Toward a Self-Inflating Bag Mechanical Ventilator, Maturation in Continuous Use, Safety, and Repeatability for Ventilatory Variables.

Background: Researchers proposed mechanical ventilators (MVs) based on the automated compression of a self-inflating bag (SIB) to save lives during the pandemic caused by the SARS-CoV-2 virus. Many proposals had problems with continuous use time, repeatability of ventilatory variables, high partial pressure of carbon dioxide (PaCO₂) values, and a decreasing fraction of inspired oxygen (FiO₂) for high respiratory rates.

Objective: This study aimed to demonstrate that our technology, based on automated compression of an SIB, can operate for several days, is repeatable in its ventilatory variables, and is safe in the ventilator-patient interaction.

Materials and methods: Ehecatl-4T (EHT) MV was based on SIB. We first validated the repeatability of the ventilatory variables using a lung simulator for different compliances (0.01 up to 0.05 L/cmH₂O) and resistances (5 up to 50 cmH₂O·s/L). Subsequently, we conducted a long-term durability test to maintain the ventilatory parameters. Finally, the EHT was tested in a preclinical study using 12 York-Landrace × Pietrain-Duroc pigs weighing 87 ± 5 kg. Six pigs were assigned to the experimental group and six were assigned to the reference group.

Results: The EHT presented a relative error within the allowed margin for both pressure and volume modes. The EHT was operated for over 32 days without affecting the ventilatory variables. In the preclinical study, the PaCO₂ and FiO₂ values were close to the reference levels.

Conclusion: The EHT showed potential for continuous use, demonstrating repeatability for ventilatory variables in bench testing. Clinical parameters were maintained according to the industry safety standards.