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Hyperventilation syndrome (HVS); also chronic hyperventilation syndrome (CHVS) and dysfunctional breathing hyperventilation syndrome is a respiratory disorder, psychologically or physiologically based, involving breathing too deeply or too rapidly (hyperventilation). HVS may present with chest pain and a tingling sensation in the fingertips and around the mouth (paresthesia) and may accompany a panic attack. People with HVS may feel that they cannot get enough air. In reality, they have about the same oxygenation in the arterial blood (normal values are about 98% for hemoglobin saturation) and too little carbon dioxide (hypocapnia) in their blood and other tissues. While oxygen is abundant in the bloodstream, HVS reduces effective delivery of that oxygen to vital organs due to low--induced vasoconstriction and the suppressed Bohr effect. The hyperventilation is self-promulgating as rapid breathing causes carbon dioxide levels to fall below healthy levels, and respiratory alkalosis (high blood pH) develops. This makes the symptoms worse, which causes the person to try breathing even faster, which further exacerbates the problem. The respiratory alkalosis leads to changes in the way the nervous system fires and leads to the paresthesia, dizziness, and perceptual changes that often accompany this condition. Other mechanisms may also be at work, and some people are physiologically more susceptible to this phenomenon than others.〔(【引用サイトリンク】title=eMedicine - Hyperventilation Syndrome: Article by Edward Newton, MD )〕 ==Causes== Hyperventilation syndrome is believed to be caused by psychological factors and by definition has no organic cause. It is one cause of hyperventilation with others including infection, blood loss, heart attack,〔(【引用サイトリンク】title=Hyperventilation )〕 hypocapnia or alkalosis due to chemical imbalances, decreased cerebral blood flow, and increased nerve sensitivity may also underlie this symptom.〔(【引用サイトリンク】title=Neurology - Hyperventilation Syndrome | Brad McKechnie, DC, DACAN )〕 In one study, one third of patients with HVS had "subtle but definite lung disease" that prompted them to breathe too frequently or too deeply. Many people with panic disorder or agoraphobia will experience HVS. However, most people with HVS do not have these disorders.〔(【引用サイトリンク】title=eMedicine - Hyperventilation Syndrome: Article by Edward Newton, MD )〕 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 syndrome」の詳細全文を読む スポンサード リンク
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