Huge efforts being made for low-cost ventilators

The collective efforts of engineers, doctors, scientists, and even policy makers are needed for better designing and implementation of low-cost portable mechanical ventilators to effectively fight against the current and future pandemics.

The world has been fighting one of its greatest battles against Covid-19, leading to death of hundreds of thousands of people, with severe patients requiring artificial breathing. To overcome the shortage of ventilators in medical infrastructure, various low-cost, easy-to-assemble, portable ventilators were proposed to fight the ongoing pandemic. These mechanical ventilators are made from components that are generally readily available worldwide. Such components are already associated with day-to-day gadgets or items, and which do not require specialized manufacturing processes.

But many experts are against the usage of these mechanical ventilators in real-life situations, owing to poor reliability and inability of these designs to meet certain clinical requirements. Each design has its own merits and demerits.

MADVent. Developed by a team of researchers from the University of California, San Diego, this design aims to provide a low-cost alternative to expensive ventilators to fight Covid-19. This system operates in single-pressure mode and is installed with various life-support alarms to detect system failure or unintended pressure build-up. It is powered by a stepper motor whose motion can be controlled via a simple controller, with a single-arm pressing against the resuscitator bag. A backup battery is also provided to ensure continuous operation in case of power failure. The cost of this prototype is estimated to be around USD 250. The system cannot operate in volume-controlled mode, and the resuscitator bag can dislocate (as it is pressed from one side and no support is provided at ends) during operation for long hours. Also, the PEEP valve is located near the resuscitator bag rather than the mouth, leading to accumulation of CO2 in the air pipe (exhaled by the patient), leading to back-flow or adrift from the prescribed oxygen supply. The other most important aspect is that the device was tested for 24 h in normal and extreme operations, so stability might be an issue.

ABCD. Developed by a team of scientists from PGIMER, Chandigarh, artificial breathing capability device (ABCD) is an automated AMBU bag system (powered by stepper motor) with controlled PIP, ventilation rate, I/E ratio to assist patient breathing. It has been installed with various intelligent features, such as self-regulatory checks, auto cut-off during coughing, and different life-support alarms to alert authorities of blockage or system failure. Moreover, it has been tested with adult- and pediatric-size resuscitator bags. It has undergone continuous rigorous testing for more than 60 days under different settings. The cost of this compact, robust design is estimated to be around USD 800 (which can be reduced to USD 400 for mass production), offering ventilation for a wide range of population age, ranging from adults to children. Though this design provides better control over I/E ratio, it does not give any control to enable system operation in volume-controlled mode. Also, the system design is expensive as compared to other mechanical ventilators offering almost similar performance criteria. The additional advantage of this device is that it is clinically validated and approved.

SVASTA. A group of engineers developed these three different ventilators at Vikram Sarabhai Space Centre, India. SVASTA (Space Ventilator Aided System for Trauma Assistance) operates on compressed air without any electricity. It can work in different modes via varying mechanical settings alone. PRANA (Programmable Respiratory Assistance for the Needy Aid) is an automated AMBU bag compressing system, which can operate in both pressure and volume-controlled modes, with precise control over I/E ratio, tidal volume, and PIP, among others. VaU (Ventilation Assist Unit) is a pneumatic state-of-the-art ventilator, equivalent to commercially available ventilators that can operate in dual mode, and uses air/oxygen from the hospital or uses air from ambient. SVASTA is very easy to operate and has minimum electricity dependence (making it viable to use even in power-failure scenario) but suffers from poor control over ventilation parameters. PRANA can be easily assembled and requires only easily available, low-cost parts but requires manual check-ups and replacement of AMBU resuscitator on a timely basis. VaU is the most efficient system with utmost control over ventilation parameters, but many sensors and feedback systems make it costly. The device is not yet clinically approved and validated.

Automated bag-valve mask. Developed as early as 2010 by researchers at Massachusetts Institute of Technology, USA, this design marks the first attempt to automate AMBU resuscitators to be deployed as ventilators in case of the pandemic. Even though it was designed almost a decade before the emergence of the Covid-19 pandemic, researchers had carefully engineered ventilation parameters to meet tidal volume, PEEP, BPM of patients while minimizing its cost (~ USD 420 for prototype) and less than USD 200 for bulk manufacturing. In this design, the actuator mechanism is powered using pivoting cam arm, which can be easily powered using a 14.8 VDC battery. Moreover, all the accessories used were arranged in a very compact manner, taking its weight to mere 4.1 kg, making it easy to handle and transport without much effort. Though it was the first reported study demonstrating automation of AMBU resuscitators, they have not conducted any test results either on test lung or human trials to prove the efficacy of the proposed device.

Non-invasive bilevel pressure ventilator. Developed by a group of scientists from Spain, they presented a non-invasive, low-cost, easy-to-build portable ventilator using a high-pressure blower to push air to assist patient breathing. Along with providing control over basic ventilation parameters, such as I/E ratio, breathing rate, they also tested their prototype on 12 patients against a commercially available ventilator. They observed better patient therapy using the prototype. The low cost of this device makes it feasible to be easily assembled and used in low/middle-income countries. But this design does not provide any control to operate the device in pressure or volume-controlled modes. Moreover, it uses a high-pressure blower to push air, resulting in air heating after continuous use.

Low-cost mechanical ventilator. Another team of scientists from Spain and Brazil also developed a low-cost portable ventilator, using rack-and-pinion arrangement to compress AMBU resuscitators, assisting patient’s breathing. They provided precise control over the I/E ratio, oxygen delivery percentage, and volume delivered per breath. Along with this, they offered a complete description of electronics used in the device to replicate system designs for easy deployment. But this design is also unable to operate in volume-controlled mode. Also, the PEEP valve is connected far away from patient exhalation, leading to the accumulation of CO2 in air delivery pipe, leading to an inaccurate O2 delivery ratio.

New research from the Additive Manufacturing Lab at Simon Fraser University in British Columbia is using origami to help the fight against the Covid-19 pandemic. Based on 3D-printed origami technology, their breakthrough could lead to inexpensive and portable ventilators that improve the treatment of the most critically sick Covid-19 patients.

The technology, a patented, intelligent 3D-printed origami tube, looks to copy the precision folding of origami to develop 3D printable technologies for ventilators. Mechanical ventilators have two key components – an active airbag and a venting control system. Here, an active airbag was designed using mechanically tunable 3D origami structures that offer reliable and reconfigurable characteristics, such as the airbag’s volume being tuned by controlling the triangular angles in the 3D origami-folding plates.

A mechanical ventilator with a 3D origami tube was produced to replace the standard rubber air bag with the capability of self-monitoring air pressure using 3D-printed sensors on the air tube surface. As research leader Woo Soo Kim told Materials Today, “3D designs and printing gave us an opportunity of customization of the origami ventilator’s air-volume capacity with reliable monitoring.”The portable mechanical ventilator can assist breathing by accurately contracting a 3D-printed origami tube instead of using the usual bag-valve-mask (BVM) approach, which helps reduce the size of the assisted breathing machine while offering improved mechanical strength. The design and lightweight materials used in the portable origami ventilator also reduce production costs as over 95 percent of the components can be 3D-printed.

The small and lightweight design, and low production costs means the portable ventilator is useful for treating Covid-19 patients, or patients who need a compact and transportable device away from a hospital, such as long-term care homes or in remote rural areas and developing countries. This is especially crucial due to the growing concerns about a lack of ventilators to handle the increased demand brought on by the pandemic.

With the same strategy, the team is also developing 3D origami dry electrodes for monitoring patient health. These dry electrodes can detect and monitor physiological signals, such as heartbeat, breathing, temperature, and muscle movements, just with the touch of the electrodes, technology that one day could be used to assist doctors and nurses by allowing them to assess patients’ health remotely through a robot helper.

Although the new ventilators still need medical approval before they can be used in a clinical environment, the researchers are seeking co-design and collaboration with the biomedical sector for a user-centered design approach.

These systems are being developed in many stages – R&D by researchers, testing by clinicians, and mass production by manufacturers, some gaps may be there at each stage of development.

The common problems, such as putting exhaust valve near patient to stop accumulation of CO2 in the air pipe, proper sterilization of air ducts after use, providing better control over ventilation parameters, operation in pressure and volume-controlled modes, needs to be integrated in future portable ventilator designs, for better outcomes. Moreover, these designs need to be put into test in real-life conditions, where they have to operate continuously for days, without supervision under high-load conditions in hospitals. To provide better insight to fill the gaps in the performance of these low-cost-portable designs, complete bench-testing of these ventilators is required. Every system needs to be in accordance with the guidelines provided by various health organizations, rather than the temptation of making quick profits. Government bodies can also intervene at this stage to ensure that proper instrumentation and methodology is being used for developing the automated mechanical resuscitator systems. It is the collective efforts of engineers, doctors, scientists, and even policy makers that will bring better designing and implementation of these low-cost portable mechanical ventilators to effectively fight against the current and future pandemics.