Impedance techniques are frequency dependent, and relate to normal breathing. FEV1 is an artificial, one breath maximal effort requiring patient collaboration. It would be very difficult to drive an analytical relationship.

the attached paper deals with statistical comparisons and other matters.

further paper of interest

Article Counterpoint: Lung Impedance Measurements are not More Usefu...

Look i'm no expert on lungs, but I work with forced expiration of working fluid(gas) in bladder type heat exchanger/s, with remote hydraulic actuation, so similar to lungs. The limiting factor is not the applied force by any means, but the passage restriction to the flow of the working fluid in and out in the case of the lung.

So I'd say no relationship because the limiting factor for me, the weakest link in the chain, is the nostril opening restriction. laugh if you like.

Lung impedance requires factors related to airway alone whereas FEV1 indirectly requires alveoli interstium and airway elastic and compliance properties

@Derek, Well you are absolutely right.

I want to correlate the lung models using data obtained from spirometry and FOT. and Hence I need a mathematical expression.

I think the relationship is airway resistance as it affect both FEV1 and FOT,but you need to test it on ideal model to find the exact relationship pattern.

@Tarig, Dear Sir!

Thank you, for your comment. I am trying to do the same using airway resistance and lung compliance. But still, as you suggested, there is no mathematical expression relating all these.

@ tarig: Dear Doctor, even if we assume it mathematically as done. would that "relation" be the same for both healthy and damaged lung? we all know, a damaged lung is less compliant, and so high resistances would be scored to get a small mobilized volume. then we are just talking here of "another" way to calculate the pulmonary compliance !!