Hess offers iron lung for COVID-19
Businessman Mark Hess got the idea after a statewide conference call at the end of March with Kansas’ U.S. Sens. Jerry Moran and Pat Roberts.
“They were saying there was a shortage of ventilators, and our team kind of got together to think about what we could do,” said Hess, vice president of operations at privately held Hess Services Inc.
The Hays-based manufacturer supplies oil field equipment throughout the United States from its 168-acre campus northwest of town. Currently all but 20 of the company’s employees are on furlough through Gov. Laura Kelly’s stay-at-home order through April 19.
“We’re a pressure-vessel manufacturer,” Hess said, recalling the call and noting Hess manufacturing plants can be readily adapted. “I said, ’Let’s just go ahead and look at making the old-style ventilators.’ They’re a positive and negative air-pressure ventilator, they’re commonly referred to as iron lungs.”
Proven during the nation’s polio epidemic lasting into the 1950s, the iron lung could make a comeback helping COVID-19 patients breathe, Hess said Tuesday from one of the plant’s fabrication buildings.
His idea to make it called for a field trip the Sunday after the call to see an iron lung at the Barton County Historical Society Museum in Great Bend.
From there, a team of five began working on the project with Hess: Morgan Gerstmann, Hess robotics manager; Luke Fox, Hess chief engineer; Matt Orr, Hess operations manager; Hays physician and Hess’ sister Katrina Hess, medical adviser on the project; and former Hess employee Jordan Huwa, now a partner with Hays electrical contractor Primary Electric.
Drawing on original iron lung designs, the Hess result is a simple-to-operate 1,200-pound chamber, 6 feet long and 36 inches around, big enough for adults, with a half-horsepower variable frequency drive motor, bellows and a programmable digital control. It plugs into a 120-volt outlet.
“It’s 3/16-inch thick A36 carbon steel,” Hess said, “same thing we make oil tanks out of.”
“It’s a tried-and-true design,” said Huwa, with the addition of the variable frequency drive. “Most of these, if they’re still around, they are in basements and moth balls. There are still a few people who use them.”
The project came together quickly, from cutting, to welding and painting, said Hess, using components readily available, and others made at the plant, whether the plasma cut stainless steel or the neoprene bellows and gaskets.
“We literally measured out the unit on Sunday. Morgan and Luke came back and did some engineering calculations through Wednesday. Thursday they came up with the shell design and we welded up the shell on Friday and Monday,” Hess said. “We also ordered all these component parts and we cut all the other components, did the assembly on it last week. And then our electrician came up with the variable frequency drive, and the HDMI screen that makes it simple for people to operate, just to change the amount of respirations per minute.”
Waiting on the FDA
Despite the call for U.S. manufacturers to step up, Hess said he’s gotten no response to several inquiries with the Food and Drug Administration, which must approve the device.
He was expecting quick approval, given the dire need for ventilators nationwide, and since the machine is classified as lower-risk because its extra-corporal, meaning there are no implants or injections.
A simple pressure-vacuum device, Hess said, the machine has built-in safeties.
“We could never exceed the maximum level of pressure or vacuum, so it’s non-injurious to the individual,” he said. “We notified them, we’re requesting guidance to get the Emergency Use Authorization, two weeks ago today. And we have yet to hear back.”
Physician and U.S. Congressman Roger Marshall, R-Kan., has tried to help, he said.
“Mark Hess reached out to our office in March when he first devised the idea for his ventilators,” said Marshall’s spokeswoman in Kansas, Katie Sawyer, when asked about the FDA and the Hess iron lung. “Our office put Mark in touch with the White House and Vice President’s Task Force on the coronavirus to begin the process of having his product registered and approved by the FDA for use in medical facilities.”
With approval, Hess could bring back 40-50 employees and start making 20 iron lungs a week, ramping up production to 100 a week, he said, and delivering them to rural communities with their fleet of 27 over-the-road trucks.
“If they told me today,” he said on Tuesday, “we could have shells welded up by Friday, get them through paint, and just continuously run them.”
Sawyer said Marshall supports enabling U.S. manufacturers and private industries to help fulfill the needs of the medical community, following review by health care experts.
“American innovation and ingenuity will lead us to a solution,” she said in an emailed response.
Designed during the polio epidemic
With all the concern U.S. hospitals will be overwhelmed by COVID-19 patients, Hess said the iron lung, which is easy to operate, could free up health care workers.
“These have actually been used for 92 years, that’s how old this technology is,” Hess said. “About a dozen patients in the United States are still using them, most of them actually polio victims.”
The Hess machine has a ballpark cost of about $20,000, he said, compared to $50,000 for a ventilator. He has no plans to patent it.
“It’s based on a design and principal that’s been used for 92 years,” Hess said. “If this is something that can help people out, I’m not going to sit here and say ‘You guys can’t make this because I want to put money in my pocket.’ That’s not a good moral, ethical stance to take, so we would never pursue that. Hell, we’ll give it open source. If anybody wants to manufacture this, we’ll give them the drawings.”
The pressure differential process is similar to the pressure vessels Hess makes for oil and gas separation.
The iron lung places the entire body, except for the head, under a vacuum, making a patient’s chest cavity expand to take deep breaths, then applying a similar positive pressure, making the patient exhale, he explained.
“When you produce oil, it comes out of the well bore, typically at around 1500 to 2000 psi,” said Hess. “The pressure pushes the oil, gas and water emulsion to one of our separators that then uses simply pressure differential or gravity to separate the oil, gas and water. Just applying that simple basic functionality of controls to this device was an easy transition for my engineering and electrical people.”
Hess tried out the Hess iron lung himself for about 15 minutes.
“It’s just a different sensation, because it will put you under a vacuum and pressure, so it will suck air into your lungs and force exhalation,” he said. “It’s not extremely unpleasant.”
Robotics manager Gerstmann, who designed the Hess lung, said it’s essentially a larger version of the Drinker Collins duplex respirator he saw in Great Bend.
Most of the components and the methods of fabrication are fairly simple, he said.
“As you can tell, these look fairly similar to those, the tanks that we build, just scaled down,” said Gerstmann, pointing to the huge vessels towering over the plant interior. “So as far as designing this, it was a pressure vessel.”
A lot of the usable features exist in most iron lungs, he said. Most iron lung designs use the same principles and are fairly similar one to another, including many with windows, making it easier to work with patients. One design used leather bellows, pulled with a mechanical arm.
“We essentially combined two different methods with a rubber bellows on the bottom but mounting on the end. So we followed a lot of existing styles,” he said. “We ended up going with a larger vessel to accommodate adults, so we had to get a larger volume.”
How it works
The Hess iron lung has a variable drive motor.
The original iron lung was completely mechanical, with a one-to-one ratio of inhalation to exhalation, Hess said. Outfitted with a mechanical variable-speed drive, the mechanical crank would change respirations between nine and 24 a minute.
“What we’ve done with the variable frequency drive is it will make it so you can inhale, and take a little pause to exhale over a period of time to make it more comfortable,” Hess said. “It’ll vary by person and their comfort level. If you’re at rest and sleeping you probably have a slower respiration rate and a deeper inhalation, and more of a pause at the end, whereas if you’re more alert it’s probably more per minute.”
Iron lungs operate on basic physics principals, said chief engineer Fox, who did the math for the lung, calculating the thicknesses of the materials, how much air volume must move to achieve the right pressures, and how much horsepower and torque was needed for the motor, for example.
“There’s no major calculus or anything really fancy, it’s just a matter of air pressure and volume,” Fox said. “Dr. Hess was the one who told us the requirements for the pressure, and there was literature about that as well, like what pressure do you need to assist someone to exhale, so those were the starting parameters and we used that to figure out the rest.”
The bellows, he said, move a certain volume of air, with a certain volume of air inside the chamber.
“So as you compress and expand, you change the pressure in the chamber, inversely to the volume,” Fox said.
Huwa did the electrical controls, including designing the programmable logic controller, or PLC, doing the PLC screen layout and functional buttons, and programming it.
“We had to come up with all the equations to make all this stuff be variable. We couldn’t just lock it in. We wanted it to be adjustable to fit the person’s needs. In doing that there’s mathematical equations we had to come up with to make that work.”
Huwa is satisfied the control is user-friendly, because his 7-year-old had no problem understanding it.
“You can change the breaths per minute, just up and down, change that ratio, start and stop,” he said. “You can monitor, we have a goal respiration rate and then we have the actual, and we’ll graph that so a doctor can see where that respiration rate is at, is it fluctuating, is it constant, something that a health care professional can look at and see what’s actually happening so they can make some adjustments.”
The motor sound alters
“That PLC is telling that motor how fast to go, when to change, and it does the math on converting from something we can understand here as breaths per minute into something the motor can understand, like how fast I need to go,” Huwa said.
The motor can go a maximum of 1,800 rpm. Tuesday it was operating on the slow side, at 565 rpm, roughly six breaths per minute, Huwa said. Fast would be just shy of 1,200 rpm, or 13 breaths per minute.
“It depends on the person and how efficient your lungs are at taking in oxygen,” Huwa said. “Your respiration rate changes throughout the day, depending on what you’re doing. If you’re just resting, it’s a lot slower than if you’re stressed or working out or something like that.”
Included in the operating manual are specifications for the materials and where to source them, said Operations Manager Orr. He figured out the materials and the coatings, and how it would fit into the way Hess manufactures.
“We spent quite a bit of time looking at the various materials, and all the different cleaners that could possibly be used, especially with some of the cleaner shortages that are going on,” Orr said. “So we looked at different things from bleach to ammonia, the different means they could disinfect these things, to find the most compatible materials to use for the windows and gasketting materials.”
They’ve worked out the bugs for making it, he said.
“It’ll manufacturer really well. There were just a couple fabrication challenges that you run into when you’re doing a first run,” said Orr. “They’ll be easily produced in the next versions.”