Abstract
In invasive mechanical ventilation (IMV), it is critical that the flow value is estimated correctly, as it is used as a trigger variable for ventilatory assistance. Furthermore, the numerical integration of the flow allows the calculation of the total volume per breath (tidal volume), which clinicians use to identify trauma or lung capacity in the patient. The current COVID-19 pandemic has demonstrated the need to develop safe and efficient techniques for measuring this spirometry variable because many mechanical ventilators delivered to hospitals were unable to measure it directly. A good device to estimate flow is a D-lite sensor, which works by the Venturi effect, is cheap, reusable, and proximal to the patient. However, the regressions applied to the flow estimation model are limited for use in real conditions. This article presents a flow estimation method that uses a D-Lite device, a fraction of inspired oxygen (FiO2) cell, and two pressure sensors as critical items. Our novel method adapts the dichotomous search algorithm instead of conventional regression algorithms to estimate flow using a D-lite sensor; this change in the standard procedure allowed us a fast calibration process, a good low-flow estimation, and low computational time for flow estimation. The method was validated experimentally to compute the tidal volume according to the measurement requirement error range of +/−10%. The consideration of FiO2 percentage in the gas mixture and the good low-flow estimation make this novel method useful for real ventilation conditions. The flow calculations have been performed at different ambient conditions and compared with gas analyzers show an average relative error of up to 4.86%. Finally, we present an analysis of the error flow estimation considering the variation in each variable. Technical recommendations for applying this novel method to achieve IMV safely are presented, based on the capabilities of the embedded system used by developers.
Highlights
M ECHANICAL ventilation is an artificial respiration procedure that uses a mechanical device to fully or partially supply ventilatory function to a person
The alternative method for flow estimation that we proposed to resolve the problem with low flow values was eliminate the regression step and store a dataset, in order to apply a binary search algorithm, which works with local instead of global errors
The COVID-19 pandemic demonstrated the capacity and willingness to support on the part of scientists to develop solutions that would help mitigate, reduce or treat the effects caused by the virus
Summary
M ECHANICAL ventilation is an artificial respiration procedure that uses a mechanical device to fully or partially supply ventilatory function to a person. Endotracheal intubation is when a clinical places a plastic tube (polyvinyl) in the trachea of a patient to provide artificial mechanical ventilation [2] This intubation is required for multiple reasons [3], [4], [5], [6], for example: 1) For postoperative treatments; 2) When there is a high risk of regurgitation of gastric contents and aspiration into the respiratory tract causing obstructive pulmonary disease; 3) In cardio-respiratory arrest where a low level of consciousness can trigger a prolonged apnea (caused by poisoning, trauma), and; 4) Acute respiratory diseases such as influenza and COVID-19, which cause acute respiratory failure [7]. Using inadequate instrumentation for the flow measurement can introduce pathogens and solids into the patient’s airway and generate severe clinical problems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
