Original ArticleThe effects of dummy/pacifier use on infant blood pressure and autonomic activity during sleep
Introduction
Despite the dramatic decline in the incidence of the Sudden Infant Death Syndrome (SIDS), >2500 infants die in the USA each year and SIDS remains the leading cause of perinatal death in Western countries [1]. Evidence from cardiorespiratory recordings prior to death suggests that SIDS occurs during sleep and may be due to a failure of autonomic cardiovascular control to compensate for a profound hypotension in conjunction with a failure to arouse from sleep [2]. In support of this hypothesis, prone sleeping, the major risk factor for SIDS, is associated with an impaired control of both heart rate (HR) and blood pressure (BP), and this is most marked at 2–3 months of age when the risk of SIDS is greatest [3], [4]. While there has been much effort to understand how major risk factors, such as prone sleeping, contribute to the fatal event of SIDS, there has been little research directed at factors known to reduce the risk of SIDS. In 1979, it was first suggested that dummy/pacifier use might decrease SIDS risk [5], and this suggestion was later supported by further studies [6], [7], [8], [9], [10], [11], [12], [13]. A meta-analysis in 2005 reported a 50% reduction in SIDS among dummy/pacifier users in the last sleep compared to a control group [14] and subsequent studies have confirmed these findings [15], [16]. Two more recently published case–control studies have also found dummies/pacifiers to be protective [17], [18]. Only one small study has failed to identify a significant protective effect [19].
The American Academy of Pediatrics recommended the use of a dummy/pacifier in 2005 [20]. This recommendation has been quite controversial, and not all countries have adopted this approach. In part, the hesitation to recommend a dummy/pacifier has been due to the lack of understanding of the mechanisms through which they provide protection [21] and the concern that dummy/pacifier use may adversely impact breastfeeding [22].
To date, there has only been one study on the effects of dummy/pacifier use on cardiovascular control of HR, and this suggested that sucking on a dummy/pacifier was associated with increased sympathetic activation during sleep [23]. No studies have investigated the impact of dummy/pacifier use on BP or autonomic BP control. The most recent epidemiological study identified that dummy/pacifier use provided the greatest protection to infants in the prone sleeping position [18]; however, no physiological studies have examined dummy/pacifier use in this position to date.
We aimed to assess HR and BP and their control during prone and supine sleep in infants who regularly used a dummy/pacifier and those who did not, and to assess the effect of active sucking in dummy/pacifier users across the first 6 months after birth when most SIDS occurs. We hypothesized that BP and HR would be elevated in dummy/pacifier users and cardiovascular control improved in the prone sleeping position.
Section snippets
Methods
Ethical approval was granted by the Southern Health and Monash University Human Research Ethics Committees. No monetary incentive was provided for participation, and written parental consent was obtained.
Results
As dummy/pacifier use was not consistent in individual infants across the three studies, infants were divided into dummy/pacifier users at the time of each study. At 2–4 weeks and 5–6 months, one infant was excluded at each age due to technical difficulties during the recording. At 2–4 weeks, 2–3 months, and 5–6 months, 16, 21 and 18 infants used a dummy/pacifier, respectively. Of the infants studied, 12 infants never used a dummy/pacifier and 11 infants always used a dummy/pacifier at all
Discussion
Regular dummy/pacifier use has consistently been shown to be associated with a reduced SIDS risk; however, the mechanism for this reduced risk is currently unknown. This was the first study to investigate both BP and HR control in infants who regularly used a dummy/pacifier and those who did not. We hypothesized that to be protective, the use of a dummy/pacifier would increase BP and improve cardiovascular control and this would be most marked in the prone sleeping position. We found that BP
Conclusions
This study identified that active sucking of a dummy/pacifier alters cardiovascular control. Specifically, the BP was higher at 2–4 weeks and 5–6 months, and HRV was also higher at 2–4 weeks in dummy/pacifier users compared to non-users, indicating that sympathetic tone may be higher. A higher sympathetic tone may protect infants from possible hypotension during sleep and thus may play a protective role in the fatal event of SIDS. However, we cannot discount that dummy/pacifier users may be
Funding sources
All phases of this study were supported by the Lullaby Trust (formerly the Foundation for the Study of Infant Deaths), The National Health and Medical Research Council of Australia and the Victorian Government's Operational Infrastructure Support Program.
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2014.07.011.
Acknowledgments
The authors would like to thank all the parents and their infants who participated in this study and the staff of the Melbourne Children's Sleep Centre where the studies were carried out.
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Financial disclosure: The authors have no financial relationships with regard to this article to disclose.