The patient slides into a clear, giant cylinder. The thick door shuts tightly behind her. The technician turns some dials, and the treatment begins.
This is how many patients begin a session of hyperbaric oxygen therapy, a treatment that has largely outgrown early skepticism and is spreading as an option for various medical conditions.
The treatment typically involves a patient entering a chamber set at a pressure two to three times greater than sea level and breathing 100 percent oxygen.
Its used to treat more than a dozen medical conditions and has become especially popular in treating serious wounds that fail to heal, including those related to diabetes or radiation from cancer treatments.
In some cases, the treatment can help patients save feet or limbs from amputation. One study found that hyperbaric oxygen therapy decreased major amputations in patients with diabetic foot ulcers from about 33 percent to almost 9 percent.
By one estimate, there are now about 20 hospital-affiliated centers in North Carolina that offer hyperbaric treatments, compared to four a little over a decade ago.
In recent years, the Duke Center for Hyperbaric Medicine and Environmental Physiology, a nationally recognized center, has been providing some 3,000 patient treatments a year.
Meanwhile, some centers offer hyperbaric therapy to treat conditions from autism to Lyme disease, even though many experts argue there isnt enough scientific evidence to prove that it works.
We have to have reasonable proof that supports the use of hyperbaric oxygen, said Dr. John Feldmeier, president of the Undersea and Hyperbaric Medical Society, based in Durham.
For those being treated for serious diabetic wounds, hyperbaric therapy allows oxygen to reach damaged tissue to help healing, even when blood flow to the area is compromised.
Jim Postell, a 56-year-old retired police officer in Concord, was afraid he was going to lose his right foot to a diabetic wound. It developed gangrene and it hurt so much that he could barely stand.
Before the treatments started, his doctor had to remove a lot of damaged tissue. Postell was shocked at how much flesh came off.
When I first saw that, I would have never thought in a million years that that was going to heal up, he said. But the therapy worked, the wound healed, and he looks forward to getting back to his old life.
Dean Pyle, a 44-year-old pastor at Harvest Community Church in Huntersville, had also been through the treatments for a serious diabetic wound. He was a bit nervous about getting in the chamber the first time, wary of what it would feel like.
When the pressure increased, his ears started popping as they do during an airplanes takeoff. But that was it. During his 40 sessions each about two hours he grew fond, much to his surprise, of watching the Live! With Kelly show on the TV outside his individual, monoplace chamber.
At Duke, the hyperbaric center has multiplace chambers that can treat 18 to 20 patients at a time. These rooms can be pressurized, and patients typically breathe oxygen through head tents.
Harry Harvin, 58, of Durham, was treated there for a large wound on his right foot from poor circulation. He had a wound on his shin as well.
After losing two toes, he was led to hyperbaric therapy to try to save the the rest of his foot. For a total of 60 sessions, Harvin came in for two sessions a day, one in the morning, one in the afternoon. He was at the center five days a week, leaving home at 7:30 a.m. and getting back close to 5 p.m.
It was like a job; I kind of got used to it, said Harvin, a retired weatherization energy auditor.
The Undersea and Hyperbaric Medical Society now has approved 14 uses based on extensive research, and treatments are generally covered by Medicare.
Longtime professionals in the field say there was early skepticism within the medical community on the credibility of the treatments. And it didnt help when photos of Michael Jackson lying in a chamber supposedly to keep him young surfaced.
They were selling chambers to people to treat, quote, problems, that there was no evidence that it worked on, said Dr. John Wassel, medical director of Presbyterian Advanced Wound Care and Hyperbaric Medicine. So there was a reaction from the medical community.
There are some clinics that offer hyperbaric therapy for conditions outside the widely accepted uses. Charlotte Metro Hyperbarics in Huntersville, for example, sees patients for autism, cerebral palsy and Lyme disease, among others. Athletes trying to speed recovery from injuries are also treated.
Patients sign a consent form where they acknowledge theyre not guaranteed the therapy will be successful in their case. Federal law prohibits clinics from promoting unapproved uses for the chambers, and Charlotte Metro Hyperbarics doesnt advertise the therapy as a cure.
Clients mostly pay out of pocket because many insurers dont cover these conditions. Treatments are typically 40 sessions, which range from $75 to $150 each.
Half of the clinics patients are local, while the other half are from out-of-state.
Were the only center, in a lot of cases, for many people that will even allow them to get in the chamber for what they want to get treated for, said clinic owner Anson Hall, whose daughter undergoes hyperbaric oxygen therapy for an autism disorder.
For treating autism, Dr. Danielle Rose, the clinics medical director, explained that the chambers can stimulate and regulate a patients immune system with the profusion of oxygen and lowering of acids in the body. She said studies have suggested that autism can be aggravated by an immune system thats out of balance.
The Autism Society of North Carolina neither endorses nor discourages hyperbaric therapy, but encourages parents to make informed decisions.
Many doctors in hyperbaric medicine maintain that theres not enough evidence to support using the therapy for autism.
I would feel (it) would be unethical for me to refer a child with autism, where I dont even have an inkling of any evidence that it actually works, Dr. Richard Moon, medical director of the Duke Center for Hyperbaric Medicine and Environmental Physiology.
Boog Atkinson, 57, of Charlotte, hopes the therapy will heal the wounds on her feet.
Its frustrating because you dont know whats going to work, she said as waited to get into a chamber for her 10th or so session. You try so many different things and nothing seems to work. And its just taking forever.
She has even asked friends: When do you give up?
In the chamber to her left was Postell, who was in the middle of his final session.
He once worried that he would lose his foot. And now he cant wait to get back to his garden. To see what it was and what its come to is nothing but a miracle to me, he said.
Harvin, of Durham, just finished his last hyperbaric session at Duke.
When he first started treatments, he noticed an improvement in just two days. Then somewhere around the 40th session, fresh, pink skin had grown back over his foot.
Now he says it looks like most of his foot is going back to normal. It just kept getting a little better and better, he said.