Altitude Flashcards
Low altitude height (m)
1250
Moderate altitude height (m)
1250-3000
High altitude height (m)
3000-6000
Severe altitude height (m)
6000+
Hypoxia
Inadequate supply of O2 to respiring tissue
Kent 1999
Link altitude + hypoxia
Altitude provides exposure to a hypoxic env.
What features come with a high altitude
⬇️ Ambient temp
⬆️ Solar radiation
⬇️ Barometric pressure
Define the change in barometric pressure
Higher = Less pressure due to less mass pushing down on top.
What % in the chemical make up of the air around us is always O2?
21%
Daltons law
Total pressure exerted = to the sum of the partial pressures of the ind gases
What happens to atmospheric pressure under daltons law
⬇️ at higher altitudes
Under Daltons law, what happens if atmospheric pressure drops?
Partial pressure will drop
% in ambient air
O2 = 21%
CO2 = 0.03%
N2 = 79%
What is barometric pressure at sea level
760mmHg
How is partial pressure calculated?
Fractional conc x total gas pressure
Normoxia
Normal O2 pressure
Hyperoxia
High O2 pressure
O2 cascade
Fall in PO2 ⬇️ driving pressure for GE in lungs + prod a cascade of effects to the level of the mit. (final destination of the O2)
What happens to O2 saturation as altitude increases?
Why?
Decreases
Due to ⬇️ in cascade of O2 pressure
Symptoms to acute mountain sickness
Headache
Nausea
Fatigue
Causes to acute mountain sickness
Ascending faster than 500m/d
Exercise vigorously
When might high altitude pulmonary oedema (HAPE) occur?
After 2-3 days at altitude >2500m
Can be fatal within hours
What is HAPE
Accumulation of fluid in lungs preventing air spaces from opening up + filling w/ fresh air w/ each breath
Symptoms to HAPE
Excess fluid in lungs
Breathlessness
Fever
Coughing frothy spit
Causes to HAPE
Ascending faster than 500m/d
Exercise vigorously
What is High altitude cerebral oedema (HACE)
⬆️ in blood flow to brain in response to low O2 levels (normal) BUT
If blood vessels in brain are damaged, fluid may leak out + result in HACE
What % of people get HACE above 3000m?
1%
Symptoms to HACE
Severe headache
Coma
Vomiting
Confusion
Causes to HACE
Ascending faster than 500m/d
Exercise vigorously
How long does it take to adapt to altitudes up to 2300m?
2 weeks
Above that, 1 week for every 610m.
Why does VO2 max decrease when we go to altitude?
⬆️ height = ⬇️ PO2 = ⬆️ ventilation + ⬇️ PP of arterial O2
⬆️ ventilation = ⬆️ CO2 removal –> Hypocapnea –> ⬇️ Ventilation (Eventually)
⬆️ ventilation = ⬆️ pH –> ⬆️ bicarbonate excretion –> ⬇️ SV
