机械通气的撤离策略

机械通气的撤机过程只能是在通气负担可以忍受的情况下进行,理想的撤机负荷取决于肺部疾病的缓解和呼吸肌力的恢复。撤机过程可突然或逐渐撤离通气。突然撤离呼吸机大约占机械通气患者的75％,其余患者需逐渐撤机。撒机是指两个分开但又密切相关的过程,即脱机和撤离人工气道。     

撤机和撤机技术

机械通气作为一种极为重要的生命支持治疗手段,为原发疾病的治疗创造了条件和争取了时间。但当病因消除或得到控制时,自主呼吸恢复到一定水平后,应及时撤离机械通气,避免造成呼吸机依赖和减少机械通气相关并发症的发生。由于目前对呼吸机的撤离尚缺乏系统的认识以及对撤机过程的最佳方法缺少一个指导性方案,机械通气的撤离已成为临床上面临的重大挑战之一。现就呼吸机的撤离及其相关技术做一综述。     

机械通气的撤离和气管导管的拔除

1 机械通气撤离1.1 撤机指征 ①一般状况好转:准备撤机的患者一般状况应较稳定,神志清楚,精神状况良好,体温正常,呼吸、循环平稳,无新并发症发生。②呼吸功能改善:主要指标有:a.自主呼吸能力增强,表现为机械通气时辅助通气频率减少且以自主呼吸为主,自主呼吸频率<20次/min。b.咳嗽有力,自主     

肺性脑病行机械通气撤机的护理体会

目的 回顾性分析肺性脑病行机械通气撤机后的临床护理及其体会.方法 回顾性研究我院收住该类患者采取包括行机械通气的有效措施以及撤机后所采取的各种护理方法.结果 48例患者在撤机后有43例1次性成功撤机,陆续好转出院.未成功1次撤机的5例中有2例发生呼吸肌疲劳、2例并发呼吸机相关肺炎、1例出现撤机困难,经再次应用呼吸机治疗后有3例成功脱机,死亡2例.结论 有效的气道管理、正确的自主呼吸试验、早期营养支持、心理疏导、避免镇静剂及肌肉松弛剂的应用等综合处理是肺性脑病撤离呼吸机后的必要护理措施.     

机械通气困难撤机/延迟撤机的病理生理学因素与解决策略

随着有创机械通气在临床上的广泛使用,救治了大量的危重症患者,但也有较多使用有创通气的患者由于各种原因导致撤机困难,严重影响患者的预后和生活质量.该文将从机械通气困难撤机/延迟撤机的病理生理学角度,阐述临床上困难撤机/延迟撤机的相关要点,总结并提出对应的处理措施.     

床旁肺部超声膈肌功能评估脓毒性休克机械通气患者指导撤机

目的 研究床旁肺部超声膈肌功能评估脓毒性休克机械通气患者指导撤机的应用效果.方法 选取本院2018年9月-2019年9月收治的80例脓毒性休克机械通气患者,按照随机数表法将其分为对照组与观察组,每组40例,对照组应用浅快呼吸指数指导撤机,观察组应用床旁肺部超声膈肌功能评估指导撤机,对比两组患者的撤机成功率、机械通气时间以及并发症发生情况(再插管、肺部气压伤、呼吸机相关性肺炎).结果 观察组患者的撤机成功率(77.5%)高于对照组(62.5%),机械通气时间(6.3±1.6)d短于对照组(8.5±2.7)d,且并发症发生率(5.0%)低于对照组(20.0%),各组对比差异均有统计学意义(P<0.05).结论 床旁肺部超声膈肌功能评估脓毒性休克机械通气患者指导撤机的应用效果显著,可明显提高撤机成功率,缩短机械通气时间,且可降低并发症发生率,值得临床推行.     

长期机械通气患者应用指令频率通气模式撤机的临床效果

目的 探讨指令频率通气（mandatory rate ventilation，MRV）在机械通气患者撤机过程中的临床应用效果。方法 2004年1月至2006年1月ICU病房长期机械通气患者28例，随机分为两组，当患者病情平稳拟行撤机时，一组应用压力支持模式（PSV）进行撤机作为对照，另一组应用MRV模式进行撤机，记录分钟通气量、呼吸频率、撤机过程所用时间和撤机成功例数。结果 应用MRV模式撤机组和应用PSV模式撤机组比较，撤机过程中分钟通气量稳定（P＜0．05），呼吸频率明显减慢（P＜0．05），撤机过程用时明显缩短（P＜0．05），但撤机成功例数比较差异无统计学意义（P〉0．05）。结论 应用MRV模式进行撤机，患者舒适程度好，呼吸稳定，人一机协调性良好，撤机过程缩短，适合临床推广应用。     

机械通气的撤离

据报道，接受机械通气治疗患者用于撤机的时间约占整个机械通气过程的42％，慢性疾病患者撤机时间可能更长。研究表明因撤机不成功所致重新插管和上机使医院获得性肺炎的发生率增加约8倍，死亡率增加6～12倍，因此，对患者撤机的可能性进行准确评价并制定合理的撤机方案具有重要意义。     

呼吸机依赖患者撤机的护理

机械通气是抢救呼吸衰竭患者不可缺少的治疗技术。有很多患者，因反复进行机械通气而发生呼吸机依赖．担心撤机后会发生呼吸困难或窒息，因而增加了撤机的难度。由于不能及时撤机可以引起严重的并发症。我们对32例气管插管机械通气患者进行临床观察，同时对多例呼吸机依赖患者采取有效措施，在合理撤机的基础上加强监测、排痰、并发症预防、营养支持及心理指导收到满意效果。     

重症心脏超声在评估机械通气撤机失败中的研究现状

机械通气是重症患者重要的呼吸支持手段,机械通气时间延长或缩短均会对患者造成不利影响。因此,准确地评估及判定撤机时间是重症患者治疗过程中的重点及难点。撤机过程可引起心血管及呼吸系统的一系列病理生理变化:如胸内压显著下降、呼吸功增加、肾上腺素能激活、低氧血症、高碳酸血症等,它们被认为是撤机所致心原性肺水肿的主要机制。最新的一系列研究提示,患者的心功能可能是影响撤机成败的关键因素之一。重症心脏超声近年来在许多疾病中均得到了广泛的研究与应用。最新研究提示,重症心脏超声能够帮助预测撤机失败,并且诊断是否为心原性原因引起。因此,重症心脏超声可能能够为指导成功撤机提供新思路。     

Protocol-guided weaning: a key-issue in reducing the duration of mechanical ventilation

Summary The process of weaning, if poorly organized, adds additional time to the duration of mechanical ventilation. Recent prospective studies have shown that the implementation of a protocol-directed weaning leads to an earlier initiation of the weaning process and a significant reduction in the duration of mechanical ventilation. Both daily screening of the respiratory function and trials of spontaneous breathing are valuable tools that should be incorporated into a weaning protocol. Extubation of the ventilated patients as soon as their recovery and ability to spontaneously breath are documented should be encouraged, because there is sufficient evidence that 65–70% of ventilated patients can be successfully extubated after a trial of spontaneous breathing is attempted. A gradual withdrawal of mechanical ventilation can be attempted in patients failing spontaneous breathing trials. Two randomized studies have found that the strategy used to discontinue mechanical ventilation influences the rate and degree of weaning success and that SIMV is the least efficient technique of weaning. Eingegangen: 6. Oktober 1998 Akzeptiert: 18. November 1998     

三种不同脱机方式在慢性阻塞性肺疾病急性加重期中的应用研究

目的：比较程序化脱机法、智能化脱机法和经验性脱机法三种脱机方式在慢性阻塞性肺疾病急性加重期（ AECOPD）患者脱机过程中的优劣。方法选取96例行有创机械通气的AECOPD患者,进行随机对照试验。结果程序组和智能组有创机械通气（ MV）时间、ICU住院时间均明显短于经验组,差异有统计学意义（P均＜0.01）。三组呼吸机相关肺炎（VAP）的发生率分别为18.8％、25.0％、46.9％,差异有统计学意义（ P＜0.05）。但三组住院病死率、脱机成功率和48 h再插管率差异无统计学意义（ P均＞0.05）。结论程序化脱机法和智能化脱机法与经验性脱机法比较,均可减少MV时间和ICU住院时间,并明显降低VAP的发生率。     

智能脱机模式在机械通气脱机阶段的应用

脱机是从完全通气支持向自主呼吸转变的一个过程,不同的通气技术被用于患者的脱机,常用的脱机方法包括T型管自主呼吸实验、同步间歇指令通气（SIMV）以及压力支持通气（PSV）。它们各有优缺点。新的通气模式开始应用到机械通气的脱机阶段,它们包括适应性支持通气（ASV）模式、Automode模式、分钟指令通气模式（MMV）和Smartcare模式等。它们减轻了医务人员的工作负担,提高了脱机的效率。     

Protocol-guided weaning: a key-issue in reducing the duration of mechanical ventilation

The process of weaning, if poorly organized, adds additional time to the duration of mechanical ventilation. Recent prospective studies have shown that the implementation of a protocol-directed weaning leads to an earlier initiation of the weaning process and a significant reduction in the duration of mechanical ventilation. Both daily screening of the respiratory function and trials of spontaneous breathing are valuable tools that should be incorporated into a weaning protocol. Extubation of the ventilated patients as soon as their recovery and ability to spontaneously breath are documented should be encouraged, because there is sufficient evidence that 65–70% of ventilated patients can be successfully extubated after a trial of spontaneous breathing is attempted. A gradual withdrawal of mechanical ventilation can be attempted in patients failing spontaneous breathing trials. Two randomized studies have found that the strategy used to discontinue mechanical ventilation influences the rate and degree of weaning success and that SIMV is the least efficient technique of weaning.     

A prospective, controlled trial of a protocol-based strategy to discontinue mechanical ventilation

Weaning protocols can improve outcomes, but their efficacy may vary with patient and staff characteristics. In this prospective, controlled trial, we compared protocol-based weaning to usual, physician-directed weaning in a closed medical intensive care unit (ICU) with high physician staffing levels and structured, system-based rounds. Adult patients requiring mechanical ventilation for more than 24 hours were assigned to usual care (UC) or protocol weaning based on their hospital identification number. Patients assigned to UC (n=145) were managed at their physicians' discretion. Patients assigned to protocol (n=154) underwent daily screening and a spontaneous breathing trial by respiratory and nursing staff without physician intervention. There were no significant baseline differences in patient characteristics between groups. The proportion of patients (protocol vs. UC) who successfully discontinued mechanical ventilation (74.7% vs. 75.2%, p=0.92), duration of mechanical ventilation (median [interquartile range]: 60.4 hours [28.6-167.0 hours] vs. 68.0 hours [27.1-169.3 hours], p=0.61), ICU (25.3% vs. 28.3%) and hospital mortality (36.4% vs. 33.1%), ICU length of stay (115 vs. 146 hours), and rates of reinstituting mechanical ventilation (10.3% vs. 9.0%) was similar. We conclude that protocol-directed weaning may be unnecessary in a closed ICU with generous physician staffing and structured rounds.     

慢性阻塞性肺疾病呼吸衰竭机械通气脱机策略

目的 探讨COPD呼吸衰竭有创机械通气脱机策略.方法 机械通气治疗COPD呼吸衰竭108例,分析治疗结果.结果 106例患者成功脱机、拔管,抢救成功率达98％.结论 采取恰当有创机械通气脱机策略,有较高抢救成功率.     

Effectiveness and safety of a protocolized mechanical ventilation and weaning strategy of COPD patients by respiratory therapists

Introduction

Prior researches have showed that weaning protocols may decrease the duration of mechanical ventilation. The effect of these protocols on chronic obstructive pulmonary disease (COPD) patients is unknown. The purpose of this study was to evaluate the impact of an extensive mechanical ventilation protocol including weaning applied by a respiratory therapist (RT) on the duration of mechanical ventilation and intensive care unit (ICU) stay in COPD patients.

Materials and methods

A novel mechanical ventilation protocol including weaning was developed and initiated for all intubated COPD patients by a respiratory therapist. Outcomes of patients treated using this protocol during a 6-month period were compared to those of patients treated by physicians without a protocol during the preceding 6 months.

Results

A total of 170 patients were enrolled. Extubation success was significantly higher (98% vs. 78%, P=0.014) and median durations of weaning, mechanical ventilation and ICU stay compared with time to event analysis were significantly shorter in the protocol based group (2 vs. 26 hours, log rank P<0.001, 3.1 vs. 5 days, log rank P<0.001 and 6 vs. 12 days, log rank P<0.001, respectively). Patients who were successfully extubated and patients in the protocol based group were more likely to have shorter ventilation duration [HR: 1.87, 95% confidence intervals (CI): 1.13-3.08, P=0.015 and HR: 2.08, 95% CI: 1.40-3.10, P<0.001 respectively].

Conclusions

In our center, a protocolized mechanical ventilation and weaning strategy improved weaning success and shortened the total duration of mechanical ventilation and ICU stay in COPD patients requiring mechanical ventilation.     

机械通气撤离的预测指标

机械通气的撤离包括脱机和拔管两个部分。成功脱机并拔管可以减少机械通气带来的副作用、缩短住院时间、降低医疗费用。但如果拔管失败，则会增加患者的死亡率，延长住院时间。因此有必要选择合适的指标，提高预测脱机、拔管的准确率。脱机和拔管指标包括呼吸力学指标和自主呼吸试验，它们可以单独使用，也可以多个指标结合在一起使用。     

Respiratory failure and mechanical ventilation: Pathophysiology and methods of promoting weaning

Respiratory failure may be manifested either by impaired gas exchange or by impaired ventilatory function. The latter results in more severe problems in weaning patients from mechanical ventilation. Ventilatory failure may result from inadequate respiratory drive, excessive respiratory workload, inadequate respiratory muscle endurance, or a combination of these factors. Simple bedside tests of ventilatory function are useful for evaluating the severity of respiratory failure and the potential for successful weaning. However, even when the results are discouraging, properly monitored weaning attempts may be successful. Although there are no convincing data to prove the superiority of either the T-piece weaning method or intermittent mandatory ventilation, we prefer to use the T-piece, and describe here a comprehensive approach to weaning the difficult patient. New approaches that have been developed to help wean difficult patients include continuous positive airway pressure breathing (CPAP), pharmacologic interventions (aminophylline and others), nutritional supplementation, inspiratory muscle resistive training, psychiatric interventions, and chronic mechanical ventilation.