Some people believe that breathing faster and deeper at high altitudes can compensate for oxygen lack. This is only partially true. Such abnormal breathing, known as hyperventilation, also causes you to flush from your lungs and blood much of the carbon dioxide your system needs to maintain the proper degree of blood acidity. The chemical imbalance in the body then produces dizziness, tingling of the fingers and toes, sensation of body heat, rapid heart rate, blurring of vision, muscle spasm and, finally, unconsciousness. The symptoms resemble the effects of hypoxia and the brain becomes equally impaired.
You are most likely to hyperventilate while flying under stress or at high altitude. For example, the stressful feeling of unexpectedly entering instrument conditions, noting both gas guages bouncing on empty, or developing a rough-running engine over water or mountainous terrain may make you unconsciously breathe more rapidly or deeply than necessary.
A pilot who suffers an unexpected attack of hyperventilation, and has no knowledge of what it is or what causes it, may become terrified, thinking that he is experiencing a heart attack, carbon monoxide poisoning, or something equally ominous. In the resulting panic and confusion, he may actually lose control of the aircraft, exceed its structural limits, and crash.
A little knowledge is all you need to avoid hyperventilation problems. Since the word itself means excessive ventilation of the lung, the solution lies in restoring respiration to normal. First, however, be sure that hyperventilation, and not hypoxia, is at the root of your symptoms. If oxygen is in use, check the equipment and the flow rate. Then, if everything appears normal, make a strong conscious effort to slow down the rate and decrease the depth of your breathing. Talking, singing, or counting aloud often helps. Normally paced conversation tends to slow down a rapid respiratory rate. If you have no one with you, talk to yourself. Nobody will ever know.
Normal breathing is the cure for hyperventilation. The body must be allowed to restore the proper carbon dioxide level, after which recovery is rapid. Better yet, take preventive measures. Know and believe that overbreathing can cause you to become disabled by hyperventilation.