Media reported that British engineers are developing a modern version of the negative pressure ventilator, or NPV. But we are more familiar with, should be “iron lung” this commonly known. As a relief to the respirator shortage caused by the COVID-19 epidemic, this simple, inexpensive alternative can provide much-needed support for critically ill patients.
exovent rendering (from: John Hunter / Steer Energy)
In response to the current epidemic and projected demand, health authorities need to strike a difficult balance between ensuring the quantity and safety of medical equipment.
Even with the relevant equipment, it needs to be monitored by trained professionals. In addition, in the process of intubation, its danger to patients and medical workers can not be ignored.
It should be noted that the iron lung (negative pressure ventilator) works almost the opposite of an intermittent positive pressure ventilator (IPPV). The latter pumps air or oxygen directly into the lungs to help the patient breathe.
As a concept proposed in the 17th century, its classic shape is to create a larger, airtight cylinder-shaped chamber large enough to hold a pleasant one, with the patient’s head protruding through a special collar.
There is a diaphragm hanging from the motor in the chamber, and the crank operates under the drive of the motor, causing the diaphragm to expand and contract. As the volume of the chamber changes, the resulting air pressure will rise and fall.
Even if the patient is completely paralysed, the negative pressure ventilator can cause the patient’s chest to expand and contract. At the height of polio in the 20th century, this iron lung was common in hospitals and even homes.
Although it has since been replaced by more advanced machines, the crisis caused by the COVID-19 pandemic has left many once again looking to it.
The University of Warwick, Marshall Aerospace and Defence Group, Imperial NHS Trust, Royal Ear, Nose and Throat Hospital, and a team of citizen scientists, clinicians, academics, manufacturers and engineers have developed the new NPV device known as “exovent.”
The device is currently in the prototype phase and will be tested at two intensive care clinics in the UK. Unlike ventilators, exovent does not require intubation and is easier to design and operate.
The designer says patients are able to stay awake, take medication, eat, and talk to people over the phone. In addition, the machine improves heart efficiency by 25% compared to conventional ventilators, so you need to be aware of the adverse effects on heart function.
The developers said that once approved, the UK is on track to build 5,000 exovents in a week. In addition, the device can be used in regular wards, freeing up valuable ICU resources for critically ill patients.
Since the machine only closes the chest cavity to compress air and oxygen, several moving parts involved can be used at any time and can be personalized to the patient.