Journal of Applied Physiology, Vol 79, Issue 4 1093-1099, Copyright © 1995 by American Physiological Society
Effect of periodic thermal stimulus on heart rate in term newborn infant
M. K. Hathorn, P. A. Mannix and K. Costeloe
University of London: Joint Academic Department of Child Health Medical College, St. Bartholomew's Hospital, London, United Kingdom.
We studied heart rate changes in 25 term infants aged 1-7 days in quiet
sleep during periodic thermal stimulation of one foot to widen the range of
frequencies previously studied by others and to develop spectral analysis
methods to quantify responses to thermal and other periodic sensory
stimuli. The stimulation frequency was 0.10 Hz in all babies and ranged
from 0.05 to 0.15 Hz in some. At 0.10 Hz, there was 1) an increase in
spectral power at the frequency of stimulation (P < 0.001), 2) a
tendency for overall low-frequency power to increase, 3) a reduction in
respiratory sinus arrhythmia (P < 0.025), and 4) attenuation in the
response between the first and second minute of stimulation (P < 0.01).
At other frequencies of stimulation, essentially similar results were
obtained. Respiration and other types of periodic sensory stimulation may
also entrain the heart rate; we raise the question of whether low-frequency
oscillations in heart rate are in fact related to thermoregulation or are a
nonspecific feature of integrative processes in the brain stem.
