Engineering ways to keep doctors safe from COVID-19

In the ongoing fight against COVID-19, doctors and researchers are working around the clock to find innovative ways to stop the virus’ spread. From developing and testing new vaccines to understanding the immune systems of those with preexisting conditions, researchers are tackling the problem from every angle. But sometimes, even simple solutions can make a world of difference.

That’s why, when Allegheny Health Network (AHN) and Magee Plastics needed help testing and perfecting their simple solution to reducing viral spread in hospitals, they turned to Carnegie Mellon University’s Coty Jen and Ryan Sullivan. Both Sullivan and Jen are members of the Center for Atmospheric Particle Studies (CAPS) and experts in the behavior of aerosol particles in the air.

“The goal of the project,” says Sullivan, and associate professor of chemistry and mechanical engineering, “is to design and determine the proper implementation of an intubation cube—a plastic housing that can be fitted over the patient to help contain the spread of COVID-19 particles when they are being connected to a ventilator. These types of enclosures have been deployed in some hospitals over the course of the pandemic, but we’re looking to create something that is inexpensive and easier to clean, while also quantifying how effective these enclosures are at containing aerosolized particles during hospital use.”

The problem lies in the way that COVID-19 particles spread during the tracheal operations that are often required to help patients in severe cases of the virus. Healthcare providers must stand close to the patient during intubation and extubation—inserting and removing a tube down their throat to help them breathe. These operations, especially extubation, can result in severe coughing fits that spread infectious droplets to nearby healthcare providers. In fact, even the patient talking or breathing can produce small aerosolized particles that may contain the virus, which can also infect nearby healthcare workers. The potential for exposure to infectious aerosol particles puts anyone in the operating room at risk of contracting the virus during intubation procedures.

The enclosure initially designed by AHN and Magee Plastics is quite simple: a transparent cube made of sturdy plastic that fits over the patient’s head and torso as they lie on the operating table. The cube has a large hole where it fits over the patient’s waist, a hole in the front for the surgeon’s hands, and a small side hole for the ventilator tube to pass through. But of course, in a solution designed to keep airborne particles inside, any number of holes can decrease the performance.

These tests are vital in assuring health care providers that these methods can keep them safe, so they are no longer operating in the dark.

Coty Jen, Assistant Professor , Chemical Engineering

“The first issue in knowing how to stop the spread of these particles,” says Jen, an assistant professor in chemical engineering, “is knowing how they spread in the first place. For instance, during extubation, how far do the particles actually go? What is their trajectory? How long do they remain in the air? These are all pretty basic questions that can be answered through simple engineering experiments. Yet these tests are vital in assuring health care providers that these methods can keep them safe, so they are no longer operating in the dark.”

The researchers’ first step was to design a method for covering the necessary holes in the box that would most effectively keep particles contained inside. But instead of high-tech methods like rubberized glove inserts or vacuum hoods, Jen and Sullivan focused their efforts on solutions that can be implemented using single-use materials that most hospitals already have on hand.

“The solution we discovered as being most effective involves a multi-layer seal technique,” says Jen. “Using cheap and easy-to-acquire cling wraps that most hospitals already have in stock, the holes can be sealed around the surgeon’s hands, allowing them access to the patient while still containing the particles inside the cube. Then, a plastic drape cloth can be laid over top of the cling wrap to close off both the hand and waist entrances. This way, hospitals could have a few of the enclosures on hand for re-use, then change out the plastic coverings for each patient. Using plastic coverings in conjunction with the enclosure, we have measured a 99% reduction in particles transferring from inside the cube to the room outside.”

In tests to perfect this design, the team used common techniques for tracking and measuring the movement of particles, techniques well known to many researchers who study aerosol science and the chemistry of particles in our atmosphere. Their measurements found that when the cube is properly in place and draped according to their proposed method, 90% of the aerosol particles have settled to the bottom of the cube within fifteen minutes, and the few particles that can escape only travel as far as a foot away from the patient.

Though the studies the team performed were relatively simple and turned up few surprises, it highlights how important it is to broadly share scientific information across disciplines. What may seem like easy-to-acquire information for experts in one field, could be lifesaving in another.

Now that the team has proven the effectiveness of these boxes, the next goal is to implement them across all hospitals in the Allegheny Health Network. But thanks to the simplicity of this elegant solution, these boxes could be implemented in any hospital, even those in rural areas or others with limited funding.

“Our new box and multi-layer sealing method is easy to sanitize, uses inexpensive components, and has been proven effective in reducing the spread of aerosol droplets during simulated intubation procedures,” says Sullivan. “We think this could really help to protect frontline healthcare providers as they treat patients suffering from severe cases of COVID-19 and other respiratory diseases in the future.”