Definition
A form of hypoxia in which the blood is unable to carry a sufficient amount of oxygen to the body's cells, even though enough oxygen is available in the lungs. Causes include blood loss, anemia, and the displacement of oxygen on the hemoglobin molecule by carbon monoxide.
Plain English
Your lungs are getting plenty of oxygen, but your blood can't carry enough of it around your body. The supply is there, but the delivery system is the problem.
Context Anchor
Seen in aeromedical discussions of hypoxia, especially when learning about carbon monoxide from exhaust leaks, smoking, blood loss, and other conditions that reduce oxygen delivery.
Derivation
From the Greek 'haima' meaning blood, plus 'hypoxia' (low oxygen). So 'hypemic' literally points to a blood-related cause — which is exactly where this type of hypoxia originates.
Why Pilots Care
It can occur at any altitude from exhaust leaks, faulty heaters, or smoking, producing performance loss without the usual altitude cues.
Analogy
Think of the blood as the delivery system for oxygen. In hypemic hypoxia, the oxygen may be available, but the delivery system does not have enough working capacity to get it where it needs to go.
Grounding Statement
If carbon monoxide enters the cabin from an exhaust leak, it can keep the blood from carrying oxygen normally, so the pilot can become hypoxic even while breathing air that seems normal.
Intuition Check
Do not assume hypoxia always means there is not enough oxygen in the outside air. In hypemic hypoxia, the main problem is that the blood cannot carry enough oxygen to the body.
Example Sentence 1
After noticing a faint exhaust smell in the cabin and feeling lightheaded, the pilot suspected hypemic hypoxia from carbon monoxide and opened the fresh air vents while descending.
Example Sentence 2
Smoking the night before a flight raised the chance of hypemic hypoxia at even moderate altitudes.