Abstract: Background　As a common complication of clinical mechanical ventilation patients，difficulty weaning could seriously affect patients' prognosis and quality of life. Although corresponding measures have been taken clinically，the weaning strategy for patients with dysfunctional ventilatory weaning response（DVWR）is still unknown.Objective　To explore the application effect of invasive to noninvasive mechanical ventilation step-down therapy strategy in ventilator dependent patients with tracheotomy.Methods　From November 2017 to August 2018，60 patients in the Respiratory Intensive Care Unit，Henan Provincial People's Hospital were selected. All of them received a step-down therapy：the noninvasive positive pressure ventilator was linked with the split humidifier，single breathing tube，the P-V platform valve，the extension tube and the endotracheal tube，and a leaky single breathing loop was formed for conducting invasive-to-noninvasive ventilation. Two patients withdrew for personal reasons. The heart rate，respiratory rate，systolic blood pressure（SBP），diastolic blood pressure（DBP），finger pulse oxygen saturation（SpO2），pH，arterial carbon dioxide partial pressure（PaCO2），arterial oxygen partial pressure（PaO2），bicarbonate ion（HCO3-），base excess（BE），and sputum viscosity 1 hour prior to the step-down therapy and 2，and 24 hours posterior to the therapy were recorded and compared. Post-therapy RICU and outcome were collected and analyzed.Results　Heart rate and respiratory rate increased significantly after 2 hours of the step-down therapy（P<0.05）. Heart rate decreased more significantly after 24 hours of the therapy（P<0.05）. PaCO2 increased significantly after 2 hours of the therapy（P<0.05）. PaO2 showed a significant decrease after 2 hours of the therapy，but demonstrated a more significant increase after 24 hours of the therapy（P<0.05）. The sputum viscosity showed no significant changes during the period of pre- and post-therapy（χ2trend=2.36，P=0.670）. The average post-therapy RICU stay was（15.6±4.3）days. All patients received a 24-week follow-up，during which 28（48.2%）had successful weaning with tracheal extubation and closure of tracheotomy incision，15（25.9%）weaning from MV and switched to warmed humidified oxygen inhalation through the tracheotomy incision，12（20.7%）switched to noninvasive positive pressure ventilation and transferred to the general ward，rehabilitation hospital or home，and 3（5.2%）died in the RICU due to infection. 4 out of the 28 extubated patients（14.3%）underwent tracheotomy again due to sputum problems. 2 out of 15（13.3%）weaning patients from MV with retained oxygen therapy delivered through a tracheostomy were retreated with noninvasive ventilation. By the end of follow-up，no obvious discomfort and intolerance occurred .Conclusion　The invasive to noninvasive mechanical ventilation step-down therapy strategy can improve the successful rates of ventilation withdrawal and the quality of life of DVWR patients with tracheotomy，and can be used as a safe alternative to invasive mechanical ventilation.

Key words: Ventilators, negative-pressure；Respiratory insufficiency；Respiratory failure；Dysfunctional ventilatory weaning response；Noninvasive bi level positive pressure ventilation；Step-down therapy；Artificial airway

摘要： 背景　撤机困难作为临床机械通气患者常见并发症，严重影响患者预后与生活质量，虽临床已采取相应措施，但针对撤机失败呼吸机依赖（DVWR）患者的撤机策略仍在探索。目的　探讨有创-无创机械通气降级治疗策略在DVWR患者中的应用效果。方法　选择2017年11月—2018年8月河南省人民医院呼吸重症监护病房（RICU）患者60例为研究对象，将无创正压呼吸机经分体式湿化器与单呼吸管道、P-V平台漏气阀、延长管和人工气道导管直接连接，形成漏气的单呼吸环路，进行有创-无创机械通气降级治疗，其中2例患者因个人原因退出。记录改用无创机械通气降级治疗前1 h和降级治疗后2 h、24 h时患者的心率、呼吸频率、收缩压（SBP）、舒张压（DBP）、指脉氧饱和度（SpO2）、pH值、动脉二氧化碳分压（PaCO2）、动脉氧分压（PaO2）、碳酸氢根离子（HCO3-）、剩余碱（BE）、痰液黏稠度等情况以及患者无创机械通气降级治疗后RICU住院时间及转归情况，并比较降级治疗前后相关指标有无差异。结果　降级治疗后2 h心率、呼吸频率大于降级治疗前1 h，降级治疗后2 h心率大于降级治疗后24 h（P<0.05）。降级治疗前1 h PaCO2水平低于降级治疗后2 h，PaO2水平高于降级治疗后2 h，降级治疗后2 h PaO2水平低于降级治疗后24 h（P<0.05）。患者痰液黏稠度分级不随降级治疗前后时间变化而变化，差异均无统计学意义（χ2趋势=2.36，P=0.670）。降级治疗后患者RICU平均住院时间为（15.6±4.3）d，观察随访58例患者24周后，28例（48.2%）患者撤机并拔出气管导管，封闭气管切口；15例（25.9%）患者撤机改为经气管切开处加温湿化吸氧；12例（20.7%）患者自配无创正压呼吸机，转入普通病房、康复医院及家庭继续实施降级治疗；3例（5.2%）患者在RICU因感染死亡。其中28例拔管患者中有4例（14.3%）因痰液问题再次行气管切开，15例撤机保留气管切开氧疗患者中2例（13.3%）中途再次应用无创呼吸机治疗。随访截止时，采用降级治疗患者均无明显不适和不耐受现象。结论　有创-无创机械通气降级治疗策略可有效提高气管切开DVWR患者的撤机成功率及生活质量，可作为有创机械通气的一种安全替代方案。

关键词: 通气机, 负压, 呼吸功能不全, 呼吸衰竭, 呼吸机依赖, 无创正压机械通气, 降级治疗, 人工气道