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Entrainment of respiration to rocking in premature infants: coherence analysis
1Department of Physiology, Dartmouth School of Medicine, Lebanon, New Hampshire 03756.
Insights
Rocking premature infants can influence their breathing patterns, with most babies showing synchronized breathing. This vestibular stimulation may be a maturational reflex in newborns.
Area of Science:
- Neonatal Physiology
- Neuroscience
- Respiratory Control
Background:
- Premature infants often have immature respiratory control.
- Vestibular system stimulation is known to affect motor activity.
- The impact of vestibular input on infant breathing patterns requires further investigation.
Purpose of the Study:
- To investigate the influence of vestibular stimulation via rocking on the breathing patterns of premature infants.
- To determine if rocking can entrain the respiratory rhythm in neonates.
- To explore potential maturational changes in this reflex.
Main Methods:
- Respiratory abdominal movements were recorded in 18 premature infants.
- Infants were manually rocked at varying frequencies (30-60 cycles/min).
- Coherence analysis was used to quantify the synchronization between rocking and breathing.
Main Results:
- 15 of 18 infants showed entrainment of their breathing to rocking.
- Common entrainment ratios included 2:1 and 1:1 at specific rocking frequencies.
- Infants older than 35 weeks postconceptional age demonstrated significantly greater coherence to rocking.
Conclusions:
- Manual rocking provides a phasic input that can reset and entrain the respiratory pattern generator in premature infants.
- Vestibular influences on breathing appear to mature with postconceptional age.
- Rocking may serve as a non-pharmacological method to support respiratory stability in neonates.
Abstract:
Vestibular influences on breathing pattern were investigated in 18 premature infants in the neonatal intensive care nursery. Respiratory abdominal movements were recorded while the babies were manually rocked at varying rates between 30 and 60 cycles/min (cpm). Coherence spectra were estimated between the respiratory and rocker signals, and their magnitudes were evaluated at the rocking frequency, with coherence spectra > 0.85 indicative of strong entrainment to rocking. At least one incident of entrainment was seen in 15 of 18 infants, with 2:1 ratios (2 breaths/rocker cycle) occurring at rocking frequencies of 30-40 cpm (8 of 18 subjects) and 1:1 entrainment at rates of 42-50 cpm (5 of 18 subjects). More complex synchronization was observed in three infants, with patterns consisting of alternans between 2:1 and 3:2 ratios (5:3 entrainment). Infants > 35 wk postconceptional age exhibited greater coherence to rocking than infants < 35 wk (P < 0.01), indicating a maturational change in the reflex may occur. Results show that the natural stimulation of rocking a newborn provides a phasic input to its respiratory pattern generator that is capable of resetting the system's oscillation and entraining its rhythm.