Deranged Physiology of Aviation

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Ever flown on a plane?  

Fascinating gas laws apply to physiology and medicine at altitude.

So if you have flown before (most of us) have you ever wondered why you get wee bit bloated or why oxygen is required in the event of depressurisation?

While not all the implications of the ‘gas laws‘ are applicable to our usual medical practice at sea level they are quite interesting to discuss in a short post.

These laws are essential to be aware of if we are attempting to practice emergency medicine at high altitude or deep underwater.

So does anything make your blood boil?  Well if you decided to be an astronaut then an unfortunate loss of ‘pressurisation’ in a high flying vehicle could actually do this due to the amazing properties of gases at different pressures and temperatures.

Enough to make your blood boil?


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Oh’s Summary of Altitude Changes

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The Gas Laws

The Name

The Law

The Implications

Dalton’s Law The ‘pressure’ of a gas mixture is equal to the sum of the ‘partial pressures’ of the gases in the mixture. Hypoxia at altitude                     (lower oxygen with less molecules higher up in the air)
Boyle’s Law The volume of a gas is inversely proportional to pressure (as long as temp is constant). Expansion of gases at altitude (more farts and bigger pneumothorax).  Endotracheal tube cuffs may expand.
Henry’s Law The amount of a gas dissolved in solution is directly proportional to the pressure of the gas over the solution. Decompression sickness           (the bends)
Charles’ Law Gases tend to expand when heated. The volume of a gas is proportional to its temperature. O2 flow rates at altitude change. Hot Air Balloons.
Gay-Lussac’s Law The pressure of a gas is directly related to temperature. Gunshot wounds – When gunpowder burns it creates a superheated gas the pressure pushes out a bullet at speed.

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Interesting #FOAMed Links