Due to premature closing of the airways on expiration, the FVC will also decrease but not as much as the FEV1. The FEV1/FVC will fall. The flow/volume graph has a concave appearance (Fig 1). The ...

If a doctor suspects you have a lung condition, they’ll calculate your FEV1/FVC ratio. This represents the percentage of your lung capacity you can expel in one second.

There is significant disparity in the ratios for postbronchodilator FEV1/FEV6 and FEV1/FVC %, and this disparity is very pronounced in women.

FVC% and FEV1% thresholds that best separated hypercapnic from normocapnic patients were 56% and 33% of predicted values, according to cross-validation analysis.