Oxygen makes up about 21 percent of the air we breathe, with each breath bringing luxuriant, life-sustaining nutrients to the lungs, blood, brain, and body.

In its purest form, oxygen, when inhaled at high pressure, can have rejuvenating therapeutic and physiological effects, such as treating radiation damage from cancer treatment and non-healing wounds.

Hyperbaric Medicine at Penn utilizes hyperbaric oxygen therapy—breathing 100 percent oxygen at an elevated ambient pressure—to treat patients with an assortment of ailments. Specialists in hyperbaric medicine use oxygen like a drug, dosed through a state-of-the-art hyperbaric chamber, which helps to increase the amount of blood vessels to areas of the body that may lack an adequate supply of oxygen.

Matthew Kelly, director of clinical services in Hyperbaric Medicine and a clinical assistant professor in the Department of Emergency Medicine at the Perelman School of Medicine, says the classic definition of hyperbaric oxygen is the delivery of oxygen at an increased pressure greater than the pressure at which human beings are currently living.

“That’s what hyperbaric means,” he says, “‘hyper’ being high and ‘baric’ being pressure. It’s taking the body and placing it under pressure, and the way we do that is with the hyperbaric chamber.”

Kelly says human beings live under about one atmosphere of pressure. The entire column of air from the Earth’s crust all the way up to space, “all that weight with gravity pushing against us,” Kelly says, is one atmosphere of pressure, the equivalent of about 33 feet of seawater.

“If you were to swim 33 feet under seawater, that’s about the equivalent to the entire column of air above your head,” he says, “obviously water being more dense than air.”

Most patients in Penn’s hyperbaric chamber are treated under two atmospheres of pressure, or about 66 feet of seawater.

“Most of our treatments are at 2 to sometimes up to 2.8 or 3 atmospheres of pressure,” Kelly says. Under extreme conditions, patients are treated at the equivalent of 165 feet of seawater. The chamber was originally built to handle a maximum depth of 1,800 feet, one of the few in the United States that is capable of handling such a large amount of pressure.

Housed in the basement of the John Morgan Building, the hyperbaric chamber—built by the U.S. Navy in 1968—is a massive, submarine-like, multi-place chamber made up of four interconnecting sections. It is around eight feet in circumference and about 30 feet long.

“You can easily treat six to eight patients at a time,” Kelly says.

The chamber room is compressed, but does not contain elevated levels of oxygen; patients breathe 100 percent oxygen through a mask.

The Hyperbaric Medicine team consists of nurses, physicians, physicians-in-training, EMT paramedics who also function as hyperbaric technicians, and support staff.

“There’s always a paramedic or an EMT inside the chamber with the patient,” Kelly says.

Close to 75 percent of Penn’s hyperbaric patient load consists of individuals seeking treatment for radiation damage to soft tissue, bone, or the bladder, and non-healing diabetic wounds. Hyperbaric Medicine is a part of the Department of Emergency Medicine, and Kelly and his team perform emergency services as well, including treating decompression sickness, which can afflict scuba divers and airplane pilots, carbon monoxide poisoning, gas embolism (bubbles in the bloodstream), and occasionally severe infections like a flesh-eating bacteria.

Therapy sessions usually last around two hours; the number of sessions necessary depends on the condition. Kelly says some patients with carbon monoxide poisoning need only three treatments; those with radiation damage or a non-healing diabetic wound can require anywhere between 20 and 60.

“Sometimes it’s one,” he says, “but most of them are multiple.”

Patients are referred to Hyperbaric Medicine from a variety of different departments and sources. People experiencing radiation damage to the bladder come from Urology; those with colon damage come from Gastroenterology; and individuals suffering from ear, nose, or throat damage come from Oral and Maxillofacial Surgery or Otolaryngology. Patients are also referred by the two wound care departments at Penn, primary care offices, and plastic or general surgeons.

The age of patients ranges from babies to senior citizens.

“We’ll sometimes have to treat infants and kids for carbon monoxide poisoning and severe infections, all the way up to patients in their 90s,” Kelly says. “Most of our patients tend to be middle-age or older.”

As with any medication, there are side effects to breathing 100 percent oxygen. Kelly says too much oxygen in the brain can, in rare instances, cause a seizure, a side effect more common among people being treated for carbon monoxide poisoning.

Kelly says 99 percent of patients do not experience any difficulties besides pressure in the ears, which is usually resolved by chewing gum, taking sips of water, pinching the nose and swallowing, or yawning.

Penn’s hyperbaric chamber is one of the few in the country with specialists on call 24 hours a day, seven days a week, and serves patients from a large geographic area.

Kelly says he became interested in hyperbaric medicine after finishing up his residency in emergency medicine at Louisiana State University in New Orleans, an area that conducts a large amount of hyperbaric research in diving medicine because of the numerous offshore oilrigs.

“It’s a fun way to practice medicine,” he says. “It’s unique. It’s very unique.”