Journal of Applied Physiology, Vol 78, Issue 1 359-367, Copyright © 1995 by American Physiological Society
Characterization of a density-corrected ultrasonic pneumotachometer for horses
R. E. Beadle, A. J. Guthrie and A. H. Kou
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803.
A density-corrected ultrasonic pneumotachometer designed specifically for
horses (UF202) was evaluated and characterized with the aid of a
custom-built apparatus. UF202 provided voltage outputs for airflow through
and gas density within the flowhead. Baseline stability for flow channel
output (VUF202) was < 0.35% full scale (FS), and VUF202 was linear over
a range of +/- 50 l/s (R2 > or = 0.9976). Under optimal conditions,
VUF202 accuracy was determined to be +/- 1.00% FS and repeatability was +/-
0.78% FS. VUF202 resolution was 24 ml/s. The rise time for VUF202 was 18
ms, and the -3-dB point was 18 Hz; digital compensation provided a flat
frequency response to 32 Hz. VUF202 gain appeared to be stable over a
period of 8 days. Density channel output (PUF202) was linear over a range
of 1.11-1.23 g/l (R2 > or = 0.9645). PUF202 accuracy was calculated to
be +/- 0.50% FS, and PUF202 repeatability was determined to be +/- 0.30%
FS. Resistance of the flowhead was determined to be 0.013 cmH2O.l-1.s at a
flow of 40 l/s. On the basis of this study, we conclude that UF202 should
facilitate accurate measurement of breath-by-breath airflow of exercising
horses.
