Vaporizers at High Elevations

In this video from Count Backwards from 10, we look at the question, what happens when we travel to elevations high above sea level and attempt to use our vaporizers. This comes up a good amount on examinations, even if clinically it isn’t the most relevant topic to anyone practicing outside of the Rockies, but the concepts remain relevant.
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[@sabarikarthick6286]

SVP doesn't vary with Ambient pressure. It is because of the relative increase in percentage of the SVP when compared with the decreasing Ambient pressure, the vapor output increases. Not because of the Ambient pressure per se!

[@connorbrown2364]

Re. 4:24 - SVP doesn't vary with ambient pressure;SVP only varies with temperature

[@akyiaaantwi5504]

Wow! where has your channel been! you make concepts easy to understand! pls make more videos

[@johnolive9477]

Great explanation.
Thanks!

[@nanoukituandamakombele5943]

I decided to do anaesthesia ,,thanks your videos/ lessons help me to understand ,THANKS A LOT please be my second mentor

[@RuhulAmin-ti5pg]

Thanks for the easy explanation

[@jessicaleung8312]

Fantastic explanation

[@adams303]

I’m not sure I follow your explanation here. The variable bypass vaporiser works via a splitting ratio. The percent on the dial relates to % of Patm, but that’s just so it’s easier to work out instead of having it expressed as mmHg or kPa. Since SVP does not change with ambient pressure then it doesn’t change the output, assuming the pressure of input gas remains constant. After all it’s the partial pressure and not the concentration that exerts the anaesthetic effect right? If the des vapouriser is heated to 2x SVP and dial is kept at 6% - it’s output would be constant. It might output a larger fraction of PB at altitude, but that doesn’t alter it’s effect. The only effect I’d expect with altitude is a decrease in ambient temperature which could reduce SVP.

[@freecopt4003]

You are my physics teacher Thanks

[@nevilleslightlylargerbotto1726]

I get why you have to pressurize desflurane so as to make it more likely to remain a liquid and not just all evaporate. But why additionally heat it? Doesn’t the tendency of heating liquids and causing them to turn into vapors defeat the purpose of so highly pressurizing desflurane in the first place? It seems you put in one mechanism to make it a liquid (2 x atm) and another to offset that and keep it a gas (heating it to 39 Celsius). That confuses me

[@vlk092]

you keep it at a constant temperature so that the saturated vapour pressure is maintained constant. since the desflurane vaporizer is not a variable bypass vaporizer and delivers the gas directly, if you dont keep the pressure and temperature always the same, you would be delivering variable amounts of the gas

[@nevilleslightlylargerbotto1726]

@@vlk092 ah, that makes more sense. Thank you!

[@vlk092]

@@nevilleslightlylargerbotto1726 you're welcome bro💪

[@che_mahii]

facts are wrong . SVP only change with temparature. One molecule will not push another moluecule to change the pressure . thats what dalton told