Biological evaluation of a mechanical ventilator that operates by controlling an automated manual resuscitator. A descriptive study in swine

Background The Covid-19 outbreak challenged health systems around the world to design and implement cost-effective devices to complement mechanical ventilators that can be produced locally. Masi works as a mechanical ventilator to bring life-support by automating a resucitation bag to closely control ventilatory parameters. Methods This pre-clinical trial was designed to study the physiological responses of healthy swine maintained under volume- or pressure-controlled mechanical ventilation. Thus, physiological parameters were measured in eight sedated animals (t0), prior to inducing deep anesthesia, as well as during the next six hours of mechanical ventilation with Masi (t1-7). Hemodynamic conditions were monitored periodically using a gas analyzer machine (i.e. BEecf, HCO3, SaO2, lactate, pH, PaO2, PaCO2) and a capnometer (i.e. ETCO2). Electrocardiogram, echocardiography and lung ultrasonography were performed to detect in vivo alterations in these vital organs and pathological findings from necropsy are reported. Results The mechanical ventilator properly controlled physiological levels of blood biochemistry such as oxygenation parameters (PaO2, PaCO2, SaO2, ETCO2), acid-base equilibrium (pH, HCO3−, BEecf), and perfusion of tissues (lactate levels). In addition, histopathological analysis showed no evidence of acute tissue damage in lung, heart, liver, kidney, or brain. Moreover, all animals were able to breathe spontaneously after undergoing mechanical ventilation controlled by Masi device. The results demonstrate that Masi mechanical ventilator allows the regulation of body gas exchange and maintain the physiological parameters in the normal range for swine. Conclusions These preclinical data, added to the appropriate performance of Masi in engineering laboratory tests, support the biological safety of the medical device to move forward to further evaluation in clinical studies.