fev1 over fvc, what's that? (dr. make) that's how fast the air comes out. it's a general measure of how much air comes out in the first second when you blow out hard and fast compared to the total amount of air. (peter) alright, forty-eight percent predicted and her's was fifty percent. (dr. levy) so the ratio is fifty percent? (peter) correct. (dr. levy) between the one second value and the total amount. (peter) aha. (dr. levy) so that's markedly reduced and the normal patient will generally be able to get at least seventy percent of their total lung volume out within that first second. but for her to be cutting off at fifty percent, that's really a sign of obstructed. (dr. make) so if you think about it this way, the air passages are like tubes or pipes. the smaller they are, the less fast the air comes out. the bigger they are, the faster it comes out. and this indicates the air's coming out pretty slow, so there's some problem with the air passages being smaller than they should be. (peter) well elaine's doctor makes a diagnosis on the basis of this alo