Why is it important to distinguish between hypoxia and hyperventilation?

8-1-3. Hyperventilation in Flight
a. Hyperventilation, or an abnormal increase in the volume of air breathed in and out of the lungs, can occur
subconsciously when a stressful situation is encountered in flight. As hyperventilation "blows off" excessive
carbon dioxide from the body, a pilot can experience symptoms of lightheadedness, suffocation, drowsiness,
tingling in the extremities, and coolness and react to them with even greater hyperventilation. Incapacitation can
eventually result from incoordination, disorientation, and painful muscle spasms. Finally, unconsciousness can
occur.
b. The symptoms of hyperventilation subside within a few minutes after the rate and depth of breathing are
consciously brought back under control. The buildup of carbon dioxide in the body can be hastened by controlled
breathing in and out of a paper bag held over the nose and mouth.
c. Early symptoms of hyperventilation and hypoxia are similar. Moreover, hyperventilation and hypoxia can
occur at the same time. Therefore, if a pilot is using an oxygen system when symptoms are experienced, the
oxygen regulator should immediately be set to deliver 100 percent oxygen, and then the system checked to assure
that it has been functioning effectively before giving attention to rate and depth of breathing.