Edward Sivak is a professor of medicine and a pulmonologist associated with the MDA/ALS Center at the State University of New York in Syracuse.
Q: Does ALS affect breathing?
A: Most people with ALS, sooner or later, have some breathing difficulties. This is because the muscles involved in respiration — moving air into and out of the lungs — gradually weaken. In some people, this occurs early in the disease course, while in others, it occurs later.
Unless the patient has another disease in addition to ALS, there's no direct involvement of the lungs themselves in the beginning. Lungs can be affected later, however, secondarily to the muscle weakness that leads to collapsed air spaces, or atelectasis.
Q: What happens if respiratory muscles become too weak to move enough air in and out of the lungs? Do you suddenly stop breathing?
A: No. Respiratory impairment in ALS is a gradual process. You can slowly lose respiratory function and may not even realize it's happening.
Q: What should I look for?
A: People with ALS, if they're still able to exercise or propel a manual wheelchair, may feel short of breath with exertion.
Shortness of breath when lying down (orthopnea) is common, but it can be hard to recognize for what it is. In a horizontal position, the weakened respiratory muscles are further compromised by gravity. People with weak breathing muscles feel anxious when they lie down.
As respiratory muscles weaken, delivery of oxygen to the lungs and expulsion of carbon dioxide from them become progressively impaired. This is particularly so during sleep, a time when respiratory efforts are normally reduced compared to when we're awake. If oxygen is inadequate during sleep, restlessness, light sleep and frequent waking or near-waking occur.
Here, too, you aren't likely to recognize that the problem is your breathing unless you're schooled in respiratory physiology. You may just feel that you're not sleeping very well, or notice that you're dozing off a lot during the day. You may notice that mental processes are "blunted" or "fuzzy," or that you often have a headache when you wake up. This last is thought to be due to a buildup of carbon dioxide.
Q: Are there medications that can make respiratory problems worse?
A: Yes. Unfortunately, they're often the very ones prescribed for the patient who appears to be anxious and not sleeping well — the person who probably has unrecognized underventilation (hypoventilation).
Almost all medications prescribed for insomnia or anxiety can depress respiration, affecting blood oxygen and carbon dioxide levels in the person with ALS. I can't think of any that are safe, especially if the underlying respiratory problem isn't being treated.
The best way to evaluate insomnia or anxiety in an ALS patient is to look for a respiratory problem first. If that's already being treated and respiratory function is being monitored, then some anti-anxiety medications, if they're needed, can be used - with caution.
Q: What should I do if I suspect I have a breathing problem?
A: First, of course, see your doctor. Many tests can be done, ranging from the very simple to the very complicated, to check the status of your respiratory efforts.
One simple test has you blow into a machine called a spirometer that measures how much air you can move in and out of your lungs. This measurement should always be taken in both the sitting and supine (back-lying) positions to determine the strength of the diaphragm muscle.
Another test uses an electrode placed on the finger or earlobe to measure the amount of oxygen in the blood. The device is called an oximeter.
Your doctor may also want to measure the concentration of dissolved oxygen and carbon dioxide in your blood, a test known as blood gas levels.
These tests may show normal or nearly normal values when taken during the day, but if there are symptoms of inadequate respiration, an overnight test is usually warranted. In my practice, I have a low threshold for ordering what's called a sleep study or polysomnography study. The patient is asked to stay overnight in a sleep lab, where electronic sensors monitor his or her brain waves, heart rate, respiratory movements (the rise and fall of the chest and abdomen), and blood levels of oxygen and sometimes carbon dioxide.
It may seem like a lot of trouble, but a sleep study is worthwhile because it picks up low oxygen levels or retention of carbon dioxide during the deeper phases of sleep, which is when they first occur in ALS. A sleep study can also reveal that deep sleep levels aren't being achieved.
Q: If I have low oxygen or high carbon dioxide, what can be done about it?
A: At our clinic, we offer the patient what's known as noninvasive positive pressure ventilation. NIPPV delivers either a set volume or a set pressure of air (not oxygen, just room air) into the lungs via a mechanical device. There are a number of these devices on the market now, and each one has some advantages and disadvantages. The details are best addressed on an individual basis with your physician and respiratory therapist.
The word "noninvasive" means that the air is delivered by a mask over the nose, mouth or both. "Invasive" ventilation means that air is delivered through a surgical hole in the throat, called a tracheostomy (or trach).
NIPPV offers the person with failing respiratory muscles a kind of splint for these muscles, propping up their function with a little extra power. NIPPV doesn't have to be used all the time. It's usually needed during the sleeping hours at first and then extended into daytime use, sometimes for only short periods at first and then for longer periods.
Q: Is NIPPV for everyone?
A: No. Each case is individual, and not everyone tolerates this form of ventilation. People without teeth, with short jaws, or with weakness of the mouth and throat muscles may have special problems using a mask.
Q: Is NIPPV a permanent solution?
A: Unfortunately, no. Eventually, in ALS, the time usually comes when the respiratory muscles have deteriorated to such an extent that breathing can no longer be maintained with NIPPV. At this point, the person has to decide whether or not to move to invasive ventilation. Trach ventilation delivers air more directly to the lungs, bypassing the mouth and throat and any leaks that may occur along the way from the machine to the trachea (windpipe). Therefore, it's usually more effective for end-stage respiratory muscle degeneration than is NIPPV.