|ICD9= |_}} In medicine, hyperventilation (or overbreathing)'s the state of breathing faster and/or deeper than necessary, bringing about lightheadedness and other undesirable symptoms often associated with panic attacks. Hyperventilation can also be a response to metabolic acidosis, a condition that causes acidic blood pH levels. Counterintuitively, such side effects aren't precipitated by the sufferer's lack of oxygen or air. Rather, the hyperventilation itself reduces the carbon dioxide conce… (More on Hyperventilation)