Beat-by-beat forearm blood flow with doppler ultrasound and strain
gauge plethysmography.
Tschakovsky, M. E., J. K. Shoemaker, and R. L. Hughson.
Department of Kinesiology, University of Waterloo, Waterloo, Ont.
Canada, N2L 3G1
APStracts 2:0164A, 1995.
Simultaneous Doppler ultrasound estimates of brachial artery mean
blood velocity (MBV) and venous occlusion strain gauge
plethysmography measures of forearm blood flow (FBF) were performed
in order to determine the beat-by-beat relationship between the two
methods and provide a method for flow calibration of Doppler MBV
estimates. Such a calibration of Doppler MBV eliminates the need for
knowledge of vessel cross-sectional area and angle of insonation,
while allowing for the quantification of limb blood flow. Six healthy
subjects (5 males, 1 female) performed 40 seconds of isometric
forearm contraction at 35% maximal voluntary contraction with
arterial inflow occluded. This resulted in elevated blood flow upon
relaxation and cuff deflation, and simultaneous beat-by-beat Doppler
MBV and strain gauge FBF measurements were then made over a period of
two to three minutes as flow gradually decreased to resting levels.
The r2 values for the fitted regression lines over a wide range of
flows ranged from 0.87 to 0.98 and the mean square error terms from
0.88 to 3.07 ml/100ml/min. Significant day to day variation of the
fitted regression parameters within subjects indicated that
quantitative estimates of FBF from Doppler MBV require a calibration
to be performed for each experiment. The finding of a strong, linear
relationship between Doppler MBV and venous occlusion strain gauge
plethysmography, as well as the marked beat-by-beat effect of cuff
inflation on blood flow, confirms the importance of calibration on
the same beats, not adjacent segments of beats.
Received 19 January 1995; accepted in final form 14 April 1995.
APS Manuscript Number A64-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.