Am. J. Respir. Crit. Care Med., Vol 150, No. 6, Dec 1994, 1575-1580.
Volume spirometers need automated internal temperature sensors
LR Johnson, PL Enright, HT Voelker and DP Tashkin
Lung Health Study Research Group, Oregon Health Sciences University, Portland.
Spirometer temperature was measured automatically during all years of the
Lung Health Study. Short- and long-term changes in temperature were
analyzed for the 23 dry-rolling-seal volume spirometers used at the 10
clinical centers involved in the study. Within-test-session spirometer
temperature increased a mean of 0.3 degrees C, and as much as 3.0 degrees C
during methacholine challenge testing. The maximal change in spirometer
temperature during a test day exceeded 4 degrees C more than 5% of the
time. Month-to-month changes of more than 15 degrees C were not uncommon.
If ambient temperature had been assumed to apply to all maneuvers and used
for BTPS corrections, FEV1, and FVC measurement errors of up to 6% would
have occurred. When using volume spirometers, the temperature of air inside
the spirometer should be measured accurately during each breathing
maneuver.
