Altered arousal response in infants exposed to cigarette smoke

Abstract

Aims: A failure of the arousal mechanism is a key feature in the apnoea theory for sudden infant death syndrome (SIDS). In infants studied at an age when the incidence of SIDS is highest, we evaluated whether in utero smoke exposed infants have altered arousal response to standardised auditory stimuli, and/or sleep pattern, as recorded on overnight complex sleep polysomnography. Methods: A standardised sequence of audiology stimuli was applied binaurally to 20 in utero smoke and non-smoke exposed infants aged 8-12 weeks during a rapid eye movement (REM) and NREM epoch, in a controlled (temperature, position, pacifier use, noise) sleep environment. Infants were monitored for 10-12 hours using complex sleep polysomnography. Results: Five infants exposed to in utero tobacco smoke did not have behavioural arousal response, whereas all non-smoke exposed infants aroused during NREM (p = 0.016). There was, however, no difference in REM sleep, and the groups did not differ in routine overnight complex sleep polysomnography parameters. Conclusion: At the age when the incidence of SIDS is at its peak, infants of smoking mothers are less rousable than those of non-smoking mothers in NREM sleep; this may partly explain why such infants are more at risk of SIDS.

Maternal smoking and sudden infant death syndrome: epidemiological study related to pathology

“…Several authors have attempted to explain why infants of smoking mothers are at higher risk of SIDS [6,7,13,54]. The most common belief is that environmental smoke may influence the arousal mechanism, a key feature in the apnea theory for SIDS [6,55].…”

“…The most common belief is that environmental smoke may influence the arousal mechanism, a key feature in the apnea theory for SIDS [6,55].…”

Brainstem mechanisms underlying the sudden infant death syndrome: Evidence from human pathologic studies

“…We speculate that the nicotinic change in the SIDS infant with the 5-HT 1A vulnerability in the hypoglossal nucleus and nucleus of the solitary tract, for example, some way increases the risk for sudden death. Of note, prenatal exposure to cigarette smoke alters arousal responses in the infant period (Chang et al, 2003;Franco et al, 1999;Lewis & Bosque, 1995), suggesting that a site of interaction of nicotine with 5-HT neurons is in the medullary raph e and extra-raph e (paragigantocellularis lateralis). Both regions demonstrate reduced 5-HT 1A binding in SIDS infants, and both have recently been shown in piglets to influence cycling among REM, NREM, and waking Darnall et al, 2005).…”

SIDS and Other Sleep-Related Infant Deaths: Expansion of Recommendations for a Safe Infant Sleeping Environment

“…Thirdhand smoke refers to residual contamination from tobacco smoke after the cigarette has been extinguished 206 ; there is no research to date on the signifi-cance of thirdhand smoke with regards to SIDS risk. Smoke exposure adversely affects infant arousal [207][208][209][210][211][212][213] ; in addition, smoke exposure increases risk of preterm birth and low birth weight, both of which are risk factors for SIDS. The effect of tobacco smoke exposure on SIDS risk is dosedependent.…”