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Hypoxia symptoms, altitude & types

Hypoxia: too little oxygen reaching tissues. Insidious: usually unnoticed (TC AIM AIR 3.2.1; FAA PHAK ch.17).

Symptoms:

First: euphoria (carefree feeling), loss of night vision (at night use oxygen from the ground up, TC AIM AIR 3.5)
Later: impaired judgement and coordination, tunnel vision, cyanosis (blue lips and nails)

Altitude effects:

Altitude	Effect	Cite
5,000 ft	Some people impaired	PHAK ch.12
8,000 ft	Some notice rise in heart and breathing rate	TC AIM AIR 3.2.1
10,000 ft	All pilots mildly hypoxic, some symptomatic: no flight above without supplemental oxygen or cabin pressurization	TC AIM AIR 3.2.1
10,000 ft	Average person impaired (approx.)	PHAK ch.12
18,000 ft	Reduced partial pressure of oxygen impairs normal body function	PHAK ch.12

Time of useful consciousness (PHAK ch.17):

Altitude	Time
20,000 ft	30+ min
45,000 ft	9-15 sec

Treatment: descend and/or use supplemental oxygen. All pilots susceptible regardless of fitness or acclimatization (PHAK ch.17).

Four types, by where the oxygen chain breaks:

Type	Break	Causes	Ref
Hypoxic	Low oxygen in bloodstream	Mostly altitude	-
Anaemic	Blood cannot carry oxygen	Anaemia, recent blood donation	TC AIM AIR 3.2.1
Stagnant	Poor circulation	High G, extreme cold	TC AIM AIR 3.2.1
Histotoxic	Cells cannot use oxygen	Drugs, chemical poisons	-

Anaemic:

Stagnant (ischaemic):

Blood donation (TC AIM AIR 3.2.1, 3.12):

Cuts red-cell count.
In some people, disturbs circulation for several days, though it feels fine on the ground.
Flying then risks anaemic hypoxia.

Trap: waiting to feel hypoxia before acting. Onset insidious, may feel like well-being.

PPL Tester