Effect of perception of mechanical loading upon human respiratory pattern regulation. Daubenspeck, J. A., and Erik S. Rhodes. Department of Physiology, Dartmouth Medical School, Lebanon, NH 03756, and Thayer School of Engineering, Dartmouth College, Hanover, NH 03755
APStracts 2:0076A, 1995.
We applied external flow resistive (R) and elastic (E) mechanical loads over the entire respiratory cycle to 5 normal subjects using a pseudorandom loading protocol. Loads ranged in magnitude from imperceptible (R0/E0) through just perceptible (R1/E1) to large (R2/E2), and resulted in respiratory pattern responses that were due to reflex responses alone (R0/E0) or to a combination of reflex responses and behavioral reactions to the perception of impeded breathing (R1/E1 and R2/E2). Pattern regulation dynamics were estimated from the computed impulse responses of tidal volume (VT), and inspiratory (TI) and expiratory (TE) durations. We anticipated that emergence of behavioral contributions would be marked by increased variability in response strategies and by increased nonlinearity in the observed responses. Regarding the immediate pattern response to loading, there was a tendency for increased qualitative variation across subjects as the load size increased, but the within subject variability (coefficient of variation) was unaffected. We found no evidence for increased nonlinearity as loads became perceptible. The emergence of behavioral control in some instances seemed to be marked by reduction of complexity of the impulse response to one dominated by the zeroth order lag, leading to dynamically simpler responses compared to control. 

Received 25 August 1994; accepted in final form 1 February 1995.
APS Manuscript Number A897-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.