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. 2024 Feb 24;24(5):1481.
doi: 10.3390/s24051481.

A New Model of Air-Oxygen Blender for Mechanical Ventilators Using Dynamic Pressure Sensors

Gabryel F Soares  1 , Gilberto Fernandes Jr  2 , Otacílio M Almeida  1 , Gildario D Lima  3 , Joel J P C Rodrigues  4
Affiliations

A New Model of Air-Oxygen Blender for Mechanical Ventilators Using Dynamic Pressure Sensors

Gabryel F Soares et al. Sensors (Basel). .

Abstract

Respiratory diseases are among the leading causes of death globally, with the COVID-19 pandemic serving as a prominent example. Issues such as infections affect a large population and, depending on the mode of transmission, can rapidly spread worldwide, impacting thousands of individuals. These diseases manifest in mild and severe forms, with severely affected patients requiring ventilatory support. The air-oxygen blender is a critical component of mechanical ventilators, responsible for mixing air and oxygen in precise proportions to ensure a constant supply. The most commonly used version of this equipment is the analog model, which faces several challenges. These include a lack of precision in adjustments and the inspiratory fraction of oxygen, as well as gas wastage from cylinders as pressure decreases. The research proposes a blender model utilizing only dynamic pressure sensors to calculate oxygen saturation, based on Bernoulli's equation. The model underwent validation through simulation, revealing a linear relationship between pressures and oxygen saturation up to a mixture outlet pressure of 500 cmH2O. Beyond this value, the relationship begins to exhibit non-linearities. However, these non-linearities can be mitigated through a calibration algorithm that adjusts the mathematical model. This research represents a relevant advancement in the field, addressing the scarcity of work focused on this essential equipment crucial for saving lives.

Keywords: FIO2; blender; mechanical ventilator; simulation.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Flowchart of a blender from three pressure sensors. (Air Source in blue (PA), Oxygen source in green (PO) and a general pressure sensor in yellow (PG)).
Figure 2
Figure 2
Model simulation diagram.
Figure 3
Figure 3
Application of the (8) as a function of the oxygen inlet pressure.
Figure 4
Figure 4
Distribution of O2 saturation curves in relation to changes in O2 pressure. Note that S* is the theoretical result from Equation (8).
Figure 5
Figure 5
Distribution of dynamic inlet pressures for oxygen and air obeying the relation PG=PA+PO.
See this image and copyright information in PMC

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