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- Air displacement plethysmography uses the displacement of air, rather than water. I just thought I'd share it because it's a cool method.
Air displacement plethysmography
I saw a tv programme many years ago which shows this method of measuring the volume of a patient's body. Air displacement plethysmography was a procedure that I saw being used and, tbh, I never asked myself how it works, until now. It's smart, imo. You put someone in a sealed box full of air and then you determine the volume of air with the body in it. You just take a measured volume of air out of the container and measure the drop in pressure. Boyle's Law allows you to calculate the original volume of air (= containter volume - body volume).
There will be a number of practicalities, including keeping the air temperature constant (or accounting for any change when a warm patient is put in. Claustrophobia could be problem for some people - even with a large window.
I saw a tv programme many years ago which shows this method of measuring the volume of a patient's body. Air displacement plethysmography was a procedure that I saw being used and, tbh, I never asked myself how it works, until now. It's smart, imo. You put someone in a sealed box full of air and then you determine the volume of air with the body in it. You just take a measured volume of air out of the container and measure the drop in pressure. Boyle's Law allows you to calculate the original volume of air (= containter volume - body volume).
There will be a number of practicalities, including keeping the air temperature constant (or accounting for any change when a warm patient is put in. Claustrophobia could be problem for some people - even with a large window.