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

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