[论文解读] Splitting one ventilator for multiple patients -- a technical assessment

T Martinsen, C Tronstad+7 more|arXiv (Cornell University)|Mar 27, 2020

Respiratory Support and Mechanisms参考文献 5被引用 13

一句话总结

本技术评估研究了在重症护理高峰期（如新冠疫情）期间，将一台机械通气机拆分以支持多名患者的技术可行性。通过使用具有不同顺应性和阻力的模拟肺，研究显示在容量控制通气模式下，患者之间潮气量存在显著差异，表明在缺乏先进控制系统的情况下，该方法存在较高风险且可靠性有限。

ABSTRACT

Due to the recent coronavirus outbreak, many efforts and innovative solutions have surfaced to deal with the possible shortage of ventilators upon catastrophic surges of patients. One solution involves splitting one ventilator to treat multiple patients and is in principle easy to implement, but there are obvious risks, and little is known on how the technique would work on patients with ARDS from Covid-19. Previous studies have shown that multiple test lungs of equal characteristics can be successfully ventilated from one machine, but that large variations in tidal volume delivery occurs when lungs with different compliance are connected. In contribution to the discussion of the feasibility of the technique, a technical assessment was done including experiments expanding on the previous studies using two types of test lungs, different ventilator settings and test lung characteristics. Using two test lungs connected to a ventilator, the tidal volumes and pressures into both lungs were measured for different combinations of lung compliance, airway resistances, modes of ventilation, inspiratory and end-expiratory pressure levels. We found discrepancies in delivered tidal volumes for paired test lungs proportional with compliance differences, little influence from differences in airway resistances, and that changes in compliance of only one test lung would also change the tidal volume delivered to the other test lung when in volume controlled mode. For one of the test lung types, we also found that higher PEEP settings could strongly influence the tidal volume balance between the test lungs. From this study and from a technical point of view, we were not able to identify reliable settings, adjustments or any simple measures to overcome the hazards of this simple technique, and a more advanced solution is indicated for mitigating risks.

研究动机与目标

• 评估在重症护理高峰期使用一台通气机支持多名患者的技术可行性。
• 研究肺顺应性和气道阻力差异对双肺模型中潮气量分布的影响。
• 评估不同通气模式和呼气末正压（PEEP）水平对患者间通气平衡的影响。
• 确定是否可通过简单调整在通气机拆分设置中可靠地均衡潮气量。
• 识别出在缺乏先进控制机制时，阻碍安全实施的技术限制和风险。

提出的方法

• 使用具有不同顺应性和阻力特性的两个模拟肺进行实验。
• 将一台机械通气机并联连接至两个模拟肺，以模拟多患者通气。
• 在不同通气机设置下（包括容量控制和压力控制模式），测量每个肺的潮气量和气道压力。
• 测试不同水平的呼气末正压（PEEP），以评估其对潮气量分布的影响。
• 分析在容量控制模式下，一个肺顺应性变化对另一肺潮气量输送的影响。
• 收集多种肺顺应性、阻力、PEEP水平和通气模式组合下的数据，以评估系统稳定性和不平衡性。

实验结果

研究问题

• RQ1 当两名患者的肺顺应性不同时，一台通气机能否可靠地向两人输送均衡的潮气量？
• RQ2 患者之间气道阻力的差异如何影响通气机拆分时的潮气量分布？
• RQ3 在双患者通气机设置中，改变PEEP水平在多大程度上影响潮气量不平衡？
• RQ4 在容量控制模式下，改变一名患者肺顺应性是否会影响另一名患者所获得的潮气量？
• RQ5 是否存在简单且可靠的设置或调整方法，可减轻通气机拆分系统中的潮气量差异？

主要发现

• 当肺顺应性不同时，模拟肺之间出现显著的潮气量差异，顺应性较低的肺接收的潮气量不成比例地更小。
• 气道阻力的差异对潮气量分布影响极小，表明顺应性是导致不平衡的主要因素。
• 在容量控制模式下，改变一个模拟肺的顺应性会改变其对另一肺潮气量的输送，表明患者之间存在相互依赖性。
• 对于某一类型的模拟肺，较高的PEEP水平显著破坏了潮气量平衡，加剧了两肺之间的差异。
• 未发现可通过简单设置或调整可靠克服潮气量不平衡的方法，表明该方法存在固有的技术局限性。
• 研究结论认为，为在临床实践中安全实施通气机拆分，必须采用更先进的控制系统。