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Hyperventilation occurs when the rate and quantity of alveolar ventilation of carbon dioxide exceeds the body's production of carbon dioxide.〔()〕〔(yourdictionary.com > hyperventilation ) Citing: The American Heritage® Dictionary of the English Language, 4th edition Copyright 2010〕 Hyperventilation can be voluntary or involuntary. When alveolar ventilation is excessive, more carbon dioxide will be removed from the blood stream than the body can produce. This causes the concentration of carbon dioxide in the blood stream to fall and produces a state known as hypocapnia. The body normally attempts to compensate for this metabolically. If excess ventilation cannot be compensated metabolically, it will lead to a rise in blood pH. This rise in blood pH is known as respiratory alkalosis. When hyperventilation leads to respiratory alkalosis, it may cause a number of physical symptoms: dizziness, tingling in the lips, hands or feet, headache, weakness, fainting and seizures. In extreme cases it can cause carpopedal spasms (flapping and contraction of the hands and feet).〔()〕 ==Terminology== In very general terms, hyperventilation is an increased alveolar ventilation. This is not to be confused with the term hyperpnea which pertains to an increased minute ventilation. In hyperpnea, increased ventilation is ''appropriate'' for a metabolic acidotic state (also known as respiratory compensation) whereas in hyperventilation, increased ventilation is ''inappropriate'' for the metabolic state of blood plasma. Hyperventilation should not be confused with tachypnea (fast breathing) or hyperpnea (breathing that is faster or deeper than normal). Both these terms neutrally describe the manner of breathing rather than the impact that breathing has on carbon dioxide levels. Exercise, fever, shivering, and other disorders can cause the body to produce more carbon dioxide than normal. The body attempts to correct for this by breathing more rapidly and deeply. This corrective behavior does not lead to excess ventilation. Rather it brings the body into balance by compensating for excess CO2 production. Thus hyperpnea in this context is not hyperventilation. In fact, if the excess CO2 production cannot be completely cast off via hyperpnea, then a person will in fact be hypoventilating even though they are breathing faster or more deeply than normal. For example, in certain respiratory disorders, the transfer of carbon dioxide from the blood to the alveoli may be blocked. No matter how deep or fast the person tries to breathe, they cannot expel enough carbon dioxide. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hyperventilation」の詳細全文を読む スポンサード リンク
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