Postnatal autonomic activity in the preterm lamb

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• 作者：Hugues Patural ; Marie St-Hilaire ; Vincent Pichot ; Alain Beuché ; e ; Nathalie Samson ; Charles Duvareille ; Jean-Paul Praud
• 关键词：Lamb ; Heart rate variability ; Baroreflex sensitivity ; Laryngeal chemoreflexes ; Newborn lamb
• 刊名：Research in Veterinary Science
• 出版年：2010
• 出版时间：October 2010
• 年：2010
• 卷：89
• 期：2
• 页码：242-249
• 全文大小：360 K

文摘

Background

Early postnatal abnormalities of autonomic nervous system (ANS) activity, including at baseline and following cardiorespiratory challenge, are involved in apneas–bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome. Literature data suggest that baseline ANS activity does not mature normally after premature birth.

Objectives

This study performed in preterm lambs was aimed at assessing ANS maturation at baseline and following laryngeal chemoreflexes (LCR), a group of reflexes triggered by the contact of liquids with the laryngeal mucosa.

Methods

Heart rate variability (HRV) and baroreflex sensitivity (BRs) were measured at baseline and after LCR during polysomnographic recordings performed in five non-sedated lambs born 15 days prematurely. Laryngeal chemoreflexes were induced by distilled water or acid (pH 2) during sleep and wakefulness on postnatal days 7 (D7) and 14 (D14, full-term equivalence).

Results

While the life-threatening cardiorespiratory events of the LCR observed at D7 were no longer present at D14, baseline and post-LCR HRV and BRs indices were significantly lower at D14 compared to D7 (up to p < 0.001). These results suggest that an initial autonomic overactivity was present at D7 and normalized at D14.

Conclusion

The autonomic cardiac and baroreflex control appears to follow a specific evolution in the preterm compared to the full-term newborn lamb, with an important initial autonomic stress, which normalizes at an age equivalent to full-term. Potential relevance of these findings in relation to anomalies of cardiac control in the early postnatal period, such as apneas–bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome, awaits further studies.