I don't think there is a direct correlation between arterial PaO2 and
weight. However it is well recognised that obese patients desaturate very
rapidly when faced with hypoxic situations e.g. airway obstruction. This is
explained by their relatively low FRC, which effectively means they can't
build up an oxygen reservoir in the same way that non-obese patients can. So
while a healthy (slim) preoxygenated adult can remain saturated for up to 8
minutes of apnoea, an obese patient will only manage 2 or 3 minutes in the
same situation. By the same token children also desaturate quickly, again
partly because of a low FRC but also because of higher metabolism. A
preoxygenated child can only withstand apnoea for a minute or two if you're
lucky!
Is this what you were after, or am I on the wrong track entirely?
Regards
Adrian Fogarty
> -----Original Message-----
> From: Adrian Kerner
> Subject: re : Pa O2 and weight
>
> Is their a relationship between Arterial partial pressures of
> oxygen and a person's weight?
>
> Do you need higher PaO2 to maintain physiology with increasing
> tissue mass?
>
> What implications would this have for interpreting ABG's in extremes of
> weight etc?
>
> Answers on a post card please!
>
> Thanks
>
> Adrian Kerner
> Leeds.
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