Spirometric reference values for the 6-s FVC maneuver.
OBJECTIVE
The guidelines of the National Lung Health Education Program for COPD screening proposed a shorter FVC maneuver (forced expiratory volume at 6 s of exhalation [FEV(6)]). Although reference values for FEV(6) are available from the third National Health and Nutrition Examination Survey, forced expiratory flow between 25% and 75% of FVC (FEF(25-75%)) reference values for the shorter 6-s maneuver are not available and are needed. In particular, calculation of largest observed volume during the first 6 s of an FVC maneuver (FVC(6)), from a shortened FVC maneuver, is necessary because the FEF(25-75%) measurement is based on a percentage of FVC or, for a shorter maneuver, FVC(6).


METHODS
We reanalyzed the raw volume-time curves from the third National Health and Nutrition Examination Survey to calculate FVC(6), forced expiratory volume at 0.5 s of exhalation, forced expiratory volume at 3 s of exhalation, ratio of the FEV(1) to largest observed volume during the first 6 s of an FVC maneuver expressed as a percentage (FEV(1)/FEV(6)%), and forced expiratory flow between 25% and 75% of the largest observed volume during the first 6 s of an FVC maneuver (FEF(25-75%6)) in addition to the previously reported values for FEV(1), FEV(6), and FEV(1)/FEV(6)%.


METHODS
Using the same normal, asymptomatic, nonsmoking reference population from a previous study, reference values for these parameters were derived from best values.


RESULTS
A total of 2,261 white, 2,564 African-American, and 2,666 Mexican-American subjects aged 8 to 80 years were included in the analysis. Fifty-four subjects from the previous study were not included due to missing raw volume-time curves.


CONCLUSIONS
These reference values, utilizing the FVC(6), provide investigators with the means of evaluating the relative merits of using the shorter FVC maneuver as a surrogate for the traditional FVC. They are needed particularly for calculating FEF(25-75%), as statistically significant differences were observed between the FEF(25-75%) and FEF(25-75%6).
Hankinson
John L
JL
Hankinson Consulting, Valdosta, GA 31604-3905, USA. hankinson@bellsouth.net
Crapo
Robert O
RO
Jensen
Robert L
RL
D000293:Adolescent; D000328:Adult; D001741:Black or African American; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D017058:Mexican Americans; D008875:Middle Aged; D012016:Reference Values; D013147:Spirometry / Q000592:standards*; D014797:Vital Capacity; D044465:White People