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While the researchers from King’s College and Imperial College London said the method should only ever be considered “in the most extreme circumstances”, they said their work had mitigated some of the risks.
The government issued an urgent call for new ventilators in March amid fears that NHS capacity would be swamped by Covid-19 patients. Although forecast demand was thankfully overstated, high numbers of international coronavirus cases means ventilator capacity could be stretched elsewhere. The machines, which ‘breathe’ for patients when they are unable to do so themselves, are also useful when treating other conditions or injuries.
Ventilators are normally specifically programmed to each patient, as each patient requires individual pressures and volumes of airflow. The researchers developed a theoretical approach by which one ventilator could help two patients with varying lung problems at the same time, with airflow – or tidal volume – for one patient manipulated independently of the other.
The team developed a theoretical model, based on an electrical circuit analogy, and used it to test various configurations for connecting a single ventilator to two patients. They found that providing tailored ventilation to different patients from one ventilator was theoretically possible when variable resistances and one-way valves were added into the inhalation and exhalation paths of the ventilator circuit.
The researchers say the theoretical model could be used by other teams to evaluate other potential solutions.
“Beyond the Covid-19 pandemic, the approach could potentially be useful in a range of other extreme scenarios, such as coping with acute disaster surge capacity limitations or in a military battle field context,” said study co-author Dr Peter Vincent from Imperial.
Co-author Dr Steven Williams from King's said: “We show that our proposed modified splitter can help by allowing one particular ventilation parameter – tidal volume – to be adjusted.”
There are a range of “significant” issues associated with ventilator splitting, the team said, and it should only be considered in extreme circumstances because of the serious risks. Their method could be considered as a ‘last resort’, however.
The team is now looking for international feedback, and the researchers hope to start bench testing the approach.
The work was published in Royal Society Open Science.
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