心外科术后长期机械通气失败的原因分析

Analysis of factors related to weaning failure of prolonged mechanical ventilation after cardiac surgery

目的:分析心外科术后长期机械通气(prolonged mechanical ventilation, PMV)的原因及相应的干预方法。方法:以心外科术后机械通气时间超过7 d的40例气管切开患者为研究对象,床旁心超评估左心及右心功能,用超声和CT评估肺部渗出情况,膈肌超声评估膈肌功能,并进行针对性处理及康复锻炼。定期评估患者是否能脱机,并分析患者脱机成功及失败的原因。结果: 8例患者存在单纯心功能不全,20例存在呼吸功能不全,2例存在膈肌功能不全,5例患者同时存在心肺功能不全,2例存在心脏和膈肌功能不全,3例存在呼吸和膈肌功能不全。最终24例患者脱机成功并转出监护室,16例患者脱机失败。心功能不全患者脱机失败率达80%;膈肌功能不全患者脱机失败率为28.5%;呼吸功能不全患者脱机失败率为20%。对影响脱机的原因进行单因素和多因素分析,发现心功能不全是导致脱机失败的独立危险因素(OR=3.431, 95%CI 1.083~ 10.867 , P = 0.036 );初始存在呼吸功能不全者最终脱机失败率较低(OR=0.039, 95%CI 0.001~0.751, P =0.003);膈肌功能不全不影响最终的脱机结局。结论:心功能不全是导致心外科术后PMV患者脱机失败的主要原因。

Objective: To analyze factors related to weaning failure of prolonged mechanical ventilation (PMV) and corresponding intervention methods. Methods: The subjects included 40 patients who had undergone cardiac surgery and tracheotomy with PMV over 7 days. Cardiac function was assessed by echocardiography, pleural effusion and lung aeration were assessed by ultrasonography and computed tomography (CT), diaphragmatic function was assessed by diaphragm ultrasound. The rehabilitation exercise was performed. The readiness of weaning was evaluated regularly and the reasons for success or failure were analyzed. Results: Among the 40 patients, 8, 20, and 2 patients had cardiac dysfunction, respiratory dysfunction, and diaphragmatic dysfunction, respectively. Five patients had both cardiac and respiratory dysfunctions, 2 patients had both cardiac and diaphragmatic dysfunctions, and 3 patients had both respiratory and diaphragmatic dysfunctions. Among the 40 patients, 24 patients had weaning success and 16 had weaning failure. Cardiac dysfunction led to 80% of weaning failure, diaphragmatic dysfunction led to 28.5% of weaning failure, and respiratory dysfunction led to 20% of weaning failure. Univariate and multivariate analysis revealed that cardiac dysfunction was the risk factor that led to weaning failure (OR= 3.431 , 95%CI 1.083-10.867, P =0.036). PMV patients with initial respiratory insufficiency had lower failure rate (OR= 0.039 , 95%CI 0.001-0.751, P =0.003). PMV patients with diaphragmatic dysfunction did not affect the weaning outcome. Conclusions: Cardiac dysfunction may be the leading cause for weaning failure in cardiac surgical patients.