SAN DIEGO -- Dolores Thompson hops on the gurney, lies flat on her back and pulls herself into the long, metal tank.
Only her head is visible and she can't move.
Thompson stares at her bedroom's plain white ceiling, as she has for the last 55 years. A rhythmic whirring breaks the silence. She draws her lips to a tight smile, obviously at peace.
This is her bed, her security blanket, her life support -- her iron lung machine.
"It's almost like a heart beat," said Thompson, 65, her head resting on a faded pillow.
Looking like part coffin, part sci-fi contraption, the iron lung invented by a Harvard engineer became the feared symbol of polio during raging epidemics in the 1940s and 50s.
For thousands of American children, the device called the Drinker respirator was a lifesaver -- the only known gadget to help them expand and contract their lungs so they could breathe.
Most iron lungs disappeared soon after the arrival of the Salk vaccine in 1955.
She contracted polio when she was 9 and has needed the machine ever since -- to take afternoon naps and to sleep at night. She needs it to recharge her worn out chest muscles anytime breathing becomes too cumbersome. Without it, she fears she will suffocate.
"I don't know why I didn't die, but this is my reality," said Thompson, a trim woman with large eyes and cropped, salt-and-pepper hair.
About 60 people across the U.S. still use the nearly extinct iron lung. They are among the more than 300,000 polio survivors who suffer from a disease known as post-polio syndrome. The condition affects one in four of the estimated 1.5 million Americans who had polio.
Those with post-polio syndrome say they have been twice victimized. They thought they conquered polio as children, only to be hit with new symptoms as adults.
Post-polio patients suffer from overwhelming fatigue, muscle weakness and joint pain. They also suffer from sleep disorders, cold intolerance and swallowing problems, according to Dr. Richard L. Bruno of Englewood Hospital in New Jersey.
Bruno, one of a handful of doctors in the U.S. who treats the illness, says these problems occur because polio damaged most of the neurons -- the cells in the spine and muscle that control movement -- and those that remain are burned out from the disproportionate burden they've had to bear over a lifetime of use.
"These people have lost half the neurons that activate their muscles," said Bruno, a clinical psychophysiologist. "That's why we need to teach them to conserve to preserve; conserve energy so you preserve your neurons. If they can listen to their bodies and slow down, they can feel better and function better."
But scientists still aren't sure why people suffer from post-polio syndrome. Is it because overworked nerve cells are being further exhausted by the normal aging process• Or is it because poliovirus lingers in the body long after the disease is gone•
No research has ever identified infectious polio in a post-polio patient, according to Dr. J. Lindsay Whitton, who studies Coxsackie viruses similar to polio at the Scripps Research Institute in La Jolla, Calif. But several studies have identified fragments of the poliovirus genome in the spinal cord of post-polio patients.
It is unknown whether those fragments are responsible for any of the post-polio complications, Whitton said.
"We are an aging population and older people get weaker," said Whitton, himself a polio victim. "With post-polio, that weakness is exaggerated. There's no question in my mind this is a real disease. What causes it remains entirely, absolutely undecided."
Few doctors are familiar with the cruel irony of post-polio syndrome, Bruno said. Patients say the medical community has ignored their problems. They say the discovery of a preventative polio vaccine caused society to forget about those already stricken by the disease -- those for whom the vaccine came too late.
Such amnesic thinking dates back decades, according to Northwestern University history professor Jane S. Smith.
"It seemed that the public expected the past victims of polio to rise up and walk away, cured by the miracle," Smith wrote in her seminal account of Salk's war on polio, "Patenting the Sun: Polio and the Salk Vaccine."
Next week's 50th anniversary of the Salk vaccine has renewed worries among doctors in the field that those living with post-polio are not getting adequate care.
"We are very concerned that in all of the excitement of the 50th anniversary celebration, polio survivors are totally going to be ignored," said Bruno, chairman of the International Post-Polio Task Force, a group lobbying for funding and raising awareness about post-polio.
Bruno's New Jersey clinic -- one of about a half-dozen in the country -- treats thousands of post-polio patients every year. They learn to conserve energy by using a pedometer to measure their steps; to change their diets to include more protein and less sugar; and to reduce the emotional stress that comes with post-polio.
Patients unable to get such specialized care are forced to rely on primary-care doctors who know little about polio or its aftereffects because they never treated the disease.
"These people are being pummeled, they're getting beat, their bodies are falling apart," Bruno said. "They go to local doctors and they don't know what's going on with them. Or they go to the doctor, and doctors simply shake their head and tell them there's nothing I can do."
That's what happened to Mary Clare Schmitt Schlesinger, a former Fox Chapel resident who now lives in Escondido, about 30 miles north of San Diego.
Polio hit Schlesinger in 1952, when she was 3 years old and growing up outside Toledo, Ohio. Her legs and her body ached so badly, she couldn't stand up. They rushed her to a hospital, where she was so scared she couldn't stop crying. To keep her quiet, nurses put her in a storage room.
Soon after her family moved to Pennsylvania in 1962, complications from the disease began to ravage her respiratory system. She taught herself to walk after spending years in a wheelchair. In 1972, she and her husband, Steve, moved to San Diego because the capricious Pittsburgh weather wreaked havoc on Mary Clare's lungs.
"Every time it rained, I ended up in West Penn Hospital," said Schlesinger, 56, whose petite 4-foot 11-inch frame betrays a curved spine that is the product of polio. "When I moved to California, it probably added years to my life."
After several healthy years in California, however, Schlesinger began losing muscle strength. The joint pain intensified. The left side of her body was literally falling apart. In the 1990s, she began experiencing breathing problems and by 2001 a serious episode of respiratory failure left her on life support.
She eventually healed, but every cold still leads to complications.
"You're always grieving for your loss," she said. "For me, polio has never left."
Schlesinger eventually found a doctor who understood her disease. She gained enough confidence to get pregnant. She now manages her pain with medication and relies on her dog, Dylan, to maintain balance when she's walking.
Through it all, she continues to worry about others less fortunate.
"A lot of people in the post-polio community have given up," she said. "I haven't because I want my life. I want the best quality of life that I can have."
So does Thompson, the iron lung user.
Polio left Thompson paralyzed from the neck down at age 10 when she was growing up in southwestern Virginia. The illness hit her so hard she fell into a coma. When the little girl opened her eyes, she was inside an iron lung.
Thompson's condition improved over the years and she mustered enough strength to move in with an aunt in San Diego in 1971. Through intensive therapy, she regained mobility. She learned how to drive using a special contraption attached to the steering wheel and earned a bachelor's degree in English from San Diego State University.
Over the years, she tried to use other respirators, but never got used to them. None provide the relief and peace of mind of the iron lung.
She worries that her 50-year-old, 700-pound iron lung will break down. It has happened before, as recently as February. She waited two days to get scarce replacement parts.
Her worries have been intensified because the supplier of those parts, Murrysville-based Respironics Inc., has told her it can't repair the machine should the company not have the necessary parts. Respironics took over operations from the original maker, J. H. Emerson Co., in 1970 and says it doesn't have Emerson's blueprints.
The company is encouraging iron lung users to switch to one of 16 alternatives, said Tim Murphy, a Respironics vice president. Two of them work on the principle of negative pressure, similar to the iron lung, essentially pulling the chest wall outward so air can get into the lungs.
Those who have made the switch say they don't regret their decision and encourage others to keep an open mind.
"If some equipment is better, I'm not afraid to try it," said Billy Beer, 74, of New Orleans, who in 1999 got rid of the iron lung where he once slept.
Beer was struck with polio in 1956. He used a Respironics-serviced iron lung until the company suggested he try an artificial respirator instead. Beer said his oxygenation level is higher than that of his healthy wife, Marcia.
"I'm 100 percent better off now than I was with the iron lung," he said.
Respironics officials said 12 of 35 people who use their iron lung machines have switched to new equipment.
But not all iron lung users can make this switch, experts say.
"What someone gets used to and comfortable with, especially when it comes to breathing, is really important," said Dr. Julie K. Silver, an assistant professor at Harvard Medical School in the department of physical medicine and rehabilitation. "These people are very marginal. This is a real life threatening thing. If they begin to panic, they truly will suffocate."
Relief may come for Thompson in another way. A friend in Minneapolis who uses an iron lung told Thompson she can have her machine once she dies. The woman is in a coma, and her prognosis isn't good.
Thompson's iron lung is the centerpiece of her government-subsidized apartment. It sits in the middle of her bedroom, angled just so between a dresser and a desk. She turns it on herself, using a switch underneath the metal cylinder, and gets help from a personal care attendant to climb inside.
For eight hours every night, she slips into the 7-foot-long machine. Sometimes with her cat, Dexter, resting on the floor below, she dreams up poems about love and nature. Sometimes she looks at pictures of cats taped above her head.
She drifts to sleep, comforted by the slow hum of the iron lung.
"My body has been breathing like this for 55 years. It's used to it," Thompson said. "It is my reality and since it is my reality, it is my wish to die this way."