Multiplex Ventilation: A Simulation-Based Study of Ventilating 2 Patients With a Single Ventilator

Area of Science:

• Critical Care Medicine
• Respiratory Physiology
• Biomedical Engineering

Background:

• COVID-19 increased demand for mechanical ventilators, prompting interest in multiplex ventilation.
• Limited evidence and no human studies exist for multiplex ventilation safety and efficacy.
• Risks include uncontrollable ventilation and PEEP effects due to patient resistance and compliance differences.

Purpose of the Study:

• To evaluate the effects of resistance-compliance imbalance on ventilation parameters during simulated multiplex ventilation.
• To compare the safety and effectiveness of volume control vs. pressure control ventilation modes in multiplex scenarios.

Main Methods:

• A simulation-based study using two breathing simulators and a mechanical ventilator.
• Simulated varying degrees of resistance and compliance differences between "patients" (6 pairs).
• Recorded differences in tidal volume (V_T), end-expiratory lung volume (EELV), and pH.

Main Results:

• Differences in V_T ranged from 1% to 79%, and EELV differences ranged from 2% to 109%.
• Excessive EELV difference (>10%) occurred in 50% of simulated patient pairs.
• No significant difference in failure rates between volume control and pressure control modes.

Conclusions:

• Multiplex ventilation can lead to markedly different ventilation and oxygenation in patients with uneven respiratory impedances.
• Key challenges include individual flow partitioning, V_T measurement, and individual PEEP.
• Solutions are proposed to mitigate risks associated with multiplex ventilation.