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Yoga physiology, anatomy and movement science
In the previous two parts of this series I covered the physiology of hyperventilation—what happens when we breathe more than we need to. This installment will look at what happens when people chronically hyperventilate.
In the 1930s, Dr. William Kerr proposed that chronic, low-level hyperventilation could be behind a host of non-specific symptoms in patients suffering from anxiety, where no organic dysfunction could be found. This has sometimes been called the “fat folder syndrome” for the thickness of the patient’s medical file. These patients complained not only of anxiety or panic, but also feelings of air hunger, chest pain, dizziness and faintness, visual disturbances, fatigue, muscle cramps and poor sleep. Many had shuttled from doctor to doctor for years without a definitive diagnosis. Often they were told that the symptoms were all in their head.
To be fair to the doctors, it’s not obvious that a person is a habitual over-breather. Once hyperventilation begins and CO2 levels drop, it only takes an occasional deep breath to maintain that state. However, there are common tell-tale signs. Chronic hyperventilators are typically upper chest breathers. Their breathing tends to be rapid and unsteady, with frequent sighing.
Kerr diagnosed the syndrome by having patients intentionally hyperventilate. If this provocation reproduced their symptoms, he attributed their ailments to chronic hyperventilation, with the presumed mechanism being low levels of blood CO2. In the following years the diagnosis became more common, with the diagnostic test remaining basically the same. Many doctors reported that “fat folder” patients could be helped by restoring healthy breathing patterns.
In the 1980s other doctors began to question the existence of hyperventilation syndrome. Many people who were assumed to be chronic hyperventilators actually had normal CO2 levels, while others who did have low levels of CO2 didn’t have symptoms of the syndrome. Patients who once would have been diagnosed with hyperventilation syndrome were now seen as primarily suffering from anxiety or panic disorders. Hyperventilation was at most a side effect, not the root cause. Researchers also questioned the validity of Kerr’s hyperventilation provocation test; other stressors, such as difficult mental tasks, were found to provoke similar responses. Plus, for patients who improved with breathing retraining, those benefits were found to be as likely to stem from relaxation as from changes in CO2 levels.
Additionally, there were safety concerns. Serious, even life-threatening, conditions such as diabetic ketoacidosis, hypoglycemia or asthma could be masked by the diagnosis of hyperventilation syndrome. (Interestingly, the traditional remedy for hyperventilation, breathing into a paper bag—which in theory involves the hyperventilator re-breathing his own CO2-laden exhaled air until blood CO2 levels normalize—has also been abandoned because of its potential danger for people suffering from hypoxia due to undiagnosed lung disease.)
Since then, the term hyperventilation syndrome has fallen into disuse. Still, there seems to be some association between frequent hyperventilation and the maladies attributed to the syndrome, especially anxiety and panic disorders, even if the causal linkages are not clear. Symptoms of hyperventilation—chest pains, air hunger, dizziness and so forth—could provoke fear, and fear could lead to hyperventilation. It’s just hard to know what’s the chicken and what’s the egg.
You can easily see how chest pains—which could arise from strains to the intercostals and other thoracic muscles from habitual upper chest breathing—might feed into anxiety by triggering fears of a heart attack.
Air hunger is the feeling that it’s difficult to get enough air into the lungs and probably also results from the habit of upper thoracic breathing. The ribcage is elastic; to take a big chest breath you have to overcome that elasticity by forcibly expanding the ribcage. It tends to shrink back to its resting shape and size when you exhale, so to keep it chronically inflated takes a lot of work. You can try this yourself, to get a feeling for what it’s like. Take a big chest breath, keep the chest expanded as you exhale, then try to inhale again. You’ll immediately feel how much effort it is to breathe, and you might feel that you can’t get enough air in. It becomes obvious why those who habitually breathe in this way could feel a need to take deeper and deeper breaths to replenish their lungs.
Of course, if the problem is over-breathing in the first place, trying to breathe more deeply only makes it worse, leading to an upward spiral of increasing breathlessness and anxiety. So, whatever the underlying cause of the ailments of those with fat folder syndrome, we probably can’t discount completely a role for hyperventilation in exacerbating them.
So what does this mean for you? Well, regardless of the existence or non-existence of hyperventilation syndrome as a clinical diagnosis, it’s probably not a good idea to chronically over-breathe, especially if you tend to suffer from anxiety or panic.
How do you tell if you are over-breathing? It’s not obvious. However, because chronic hyperventilation is often coupled with an upper chest breathing pattern, noticing where the movement of your inhale begins is a good first clue. Breathing normally, place one hand on your upper sternum and the other on your abdomen. Where do you feel movement first? While there’s no one right way to breathe, and while under many circumstances it may be advantageous to breathe thoracically, if you habitually move the sternum before the belly, you may tend towards over-breathing.
If so, it will be useful for you to periodically lie on your back and spend a few minutes observing what it’s like to breathe. Particularly notice any feelings of air hunger. Do you feel a need to effort or strain to get air into your lungs? The amount of air that moves in and out of your lungs when you are relaxed is actually quite small, only about a pint per breath. It doesn’t take a lot of effort to move that much air. Just a small increase in the volume of the lungs, and the air will flow into you as a result of the pressure differential. You don’t need to strive to pull the air in.
The muscle that can most efficiently expand the volume of the lungs is the diaphragm. When you reduce extraneous effort enough to let the diaphragm do its job without interference, you’ll feel that the movement of your inhale takes place mostly in the belly and lower ribs, not in the upper chest. The belly rises and the lower ribs widen as the diaphragm contracts on the inhale, and they fall back towards their resting position as the diaphragm relaxes on the exhale. And regardless of the controversy about hyperventilation syndrome, if you re-establish that pattern of relaxed, easy breathing, you will find that it can do wonders for your mental and physical well-being.
Bass C. Hyperventilation syndrome: a chimera? J Psychosom Res. 42(5):421-6, 1997
Gardner WN. The Pathophysiology of Hyperventilation Disorders. Chest. 109:516-534, 1996
Kerr WJ, et al. Physical Phenomena Associated with Anxiety States: The Hyperventilation Syndrome. Cal West Med. 48(1):12-6, 1938
Lum LC. Hyperventilation and anxiety state. J R Soc Med. 74(1):1-4, 1981
Lum LC. Hyperventilation syndromes in medicine and psychiatry: a review. J R Soc Med. 80(4):229-31, 1987
Lum LC. Hyperventilation: the tip and the iceberg. J Psychosom Res. 19(5-6):375-83, 1975