You predominantly use one of two breathing patterns: chest (thoracic) or abdominal (diaphragmatic) breathing. Chest breathing is associated with hyperventilation, which is characterized by fast, shallow breaths, and intermittent sighing. This breathing pattern may not be so obvious, yet it alters your chemistry and affects your physical sensations.(see list of symptoms) Carbon dioxide (CO2) gets expired too quickly, which sharply lowers the CO2 in the blood. This offsets your blood pH level making it more alkaline. Your arteries constrict, and an internal oxygen deficit prompts the need for air. Your nervous system kicks in at this point to get more oxygen, and creates the feelings of dizziness, panic, and anxiety.
Chronic hyperventilation can explain panic that wakes you in the middle of the night. When your breathing slows down while sleeping, it now causes you to retain more carbon dioxide in the blood, making your blood pH more acidic. This too can bring on sudden feelings of panic.
We have a limited carbon dioxide tolerance before the blood pH strays from its normal 7.4 value, becoming too acidic or alkaline. In order to keep your blood pH balanced, your kidneys secrete a reserve called bicarbonate. However, those who habitually hyperventilate use up this reserve, and lack the buffer to quickly regain equilibrium.
While hyperventilation causes physical sensations of panic, emotions can have a dramatic affect on your breathing. Just thinking about a stressful event can change your breathing pattern and alter your pH balance.
A capnometer is a gas analyzer that measures how much carbon dioxide (CO2) is exhaled, thereby assessing your susceptibility to panic. A normal reading is 38-40 torr, but those prone to panic can get as low as their teens. I've also seen patients breathe normally into a capnometer with no effect. After introducing a "think test," where they were asked to vividly recall a recent stressful event, the capnometer reading dramatically dropped to reflect an increase in stress arousal.
In general, those who chronically hyperventilate have a lower threshold for pH imbalance. It takes less over or under breathing to alter the limited carbon dioxide tolerance, and their depleted reserves can't compensate quickly enough. This is why proper breathing is particularly important for those who suffer from panic or anxiety.
