体外膈肌起搏对老年神经调节辅助通气患者预后的改善作用

目的探讨体外膈肌起搏（external diaphragm pacemaker, EDP）对老年神经调节辅助通气（neurally adjusted ventilatory assist, NAVA）患者预后的改善作用。 方法选择2017年1月至2019年6月浙江医院收治的60例老年机械通气患者,采用随机数字表法分为NAVA组（25例）和NAVA+EDP组（35例）。NAVA组患者给予常规治疗,NAVA+EDP组患者在常规治疗的基础上增加EDP,两组患者均符合脱机程序并应用NAVA模式进行脱机。观察比较两组患者入组时和撤机时的呼吸力学指标、膈肌活动度（diaphragm excursion, DE）、膈肌增厚分数（diaphragm thickening fraction, DTF）,以及机械通气时间和14 d撤机成功率。组间计量资料的比较采用t检验,计数资料的比较采用χ²检验。 结果两组患者入组时的呼吸力学指标及DE、DTF的差异均无统计学意义（t=0.505、0.026、0.506、1.203、0.561、0.979,P>0.05）。撤机时,两组患者呼吸力学指标均较入组时显著降低（t=20.560、13.389、20.206、8.237,12.488、8.961、12.478、4.919;P<0.01）、DE和DTF均较入组时显著增高（t=23.839、16.982,10.336、8.688;P<0.01）;而且与NAVA患者组比较,NAVA+EDP患者组呼吸力学指标均明显降低（t=12.488、8.961、12.478、4.919,P<0.05）、DE和DTF均显著增高（t=9.943、5.919,P<0.01）。NAVA+EDP组患者机械通气时间显著短于NAVA组、14 d撤机成功率明显高于NAVA组,差异均有统计学意义（t=4.033,χ²=5.350;P<0.05或0.01）。 结论对于采用NAVA模式的老年机械通气患者,EDP能一定程度改善肺功能和膈肌功能,从而改善预后。     

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.     

神经电活动辅助通气对急性呼吸窘迫综合征患者人机同步性的影响

目的 观察神经电活动辅助通气(NAVA)对急性呼吸窘迫综合征(ARDS)患者人机同步性的影响.方法 以2008年1月至6月入住东南大学附属中大医院ICU 18例ARDS机械通气患者为研究对象,按随机数字表法选择NAVA或压力支持通气(PSV)模式进行通气,通气支持水平分4步递增.PSV压力支持水平从5 cm H2O(1 cm H2O=0.098 kPa)开始,每5 min增加5 cm H2O,分别为5、10、15、20 cm H2O.NAVA支持水平每5 min增加0.2～1.0 cm H2O/μY,使NAVA中通气支持水平分别与PSV 4个压力支持水平相当,观察不同支持条件下(PSV1～PsV4及NAVA1～NAVA4)人机同步性、呼吸肌负荷、血流动力学以及呼吸力学等指标.结果 (1)吸气触发:①触发延迟时间:随着支持水平增加,PSV中触发延迟时间明显延长(P<0.05),而应用NAVA通气时触发延迟时间无明显延长.与相同支持水平的PSV比较,应用NAVA的触发延迟时间均明显缩短(P<0.05).②无效触发:随着PSV支持水平增加,无效触发明显增加,PSV1时无效触发2.3%,PSV4时无效触发为22%(P<0.05).应用NAVA时,不同支持水平下,均未见无效触发.(2)吸/呼气转换:随着支持水平增加,PSV中吸/呼气转换延迟时间明显延长(P<0.05),而应用NAVA通气时吸/呼气转换延迟时间无明显延长.与相同支持水平的PSV比较.应用NAVA时吸/呼气转换延迟时间均明显缩短(P<0.05).(3)通气支持幅度(潮气量):PSV1和NAVA1的潮气量分别为(361±121)ml和(361±69)ml,差异无统计学意义.但NAVA3和NAVA4时的潮气量分别为(417±71)ml和(427±80)ml,明显低于PSV3和PSV4时的潮气量[分别为(604 ±141)ml和(675±108)ml,均P<0.05].(4)呼吸肌负荷:随着支持水平增加,应用NAVA和PSV通气的膈肌电活动幅度、食管压力时间乘积均逐渐降低(P<0.05).在相同支持水平时,两绢比较差异无统计学意义.结论 与PSV相比,NAVA通气支持时间、通气支持水平与自身呼吸形式更加匹;配,应用NAVA更能改善ARDS患者人机同步性.     

神经电活动辅助通气:一种新的机械通气模式

机械通气是呼吸衰竭患者重要的支持手段,但传统的机械通气存在明显人机不同步,可能导致机械通气时间延长、呼吸机相关肺损伤等相关并发症.神经电活动辅助通气,通过监测膈肌电活动.根据自身吸气驱动,成比例地持续辅助通气.目前研究表明神经电活动辅助通气明显改善有创及无创机械通气人机同步性;减轻呼吸肌肉负载;能自动调节通气支持水平,具有一定的肺保护作用;利用膈肌电活动,发挥独特的监测功能.     

神经调节辅助通气对急性呼吸窘迫综合征兔呼吸机相关性膈肌功能障碍的影响

目的 探讨神经调节辅助通气(NAVA)对ARDS呼吸机相关性膈肌功能障碍(VIDD)的预防作用.方法 将20只成年新西兰大白兔按随机数字表法分为对照组、容量控制通气组(VC组)、压力支持通气组(PSV组)和NAVA通气组(NAVA组),每组5只.VC、PSV及NAVA组在机械通气4 h后取膈肌标本,对照组麻醉后立即取膈肌标本.测定各组膈肌中丙二醛、超氧化物歧化酶(SOD)以及还原型谷胱甘肽(GSH)含量,观察各组膈肌纤维病理结构的改变.结果 (1)丙二醛:NAVA组膈肌中丙二醛含量为(0.28±0.19)nmol/mg,与对照组的(0.15±0.06)nmol/mg、PSV组的(0.30±0.11)nmol/mg比较,差异无统计学意义(F=2.730,P＞0.05);VC组膈肌中丙二醛含量为(0.40±0.16)nmol/mg,明显高于对照组(P＜0.05).(2)SOD:NAVA组膈肌中SOD含量为(94±9)U/mg,与对照组的(111±12)U/mg、PSV组的(93±4)U/mg比较,差异无统计学意义(F=4.422,P＞0.05);VC组膈肌中SOD含量为(80±21)U/mg,明显低于对照组(P＜0.05).(3)GSH:NAVA组膈肌中丙二醛含量为(5.6±1.0)mg/g,与对照组的(5.3±1.0)mg/g、PSV组的(4.5±1.2)mg/g比较,差异无统计学意义(F=3.001,P＞0.05);VC组膈肌中GSH含量为(3.3±1.7)mg/g,明显低于对照组(P＜0.05).(4)光镜观察:VC组出现肌纤维变性、坏死,部分肌纤维萎缩;NAVA、PSV组以及对照组肌纤维形态基本正常.(5)电镜观察:VC组肌原纤维断裂,线粒体肿胀;NAVA组、PSV组以及对照组超微结构无明显异常.(6)膈肌纤维横截面积:NAVA组平均肌纤维横截面积(像素)为2573±278,与对照组的3070+175、PSV组的2508±670比较,差异无统计学意义(F=1.775,P＞0.05);VC组Ⅱ型肌纤维横截面积为2210±971,明显低于对照组的3477±187(P＜0.05).结论 与控制通气相比较,NAVA可减轻ARDS膈肌氧化应激、膈肌萎缩和膈肌结构损伤,NAVA较控制通气更能预防VIDD.

Abstract：

Objective To evaluate the effect of neurally adjusted ventilatory assist (NAVA) on prevention of ventilator-induced diaphragmatic dysfunction (VIDD) in ARDS rabbits.Methods Twenty New Zealand white rabbits were randomly divided into 4 groups: ( 1 ) control group ( n = 5 ); ( 2 ) Volume control (VC) group ( n = 5 ); ( 3 ) Pressure support ( PSV ) group ( n = 5 ); (4) NAVA group ( n = 5 ).In VC, PSV and NAVA groups, the rabbits were killed and the diaphragm was removed after 4 hours of ventilation.Animals in the control group were not mechanically ventilated, and the diaphragm was also removed immediately after anesthetizing.In all rabbits, malondialdehyde ( MDA), superoxide disrmutase (SOD) and glutathione(GSH) of diaphragm were measured.Structure of diaphragm was observed by light microscope, electron microscope, constituent ratio and mean cross-sectional area (CSA) of diaphragm fiber.Results (1)MDA: Compared with the control [(0.15 ±0.06)nmol/mg], PSV group[(0.30 ±0.11)nmol/mg], there was no significant difference in MDA of diaphragm in NAVA group [( 0.28 ± 0.19 )nmol/mg] (F = 2.730, P ＞ 0.05).MDA in VC group [(0.40 ±0.16)nmol/mg] was significantly higher than the control group (P＜0.05).(2) SOD: Compared with control [( 111 ± 12) U/mg], PSV group [(93 ± 4) U/mg], there was no significant difference in SOD of diaphragm in NAVA group [( 94 ± 9 )U/mg] (F=4.422,P ＞0.05).SOD in VC group [(80 ±21 )U/mg] was significantly lower than the control group(P ＜0.05).(3)GSH: Compared with control [(5.3 ± 1.0)mg/g] and PSV group [(4.5 ±1.2)mg/g], there was no significant difference in GSH of diaphragm in NAVA group [(5.6 ± 1.0) mg/g](F =3.001 ,P ＞ 0.05 ).GSH in VC group [(3.3 ± 1.7)mg/g] is significantly lower than control and NAVA groups ( P ＜ 0.05 ).( 4 ) Light microscope: In VC group, many changes were observed in the muscle, such as myofibrosis, necrosis, and some of muscle fibers became atrophy, but these were no obvious changes of pathological structure in control, PSV or NAVA groups.(5)Electron microscope: In control, PSV and NAVA groups, the ultrastructure of diaphragm was normal Different from the above 3 groups, some abnormal ultrastructure was observed in VC group, including disrupted myofibrils, swollen mitochondria.(6)CSA of diaphragm fiber: Compared with control and PSV group, there was no significant difference in CSA of diaphragm fiber in NAVA group ( P ＞ 0.05 ); The CSA of type Ⅱ fibers in VC group was markedly lower than control group ( P ＜ 0.05 ) .Conclusions Compared with volume control ventilation, NAVA may mitigate diaphragmatic oxidative stress, atrophy and injury, and prevent VIDD better than VC.     

神经调节辅助通气对急性呼吸窘迫综合征兔呼吸机相关性膈肌功能障碍的影响

Objective To evaluate the effect of neurally adjusted ventilatory assist (NAVA) on prevention of ventilator-induced diaphragmatic dysfunction (VIDD) in ARDS rabbits.Methods Twenty New Zealand white rabbits were randomly divided into 4 groups: ( 1 ) control group ( n = 5 ); ( 2 ) Volume control (VC) group ( n = 5 ); ( 3 ) Pressure support ( PSV ) group ( n = 5 ); (4) NAVA group ( n = 5 ).In VC, PSV and NAVA groups, the rabbits were killed and the diaphragm was removed after 4 hours of ventilation.Animals in the control group were not mechanically ventilated, and the diaphragm was also removed immediately after anesthetizing.In all rabbits, malondialdehyde ( MDA), superoxide disrmutase (SOD) and glutathione(GSH) of diaphragm were measured.Structure of diaphragm was observed by light microscope, electron microscope, constituent ratio and mean cross-sectional area (CSA) of diaphragm fiber.Results (1)MDA: Compared with the control [(0.15 ±0.06)nmol/mg], PSV group[(0.30 ±0.11)nmol/mg], there was no significant difference in MDA of diaphragm in NAVA group [( 0.28 ± 0.19 )nmol/mg] (F = 2.730, P ＞ 0.05).MDA in VC group [(0.40 ±0.16)nmol/mg] was significantly higher than the control group (P＜0.05).(2) SOD: Compared with control [( 111 ± 12) U/mg], PSV group [(93 ± 4) U/mg], there was no significant difference in SOD of diaphragm in NAVA group [( 94 ± 9 )U/mg] (F=4.422,P ＞0.05).SOD in VC group [(80 ±21 )U/mg] was significantly lower than the control group(P ＜0.05).(3)GSH: Compared with control [(5.3 ± 1.0)mg/g] and PSV group [(4.5 ±1.2)mg/g], there was no significant difference in GSH of diaphragm in NAVA group [(5.6 ± 1.0) mg/g](F =3.001 ,P ＞ 0.05 ).GSH in VC group [(3.3 ± 1.7)mg/g] is significantly lower than control and NAVA groups ( P ＜ 0.05 ).( 4 ) Light microscope: In VC group, many changes were observed in the muscle, such as myofibrosis, necrosis, and some of muscle fibers became atrophy, but these were no obvious changes of pathological structure in control, PSV or NAVA groups.(5)Electron microscope: In control, PSV and NAVA groups, the ultrastructure of diaphragm was normal Different from the above 3 groups, some abnormal ultrastructure was observed in VC group, including disrupted myofibrils, swollen mitochondria.(6)CSA of diaphragm fiber: Compared with control and PSV group, there was no significant difference in CSA of diaphragm fiber in NAVA group ( P ＞ 0.05 ); The CSA of type Ⅱ fibers in VC group was markedly lower than control group ( P ＜ 0.05 ) .Conclusions Compared with volume control ventilation, NAVA may mitigate diaphragmatic oxidative stress, atrophy and injury, and prevent VIDD better than VC.     

Effect of neurally adjusted ventilatory assist on trigger of mechanical ventilation in acute exacerbation of chronic obstructive pulmonary disease patients with intrinsic positive end-expiratory pressure

<正>Objective To compare the trigger delay and work of trigger between neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) in acute exacerbation of chronic obstructive pulmonary disease(AECOPD) patients with intrinsic positive end-expiratory pressure (PEEP) during mechanical ventilation.     

解读神经调节通气辅助模式

神经调节通气辅助模式(NAVA)是利用膈肌电活动(Ed i)控制呼吸机送气的全新通气模式。在NAVA模式下,呼吸中枢可以直接控制呼吸机的辅助水平,呼吸机变成了"呼吸肌"。目前研究表明,NA-VA可实现个体化的通气支持,极大地改善人机协调性,有效减轻呼吸中枢负荷,并能防止肺过度膨胀。