吸力学相关参数的影响

【摘要】 目的 研究神经调节辅助通气（NAVA）对早产儿呼吸窘迫征（RDS）的临床效果及对血气指标、呼吸力学相关参数的影响。方法 收集医院早产儿重症监护病房自2015年3月~2017年4月收治的RDS患儿88例，按随机数字表法分为观察组与对照组各44例。观察组给予NAVA模式行辅助通气，对照组给予同步间歇指令通气（SIMV）模式行辅助通气。治疗后对两组血气指标、呼吸力学相关参数及并发症发生率进行对比评价。结果 观察组吸气触发延迟时间明显短于对照组（P<005）；两组的动脉血pH、SpO2、PaO2、PaCO2以及PaO2/FiO2等血气指标改善程度均明显优于治疗前（P<005）；但两组对比差异无统计学意义（P＞005）；两组的RR、MAP、PIP、EAdi峰值、EAdi谷值、MVi、VTi、WOB等呼吸力学相关参数改善情况均明显优于治疗前（P<005）；但观察组膈肌电活动信号、RR、PIP以及WOB等指标均明显低于同时期的对照组（P<005）；两组在并发症发生率上对比差异无统计学意义（P＞005）。结论 在早产儿RDS的治疗中，应用NAVA通气模式可有效缩短触发延迟，能以更低的气道压力实现同样的气体交换，还可减少膈肌负荷，降低气道峰压及呼吸做功且不会增加并发症发生率，安全可靠，可作为临床最优的机械通气模式进行推广。     

Inspiratory muscle unloading by neurally adjusted ventilatory assist during maximal inspiratory efforts in healthy subjects

BACKGROUND: Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation in which the ventilator is controlled by the electrical activity of the diaphragm (EAdi). During maximal inspirations, the pressure delivered can theoretically reach extreme levels that may cause harm to the lungs. The aims of this study were to evaluate whether NAVA could efficiently unload the respiratory muscles during maximal inspiratory efforts, and if a high level of NAVA would suppress EAdi without increasing lung-distending pressures. METHOD: In awake healthy subjects (n = 9), NAVA was applied at increasing levels in a stepwise fashion during quiet breathing and maximal inspirations. EAdi and airway pressure (Paw), esophageal pressure (Pes), and gastric pressure, flow, and volume were measured. RESULTS: During maximal inspirations with a high NAVA level, peak Paw was 37.1 +/- 11.0 cm H(2)O (mean +/- SD). This reduced Pes deflections from - 14.2 +/- 2.7 to 2.3 +/- 2.3 cm H(2)O (p < 0.001) and EAdi to 43 +/- 7% (p < 0.001), compared to maximal inspirations with no assist. At high NAVA levels, inspiratory capacity showed a modest increase of 11 +/- 11% (p = 0.024). CONCLUSION: In healthy subjects, NAVA can safely and efficiently unload the respiratory muscles during maximal inspiratory maneuvers, without failing to cycle-off ventilatory assist and without causing excessive lung distention. Despite maximal unloading of the diaphragm at high levels of NAVA, EAdi is still present and able to control the ventilator.     

COPD机械通气患者运用NAVA技术的研究进展

慢性阻塞性肺疾病(COPD)患者由于存在呼吸受限、呼吸困难、气短等现象,常需进行机械通气治疗,但长期进行机械通气治疗会导致患者对呼吸机产生依赖,造成脱机困难,并造成肺损伤等系列并发症,对治疗产生不良影响。因此,需要优化通气模式,减少因通气过度或不足造成的不良影响。NAVA作为一种新型机械通气模式,可以通过收集监测到的膈肌电信号(Edi)触发呼吸机功能,根据患者实际需求调整通气量,更好实现人机同步。本文通过对COPD机械通气患者运用NAVA技术的最新进展进行研究、总结,以期为后续提高临床机械通气治疗效果提供参考依据。     

Neurally adjusted ventilatory assist vs pressure support ventilation in infants recovering from severe acute respiratory distress syndrome: Nested study

Objective

Neurally adjusted ventilatory assist (NAVA) is a new ventilator modality with an innovative synchronization technique. Our aim is to verify if NAVA is feasible and safe in terms of physiological and clinical variables in infants recovering from severe acute respiratory distress syndrome (ARDS).

Design

This is a pilot nested study to help future trial design.

Setting

The study was performed in third-level academic pediatric intensive care units.

Patients

Infants affected by severe ARDS requiring high-frequency ventilation and weaned with NAVA during 2010 were included. Controls (2:1 ratio) were ARDS infants weaned with pressure support ventilation (PSV) during 2008-2009 matched for age, gas exchange impairment, and weight.

Main outcome measures

The main outcome measures were the physiological and ventilator parameters and the duration of ventilator support in PSV or NAVA.

Results

Ten infants treated with NAVA and 20 with PSV were studied. Heart rate (P < .001) and mean arterial pressure (P < .001) increased less during NAVA than during PSV. Similarly, Pao₂/Fio₂ ratio decreased less in NAVA than in PSV (P < .001). Neurally adjusted ventilatory assist also resulted in lower Paco₂ (P < .001) and peak pressure (P = .001), as well as higher minute ventilation (P = .013). COMFORT score (P = .004) and duration of support were lower in NAVA than in PSV (P = .011).

Conclusions

Neurally adjusted ventilatory assist is safe and suitable in infants recovering from severe ARDS. It could provide better results than PSV and is worth to be investigated in a multicenter randomized trial.