Sleeping position of infants and the sudden infant death syndrome

The recent fall in postperinatal mortality in New Zealand and the Safe Sleep programme

AIM

Postneonatal mortality rates changed very little from 2000 until recently. There has been a decrease in mortality in New Zealand from 2009 to 2015. This study describes an infant Safe Sleep programme and postulates it is the cause for the recent decrease in deaths.

METHODS

The Safe Sleep programme involved as follows: a focus on preventing accidental suffocation, a 'blitz' approach to SUDI education, the targeted provision of portable infant Safe Sleep devices (ISSD) and the development of Safe Sleep policy across all district health boards (DHBs).

RESULTS

Participation in the education 'blitz' by health professionals exceeded one in 23 live births, distribution of Safe Sleep leaflets exceeded two for every live birth, and over 16 500 ISSDs have been distributed to vulnerable infants. Postperinatal mortality fell 29% from 2009 to 2015 (2.8 to 2.0/1000 live births). The fall has been greatest for Māori and in regions with the most intensive programmes.

CONCLUSION

The recent fall in postperinatal mortality has not happened by chance. It is likely that the components of end-stage prevention strategy, a focus on preventing accidental suffocation, the education 'blitz', the targeted supply of ISSDs and strengthened health policy, have all contributed to varying degrees.

Bed Sharing, SIDS Research, and the Concept of Confounding: A Review for Public Health Nurses

Confounding is an important concept for public health nurses (PHNs) to understand when considering the results of epidemiological research. The term confounding is derived from Latin, confundere, which means to "mix-up" or "mix together". Epidemiologists attempt to derive a cause and effect relationship between two variables traditionally known as the exposure and disease (e.g., smoking and lung cancer). Confounding occurs when a third factor, known as a confounder, leads to an over- or underestimate of the magnitude of the association between the exposure and disease. An understanding of confounding will facilitate critical appraisal of epidemiological research findings. This knowledge will enable PHNs to strengthen their evidence-based practice and better prepare them for policy development and implementation. In recent years, researchers and clinicians have examined the relationship between bed sharing and sudden infant death syndrome (SIDS). The discussion regarding the risk of bed sharing and SIDS provides ample opportunity to discuss the various aspects of confounding. The purpose of this article is to use the bed sharing and SIDS literature to assist PHNs to understand confounding and to apply this knowledge when appraising epidemiological research. In addition, strategies that are used to control confounding are discussed.

Cardiovascular control during sleep in infants: Implications for Sudden Infant Death Syndrome

In infants the cardiorespiratory system undergoes significant functional maturation after birth and these changes are sleep-state dependent. Given the immaturity of these systems it is not surprising that infants are at risk of cardiorespiratory instability, especially during sleep. A failure of cardiovascular control mechanisms in particular is believed to play a role in the final event of Sudden Infant Death Syndrome (SIDS). The "triple risk model" describes SIDS as an event that results from the intersection of three overlapping factors: (1) a vulnerable infant, (2) a critical development period in homeostatic control, and (3) an exogenous stressor. This review summarises normal development of cardiovascular control during sleep in infants and describes the association of impaired cardiovascular control with the three overlapping factors proposed to be involved in SIDS pathogenesis.

SIDS: past, present and future

Despite the large reduction in SIDS mortality, which occurred in the early 1990s following the 'Back to Sleep' campaigns, SIDS remains the leading cause of death in the postneonatal age group. This paper describes the position in the 1980s, the contribution of the New Zealand Cot Death Study, what should be recommended and the current research priorities.

CONCLUSION

SIDS is preventable. Application of what we currently know could eliminate SIDS. The challenge is to find ways of implementing our knowledge.

[Definitions and prevention of cardiorespiratory arrest in children]

In cardiopulmonary resuscitation ages are divided in neonates (in the inmediate period after the birth), infant (from birth to 12 months) and child (from 12 months to puberty). Respiratory arrest is defined by the absence of spontaneous respiration (apnea) or a severe respiratory insufficiency (agonal gasping) that require respiratory assistance. Cardiac arrest is defined as the absence of central arterial pulse or signs of circulation (movement, cough or normal breathing) or the presence of a central pulse less than 60 lpm in a child who does not respond, not breath and with poor perfusion. After resuscitation the return of spontaneous circulation is defined as the recuperation of central arterial pulse or signs of circulation in a child with previous cardiorespiratory arrest. It is maintained when the duration is longer than 20 minutes. Injuries, sudden infant death syndrome, and respiratory diseases are the most frequent etiologies of cardiorrespiratory arrest in children. The prevention and the formation of citizens in basic cardiopulmonary resuscitation are the most effective measures to reduce the mortality of cardiorespiratory arrest in children.

Effects of prematurity on heart rate control: implications for sudden infant death syndrome

In Western countries, 5-11% of all infants are born before 37 weeks of gestation, and with improvements in modern intensive care techniques the number of these preterm infants that survive continues to increase. Preterm birth is one of the leading causes of neonatal morbidity and mortality in developed countries, accounting for 60-80% of infant deaths in those without congenital anomalies. Furthermore, in the post-neonatal period, preterm infants are at four-times greater risk of sudden infant death syndrome. It has been suggested that this increased risk is due to immature autonomic control. This article provides an overview of studies assessing autonomic control of the cardiovascular system in preterm infants.

Effects of sleep position, sleep state and age on heart rate responses following provoked arousal in term infants

Previous studies have suggested that autonomic dysfunction may be involved in Sudden Infant Death Syndrome (SIDS). The major risk factors for SIDS are the prone sleeping position and maternal smoking. Our aim was to examine the effects of sleeping position and maternal smoking on the postnatal maturation of autonomic function by examining heart rate responses following arousal in healthy term infants. Twenty-four infants (11 born to mothers who smoked during pregnancy and 13 to mother who did not smoke) were studied using daytime polysomnography and multiple measurements of arousal threshold (cm H(2)O) in response to air-jet stimulation applied alternately to the nares were made in both active sleep (AS) and quiet sleep (QS). We demonstrated no difference between smoking and non-smoking groups of infants in any of our measurements, and thus combined data from the groups. Baseline (BHR) was elevated in the prone compared to the supine position in quiet sleep (QS) at 2-3 weeks (p<0.001) and 5-6 months (p<0.001), and in active sleep (AS) at 2-3 and 5-6 months (p<0.05). BHR was significantly elevated in AS compared to QS in the supine position at all ages (p<0.01) and in the prone position at 2-3 (p<0.001) and 5-6 months (p<0.05). Increases in heart rate (deltaHR%) following arousal were significantly greater in the supine compared to the prone position in QS at 2-3 weeks (p<0.05) and in AS at both 2-3 (p<0.01) and 5-6 months (p<0.05). DeltaHR% was significantly greater in AS compared to QS in both supine (p<0.05) and prone (p<0.001) positions at 2-3 weeks and in the supine position at 2-3 months (p<0.001). We conclude that sleep state, sleep position and postnatal age affect the cardiac responses following arousal from sleep in healthy term infants. Impairment of heart rate control in the prone position may be important in understanding the increased risk for SIDS in this position.

Effect of infant sleeping position on sleep spindles

Sleep spindles play an active role in inducing and maintaining sleep and may affect arousal by blocking the transmission of external stimuli through the thalamus to the cortex. Previously we have demonstrated that sleeping in the prone position impairs arousal in infants at 2-3 months of age, but not at 5-6 months. We aimed to examine if sleeping position and postnatal age affected duration and/or density of sleep spindles. Twenty-one healthy term infants were studied using daytime polysomnography at 2-3 months and 16 were again studied at 5-6 months. Infants slept both prone and supine at each study. The mean duration of non-rapid eye movement (NREM) sleep was not different between the two studies in either position. At 2-3 months both spindle density (P < 0.001) and proportion of NREM sleep (P < 0.025) with spindles were significantly greater in the supine than in the prone position. At 5-6 months spindle duration was longer in the supine than in the prone position (P < 0.03). Spindle density in the supine position was not different between the two studies, however, when infants slept prone, it was significantly increased at 5-6 months compared with 2-3 months (P < 0.001). Arousal threshold was not correlated with either spindle density or percentage of NREM sleep with spindles in either position at either study. In this study spindle density and the percentage time spent with spindles were not well correlated with infant arousability, and hence may not be able to be used as markers of depressed arousal responses in infants.

Arousal responses and risk factors for sudden infant death syndrome

BACKGROUND

Failure to arouse from sleep has been postulated as a mechanism to explain the final pathway of sudden infant death syndrome (SIDS).

METHODS

We have reviewed the effects of the major risk factors for SIDS, prone sleep position, maternal smoking, prematurity and recent infection on arousability from sleep. In human infants it has been consistently demonstrated that arousal from sleep in response to a variety of stimuli is more difficult to induce from quiet sleep (QS) compared to active sleep (AS) over the first 6 months of life.

RESULTS

In the prone position both stimulus-induced and spontaneous arousability from both QS and AS were impaired at 2-3 weeks and 2-3 months, but not at 5-6 months of age in both term and preterm infants. In term infants exposed to maternal smoking during pregnancy both stimulus-induced and spontaneous arousability were impaired when infants slept supine in QS at 2-3 months of age. Healthy preterm infants showed no impairment in arousability compared with term infants at matched postconceptional ages. However, preterm infants with a history of apnoea and bradycardia of prematurity showed decreased arousal responses in both QS and AS and this impairment was positively correlated to their 'perinatal risk score'. Infants who had recently suffered an infection requiring hospitalization showed decreased arousability in QS on the day of discharge when compared to 2 weeks later when they were completely well.

CONCLUSIONS

In summary it has been found that the major risk factors for SIDS identified from epidemiological studies also decrease arousability from sleep in infants. We propose that this decreased arousability from sleep may be involved in the final pathway of SIDS.

Effects of body position on sleep and arousal characteristics in infants

The prone sleeping position has been identified in world-wide epidemiological studies as a major risk factor for sudden infant death syndrome (SIDS). Public awareness campaigns throughout the western world have led to an over 50% reduction in postneonatal mortality and frequency of SIDS. This reduction in mortality has been mainly attributed to the avoidance of the prone sleep position. Various mechanisms have been postulated to explain the increased risk of SIDS associated with prone sleeping, among these, impairment of arousal from sleep. This paper reviews the effects of prone sleeping on infant sleep architecture, arousability from sleep and cardiorespiratory controls. Sleeping in the prone position has been shown to increase the amount of time spent sleeping, particularly time spent in quiet sleep (QS). Sleeping prone has also been demonstrated to be associated with a reduced responsiveness to a variety of arousal stimuli. Such impairment of arousal has been demonstrated to be associated with changes in control of autonomic cardiac function. During arousal, heart rate, blood pressure and breathing movements increase, while gross body movements occur to avoid the stimulus. Any impairment in arousability from sleep such as could occur when infants sleep in the prone position, could possibly contribute to the final pathway to SIDS.

The contribution of prone sleeping position to the racial disparity in sudden infant death syndrome: the Chicago Infant Mortality Study

BACKGROUND

Rates of sudden infant death syndrome (SIDS) are over twice as high among African Americans compared with Caucasians. Little is known, however, about the relationship between prone sleeping, other sleep environment factors, and the risk of SIDS in the United States and how differences in risk factors may account for disparities in mortality.

OBJECTIVE

To assess the contribution of prone sleeping position and other potential risk factors to SIDS risk in a primarily high-risk, urban African American population.

DESIGN, SETTING, AND POPULATION

Case-control study consisting of 260 infants ages birth to 1 year who died of SIDS between November 1993 and April 1996. The control group consists of an equal number of infants matched on race, age, and birth weight. Prospectively collected data from the death scene investigation and a follow-up home interview for case infants were compared with equivalent questions for living control participants to identify risk factors for SIDS.

MAIN OUTCOME MEASURES

Risk of SIDS related to prone sleeping position adjusting for potential confounding variables and other risk factors for SIDS, and comparisons by race-ethnicity.

RESULTS

Three quarters of the SIDS infants were African American. There was more than a twofold increased risk of SIDS associated with being placed prone for last sleep compared with the nonprone positions (odds ratio [OR]: 2.4; 95% confidence interval [CI]: 1.6-3.7). This OR increased after adjusting for potential confounding variables and other sleep environment factors (OR: 4.0; 95% CI: 1.8-8.8). Differences were found for African Americans compared with others (OR: 1.8; 95% CI: 1.2-2.6 and OR: 10.3, 95% CI: 10.3 [3.2-33.8, respectively]). The population attributable risk was 31%. Fewer case mothers (46%) than control mothers (64%) reported being advised about sleep position in the hospital after delivery. Of those advised, a similar proportion of case mothers as control mothers were incorrectly told or recalled being told to use the prone position, but prone was recommended in a higher proportion of black mothers (cases and controls combined) compared with nonblack mothers.

CONCLUSIONS

Prone sleeping was found to be a significant risk factor for SIDS in this primarily African American urban sample, and approximately one third of the SIDS deaths could be attributed to this factor. Greater and more effective educational outreach must be extended to African American families and the health personnel serving them to reduce prone prevalence during sleep, which appears, in part, to contribute to the higher rates of SIDS among African American infants.

Effects of maternal tobacco smoking, sleeping position, and sleep state on arousal in healthy term infants

OBJECTIVES

To investigate whether a history of maternal tobacco smoking affected the maturation of arousal responses and whether sleeping position and infant age alters these relations.

DESIGN

Healthy term infants (13 born to mothers who did not smoke and 11 to mothers who smoked during pregnancy) were studied using daytime polysomnography on three occasions: (a) two to three weeks after birth, (b) two to three months after birth, and (c) five to six months after birth. Multiple measurements of arousal threshold in response to air jet stimulation were made in both active sleep (AS) and quiet sleep (QS) when infants slept both prone and supine.

RESULTS

Maternal smoking significantly elevated arousal threshold in QS when infants slept supine at 2-3 months of age (p<0.05). Infants of smoking mothers also had fewer spontaneous arousals from QS at 2-3 months in both prone (p<0.05) and supine (p<0.001) sleeping positions. In infants of non-smoking mothers, arousal thresholds were elevated in the prone position in AS at 2-3 months (p<0.01) and QS at 2-3 weeks (p<0.05) and 2-3 months (p<0.001).

CONCLUSIONS

Maternal tobacco smoking significantly impairs both stimulus induced and spontaneous arousal from QS when infants sleep in the supine position, at the age when the incidence of sudden infant death syndrome is highest.

Medial smooth muscle thickness in small pulmonary arteries in sudden infant death syndrome revisited

Increased relative medial thickness (RMT) of smooth muscle in small pulmonary arteries, peripheral extension of smooth muscle into the alveolar wall arteries, and right ventricular hypertrophy (RVH), in response to purported prolonged hypoxia, have been reported in sudden infant death syndrome (SIDS). Prone sleep position, an important risk factor for SIDS, predisposes infants to hypoxia from airway obstruction or rebreathing. Since publication of the earlier pulmonary artery studies, the SIDS definition has been expanded, and sudden infant death investigational protocols have been implemented. Our aims in this study were to (1) compare RMT in preacinar arteries (PA), intra-acinar arteries accompanying small airways (SIA), and alveolar wall arteries (AW) in SIDS infants and controls; (2) correlate RMT with postmortem variables; (3) determine if peripheral extension occurred more often in SIDS infants than in controls; and (4) determine if RVH occurred in SIDS. Movat-stained sections from standardized tissue blocks taken prospectively from the apex of the right upper lobe from 88 SIDS cases and 17 controls were evaluated using a computer-assisted digitizing system with images obtained from a microscope with an attached video camera. When adjusted for age, the RMT values for the SIA arteries were significantly greater in controls, while the PA and AW arteries were not statistically different between the SIDS cases and controls. Peripheral medial smooth muscle extension did not differ between the groups, and RVH was not seen in SIDS cases. Given the recent identification of brain stem abnormalities interfering with protective cardiorespiratory responses against acute life-threatening hypoxia perhaps precipitated by prone sleeping, our data suggest that SIDS is an acute event not preceded by recurrent or prolonged apnea and hypoxia.

Interaction between bed sharing and other sleep environments during the first six months of life

This investigation was carried out to determine the relationship between bed sharing and other places of infant sleep in the first six months of life, and to identify patterns of change in the place of infant sleep for infants who do and do not routinely bed share in the first six months of life. The sleep--wake behaviour and place of infant sleep were recorded, at weekly intervals, for bed sharing (n=25) and non-bed sharing (n=68) infants between 2 and 24 weeks after birth. Bed sharing infants spent a significantly increased proportion of their total sleep time per 24 h in other sleep environments which favoured close parental proximity and significantly less time in solitary sleep. Non-bed sharing infants spent a substantial proportion of their time sleeping alone from 2 weeks of age whereas the transition to sleeping alone occurred after 16 weeks for bed sharing infants. We have found that bed sharing acts as a proxy for increased close parental proximity during the first six months of life. This may be of significance in studies which examine the relationship between bed sharing and sudden infant death syndrome.

The prone sleeping position impairs arousability in term infants

OBJECTIVE

To investigate whether the prone sleeping position impaired arousal from sleep in healthy infants and whether this impairment was related to cardiorespiratory variables, temperature, or age.

STUDY DESIGN

Healthy term infants (n = 24) were studied with daytime polysomnography on 3 occasions: 2 to 3 weeks after birth, 2 to 3 months after birth, and 5 to 6 months after birth. Multiple measurements of arousal threshold (cm H(2)O) in response to air-jet stimulation applied alternately to the nares were made in both active sleep and quiet sleep when infants slept both prone and supine.

RESULTS

Arousal thresholds were significantly higher in both active sleep and quiet sleep when infants slept prone at 2 to 3 weeks and 2 to 3 months, but not at 5 to 6 months. These increases were independent of any sleep position-related change in either rectal or abdominal skin temperature, respiratory rate, oxygen saturation, or heart rate.

CONCLUSIONS

The prone position significantly impairs arousal from both active sleep and quiet sleep in healthy term infants. This impairment in arousability occurred with no clinically significant changes in cardiorespiratory variables or body temperature. Decreased arousability from sleep in the prone position provides an important insight into its role as a risk factor for sudden infant death syndrome.

CLINICAL REVIEW ARTICLE: Is changing the sleep environment enough? Current recommendations for SIDS

Sudden infant death syndrome (SIDS or cot death) was the major cause of post-neonatal infant death in many countries in the late 1970s and 1980s. There is now very strong evidence that public intervention campaigns targeting the prone sleeping position, which had been identified by epidemiological studies as a major risk factor, were followed by substantial falls in the rate of SIDS. In the present review we discuss the evidence on which current recommendations for the prevention of SIDS are based. The prone sleeping position is now clearly causally associated with SIDS. Further reductions in SIDS may be produced by recommending the back sleeping position as opposed to the side position. Maternal smoking in pregnancy and bed sharing by infants of mothers who smoke are also strongly associated with SIDS, but have been harder to influence. Paternal smoking has also been implicated, although the magnitude of the reported risk is small. Finally, breastfeeding, pacifier use and having the infant sharing the parents bedroom, but not the bed, may also reduce risk. Continued reductions in SIDS mortality will require innovative public health education to target these major risk factors, while building on the "back to sleep" approach.

Functional gastrointestinal disorders

When clinicians label a child as having a functional disorder, there is often a pejorative connotation that the symptoms are psychological, imagined, or faked. These symptoms range from chronic abdominal pain to recurrent headaches to fatigue. We say the complaints are functional because we are unable to demonstrate any structural or biochemical abnormality causing them. The degree to which we go searching for these abnormalities varies from case to case and often depends on our own clinical experience, insecurities, and demands of the patient's family. Labeling a child as having a functional complaint can put a tremendous burden on the child and family, because if this concept is presented improperly (as implied above), it can suggest that it is their fault there are symptoms and that if they "got their act together" the symptoms would melt away. Functional gastrointestinal disorders are defined as conditions in which a variable combination of chronic or recurrent gastrointestinal symptoms are present in the absence of demonstrable disease. There may indeed be physiologic abnormalities underlying the symptoms, but at the present time we are unable to detect them. We make a diagnosis based on symptoms, not on demonstrable abnormalities in physical examination or laboratory tests. A number of common pediatric diagnoses fall into this category, including infant regurgitation, chronic nonspecific diarrhea, irritable bowel syndrome, non-ulcer dyspepsia, infant dyschezia, and functional constipation. This paper presents a brief review of our current understanding of each diagnosis and gives suggestions for management.

The changing epidemiology of SIDS following the national risk reduction campaigns

Prone sleeping position is causally associated with SIDS. The change in the proportion of infants sleeping prone has resulted in a dramatic reduction in SIDS and total postneonatal mortality. The effect of prone sleeping position is modified by season, latitude, illness, thermal insulation and sheepskins. This suggests that the mechanism by which prone sleeping position causes SIDS is in some way related to temperature.

Problems on the diagnosis of sudden infant death syndrome

Various autopsy cases of sudden unexpected death (SUD) in infancy were examined at the Tokyo Medical Examiner's Office between 1985 and 1994. More than half of the SUD were diagnosed as sudden infant death syndrome (SIDS), but a number of other causes, such as mechanical asphyxia, were also diagnosed. SIDS is diagnosed by autopsy, but there are no clear diagnostic criteria differentiating SIDS from other causes of SUD. SUD is diagnosed as SIDS when other causes are excluded, but it is difficult to distinguish between SIDS and mechanical asphyxia. There was not a large difference in autopsy findings, or in death scene or statistical data, between SIDS and non-SIDS cases. In their estimation of the diagnostic ratio of SIDS to other causes of death, medical examiners might be divided into three groups: 'SIDS tolerationist' examiners think that SUD should be positively diagnosed as SIDS, insofar as another cause of death is not proved clearly. A second group of examiners might be regarded as 'SIDS exclusionist': these consider microscopic findings or peculiar death scenes as important contributing factors leading to death. The third group represents a middle stance somewhere between these two. We thought that (forensic) pathologists as well as medical examiners in Japan might have differing stances on SIDS diagnosis. The statistical analysis of SIDS in certain research areas may be affected by the diagnostic 'preference' of pathologists belonging to a certain institute.

Temporal disparity between reduction of cot death and reduction of prone sleeping prevalence

According to several reports sudden infant death rates have decreased significantly after public campaigns aimed at reducing the incidence of sleeping in a prone position. The Styrian population (1.2 million inhabitants), who have been studied from 1984, also showed a significant drop in the incidence of cot death during 1989 (from 2/1000 to 1/1000%). The year before, a campaign for the prevention of cot death had been launched. This included the recommendation to prevent infants from lying in a prone position during sleep. Part of the prevention programme consisted of a detailed questionnaire filled in and returned by the parents. These data, on 29970 infants from 1989 to 1994, provided information on the frequency of prone sleeping in 37% of our total population and as a consequence on parental response to the campaign. Calculating the data per year led to the surprising result that the reduction by half (from 50% to 25%) in the prevalence of sleeping in a prone position did not occur in 1989, when the drop in the incidence of cot death occurred, but 3 years later, in 1992. The following years saw a further decrease of prone position to 7% but no appreciable change in the incidence of cot death. However, during those 11 years of study about 80% of the victims were consistently found dead lying in a prone position. Our results show a temporal disparity between the reduction of sudden infant death and the decrease of prone sleeping in a population. Although we do not deny sleeping in a prone position as a risk factor for cot death, there cannot be a simple relationship between sleeping habits in the population and incidence of cot death.

Influence of sleep states on laryngeal and abdominal muscle response to upper airway occlusion in lambs

This study was aimed at describing abdominal and laryngeal muscle responses to upper airway occlusion (UAO) in early life and the effect of sleep states on these responses. Twelve nonsedated, 9-26-d-old lambs were studied. We simultaneously recorded 1) airflow (pneumotachograph + face mask); 2) sleep states (electrocorticogram and electrooculogram); 3) abdominal muscle (external obliquus) electromyogram (EMG); and 4) glottic constrictor (thyroarytenoid) and dilator (posterior cricoarytenoid and cricothyroid) muscle EMGs. The pneumotachograph was repeatedly occluded for 15-30 s in wakefulness and natural sleep. We analyzed 90 occlusions during wakefulness (11 lambs), 28 during non-rapid eye movement (nREM) sleep (six lambs), and 23 during rapid eye movement (REM) sleep (five lambs). A phasic expiratory external obliquus EMG was present during baseline and progressively increased throughout UAO in wakefulness and nREM sleep, but not in REM sleep. Phasic thyroarytenoid EMG progressively increased during inspiratory efforts throughout UAO in wakefulness and nREM sleep, paralleling the increase in glottic dilator (posterior cricoarytenoid and cricothyroid) EMG. In contrast, glottic muscle response to UAO in REM sleep was severely blunted or disorganized by frequent swallowing movements. We conclude that UAO triggers complex and coordinated laryngeal and abdominal muscle responses during wakefulness and nREM sleep in lambs; these responses are largely absent, however, in REM sleep. These unique results, together with the defective arousal response in REM sleep, suggest that vulnerability to airway occlusion could be increased during REM sleep in early life. Possible implications for understanding severe postnatal apneas are discussed.

[Sleeping position, prevention of sudden death syndrome and gastroesophageal reflux]

Based on results of epidemiological studies, dorsal or lateral sleeping positions are now recommanded in the prevention of sudden infant death syndrome (SIDS). This raises an ethical question about the attitude towards the ventral positioning therapy for gastroesophageal reflux (GOR). The consensus conference considers that the ventral position should only be recommanded in GOR when the benefit appears to outweigh the risk of SIDS that it induces. The conference proposes that for infants with simple uncomplicated reflux, sleeping in the prone position should not be introduced in the first line treatment. Prone positioning should be restricted to complicated cases resistant to dietary and medical measures.

Current concepts and issues in the management of regurgitation of infants: a reappraisal. Management guidelines from a working party

Regurgitation in infants is a common problem. Recent issues, such as the increased risk of sudden infant death in the prone sleeping position, the finding of persisting occult gastro-oesophageal reflux with feed thickeners, and the increasing awareness of the cost-benefit ratio of medications may challenge the currently recommended management approach. A round table was organized to elaborate on the impact of (i) the pro supine sleeping campaigns in relation to sudden infant death and (ii) advancement in medical treatment on therapeutic strategies in regurgitating infants. The participants were opinion leaders from Europe and North America (Belgium, Canada, France, UK, Italy, Switzerland and The Netherlands). The importance of parental reassurance is stressed. As a consequence of the supine sleeping campaigns aiming to decrease the incidence of sudden infant death syndrome, the "prone elevated sleeping position" is no longer advised as a first-line therapeutic approach, although it is still recommended in "complicated reflux". It is emphasized that milk thickeners are an adequate therapeutic tool for regurgitation, but not in reflux disease. According to the literature, the efficacy of (alginate )antacids, although very popular in some countries, is questionable. These recommendations will be of interest to first-line paediatricians, since about 40% of their patients, according to the literature, present because of regurgitation.

Autopsy cases of sudden unexpected infant deaths examined at the Tokyo medical examiner's office, 1964-1993

The medical examination system in Japan covers only four regions (Yokohama, Osaka, Kobe and the 23 wards in Tokyo). In almost all other regions, it is difficult to perform reliable epidemiologic studies. This report presents a chronological analysis of sudden infant deaths, including sudden infant death syndrome, over 30 years (1964-93) in the 23 Tokyo wards.

Sleeping position and sudden infant death syndrome in Norway 1967-91

OBJECTIVE

To investigate, in a population based national study, the association between sleeping position of infants and the occurrence of sudden infant death syndrome (SIDS).

DESIGN

A retrospective survey and registry based ecological study. A questionnaire based surveillance of sleeping position was obtained in a random sample (n = 34,799) and surveillance of SIDS was based on all infants born in Norway 1967-91, surviving the perinatal period. Variables studied from the questionnaire were usual sleeping position (placed), breast feeding at 3 months, and maternal smoking in pregnancy, and from the Medical Birth Registry maternal age, birth order, and birth weight.

RESULTS

Proportion of infants sleeping prone increased from 1970 (7.4%) to 1989 (49.1%) and dropped in 1990 (26.8%) and 1991 (28.3%). Occurrence of SIDS increased from 1970 (1.1/1000) to 1989 (2.0) before dropping in 1990 and 1991 (1.1). IMPLICATION AND RELEVANCE OF RESULTS: A cause effect relationship between prone sleeping and SIDS as suggested in previous studies is supported by the present; and so far only, national study of infants' sleeping position.

Cardiorespiratory adaptation during sleep in infants and children

The cardiorespiratory control system undergoes functional maturation after birth. Until this process is completed, the cardiorespiratory system is unstable, placing infants at risk for cardiorespiratory disturbances, especially during sleep. The profound influence of states of alertness on respiratory and cardiac control has been the focus of intense scrutiny during the last decade. The effects of rapid-eye movement (REM) sleep on various mechanisms involved in cardiorespiratory control are of particular significance during the postnatal period since newborns spend much of their time in this sleep state. In fullterm newborns, REM sleep occupies more than 50% of total sleep time, and this percentage is even greater in preterm newborns. From term to six months of age, the proportion of REM sleep decreases. Since respiratory and cardiac disturbances are known to occur selectively during REM sleep, the predominance of REM sleep may be a risk factor for abnormal sleep-related events during early infancy. Awareness of these developmental changes in sleep patterns is important for clinicians dealing with problems such as apparent life-threatening events (ALTE), sudden infant death syndrome (SIDS), and/or cardiorespiratory responses to respiratory disorders. Our current understanding of respiratory and cardiac control rests mainly on studies conducted during the first months of life. There is a paucity of data on late infancy and early childhood. The present paper will review available data on how sleep affects 1) ventilatory mechanics, in particular of the upper airways and the chest wall; ventilation and apnea; gas exchange; chemoreceptor function; and arousal responses; 2) changes in heart rate and heart rate variability, and the occurrence and mechanisms of bradycardia.

Travel and changes in routine do not increase the risk of sudden infant death syndrome

We investigated the relationship between travel and changes in routine and the sudden infant death syndrome (SIDS) among 485 SIDS cases compared with 1800 randomly selected control infants. There was no increased risk of SIDS with travel. Special events, such as christenings, were not associated with an increased risk of SIDS. However, visits to and by friends or relatives were associated with a significantly reduced risk of SIDS after controlling for potential confounders (odds ratios = 0.70; 95% confidence interval = 0.52, 0.96). These findings may indicate less social support in SIDS cases.