Christopher Hollinger, MD, FASA
Anesthesiologist
Governor Juan F Luis Hospital and Medical Center
Christiensted
Disclosure information not submitted.
John Lindenthal, MD
Director of Cardiac Anesthesia
Cleveland Clinic Indian River Hospital, Florida, United States
Disclosure information not submitted.
George Mitchell, DO
Director of Critical Care
Cleveland Clinic Indian River Hospital, Florida, United States
Disclosure information not submitted.
Ruby Hollinger
Medical Student
Florida International University
Doral, Florida, United States
Disclosure information not submitted.
Title: Desperate Measures: An Acute Respiratory Distress Syndrome Approach to Multiplex Ventilation
INTRODUCTION/HYPOTHESIS: As the world braces itself against new variants of SARS-CoV-2, less resource-rich facilities must consider what to do when the surge of critically ill COVID-19 patients requiring mechanical ventilation outnumbers the supply of ventilators. One solution is multiplex ventilation, where a single ventilator supports two patients. Previously proposed scenarios sacrifice volume control for pressure control in the name of safety. However, volume control ventilation, low tidal volumes, high positive end-expiratory pressure (PEEP) and high respiratory rate are key for Acute Respiratory Distress Syndrome (ARDS) ventilator management. We offer a proof of concept for an accessible multiplex ventilation model with volume protective settings.
Methods: Using one parent ventilator, two daughter circuits were improved with a 3D-printed splitter fitted with laser-cut mechanical flowmeters. Resistance valves connected to each flowmeter outflow port attach to the inspiratory limb of the daughter circuit. At the patient wye, a Luer lock attaches a dry arterial line transducer and an end-tidal CO2 monitor. A one-way check valve connects each daughter circuit expiratory limb to a T-piece at the expiratory port of the ventilator. Test lungs were used to assess whether lung-protective settings can be maintained and adjusted by measuring plateau and driving pressures with varying lung compliance.
Results: The improved sub-circuit flowmeters and valves allowed monitoring and manipulation of flow to correct tidal volume shifts with changes in patient lung compliance. Dry arterial line transducers reliably measured peak pressure, PEEP, stress index and plateau pressure on a GE monitor. One-way valves prevented expiratory gas rebreathing by the more compliant lungs.
Conclusions: We concede that two patients on one ventilator is not a good idea, but as the COVID-19 pandemic rages on, resource-poor facilities will run out of good ideas quickly. With our solution, volume control ventilation can be employed, pressures measured, alarms set, and volumes calculated and adjusted for each patient. In the spirit of Roosevelt’s call to “do what you can, with what you’ve got, where you are”, we submit that this is a relatively low-tech, inexpensive model that allows ARDS settings with just a few simple parts, anywhere in the world.