Hypoventilation

Hypoventilation is the inability to breathe fast or deep enough to properly exchange carbon dioxide in the lungs for oxygen in the air. This results in an increased concentration of carbon dioxide in the arteries and respiratory acidosis. Although it can be induced simply by holding one's breath, when it arises involuntarily, it can often indicate a serious underlying condition, such as damage to the brainstem or an overdose of narcotics or barbiturates.
Hypoventilation at Wikipedia
Category:Symptoms