Experimental Validation of the ACTIV Multi-Patient Mechanical Ventilation System

Abstract

Acute respiratory distress and respiratory disease often require patients be treated with mechanical ventilation (MV) and thus place extreme demand on intensive care units (ICUs). This burden can be unsustainably high in some periods, and particularly during pandemics, such as Covid-19. In low resource regions and countries, the result can be inequity, a problem addressable via simple technological innovation. Ventilator sharing over two or more patients has been proposed but strongly discouraged because it could not treat different patient needs and hindered individual patient monitoring. However, all these approaches ventilated patients in-parallel, each breathing at the same time.

A simple switching valve enables series breathing, one patient after the other. External, low-cost, and reusable sensor arrays enable individual monitoring, while low-cost adjustable pressure reducing valves allow pressure to be fully customised across two patients. This study uses an experimental test lung to experimentally demonstrate and validate the ability of such a system to balance ventilation across 2 simulated patients with very different lung compliances.

A method is presented to achieve equal tidal volumes in two lungs with differing compliances of 0.10 L cmH ₂O⁻¹ and 0.05 L cmH ₂O⁻¹. This goal requires driving and end-expiratory pressures of at least 20 cmH ₂O, which are clinically relatively high. The approach prioritises safety, ensuring more compliant lung is not over-ventilated during the process, reducing the risk of ventilator-induced lung injury (VILI). The system is compatible with different ventilators, and cost-effectively fabricated in low-resource settings. Strategies addressing key safety concerns, such as cross-contamination, sterilisation, and ventilator configuration, are also presented.