'Normal' lung function?
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You propose to use the standard deviation score of FEV1%(F)VC in assessing whether a patient has, or does not have, airway obstruction. |
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Absolutely correct! You are quite justified in wanting to use the standard deviation score. If you wish to refresh your memory on this subject, read “Expressing results correctly”. You are similarly absolutely right in assessing airway obstruction from FEV1%(F)VC rather than from FEV1. After all, the FEV1 (as well as the VC) may be diminished by either and obstructive or a restrictive disorder. However, only an FEV1 (the average expiratory flow during 1 second) which is disproportionately low with respect to the (F)VC (an index of lung volume) signifies expiratory airflow limitation, i.e. obstructive lung disease. Hence, FEV1%(F)VC should be the starting point for assessing airway obstruction. |
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