Simulation-based Feasibility Study of Ventilating Two Patients with One Ventilator (1090-003701) (To be presented in the session entitled, Research Abstract Oral: COVID-19)
Start time: Friday, January 22, 2021, 9:30 AM End time: Friday, January 22, 2021, 10:30 AM Session Type: Research Abstracts (Completed Studies)
The COVID-19 pandemic has created an overwhelming demand for mechanical ventilators. This demand has stimulated much interest in using one ventilator for multiple patients, called multiplex ventilation [1-4]. Many have posted methods for this on the Internet, but there is little supporting evidence and no human studies. Multiplex ventilation is associated with risk because ventilation and PEEP effects are largely uncontrollable and depend on the difference between patient resistance, (R) and compliance (C). The purpose of our simulation-based study was to allow complete control over the relevant variables during ventilation of a passive lung mode to determine the effects of various degrees of RC imbalance on tidal volume, end-expiratory lung volume (EELV), and imputed arterial pH.
Two patients were simulated with two separate breathing simulators (ASL 500, IngMar Medical, Pittsuburgh, PA). Evidence-based lung models were created to simulate a range of differences in R and C (six pairs of simulated patients). They were ventilated with a Servo-I ventilator (Getinge, Rastatt, Germany) using pressure control (PC) and volume control (VC) modes. Outcome data recorded were: differences in tidal volume, EELV, and imputed pH.
As expected, differences in outcome variables between the two simulated patients depended on differences in lung model values for R and C. Differences in tidal volume ranged from 1% to 79%. Differences in EELV ranged from 2% to 109%. Differences in pH ranged from 0% to 5%. Failure of ventilation due to excessive tidal volume (> 8 mL/kg) did not occur. Failure due to tidal volume and pH too low was 50% and 33% respectively. Failure due to excessive EELV difference (> 10%) was evident in 50% of patient pairs. There was no difference in failure rate between VC and PC.
This study confirmed the potential for markedly different ventilation and oxygenation for patients with uneven respiratory system impedances during multiplex ventilation. Three critical problems must be solved to minimize risk: (1) partitioning of inspiratory flow from the ventilator individually between the two patients, (2) measurement of tidal volume delivered to each patient, and (3) provision for individual PEEP. We provide suggestions for solving these problems