The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

DOES EXHALATION TIME OF THE FORCED VITAL CAPACITY MANEUVER SIGNIFICANTLY AFFECT MEAN ESTIMATES OF PULMONARY FUNCTION SCREENING PARAMETERS?

Kathleen Clark1, Bo Cai1, James Gibson2, Erik Svendsen1,2; 1Epidemiology and Biostatistics, University of South Carolina, Columbia, SC; 2South Carolina Department of Health and Environmental Control, Columbia, SC

BACKGROUND: Spirometry screening measurements are strongly linked to patient effort and the quality of the testing maneuver. We examined community-acquired spirometry screening data to determine if differences in exhalation times during the FVC maneuver actually did affect FeV1, FVC, and FeV1% measurements. METHODS: Spirometry was performed on 208 adults (ages:16-80 years) following an accidental release of approximately 60 tons of chlorine gas into the community. NIOSH trained therapists were used and strict adherence to ATS/ERS guidelines was attempted. Exhalation times were classified into four groups; (1) all FVC maneuvers (n=208), (2) FVC > six seconds (n=102), (3) > three seconds but < six seconds (n=91), and (4)< three seconds (n=15). One-way ANOVA identified significant differences in the percentage of predicted FeV1 (ppFeV1), percentage of predicted FVC (ppFVC), and FeV1% . Tukey multiple comparisons provided information as to which exhalation times produced significantly different results when compared to others. RESULTS: Differences were observed for all parameters (FeV1% p<0.0001, ppFeV1 p=0.03, and ppFVC p<0.0001). The FeV1% was lowest for exhalation times > three seconds (MEAN: all=81.8%, >6 sec=85.2%, >3 sec=77.6%, and < 3 sec=89.5%). Mean ppFeV1 was lowest for maneuvers less than three seconds (MEAN: all= 78.1%, > 6 sec= 77.3%, > 3 sec=81.2%, and < 3 sec=65.4%), and significant differences were seen between the > 3sec and < 3 sec groups (a=0.05). Mean ppFVC was also lowest for exhalation times < three seconds when compared to all other s (MEAN: all=78.0%, >6 sec=80.5%, >3 sec=78.6, and <3 sec=65.4%). CONCLUSION: In adults, spirometry screening is affected by the exhalation time of the FVC maneuver. This appears to be greatest when the duration of the FVC maneuver is less than three seconds. Caution should be used during spirometry screening, since shortened exhalation times may lead to erroneous results. Sponsored Research - None