Fig 1.
Experimental setup for the metrological evaluation of Masi.
The self-inflating resuscitation bag was connected in the interior of Masi and the metrological evaluation of the performance of the control of oxygen flow and pressure was done using a test lung simulator, a flux and pressure calibrator and software to validate the response and repeatability of the measurements.
Fig 2.
A preliminary study optimized anaesthesia dosing and evaluated autonomous breathing after mechanical ventilation for one hour. Since no evidence of gross pathology damage was found, the pre-clinical trial was performed. The trial included a total of eight animals whose autonomous breathing was evaluated after mechanical ventilation for six hours. During the trial, the results from the first group of four individuals were done and since no post-mortem evidence of damage to internal organs was found, the responses from a second group of four individuals were further studied.
Table 1.
Summary of standardized physiological values on cardiorespiratory parameters in swine.
Table 2.
General animal health data from animals participating in the pre-clinical trial.
Fig 3.
Timeline for experimental procedures.
The diagram shows the time-points when drugs were supplied, ventilation was controlled and interventions were performed. PC-CMV: Pressure Control-Continuous Mandatory Ventilation, VC-CMV: Volume Control-Continuous Mandatory Ventilation, PSV: Pressure support ventilation, t0 to t7: blood collection time-points.
Table 3.
Summary of baseline values (t0) for the swine participating in the pre-clinical trial.
Fig 4.
Responses over time of arterial blood biochemical markers to mechanical ventilation.
Blood samples from each pig were collected at specific time-points and blood biochemistry was assessed using a point-of-care device. pH: potential of hydrogen, HCO3-: bicarbonate ion, BEecf: base excess in the extracellular fluid compartment, SaO2: arterial oxygen saturation, PaO2: arterial oxygen pressure, PaCO2: arterial carbon dioxide pressure, ETCO2: end-tidal carbon dioxide, *: outlier measurements.
Table 4.
Summary of statistical distribution for arterial blood biochemistry values (t2-7).
Fig 5.
Distribution of physiological variables over time.
Median, lower and upper quartiles are illustrated for bicarbonate, lactate, base excess, oxygen, and carbon dioxide arterial pressure. Significant differences among time-points are represented by letters on top of the box-plots. Distributions at time-points with different letters are significantly different. HCO3-: bicarbonate ion, BEecf: base excess in the extracellular fluid compartment, PaO2: arterial oxygen pressure, PaCO2: arterial carbon dioxide pressure, ETCO2: end-tidal carbon dioxide.
Table 5.
Changes in arterial blood biochemical parameters per time point adjusted to baseline.
Fig 6.
Comparison between lung function and blood biochemistry.
A Spearman test between two relevant biomarkers of lung function (ETCO2) and blood biochemistry (PaCO2) showed no correlation between these two values. The solid line represents the linear regression. Spearman R-score = 0.046 (p = 0.718).