Respiratory Support
Most PALS die when they can no longer inhale and exhale well enough to be comfortable and functional, even with a BiPAP. However, a BiPAP typically extends life and comfort for months (in fast progression) to years (most PALS).
Sometimes this death is in sleep, sometimes it occurs very suddenly, but most often it is self-directed in the sense that drugs, such as morphine, that are given for comfort, are no longer metered in the same way as when extending life is the goal. In addition, typically interest in food and activity — overall energy — winds down around the same time as breathing. Given this natural progression, no PALS needs to die gasping for breath, choking, or suffering in any way.
This group of pages focuses on demonstrating the need for BiPAP through pulmonary function testing (PFTs), and the process of acquiring and using the machine. Some basics of positioning and secretion management are also covered.
The air we breathe in is about 21% oxygen (O2). When you inhale, your lungs take in this oxygen and other gases, mostly nitrogen, from the air. The oxygen is then pushed into the bloodstream, and sent to all the organs, bones, and soft tissue that need it. As your body's cells use the oxygen, they exchange it for carbon dioxide (CO2) into the blood, which carries it to the lungs. This process is called air exchange.
Normally, breathing out (exhaling) gets rid of the CO2 along with the other gases that are not used by the body. Since the body cannot use them, if they build up, they cause problems such as headaches, confusion and sleepiness, and, ultimately, death.
In ALS, exhaling to get rid of these waste products is more difficult due to muscle weakness, and it is also harder to breathe in the air needed for enough O2. A BiPAP pushes air into the lungs, but the muscles that control air handling become weak.
For PALS, then, CO2 buildup usually comes before a lack of oxygen. As CO2 builds up, the body is less able to process the oxygen it receives and wants to breathe faster to compensate. So, toward the end of life, not only does breathing become more difficult, organs and the body's ability to repair itself gradually shut down.
The Problem with Breathing
ALS is a neuromuscular disorder, in which the motor neurons (nerve cells that control muscles) are damaged. We don't know all the reasons this happens yet, but the muscles that control breathing are usually affected. So, it is considered a "restrictive" breathing condition, meaning that the chest cannot expand and contract as normally occurs during breathing.
However, about half of PALS will also have obstructive sleep apnea, where the air is blocked from moving freely at some point. This happens when the muscles that keep the airway open weaken and collapse. The result is that PALS may stop breathing entirely for seconds at a time (apneas), or their air flow is not enough to provide all the oxygen it normally would (hypopneas).
As another issue in breathing, secretions often build up when they are not easily sneezed, hawked, or coughed out, and when the PALS cannot easily move around. The buildup of secretions makes it harder to breathe, promotes coughing and choking, and further depletes energy.
Therefore, respiratory failure generally is the cause of death in ALS, either because someone can no longer take in enough oxygen and expel enough CO2 to sustain life, or because they have decided that the effort of doing so is more than they want to sustain.
ALS is partially a disease of metabolism, and it takes a lot of energy just to wake up and get out of bed, even when transferred in a lift, and to sit all day, even in a wheelchair, let alone to communicate, interact, and accomplish any goals.
Then add the energy it takes to breathe, even with machine support as described below, and it’s not surprising that at some point many PALS run out of energy. However, we can postpone that time with optimal respiratory support.
Respiratory Symptoms
When someone cannot inhale well, they will often start to breathe faster (to get enough oxygen) and shallowly (because their muscles are too weak to breathe deeply). This can make them dizzy and lead to CO2 buildup because they are taking in more air than their system can deal with.
When someone cannot exhale well, CO2 and secretion buildup are the result.
When the upper airway is collapsing and someone cannot move air well from the nose and mouth down the throat and into the lungs, this leads to coughing, choking, and feeling "stuck" while trying to breathe.
When respiratory function is not being adequately supported, PALS may have choking during sleep, feel sleepy during the day, have morning headaches, fatigue, fuzzy thinking, and sometimes find it difficult to fall or stay asleep. These symptoms result from upper airway obstruction due to weak bulbar muscles, along with weaker inhalation during deeper phases of sleep.
During the day, respiratory symptoms of ALS may include difficulty breathing or needing fast shallow breaths, especially in certain positions; buildup of mucus, saliva, or thicker secretions; and coughing/choking, especially after eating certain foods or when air quality is poor.
Respiratory Support Approaches
The most common ways of addressing ALS breathing challenges are positioning, BiPAP and secretion (saliva, mucus, thick "gunk") management. Managing secretions may entail medications, humidification, diet (often avoiding dairy and/or spices) manual or machine-assisted cough support, and air quality control to reduce irritation. Each is discussed in the following pages.