Australian researchers say they have successfully experimented with a new device that can help share a single ventilator between multiple patients as an absolute last resort in times of dire emergency.
The practice of ventilator splitting – using a single ventilator to assist the breathing of two or more patients – is generally avoided because it poses serious dangers.
The practice is largely unregulated, experimental and untested, and the consensus of the US Society of Critical Care Medicine and American Association for Respiratory Care, among others, is that it is not safe and should not be attempted with current equipment.
“It is better to purpose the ventilator to the patient most likely to benefit than fail to prevent, or even cause, the demise of multiple patients,” the groups advised last month.
Despite this, the Covid-19 pandemic has prompted the use of ventilator-splitting in both Italy and the US, as stretched intensive care units struggle to meet overwhelming demand with a shortage of ventilators.
A key problem with ventilator splitting is that patients have varying requirements for air pressure, flow and volume, which cannot all be met using a single machine. The practice also poses a risk of cross-infection and makes proper monitoring impossible.
A group of Australian researchers have been experimenting with a new device that could allow for a safer method of ventilator splitting, if it must be used in cases of “extreme emergencies”.
The peer-reviewed study, published in the international journal Anaesthesia, was led by Dr Alexander Clarke, of the Royal Women’s Hospital in Melbourne, and Monash University’s Dr Shaun Gregory.
The study does not recommend ventilator splitting. But the researchers did have some success in addressing one of the key risks associated with the practice.
They used a new device, built with common hospital parts, to act as a flow restrictor. The restrictor gives doctors some control over the air being delivered to different lungs.
“It works by compensating for differences between patients, to an extent,” Clarke told the Guardian. “So some patients need a lot of pressure, some patients don’t need so much pressure. By putting in the clamp, you can decrease the amount of pressure that one person gets.”
The experiments were conducted in simulated environments, using test lungs.
The device allowed researchers to modify the pressure, flow and volume for each test lung.
“We experimented with a few different devices to do this, and assembled some common hospital parts, that we should have available en-masse,” Clarke said. “Then we used some lung simulators, devices that share some of the characteristics of human lungs, and we used a standard ventilator in an intensive care unit, and took measurements using some engineering tools.”
Clarke said the results needed to be treated with caution, but were promising.
“Getting more ventilators is mostly a logistics problem. This is a stopgap measure for that,” he said. “It’s a device that none of us ever want to see used, and it’s really just about something we can get up and running very quickly, using the parts you can scramble together.”
Gregory said the devices required further trials.
“While the discovery is promising, the use of this method in the clinical context has not been validated and we don’t recommend its wider use without further trials,” he said. “We are hopeful of one day being able to get great surety with this approach to ventilator splitting so we can help save lives in dire cases of emergency.”
