Cause of equine hyperbaric oxygen chamber explosion remains unknown

Formal certification and new operating procedures for hyperbaric oxygen therapy may be on the way after a Feb. 10 explosion at a Florida equine rehabilitation center killed a 28-year-old woman and a 6-year-old Thoroughbred gelding.

The cause of the explosion at the Kentucky Equine Sports Medicine & Rehabilitation Center (KESMARC) South Equine Rehabilitation Center has not yet been determined, but multiple agencies—including the Florida State Fire Marshal and the federal Occupational Safety and Health Administration (OSHA)—are investigating.

Deborah Cox, a spokesperson for the Fire Marshal’s office, says she can’t release any details, but confirmed the investigation is ongoing.

Michael Wald, a spokesperson for OSHA’s Region 4 office, also confirmed an investigation is underway, but says the agency has up to six months to issue a final report.

Details about the explosion were described in a Feb. 17 report released by the Marion County Sheriff’s Office (MCSO). The report states that emergency workers were called to KESMARC in Morriston, Fla., Feb. 10 just before 10 a.m. The facility—housed in a large metal barn—opened its doors in 2009 and contained a number of stalls within its hyperbaric oxygen chamber. The report notes that the entire end of the barn that housed the chamber was marked by “total destruction.” The body of 28-year-old Erica Marshall, a KESMARC employee, was found buried under the rubble.

KESMARC’s manager Leonora Byrne told authorities that Marshall was operating the chamber prior to its explosion. She has operated the chamber for the past two years and was trained by the chamber’s manufacturer, Equine Hyperbarics (also known as Equine Oxygen Therapy and Veterinary Hyperbaric Oxygen).

The horse being treated was from Stonehall Farm in The Plains, Va., and owned by Jacqueline Mars, according to a statement from the U.S. Eventing Association (USEA). The 6-year-old gelding, named Landmark’s Legendary Affaire and called Tux, was receiving a general wellness treatment in preparation for the upcoming competition season.

According to Sorcha Moneley, who was injured in the blast, Tux had been in the chamber about four times before. Moneley was observing treatments that day, the MCSO report states.

The report notes conflicting statements on whether or not the horse had been sedated prior to treatment. However, Moneley told investigators that Tux had not had problems during prior treatments.

The horse was being treated for equine protozoal myeloencephalitis (EPM). Moneley reports that Tux had been in the chamber for about 22 minutes and was “unsettled.” Eventually, Tux kicked sharp to his rear, knocking a lid at the rear of the chamber. The lid became dislodged and revealed raw metal, MCSO notes. Tux, who was wearing steel shoes, dislodged protective padding inside the chamber and continued to kick. The horse’s kicks subsequently created sparks that resulted in a fire.

Upon seeing the flames, Moneley left the chamber to call the fire department. Marshall worked to bring the chamber to its normal pressure. As she left the chamber, Moneley told investigators that she heard a small explosion followed by a second, larger explosion a moment later. She was about 20 feet away from the chamber when the blast occurred, knocking her down, Moneley says.

MCSO’s report lists Marshall’s cause of death as blunt force trauma and thermal injuries as the result of an accidental explosion.

Moneley was taken by helicopter to a nearby hospital following the blast and is now in fair condition. Funeral services took place for Marshall on Feb. 17 in Florida, and she will be interred in her home state of New Jersey.

Byrne did not return phone calls by press time, and Rob Miller—one of KESMARC’s owners—declined to comment on the explosion.

Kirsten Johnson, who owns the Kentucky KESMARC facility and is affiliated with Equine Oxygen Therapy, says she cut ties to the Florida KESMARC two years ago, but expressed her sympathies for Marshall and Tux.

“Our concern and our love goes to the family of the life that was lost,” Johnson says.

Despite rumors that Equine Oxygen Therapy has sent letters to veterinarians warning them to shut down their hyperbaric chambers, Johnson says no such letter has been sent.

“At this time, we’re in communication with the folks who have chambers,” Johnson says on behalf of Equine Oxygen Therapy. “We have been since it happened. At this point, until the investigation is done, our hearts go out to family of the life that was lost, the horse and the girl that were injured. But the investigation is ongoing. It would be irresponsible to talk about any of it until it’s complete.” Johnson says veterinarians who use the company’s chambers are well aware of what is going on.

“All of the veterinarians who own hyperbaric chambers have been contacted by the company,” she adds. “Is everyone on heightened alert? Of course we are. Have we made any demands? No. We are being responsible, and we are moving forward in a responsible way.”

After the investigation is complete, Johnson says the company will provide more information about what happened and whether any changes will be made in terms of chamber operations. But nothing has been decided yet, she says.

Dennis Geiser, DVM, Dipl. ABVP, and director of hyperbaric services at the University of Tennessee’s Department of Large Animal Clinical Sciences, says hyperbaric therapy is used as both a primary and adjunctive therapy. The overall effect is to increase blood oxygen, pushing more oxygen into damaged tissue to assist with healing, he says.

In humans, hyperbaric therapy can be used to treat things like smoke inhalation and decompression sickness, but in animals, it is used more widely.

“In the animal world, since we don’t have third-party pay, we can treat a lot of different problems,” he says, listing conditions in horses like chronic wounds, joint infections, some neurologic problems, cerebral adema and laminitis.

Side effects can always occur in a pressurized environment, and sometimes animals will shake their heads or yawn to equalize pressure. Sometimes, therapists will then back off the treatment and proceed more slowly. Geiser says he has also heard of problems with bringing a patient back up from treatment depth too quickly, but he’s never seen it.

Sedation prior to using hyperbaric oxygen treatment is discretionary, he adds. Older chambers were small and sedation was often administered. But modern chambers are larger and allow horses to walk around, he says.

“If we know up front that the horse is kind of skittish or you get into a treatment and you find they’re not handling it well, we might stop and sedate them,” Geiser says, adding the decision is made on a case-by-case basis.

Until an official investigation is complete in the KESMARC case, Geiser says there is no way to know what caused the explosion.

Geiser says he is working to set up a veterinary hyperbaric medicine society as well as a certification program as another measure of safety, especially as more and more chambers are added to veterinary practices as an adjunct to therapy.