Sporn P H, Morganroth M L
Department of Internal Medicine, University of Michigan, Ann Arbor.
Clin Chest Med. 1988 Mar;9(1):113-26.
The vast majority of patients who undergo mechanical ventilation are able to discontinue ventilatory assistance within a few days. Typically, patients who require only short-term mechanical ventilation do not have severe underlying lung disease, and the problem for which they require ventilatory support is most commonly rapidly reversible. In these patients on short-term ventilatory support, parameters of spontaneous ventilatory requirements and respiratory muscle strength, including minute ventilation, maximal voluntary ventilation, vital capacity, and maximal inspiratory pressure, are useful in predicting the success of discontinuation of mechanical ventilation. Ventilatory support can generally be discontinued by a variety of techniques in these patients without the need for weaning from the ventilator per se. The smaller group of patients in whom it is not possible to discontinue mechanical ventilation within less than 7 days comprises individuals who frequently have severe acute or chronic lung disease, multisystem extrapulmonary disease, or neuromuscular disease. After a period of prolonged mechanical ventilatory support, these complicated patients require a process of progressive weaning in which they gradually become able to support spontaneous ventilation. Spontaneous ventilatory parameters do not correlate well with weaning ability in patients on long-term ventilatory support. A systematic and comprehensive approach in which attention is focused on optimizing pulmonary and nonpulmonary factors that affect the weaning process provides the best chance for successful withdrawal of ventilatory support after long-term mechanical ventilation. Inadequate ventilatory drive, respiratory muscle weakness and fatigue, increased work of breathing, excessive CO2 production, and cardiac failure are potential mechanisms that may play a role in inhibiting successful weaning. Adverse factors relevant to each of these mechanisms must be addressed and corrected to whatever extent possible. Studies have not demonstrated the superiority of either classic T-piece weaning or IMV weaning methods in difficult-to-wean patients on long-term ventilatory support. Both techniques may be used successfully as long as all patient variables that may adversely affect weaning ability are corrected or optimized and close care and attention to the details of the weaning process itself are provided.(ABSTRACT TRUNCATED AT 400 WORDS)
绝大多数接受机械通气的患者能够在数天内停止通气支持。通常，仅需要短期机械通气的患者没有严重的基础肺部疾病，他们需要通气支持的问题最常见的是可迅速逆转的。对于这些接受短期通气支持的患者，包括分钟通气量、最大自主通气量、肺活量和最大吸气压力在内的自主通气需求和呼吸肌力量参数，有助于预测机械通气撤机的成功与否。在这些患者中，一般可通过多种技术停止通气支持，而无需进行本身的撤机过程。在不到7天内无法停止机械通气的较小患者群体包括经常患有严重急性或慢性肺部疾病、多系统肺外疾病或神经肌肉疾病的个体。经过一段长时间的机械通气支持后，这些复杂患者需要一个逐步撤机的过程，在此过程中他们逐渐能够支持自主通气。对于长期接受通气支持的患者，自主通气参数与撤机能力的相关性不佳。一种系统且全面的方法，即将注意力集中在优化影响撤机过程的肺部和非肺部因素上，为长期机械通气后成功撤掉通气支持提供了最佳机会。通气驱动不足、呼吸肌无力和疲劳、呼吸功增加、二氧化碳产生过多以及心力衰竭是可能在抑制成功撤机中起作用的潜在机制。必须尽可能解决并纠正与这些机制中的每一个相关的不利因素。研究尚未证明在长期通气支持的难撤机患者中，经典的T形管撤机或间歇指令通气撤机方法具有优越性。只要所有可能对撤机能力产生不利影响的患者变量得到纠正或优化，并对撤机过程本身的细节给予密切关注和照料，这两种技术都可以成功使用。（摘要截短为400字）
