Nineteen-year-old Michael Francis of Newark, N.J., goes to school, uses a computer, collects baseball cards and listens to music. He's also been using a ventilator at night for three years, ever since an acute episode of respiratory failure from Duchenne muscular dystrophy put him in the hospital. His ventilator delivers air through his nose and is easily removed.

"No one knew what to do," his mother says of the crisis three years ago. "They intubated Michael [put a tube down his throat]. They wanted to give him a tracheotomy [hole in the trachea, or windpipe]. Then Dr. Bach came in. although Michael couldn't breathe on his own, Dr. Bach removed the tube and helped him breathe using other methods. I'll tell you, Dr. Bach has my vote."

Michael Francis, 19, uses nasal ventilation when needed. The portable ventilator is on the couch.

Starita declined a tracheotomy in 1987 when he was 17, his mother says. Dr. Bach worked hard to avoid this, and he and Starita have since been "very close." Starita started non-invasive (nontracheotomy) ventilation part time in 1987 and has used it 24 hours a day since 1989. He's now using a nasal mask.

Dr. John Bach, 44, is associate medical director of the Department of Physical Medicine and Rehabilitation at the University of Medicine and Dentistry of New Jersey in Newark, where he also co-directs the MDA clinic with Dr. Jennifer Michaels, a neurologist.

As a specialist in physical medicine and rehabilitation, or physiatrist, Bach represents a minority among doctors who treat people with neuromuscular diseases. His focus is on improving the daily lives of his patients, helping them maintain respiratory and motor functions as long as possible.

A THREEFOLD APPROACH TO RESPIRATORY FITNESS

Bach's approach to maintaining respiratory function, even in the most advanced stages of Duchenne, is threefold. It involves monitoring oxygen levels and respiratory muscle function, non-invasive ventilation by nose or mouth, and assisted coughing.

Jimmy Starita, 24, uses a nasal mask with a portable ventilator mounted on his wheelchair.

To monitor respiratory function, Bach uses three instruments. The oximeter, a portable unit that some patients have at home, instantly measures blood oxygen levels when a fingertip makes contact with a sensor.

Another device is a spirometer, also portable, which measures how much air a person can exhale after taking a deep breath, an indication of respiratory muscle function and lung capacity. The third device measures cough efficiency. Bach keeps all these devices on hand at his clinic.

When someone with Duchenne or another neuromuscular disease gets a cold or shows signs of respiratory problems, he explains, a quick check on these measures reveals whether non-invasive methods should be used.

"Most people with neuromuscular disease don't get short of breath as their respiratory function decreases," he says, "because they're in wheelchairs and aren't exercising." Instead, he explains, the symptoms are fatigue, headaches, nightmares and difficulty concentrating. These may be overlooked or not connected to breathing problems.

When a boy with Duchenne gets a cold, Bach has him measure his oxygen concentration with an oximeter. If it's below normal, he considers two possibilities in making a treatment plan.

The problem, he says, could be underventilation from weakened chest muscles. He tells the patient to take some deep breaths and then see if the oximeter shows a normal oxygen reading. If it does, the problem is weak respiratory muscles, leading to underventilation. Most boys with Duchenne can take a few deep breaths to improve ventilation but will eventually be too weak to do it consistently. Bach prescribes assisted ventilation by nose or mouth.

The other thing to consider, Bach says, is mucus in the lungs that can't be coughed up. This is a frequent complication of colds or more serious infections in people with Duchenne. For this, Bach prescribes special cough techniques or a coughing machine, a device that pulls air out of the lungs and brings up mucus.

Eventually, he says, most people with Duchenne will need to use some form of assisted ventilation part time or full time and will need the coughing machine on occasion. Even when 24-hour ventilation is needed, non-invasive methods may be used much of the time, he says.

Bach believes that, far from being the near-death interventions they once were, ventilators can be used for decades to help people lead satisfying lives without respiratory distress.

LESSONS FROM POLIO

In the 1940s and early '50s, he says, the only available method for treating respiratory failure was the "iron lung.' These were cylinders that enclosed the patient's body, leaving only the head exposed. By rhythmically lowering the air pressure around the patient, the iron lung caused automatic inflation and deflation of the lungs. Iron lungs were safe and effective, but they allowed a poor quality of life for those who used them. Polio wards with rows of patients imprisoned in iron lungs were a frequent sight in the '40s.

In 1952, Bach says, a polio epidemic swept across Denmark, and there weren't enough iron lungs to go around. Doctors started inserting tubes in patients' tracheas and connecting them to positive-pressure ventilators. The era of tracheotomy ventilation was born.

A FRENCH CONNECTION

In 1979, the work of Dr. Yves Rideau of the University of Poitiers, France, caught Bach's attention. Rideau favored surgeries to prevent contractures (abnormal joint positions from weakened muscles) and prolong walking in boys with Duchenne dystrophy.

Bach, still in training in New York, wrote to Rideau, saying he wanted to come to France and learn more about the surgeries. Rideau, it turned out, wanted to learn more about mouthpiece ventilation.

Bach spent two years in Poitiers, from 1981 to 1983. He learned the French approach to surgical intervention in Duchenne, and he and Rideau experimented with non-invasive ventilation by mouth and nose.

Rideau suggested that nasal ventilation might be a good daytime alternative to mouthpiece ventilation. But the doctors thought the seal wouldn't be as good, that too much air would escape through the mouth during sleep.

"In 1981, I hooked up two Foley catheters [narrow tubes normally used to drain the bladder] to a ventilator and stuck them in my nose," Bach says. He thought the technique might be effective for some patients.

NIGHT VIGILS

In 1984, Bach was back in the United States, working at University Hospital in Newark. A woman with a neuromuscular disease was in the hospital in a very distressed state. "She was very anxious and said she hadn't slept in three days because she couldn't breathe properly," Bach recalls. "I checked her ventilatory capacity with a spirometer and found it was way below normal." Bach set up nasal ventilation using a mask. "The ventilation was very good, and she was able to sleep," he says. "I saw that you could use nasal ventilation even during sleep. You didn't always need a perfect seal."

Bach checked on other ventilator patients with no breathing capacity. "I switched them all to nasal ventilation," he says. "I stayed up all night with each patient and watched to make sure they were all right." In every case, the patient did well. They got almost as much air as people using lip seals.

Today, Bach says, all kinds of comfortable nasal and oral delivery systems are available. Nose masks should fit the person's face precisely, he says. There are companies that provide custom-made nosepieces or nosepieces an assistant can mold to a person's face and then allow to harden.

VACUUM CLEANERS

Arlene Gray prepares a Cof-flator coughing machine from the 1950s that Bach gave to her son, Jeff. The device helps clear fluid from the patient's lungs.

The other part of Bach's respiratory program -- assisted coughing -- also stems from techniques developed during polio epidemics.

In the polio years, he says, patients with paralyzed respiratory muscles needed help coughing, and some apparently got it from vacuum cleaners. The vacuum cleaner applied negative pressure to the bronchial tubes and extracted mucus.

"O.E.M. [a medical supply company] may have been inspired by this technique when it developed the Cof-flator, because it looks very much like a canister vacuum cleaner," Bach says. He says the company sold the machines from 1952 to 1954, mostly to people who'd had polio, and then went out of the medical supply business in the early '60s.

Bach rounded up old Cof-flators (he got his first one from a medical museum) and gave them to several of his patients. Fortunately, he says, a modern version of the coughing machine is now made by the Emerson Company. It's known as an In-Exsufflator and can provide both positive and negative pressure.

HOUSE CALLS

At the end of Bach's work day, he makes a house call to see Jeff Gray, a 31-year-old man with Duchenne dystrophy in Newton, N.J., who's been using a ventilator since he was 23. Gray uses nasal ventilation at night and a wheelchair-mounted mouthpiece during the day. He can easily talk or eat between taking breaths from the mouthpiece.

Gray says he was hospitalized twice with pneumonia before he started working with Bach but hasn't had any serious respiratory problems since he started on Bach's program. He says the coughing machine has prevented serious illness.

Bach says he became a rehabilitation specialist because he wanted deeper relationships with his patients. "I have a more important role with Duchenne patients than I would otherwise," he says. "It's a source of satisfaction."

His patients appear satisfied, too.