Hyperventilation is defined as rapid breathing. The normal breathing rate is 14 to 18 breaths per minute. Carbon dioxide is the gas that normally regulates the rate of breathing. A rapid rate of breathing can occur normally after exercise. In addition, panic states and high altitude climbs can also raise the respiratory rate. When these conditions occur, individuals may have a variety of symptoms related to pH changes in their bodies caused by the hyperventilation.
In the blood, much of the carbon dioxide produced is converted into an acid, carbonic acid. When this acid reaches the lungs, it is converted back to carbon dioxide and exhaled. Hyperventilation causes a fall in the body's carbon dioxide. As a result, the amount of acid produced is decreased, leading to a rise in the body's pH. This condition is known as alkalosis.
Carbon dioxide acts on certain respiratory centers in the brain and normally stimulates breathing. A fall in carbon dioxide levels therefore causes a fall in the rate of respiration, which then serves to normalize the levels of this gas.
In aerobic exercise, additional oxygen is required by working muscles, and additional carbon dioxide is produced. This leads to a rise in carbon dioxide levels. Carbon dioxide acts on the brain to stimulate breathing. As a result, a person who is exercising often has a faster rate of respiration. This action helps maintain the adequate oxygenation of the blood and gets rid of the additional carbon dioxide.
Individuals with anxiety or panic disorder may have a suddenly increased rate of breathing in a panic attack. One of the important symptoms of panic disorders is hyperventilation. In this situation, the carbon dioxide levels fall abnormally low. As a result, a mild level of alkalosis ensues. The alkalosis can cause a number of symptoms, such as a tingling sensation around the mouth and extremities. It may also cause muscle spasms.
As an individual ascends to higher and higher altitudes, the atmospheric pressure falls. At sea level, the air pressure is 760 millimeters of mercury; at 18,000 feet above sea level, it falls to 380 millimeters of mercury. As a result, the amount of oxygen present in the atmosphere falls as well. The role of oxygen in controlling respiration is slight. However, when the oxygen level falls to a low amount, it acts to stimulate respiration as well. The increased rate of breathing maintains oxygen levels at normal ranges, but causes a fall in the carbon dioxide.
A mild state of alkalosis ensues upon reaching a high altitude; this state can produce high-altitude mountain sickness. People with this condition have nausea, headaches and dizziness. The condition usually subsides after several days as the kidneys slowly compensate for the change in the blood pH.