Development of a multi-patient ventilator circuit with validation in an ARDS porcine model

Abstract

Purpose: The COVID-19 pandemic threatens our current ICU capabilities nationwide. As the number of COVID-19 positive patients across the nation continues to increase, the need for options to address ventilator shortages is inevitable. Multi-patient ventilation (MPV), in which more than one patient can use a single ventilator base unit, has been proposed as a potential solution to this problem. To our knowledge, this option has been discussed but remains untested in live patients with differing severity of lung pathology.

Methods: The objective of this study was to address ventilator shortages and patient stacking limitations by developing and validating a modified breathing circuit for two patients with differing lung compliances using simple, off-the-shelf components. A multi-patient ventilator circuit (MPVC) was simulated with a mathematical model and validated with four animal studies. Each animal study had two human-sized pigs: one healthy and one with lipopolysaccharide (LPS) induced ARDS. LPS was chosen because it lowers lung compliance similar to COVID-19. In a previous study, a control group of four pigs was given ARDS and placed on a single patient ventilation circuit (SPVC). The oxygenation of the MPVC ARDS animals was then compared to the oxygenation of the SPVC animals.

Results: Based on the comparisons, similar oxygenation and morbidity rates were observed between the MPVC ARDS animals and the SPVC animals.

Conclusion: As healthcare systems worldwide deal with inundated ICUs and hospitals from pandemics, they could potentially benefit from this approach by providing more patients with respiratory care.

Keywords: Artificial respiration; COVID-19; Coronavirus; Pandemics; Viruses.

Fig. 1

Schematic setup for the MPVC on A an open-loop ventilator and B a closed-loop ventilator

Fig. 2

There is no statistically significant difference in PaO₂ values (A) and one difference in SpO₂ values (p < 0.001, indicated by *) (B) when comparing individually ventilated pigs (SPVC) with patient stacked pigs (MPVC). Oxygen comparison between three ARDS animals that were individually ventilated and four ARDS animals that were ventilated along with a healthy animal during ARDS development and up to 4 hours after is shown. A comparison between the two groups was performed with a two-sample heteroscedastic t test with a significance level of α = 0.05. The sample size (n) for each time step is given above the x-axis. Since some animals developed ARDS faster than others and some died before reaching the end of the study, n values (located just above the x-axis) varied but were centered around developing moderate to severe ARDS per the Berlin criteria. Three baseline measurements were taken before any LPS administration and were compared together at the beginning of the chart. The stacked ventilation pigs were placed on the same ventilator within 1 hour of reaching ARDS. Error bars indicate ± 1 SD

Fig. 3

Although the PSs became unstable in every study and required ventilator adjustments, the PHs that were attached to the same ventilator remained stable. The timelines for vital signs and events for each of the four studies are shown. Peak pressure adjustments of the ventilator significantly impacted the PSs with minimal impact on the PHs. FRE adjustments affected the vital signs of the PHs with no noticeable effect on the PSs

Fig. 3

Although the PSs became unstable in every study and required ventilator adjustments, the PHs that were attached to the same ventilator remained stable. The timelines for vital signs and events for each of the four studies are shown. Peak pressure adjustments of the ventilator significantly impacted the PSs with minimal impact on the PHs. FRE adjustments affected the vital signs of the PHs with no noticeable effect on the PSs

Fig. 3

Although the PSs became unstable in every study and required ventilator adjustments, the PHs that were attached to the same ventilator remained stable. The timelines for vital signs and events for each of the four studies are shown. Peak pressure adjustments of the ventilator significantly impacted the PSs with minimal impact on the PHs. FRE adjustments affected the vital signs of the PHs with no noticeable effect on the PSs

Fig. 3

Although the PSs became unstable in every study and required ventilator adjustments, the PHs that were attached to the same ventilator remained stable. The timelines for vital signs and events for each of the four studies are shown. Peak pressure adjustments of the ventilator significantly impacted the PSs with minimal impact on the PHs. FRE adjustments affected the vital signs of the PHs with no noticeable effect on the PSs