Portable electronic ventilator for application to patients with COVID-19
MARI PAZ DÍAZ
Huelva, April 9, 2020
A team of researchers from the University of Huelva (UHU) has developed a portable electronic respirator that can be very useful in the treatment and cure of patients with COVID-19, by guaranteeing these patients their respiratory needs in a controlled and automatic way. A medical equipment that could assist almost all those affected by the virus who need this type of respiratory resource, which would help to reduce the number of patients who need to be admitted to the ICU, since it could be used to ventilate people even on the ward, avoiding their respiratory deterioration and thus increasing the percentage of survival to the disease.
It is a respirator that was born as a result of an interdisciplinary study, developed by members of the Research group ‘Control and Robotics (TEP 192)’, directed by Professor Dr. José Manuel Andújar, and the group of ‘Structure of Materials (FQM 318)’, directed by Professor Dr. Ismael Martel. Specifically, Prof. Andújar’s group has been in charge of the design and implementation of the electronics, control systems, instrumentation and communications of the prototype, while Prof. Ismael’s team has carried out the physical/mechanical part of the respirator, performing the design and implementation of ducts, valves, sensors and integration of all the equipment in the respirator case.
These researchers were joined by three people from outside the University, whose participation has been fundamental to the success of the project, such as José Sánchez, a retired medical physicist from the Juan Ramón Jiménez Hospital, whose experience in electromedicine has been vital for the medical characteristics of the ventilator, as he has been in contact with pneumologists and intensivists from this hospital at all times; Carlos García, a specialist in design and 3D machining; and Ladislao Martínez, an expert in 3D manufacturing with resin.
The developed prototype is of the BPAP (Bilevel Positive Airway Pressure) type, with independent regulation of intrathoracic pressure, i.e. one level during inspiration, IPAP (Inspire Positive Airway Pressure), and another during exhalation, EPAP (Expire Positive Airway Pressure).
As Professor José Manuel Andújar explains, “the possibility of working with different pressures between EPAP and IPAP is fundamental, as it allows the physician to increase ventilation per minute, thus achieving the airflow demanded by the patient. To this end, the equipment designed has a sophisticated electronic pressure flow controller, which can give 120 litres/minute of air flow, enriched or not with oxygen and at the percentage that the health professional decides”.
The designed respirator also features a touch screen from which the doctor, in addition to continuously monitoring the patient’s air pressure and respiratory flow, can interact in a very ergonomic way with the respirator, controlling and selecting parameters such as IPAP pressure (cm H2O); EPAP pressure (cm H2O); I ratio. E.: ratio between the inspiration and expiration time; the trigger value for cycling by flow from expiration to inspiration (l/min); and the trigger value for cycling by time, i.e. the maximum safe time for the device to enter automatic breath control mode. Time-cycling can be used, for example, when the patient is sedated or when the patient cannot breathe on his/her own. In fact, once the trigger values have been selected by the specialist, the ventilator carries out the breathing control automatically, thus ensuring that the patient is ventilated.
In addition to the control knobs, the touch screen also shows the doctor other useful data, such as the selected IPAP and EPAP; the patient’s breathing rate (BR) or number of breaths per minute; the I-ratio: E ratio selected; the tidal volume or volume inspired by each inspiration (in milliliters); the volume of inspired air in liters/min; the percentage of oxygen supplied to the patient, from 21% in normal atmosphere to that prescribed by the physician; the real-time graph of breathing pressure (cm H2O); the respiratory flow in liters/min; and the respiratory volume in liters.
The developed equipment also has alarms to warn about the maximum and minimum pressure, the minimum breathing flow (liters/m), the maximum FR or if the patient presents apnea, that is, it detects if there is no breathing in a time interval defined by the doctor.
In practice, the device developed has two modes of operation: patient-assisted, where the patient determines the complete breathing cycle; and ventilator-controlled, when the patient is unable to support breathing on his own.
Finally, another of the advantages offered by this design is that the ventilator can be connected to a data network via cable or wifi, or even generate its own wifi network, in the event that no connection is available where it is installed. “This feature allows, for example, patients in isolation to be monitored without having to enter and exit the room,” says José Manuel Andújar.