Much of what 2-year-old Ke’Aiden has touched since birth are hard medical wires, latex surgical gloves and plastic toys. He is fed through a tube in his nose. He associates things going into his mouth with the pain of intubation or infection, so he clenches his jaw shut when anything comes near. Because he has been so sick for much of his short life, he has yet to learn to talk or stand.

A physical therapist uses a harness to help his legs learn to bear weight. An occupational therapist tries to get him to eat by snacking in front of him, safely brushing his cheek with crumbs. A specialist lets him explore textures like a feather, sandpaper, yarn and a brush.

All Ke’Aiden has known since birth has been a hospital room at St. Louis Children’s Hospital. Because of a high-tech mechanical ventilator helping him breathe, he’s only felt the outside world briefly a few times.

The breathing machine, a new technology that more safely assists the fragile lungs of premature babies, is typically used for a short period before a newborn gradually weans from the assistance. But for some reason, Ke’Aiden’s lungs are not getting better. The machine that saved his life is now keeping him from fully living it.

He’s the second child at the children’s hospital whose body is unable to wean from the machine.

Jaxen Halfhill is 3 years old and has spent more than two years in the hospital tethered to the ventilator, his physical abilities much like Ke’Aiden’s.

While medical advances are saving the lives of babies born before they should be, and even pushing the limits of viability to babies born at 22 weeks’ gestation, their cases are reminders that technology doesn’t always work as expected. Instead, doctors and families are left figuring out how to deal with the unexpected results.

“They represent a small but significant group of children who, on one hand, are success stories of our technology, but on the other hand, have challenges,” said Dr. Sessions Cole, the hospital’s chief medical officer. “The parents ask, ‘What is going to happen to him, doctor?’ ”

Doctors don’t know how long each child will need the ventilator, when he will be able to go home or what his life will be like. “The best we can say is that he is writing his own textbook,” Cole said.

Behind the medical teams trying to figure out how to make them thrive and get them home, is the steady love of their families, coming miles away from school or work to be by their sides.

Ke’Aiden beams, squeals and falls over from happiness when his mom appears in the doorway. “Hi, pumpkin,” she says.

The new mechanical ventilator is called Neurally Adjusted Ventilatory Assist, or NAVA. Rather than long-used ventilators triggered by a person’s effort to suck air, the NAVA detects when the brain is about to signal the breathing muscles to contract. A sophisticated computer algorithm synchronizes the timing and amount of ventilation with the neural transmission, perfectly matching a patient’s breathing requirements.

The technology was first introduced in 2008 and has become more widespread in the past two years, said Dr. Howard Stein, director of neonatology at Toledo Children’s Hospital, who has studied the use of NAVA. “Our experience has been that patients come off the ventilator quicker, have better tolerance to ventilation and they do very nicely with it,” Stein said.

Ke’Aiden and Jaxen were placed on NAVA when no other options were working — Ke’Aiden just before his first birthday, and Jaxen just after he turned 1. The boys have been unable to tolerate attempts to reduce the support because Ke’Aiden’s lungs have not kept up with the growth of the rest of his body, and the walls of Jaxen’s windpipe remain too weak.

Ke’Aiden’s lungs seem to be growing very slowly. Doctors are also weighing the risks of possible surgeries for both boys, looking at scenarios never seen before. “We have no road map,” Cole said.

Charges for Ke’Aiden’s care crossed the $1 million mark this year, hospital officials said. Medicaid pays for a small portion but the hospital absorbs the rest.

Doctors say when they place a baby on a ventilator, the assumption is always that the baby will improve and no longer need it. No crystal ball or mounds of research predict which babies will not. When faced with uncertainty, parents almost always fight for a chance.

“The question is not so much about the technology, but about the baby,” Stein said. “If we could predict how our babies are going to do, we could have much smarter conversations with families.”

Nothing is going as planned for Ke’Aiden’s mother. Kindness Singano, of Belleville, Mo., is 19. “I wish I hadn’t gotten pregnant so early, but now I’m just trying to do everything I can to be the best mom,”