Fig4B_standardSplitter_comparison_PressureVolumeFlow_dissimilarPatientMode ls_Patients_A_D: Variables for patient pair A-D. from A simulated single ventilator/dual patient ventilation strategy for acute respiratory distress syndrome during the COVID-19 pandemic

The potential for acute shortages of ventilators at the peak of the COVID-19 pandemic has raised the possibility of needing to support two patients from a single ventilator. To provide a system for understanding and prototyping designs, we have developed a mathematical model of two patients supported by a mechanical ventilator. We propose a standard set-up where we simulate the introduction of T-splitters to supply air to two patients and a modified set-up where we introduce a variable resistance in each inhalation pathway and one-way valves in each exhalation pathway. Using the standard set-up, we demonstrate that ventilating two patients with mismatched lung compliances from a single ventilator will lead to clinically significant reductions in tidal volume in the patient with the lowest respiratory compliance. Using the modified set-up, we demonstrate that it could be possible to achieve the same tidal volumes in two patients with mismatched lung compliances, and we show that the tidal volume of one patient can be manipulated independently of the other. The results indicate that, with appropriate modifications, two patients could be supported from a single ventilator with independent control of tidal volumes.

在新冠疫情（COVID-19）大流行高峰期，呼吸机面临急性短缺的潜在风险，由此催生了单台机械呼吸机（mechanical ventilator）为两名患者提供呼吸支持的可行性探索。为构建可用于场景理解与设计原型开发的系统框架，我们开发了一套针对单台机械呼吸机支持两名患者场景的数学模型。我们提出两种配置方案：标准配置方案中，通过模拟加装T型分流器（T-splitters）为两名患者供气；改进配置方案中，则在每条吸气通路设置可变电阻，并在每条呼气通路加装单向阀。借助标准配置方案，我们验证得出：若单台机械呼吸机为两名肺顺应性（lung compliances）不匹配的患者通气，肺顺应性最低的患者其潮气量（tidal volume）将出现具有临床意义的显著降低。通过改进配置方案，我们证明可为两名肺顺应性不匹配的患者设置一致的潮气量，且可实现两名患者各自潮气量的独立调节。研究结果表明，经过合理改装，单台机械呼吸机可实现对两名患者潮气量的独立控制，从而为其提供呼吸支持。