Definition
A form of hypoxia in which the body's tissues are unable to use the oxygen that has been delivered to them by the blood. Oxygen reaches the cells in normal amounts, but the cells cannot absorb or metabolize it. Common causes include alcohol, certain drugs, and poisons such as cyanide.
Plain English
The blood is carrying enough oxygen, but the cells can't actually use it. Things like alcohol or certain drugs interfere with how the cells process oxygen, so the body suffers even though the oxygen is right there.
Context Anchor
Seen in aeromedical discussions of hypoxia, especially when learning how alcohol, drugs, and other substances can make altitude-related impairment worse.
Derivation
From the Greek 'histos' meaning 'tissue' and 'toxic' meaning 'poisonous.' So histotoxic literally means 'tissue-poisoning.' The name points to the cause: the tissues themselves have been poisoned and can no longer use oxygen, even when it's available.
Why Pilots Care
Alcohol and certain drugs can trigger histotoxic hypoxia at any altitude, degrading judgment and reaction time without the usual warning signs of oxygen starvation.
Grounding Statement
In histotoxic hypoxia, the problem is not getting oxygen to the cells; the problem is that the cells cannot use it properly.
Intuition Check
Do not assume all hypoxia means there is not enough oxygen in the air. In histotoxic hypoxia, oxygen may be present, but the body’s tissues cannot use it normally.
Example Sentence 1
The flight surgeon explained that even one drink the night before could contribute to histotoxic hypoxia during a high-altitude flight.
Example Sentence 2
The safety briefing noted that cyanide exposure produces histotoxic hypoxia by blocking cells from using the oxygen already in the blood.