COVID-19 patients who cannot breathe on their own require ventilator support in order to survive. A tube must be placed through the mouth into the trachea.
This procedure – called endotracheal intubation – is one of most dangerous scenarios confronting health care providers fighting in the front lines of the coronavirus pandemic.
Patients often cough during the procedure, which can result in the spread of droplets and aerosols. Even if a doctor or nurse is wearing a face mask, there is a risk of being infected if droplets are not contained. Even when the patient merely breathes, there is a risk that contaminated aerosolized particles will remain suspended in the air. A common practice is to to place enclosures over the patient to contain the hazards and protect caregivers. But this can greatly complicate the procedure, especially in emergency room settings where intubation must be done quickly and efficiently.
Now, two engineering professors and a machine shop supervisor at the University of Rochester – in less than 20 days – have worked hand in hand with emergency room clinicians at Strong Memorial Hospital to customize an intubation enclosure system that provides an extra safeguard during these procedures. Their “intubation box” encloses patients – and any contaminated particles they have exhaled – yet still allows the clinicians access to perform the lifesaving procedure quickly in the ER.
“We are pleased to be able to offer this extra layer of protection to those who wish to use it,” says Amy Niertit, M.D., assistant professor of clinical emergency medicine. “It wouldn't have been possible without the hard work and dedication of the bioengineers here at the University of Rochester.
“I, for one, am proud to be part of a group of individuals and an institution that has been so responsive and supportive to one another and the community in these unprecedented times.”
For the engineers, this was not only an opportunity to lend support to their medical colleagues in the front lines, but also to “practice what we preach to our students,” says project leader Greg Gdowski, Ph.D., associate professor of biomedical engineering. Gdowski who directs a medical device design program for master’s students.
“I will be bringing this up as an example to my students for years to come.”
Starting with something simple
The project began on April 4. On that date, 504 confirmed cases and 17 deaths had been reported in Monroe County, and Strong Memorial Hospital clinicians were bracing for the possibility of an overwhelming onslaught of patients, similar to what was occurring downstate.
Chris Muir, Ph.D., a professor of mechanical engineering, and Gdowski were asked by the Strong clinicians to construct a rudimentary intubation box reported in the New England Journal of Medicine. It consisted of a simple three-sided box that was placed over the patient’s upper torso, with two holes that a clinician could reach through to carry out the endotracheal intubation. Muir created an initial design, then used a laser cutter in Gavett Hall on the River Campus to produce a prototype in a matter of hours.
“This is exactly the way I wish my students would operate,” Gdowski says. “You create a minimal viable product, so you can start getting feedback from the clients -- before you invest a lot of time in creating something they may not like.”
The next day, Gdowski took the prototype to the Medical Center, where Niertit and other emergency room physicians responded enthusiastically – and immediately offered feedback on the size and placement of the holes. “We quickly realized that the holes were too small and the box was too short to accommodate specialized video-assisted intubation tools called glide scopes,” Gdowski says.
Muir promptly revised the design that day, and this time took it to John Miller, supervisor of the machine shop at Taylor Hall, to fabricate a second prototype. Next morning, Gdowski was back at the Medical Center getting more feedback. This iteration was better, but it was clear that the corner of the box occluded the clinician’s view of the procedure.
In all, six or seven iterations were necessary, each introducing refinements suggested by clinicians, or addressing new issues inadvertently created by the refinements.
For example, the team incorporated cutouts in the sides so the box could slide over larger patients, who might take up the entire width of a bed or cot. Miller also came up with nifty way to curve the back onto the top of box, rather than meeting at a 90-degree angle, which made it easy to see the patient inside. However, these revisions made the box less stable when placed on the cushiony surface of a bed or cot.
Extending the curve of the upper portion of the box increased the torsional stiffness as well as improved the location of the center of gravity, making the structure more stable. The new design directions were simulated using Siemens/NX, a design and engineering software used on River Campus. Stiffness was modeled using Finite Element Analysis and stability by monitoring the center of gravity of the structure as the design iterations were performed.
“And that was it” Gdowski says. The process has made him “a true believer in constructing minimal viable products to ensure the final product meets the needs of the customer. I never would have guessed that the simple box we started off with would evolve into a final design that included an arched-structure.”
Niertit thanked Gdowski for “making himself constantly available, flexible and enthusiastic in helping us create a workable solution.”
The first box was delivered to Brockport Medical Associates, which is part of Strong Memorial Hospital, last Thursday. Gdowski anticipates being able to provide 10 more boxes to the Strong Hospital emergency department in the next few days.
“It really has been an intriguing process,” he says.
(Jim Zavislan, associate professor of optics, also contributed as consultant for the project.)