Clinical signs and symptoms:
(1) increased rate and/or depth of breathing (tachypnea and hypernea)
(2) dyspnea
(3) cyanosis
(4) confusion, cognitive impairment
(5) behavioral changes (excitement, other)
(6) incoordination
(7) drowsiness or loss of consciousness
(8) headache
(9) lassitude
(10) euphoria
(11) blurred or tunnel vision
(12) circumoral and/or acral (distal limbs) paresthesias (due to hypocarbia)
Astronauts and pilots are often exposed to hypoxia under controlled conditions in order to help them appreciate their idiosyncratic responses to hypoxia. Loss of control during flight can be catastrophic.
Excitement and euphoria underly the use of hypoxia by some people during intercourse or autoerotic practices.
Hypoxemia associated with lung disease tends to be more chronic and may be associated with hypercarbia.
