AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 3 653-R660, Copyright © 1989 by American Physiological Society
Breath-by-breath respiratory timing and volume control during periodic breathing
D. W. Carley, C. Maayan, J. Grimes and D. C. Shannon
Pediatric Pulmonary Unit, Massachusetts General Hospital, Boston.
We examined the control of respiratory pattern during
non-rapid-eye-movement sleep-related periodic breathing (PB) in adults,
with and without hypoxia. We analyzed 186 cycles of PB from 18 epochs
occurring in eight subjects; the mean (+/- SD) cycle duration was 30.8 +/-
8.4 s. Significant oscillations occurred in inspired tidal volume (VT),
inspiratory duration (TI), mean inspired flow, inspired minute ventilation,
and expiratory duration (TE) (P less than 0.005). For each epoch of PB,
moving cross-correlation (MCC) functions were employed to describe the
time-dependent intervariable relationships between 1) TI vs. TE, 2) VT vs.
TE, and 3) VT vs. breath duration (TT) as synchronization, a strong and
consistent intervariable correlation; relative coordination (RC), a weaker
interaction characterized by an unstable MCC function oscillating at a
subharmonic of the PB frequency; or as independence, with no statistical
evidence of interaction. Fourteen epochs showed RC between TI and TE, 11
and 12 of which also showed RC between VT and TE, and VT and TT,
respectively. In 4 epochs negative synchronization was exhibited by all
three variable pairs. In no case were the oscillations between any pair of
variables independent. The modes of coupling between variables were not
correlated to O2 saturation, end-tidal CO2 levels, or inspired O2 level. We
conclude that during sleep-related PB a nonrandom but weak coupling usually
exists between TI and TE, VT and TE, and VT and TT.(ABSTRACT TRUNCATED AT
250 WORDS)
