| FETs | forced expiratory time in seconds |
|---|---|
| FEV | familial exudative vitreoretinopathy; forced expiratory volume |
| FEV1, | FEV1 forced expiratory volume in one second |
| HFO-A | high-frequency oscillatory [ventilation]-active [expiratory phase] |
| I/E | inspiratory/expiratory [ratio]; internal/external |