Heart rate responses to non-arousing trigeminal stimulation in infants: Effects of sleep position, sleep state and postnatal age

Abstract

Aims The aim of this study was to examine the effects of maternal smoking, sleeping position, sleep state and postnatal age on heart rate changes following non-arousing trigeminal stimulation in infants. Subjects We studied healthy term infants, 13 of whom were born to mothers who did not smoke and 11 to mothers who smoked during pregnancy. Each infant was studied using daytime polysomnography on 3 occasions: (a) 2–3 weeks, (b) 2–3 months and (c) 5–6 months after birth. Nasal air-jet stimulation was presented in both active sleep (AS) and quiet sleep (QS) when infants slept both prone and supine. Results We found no difference between infants of smoking and non-smoking mothers in any of the parameters measured. Minimum HR (MinHR) following non-arousing trigeminal stimulation was significantly lower in the supine compared to the prone sleeping position at 2–3 weeks and 2–3 months of age ( p < 0.05) in AS, and at all 3 ages in QS ( p < 0.01). MinHR was significantly lower in QS compared to AS at 2–3 months when infants slept prone and at 5–6 months when sleeping supine ( p < 0.01). In QS, MinHR became lower with increasing postnatal age in both sleep positions ( p < 0.01). In AS, there was no maturational effect. The normalized bradycardia (ΔHR%) was significantly greater in AS than in QS at 2–3 weeks of age ( p < 0.05) when infants slept supine. Conclusion Our study has shown that there was a decrease in heart rate (MinHR) following trigeminal stimulation in infants up to 6 months of age and this was affected by sleep position and sleep state, being larger in the supine sleeping position and the QS state.