Use of a Single Ventilator to Support 4 Patients: Laboratory Evaluation of a Limited Concept

Abstract

INTRODUCTION:A mass-casualty respiratory failure event where patients exceed available ventilators has spurred several proposed solutions. One proposal is use of a single ventilator to support 4 patients. METHODS: A ventilator was modified to allow attachment of 4 circuits. Each circuit was connected to one chamber of 2 dual-chambered, test lungs. The ventilator was set at a tidal volume (V T ) of 2.0 L, respiratory frequency of 10 breaths/min, and PEEP of 5 cm H 2 O. Tests were repeated with pressure targeted breaths at 15 cm H 2 O. Airway pressure, volume, and flow were measured at each chamber. The test lungs were set to simulate 4 patients using combinations of resistance (R) and compliance (C). These included equivalent C and R, constant R and variable C, constant C and variable R, and variable C and variable R. Results. When R and C were equivalent the V T distributed to each chamber of the test lung was similar during both volume (range 428 -442 mL) and pressure (range 528 -544 mL) breaths. Changing C while R was constant resulted in large variations in delivered V T (volume range 257-621 mL, pressure range 320 -762 mL). Changing R while C was constant resulted in a smaller variation in V T (volume range 418 -460 mL, pressure range 502-554 mL) compared to only C changes. When R and C were both varied, the range of delivered V T in both volume (336 -517 mL) and pressure (417-676 mL) breaths was greater, compared to only R changes. CONCLUSIONS: Using a single ventilator to support 4 patients is an attractive concept; however, the V T cannot be controlled for each subject and V T disparity is proportional to the variability in compliance. Along with other practical limitations, these findings cannot support the use of this concept for mass-casualty respiratory failure.

Managing COVID-19 in resource-limited settings: critical care considerations

“…The addition of high-efficiency particulate air (HEPA) filters to the expiratory limb of the circuit can help minimize aerosolization if the ventilator does not have a closed circuit. Other creative approaches include splitting a ventilator to support several patients simultaneously by using T-tubes and pressure-cycled ventilation [6][7][8].…”

One ventilator for two patients: feasibility and considerations of a last resort solution in case of equipment shortage

“…They observed wide variability in measured tidal volume (Vt) and end-expiratory lung volume, so they concluded that the technique should be avoided because of potential danger. 3 Accordingly, the authors argued that the stockpiling of ventilators should be the firstline solution when massive emergencies are forecast; only after their depletion, strategies such as the 'double circuit' should be implemented for the shortest possible duration. 4 5 On 20 February 2020, the first case of COVID-19 emerged in the Lombardy region, northern Italy.…”

Critical Care During the Coronavirus Crisis: Challenges and Considerations for the Cardiothoracic and Vascular Anesthesia Community

“…[24][25][26][27][28] The concept of sharing a single ventilator for multiple patients has also been proposed as a solution to increase ventilator capacity during this coronavirus crisis. [30][31] A device for sharing a ventilator in this fashion has recently received emergency approval from the Food and Drug Administration in the United States. 32…”