reBreather: Prototype to reuse oxygen exhaled by patients is here, thanks to IIT-Bombay

The IIT-Bombay team has designed the prototype of a breathing device called ‘reBreather’. [Representative Image]

A team of alumni, students and professors at the Indian Institute of Technology-Bombay (IIT-B) have come up with an innovative way to reuse the exhaled oxygen and enhance the lifetime of O2 cylinders for COVID-19 patients.

Amid the rising demand for medical oxygen due to increasing COVID-19 cases in the country, the team has designed the prototype of a breathing device called ‘reBreather’. The semi-closed circular breathing system allows coronavirus patients to breathe in unused exhaled oxygen by scrubbing out carbon dioxide and blending in fresh oxygen.

The device will also help in minimising wastage of oxygen at a time when there is a heavy demand for it and hospitals are facing an acute shortage.

According to the team, a healthy person breathes in five litres of air per minute, which corresponds to about 1 litre/minute of oxygen being inhaled. Of this, approximately 0.25 litre/minute of oxygen is consumed. In the case of COVID-19 patients with severe breathing problems, a person can receive oxygen through a combination of the nasal cannula and mask at a flow rate of up to 50 litres per minute. With an open-loop breathing cycle for such patients, most of the oxygen is lost back to the atmosphere.

The researchers at IIT-B have used a concept of breathing devices, which is commonly used in diving, to create ‘reBreather’ to cut down on oxygen wastage.

“A rebreather is a closed (or semi-closed) loop system that helps the user to rebreathe the unused oxygen that they have just exhaled. To do this, rebreathers have a section that helps remove the CO2 in the exhaled air thereby preventing an increase in the CO2 concentration in the closed-loop system. The amount of oxygen absorbed by the user is replenished by a fresh supply of oxygen into the closed-loop,” according to the project detail issued by Tata Centre for Technology and Design.

The proposed method of recirculation of oxygen will help bring down the usage of over nine oxygen cylinders in a day for a critical patient to one or two cylinders, as per the calculation by the team.

Amid the rising demand for medical oxygen due to increasing COVID-19 cases in India, the team has designed the prototype of a breathing device called ‘reBreather’. (Image: github.com/TCTD-IIT-Bombay/reBreather)

The minds behind the concept are affiliated with TCTD, the department of chemical engineering, and Nex Robotics—a start-up by alumni of the institute.

The technical details of the prototype, which has been tested informally on healthy volunteers, have been made public under Creative Commons to grant access and replicate the design.

“Our objective in releasing this design now is to document the science behind the technique and test that it works in a practical context, and potentially help mitigate wastage of O2 at a time when there is a heavy demand for it,” the document stated.

A single unit of ‘reBreather’ cost the team around Rs 10,000. “We have sourced these with relative ease in Mumbai; you may find cheaper - and better - alternatives for these items,” it said.