Autoregressive spectral analysis of the phrenic neurogram during
eupnea and gasping.
Akay, Metin, Joseph E. Melton, Walter Welkowitz, Norman H. Edelman,
and Judith A. Neubauer.
Department of Medicine, University of Medicine and Dentistry of New
Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey
08903-0019, and Department of Biomedical Engineering, Rutgers-The
State University, New Brunswick, New Jersey 08903
APStracts 3:0139A, 1996.
During hypoxic gasping the phrenic neurogram (PN) has a steeper rate
of rise, an augmented amplitude, and a shorter duration than that
seen during eupnea. Since hypoxia reduces neuronal activity, we
hypothesized that gasping would be characterized in the frequency
domain by enhanced low frequency power compared to eupnea.
Autoregressive (AR) spectral analysis of the phrenic neurogram of
chloralose anesthetized, vagotomized, peripherally chemodenervated
cats was performed during eupnea and hypoxic gasping. During eupnea,
significant spectral peaks were seen at 41+/-2 (+/-SE) and 93+/-2 Hz.
In all cats, the 41 Hz spectral peak disappeared during hypoxic
gasping and was replaced by a high power, low frequency peak at 26+/
-1 Hz. No consistent change in the frequency or power of the high
frequency spectral peak was seen during gasping. To determine whether
changes in the AR spectrum of the PN during gasping result from
augmented respiratory output, we compared the AR spectra of the PN
during gasping, hypercapnia (FetCO2=0.09) and carotid sinus nerve
(CSN) stimulation. Unlike during gasping, there was no shift of power
toward lower frequencies during hypercapnia and CSN stimulation. We
conclude that the spectral characteristics of gasping, loss of the
medium frequency peak, and the appearance of a low frequency
(<30 Hz) power, are unique to this respiratory pattern.
Received 5 May 1995; accepted in final form 27 February 1996.
APS Manuscript Number A476-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96