For Chris Locke, what started out as simple surgery wound up putting him in a coma for three days. “During the pre-op physical, my blood oxygen saturation was under 50 percent,” says Locke, 40, a C5-6 quad from Whitewater, Wisc. “So they gave me oxygen. That threw off my blood-gas chemistry — my body had become so used to low oxygen levels, the extra oxygen made me delirious, like I was drunk. They had to put me in a medically induced coma to readjust my body’s blood-gas chemistry.”

That coma quite possibly saved Locke’s life.

Chris Locke wakes up ready for anything now.

Chris Locke wakes up ready for anything now.

For a healthy human being, normal blood oxygenation is in the range of 96-98 percent. Below 90 percent, pulmonary physicians become concerned. Living with oxygen levels so dangerously low put Locke at serious risk of congestive heart failure, stroke and other life-threatening conditions. Locke had noticed the symptoms for some time. “I couldn’t sleep at night. In the morning I would transfer to my power chair and then pass out all day long.” Sleeping in his wheelchair during the day meant he wasn’t repositioning himself frequently enough, contributing to his problems with pressure sores and further affecting his health.

Following the surgery, and a subsequent sleep study, Locke was diagnosed with chronic sleep apnea — a disorder in which the body stops breathing during sleep, sometimes as often as 30 times a night. He was then placed on a CPAP (continuous positive airway pressure) machine to help him breathe easier and keep him properly oxygenated as he sleeps. The difference, he says, has been dramatic — he now wakes up fully rested and has energy he didn’t have before. “I’m able to think and hold a conversation. I have more patience to deal with BS. And I’ve lost weight.”

In the three decades since it was first introduced, the use of CPAP — and its cousin, BiPAP (bilevel positive airway pressure) — has become a common treatment for many respiratory disorders, including sleep apnea and chronic obstructive pulmonary disease. Not coincidentally, people with certain conditions — SCI, muscular dystrophy and osteogenesis imperfecta, to name a few — deal with compromised respiratory systems as an effect of their disabilities. Sleep disorders and low oxygen levels are more likely in these groups. And oxygen is one of those things we never notice — until we’re not getting enough of it.

When Dr. Stephen Burns, director of the Northwest Regional Spinal Cord Injury System at the University of Washington, first began working with people with SCI, he was struck by how many, particularly people with quadriplegia, have trouble breathing at night. “It’s pretty high, compared to what’s recorded in the general population with disabilities,” he says. “A good number, maybe half of people with quadriplegia, have obstructive sleep apnea. This means that, during the deep phases of sleep, as they’re trying to breathe, the upper airway is collapsing down and not letting air through.” Burns hypothesizes that, for many, what may have been a minor problem originally worsens in the aftermath of a spinal cord injury. “A lot of people who may have just snored before their injuries, now their muscles are weaker and they can’t keep their airways open,” he says.

For a newly injured person, the lack of restful sleep can have a negative effect on their rehab, reducing their physical stamina and their ability to learn new mobility and daily-living skills. Longer term, not getting enough oxygen to the brain can contribute to depression, impair skin integrity, inhibit wound healing — and possibly, through the stresses low oxygen levels place on the heart, play a role in the high rate of sudden death among people with SCI.

“We know there are a lot of these so-called non-ischemic cardiac deaths … in the SCI population, in which the person dies suddenly without any other identified cause sometime in the first year after injury,” Burns says. Rare among people without disabilities, they make up 12.2 percent of deaths among people with SCI — the second most common cause of death following injury.

Nor is SCI the only kind of disability that can compromise respiratory function.

My Wake Up Call
Like most people with my condition, osteogenesis imperfecta, I need to be extra-vigilant about respiratory infections. Because of our abnormally shaped rib cage and reduced lung capacity, a simple cold can easily worsen into bronchitis, or even pneumonia. So, in 1998, when what began as a sore throat turned into a dry cough, and from there became a deep, body-wracking cough bringing up weirdly colored sputum, I did what I usually did — I went to the doctor and got a prescription for antibiotics and cough syrup.

There had been other symptoms, gradually worsening over the years — restless sleep, inability to concentrate during the day, headaches, shortness of breath. I shrugged them off, just as I did this latest illness. A week and a half, I figured, maybe two, and I’d be back to normal — until then, I’d drink lots of fluids, sleep sitting up so I could breathe easier, and just tough it out.

For a few nights, I seemed to be getting better.

Then I woke up one morning feeling like there was an elephant sitting on my chest. My heart was pounding, my skin was clammy, my arms and legs felt like blocks of ice. I could barely get enough air to speak to the 911 operator.

When the EMTs took a reading of my blood oxygen level, it came in at 49 percent. They seemed amazed I wasn’t already dead.

At the ER, though, I lucked out — the on-call pulmonologist was someone who’d seen patients with OI before. He put me on a BiPAP for the duration of my two-week hospital stay, and advocated for me to stay on it after going home — without the sleep study that insurers typically require.

I’ve been using one ever since.

How CPAP and BiPAP Work
We tend to think of our lungs as simply a couple of balloons, inflating and deflating every time we inhale and exhale. In truth, they’re complex organs made up of millions of tiny structures called alveoli. The purpose of the alveoli is gas exchange — removing oxygen from the air we breathe in and transferring it to the bloodstream, and removing carbon dioxide from the blood so we can expel it in the air we breathe out.

In order to work properly, these delicate structures need to maintain a certain level of air pressure. If that pressure drops, the tissue surrounding the alveoli can fill with fluid, causing them to collapse — a life-threatening condition known as pulmonary edema. Collapsed or weakened alveoli can also be damaged by viruses or bacteria such as those that cause pneumonia.

comAfter almost dying from low oxygen, Denise DiNoto learned her lesson and uses her BiPAP.

After almost dying from low oxygen, Denise DiNoto learned her lesson and uses her BiPAP.

CPAP/BiPAP devices prevent this from happening by, quite simply, keeping the lungs inflated. The user wears an airtight mask — over the nose, or often just two tiny pillows fitting inside the nostrils — that delivers a constant stream of air under gentle pressure. With a CPAP, the air pressure remains the same during both inhalation and exhalation — with a BiPAP, the pressure decreases slightly when the user breathes out.

Although there are exceptions, in most cases a health-care provider will require a sleep study before approving use of either device. Whether a CPAP or BiPAP is called for depends on the individual user, according to Burns. Some find the BiPAP more comfortable, while others need the constant pressure of the CPAP. The type of mask used varies with the individual as well. “Some get a claustrophobic feeling with the larger mask — the nasal pillows tend to cause less claustrophobia,” he says. On the other hand, some find that the pillows irritate the nasal passages and dry out the sinuses. “The nose mask works better with higher pressures, and doesn’t seem to irritate the sinuses as much.”

Adjusting Takes Time, But Is Worth It
Even if the overall effect is beneficial, using a CPAP or BiPAP device can take some adjustment.

Denise DiNoto, 39, of Waterford, N.Y., was very reluctant to use her BiPAP even after it was prescribed for her. “I fought it — I didn’t want to do it,” says DiNoto, who has spinal muscular atrophy. “I didn’t see a benefit to using it, and it was difficult for me to switch on independently.” Nor did she see any difference in her quality of life with or without the machine. “I really didn’t notice any change.”

Her perspective shifted when she was hospitalized over Memorial Day weekend of this year. “On the early morning rounds the day I was to be discharged, I was found unresponsive and not breathing. I spent the next four days in a coma, on a vent. When I woke up, I received a stern talking-to about the importance of using the BiPAP consistently. Since then, I have used it every night.”

Actually sleeping at night, waking up with more energy and being able to stay awake all day make using a BiPAP worth it for Bruce Baraw.

Actually sleeping at night, waking up with more energy and being able to stay awake all day make using a BiPAP worth it for Bruce Baraw.

“It took a lot of getting used to,” says Bruce Baraw, 57, of La Mesa, Calif., who has osteogenesis imperfecta and has been using a BiPAP since 1999. “I’d wake up in the middle of the night and find that I’d pulled the thing right off my head.” Now that he’s gotten accustomed to it, however, he says his quality of life has improved immensely — his main complaint is having to travel with it. “It’s a pain in the butt. I used to be a real low-maintenance traveler — now I have to take all this equipment with me.”

Locke, by contrast, says, “It’s super easy to travel with. When you get your machine, it comes with a travel case and it packs and unpacks real easily. The only drawback I find is, I’m now dependent on the machine. If I’ve had a long day and need a quick nap, I have to use the machine. My sleep definitely depends on it. If something’s wrong, or the mask leaks, I can’t sleep. Things stretch and wear out, so if I don’t get the parts I need in a timely manner, I don’t sleep well until it’s fixed.”

Nevertheless, he says, “The benefit I get in the morning is worth it. The first few nights at home with it, I wasn’t sure, but then I woke up in the morning feeling like I actually slept — I had energy, I felt rested and ready to go. One year later I still feel good. I can stay awake all day. I don’t just fall asleep if I sit idle for a few minutes. I can watch a whole movie without conking out.”

Most importantly, says Locke, “I can watch an entire football game — and up here in Packer country, that’s very important.”

• entry on sleep apnea;
• MedicineNet on sleep apnea;
• Northwest Spinal Cord Injury System; — type CPAP in Search Box for further reading.
• Osteogenesis Imperfecta Foundation;
• Sleep Apnea and Spinal Cord Injury;