During the COVID-19 pandemic, consideration was given to co-ventilating multiple patients on a single ventilator. Prior work had shown that this procedure was possible by ventilating four adult-size sheep for twenty-four hours, and other groups had performed this maneuver during dire circumstances. However, no investigation had examined the safety regarding cross-contamination. The purpose of our studies was to investigate if an infection could spread between individuals who were being co-ventilated.

Four sterile two-liter anesthesia bags were connected to a sterilized ventilator circuit to simulate the co-ventilated patients’ “lungs.” The circuit utilized Heat and Moisture Exchange filters and bacterial/viral filters, which were strategically inserted to prevent the transmission of infectious droplets. Serratia marcescens was inoculated into “lung” number one. The circuit was then run for 24 hours, after which each “lung” and three additional points in the circuit were cultured to see if S. marcescens had spread. These cultures were examined at 24 and 48 hours to assess for cross-contamination. This entire procedure was performed a total of four times.

S. marcescens was not identified in lungs two, three, or four or the three additional sampling sites on the expiratory limb of the tubing at 24 and 48 hours in all four trials.

Cross-contamination between co-ventilated patients did not occur within 24 hours utilizing the described ventilator circuit configuration.