Sudden infant death syndrome in South Australia 1968-97. Part I: changes over time.

OBJECTIVE: To compare the epidemiology of sudden infant death syndrome (SIDS) over three consecutive decades. METHODOLOGY: The birth history, infant's developmental and health history, infant care practices for the infant, death scene investigation and autopsy findings for all infants dying suddenly and unexpectedly in South Australia (SA) between January 1968 and December 1997 were studied. RESULTS: The incidence of SIDS in SA rose through the 1970s and early 1980s with the highest incidence being in infants born in 1986 at 2.4 per 1000 live births (LB). Two factors felt to be dangerous for some infants were identified being left unobserved in the prone position and having the head covered by bed clothes. Publicity about the risk of prone sleeping has been accompanied by a fall in SIDS deaths, to an incidence of 0.5 per 1000 LB in 1997. The incidence in Aboriginal infants, and infants living in lower socio-economic conditions has always been high, but the over-representation of these groups has increased in the last 5 years. CONCLUSION: It no infant under 8 months of age was placed prone or was able to get to prone unobserved before the age when they can easily get back to supine, and no infant was able to get the head completely covered while unobserved, the incidence of SIDS in SA should fall below 0.2 per 1000 LB.

Sudden infant death syndrome (SIDS) in South Australia 1968-97. Part 2: the epidemiology of non-prone and non-covered SIDS infants.

OBJECTIVE: To identify the risk factors for infants who die suddenly and unexpectedly, but whose deaths are not related to prone position, or having the head covered. METHODOLOGY: A case-control study was designed in which the cases were infants who had died of sudden infant death syndrome (SIDS) in South Australia between January 1974 and December 1997, who were found not prone, not bed sharing and with the head not covered. The controls were two infants for each case, born in the same year and found in the prone position (again not bed sharing and with the head not covered). RESULTS: Sudden unexpected death infancy is rare in non-prone infants with the head not covered. occurring on average twice a year in South Australia, where there are 18,000-21,000 births per year. In this group there was a higher percentage of infants with features associated with low socio-economic groups (teenage pregnancies and maternal smoking), sibling SIDS, suspicion of non-accidental injury and the presence of minor congenital anomalies, especially cardiac anomalies. CONCLUSIONS: The majority of unexpected deaths in infancy can be prevented by not allowing infants to be unobserved in prone position, and by preventing them from getting their faces covered. For the few infants not found in these positions, a careful investigation should be made for malformations or non-accidental injury.

Sudden infant death syndrome in South Australia 1968-97. Part 3: is bed sharing safe for infants?

OBJECTIVE: To examine the risk of death for bed-sharing infants. METHODOLOGY: All unexpected infant deaths occurring in South Australia between 1970 and 1997, occurring after the infant was put to rest and diagnosed by after death scene investigation and autopsy as sudden death infant syndrome, accidental death, or 'undetermined' were studied. RESULTS: Accidents were the most likely cause of death for 5% of infants who died in designated infant containers (cots, cradles, etc), 24% of those who were sharing a bed or couch, and 72% of those who were placed alone on a bed or couch. CONCLUSIONS: While bed sharing showed an increased risk of dying accidentally, when compared with infants sleeping in designated infant containers, the risk of accidental death in this study was even greater for infants left alone on adult beds or couches.

Gastric aspiration and sleeping position in infancy and early childhood.

Concern has been expressed that the recommendation of supine sleeping position for infants would result in an increase in deaths due to gastric aspiration. A review of 196 cases of infant and early childhood death in children under 3 years of age, occurring over a 9-year period (September 1989 to August 1998) was undertaken to ascertain how many cases of significant gastric aspiration had occurred. Extensive and widespread filling of the airways/alveoli with gastric contents was found in three infants/young children aged 5, 6 and 30 months, respectively. In each instance the body had been found lying face down (prone), with the face in a pool of vomitus in at least one case. No cases of significant gastric aspiration were found in infants who had been found lying on their sides or backs (supine). In addition, no significant increase in numbers of infant and early childhood deaths in South Australia due to gastric aspiration over this time could be demonstrated. Concerns that the supine rather than the prone position is more likely to result in significant gastric aspiration are not supported by this study.

Formal retrospective case review and sudden infant death.

A review of 24 consecutive sudden infant deaths was undertaken to evaluate the importance of the various stages in the postmortem assessment of such cases. Death in three cases was caused by obvious trauma. Of the remainder, 16 were attributed to sudden infant death syndrome (SIDS), 4 to accidental asphyxia (identified by death scene examination and/or formal case review) and 1 to a lingual thyroglossal duct cyst. Three (14%) of 21 deaths thought to be SIDS after postmortem examination were attributed to asphyxia following subsequent formal case review.

V-shaped pillows and unsafe infant sleeping.

OBJECTIVE: To investigate the possibility that adult size V-shaped pillows may be associated with accidental asphyxial deaths in infants. METHODOLOGY: Review was undertaken of all cases of sudden infant death presenting to the Women's and Children's Hospital in Adelaide involving infants who had been found on adult size V-shaped pillows. RESULTS: Four cases of sudden infant death were found in which infants were found sleeping on V-shaped pillows. All of the deaths had occurred in 1995. In two of the cases the pillows were considered to be implicated in the cause of death as the potential for obstruction of the infants' airways could be demonstrated on death scene reconstruction. CONCLUSION: Adult size V-shaped pillows may be unsafe for use in small infants who may accidentally suffocate if trapped between the two arms, or under, the pillow. The use of such pillows to maintain the body position of sleeping infants should be discouraged.

Assessment of pulmonary and intrathymic hemosiderin deposition in sudden infant death syndrome.

The aim of this study was to stain lung and thymus gland sections that had been taken from infants who had died of sudden infant death syndrome (SIDS) for interstitial hemosiderin and to compare the results with those obtained for controls. There were two groups of SIDS infants, one with, and a second group without, histories of apparent life-threatening events (ALTEs). No significant difference in numbers of cases with interstitial hemosiderin deposition was found between SIDS infants with histories of ALTEs (n = 4 of 12, 33.3%), SIDS infants without histories of ALTEs (n = 4 of 22, 18.2%), and controls (n = 4 of 24, 16.7%). However, if four of the control cases with histories of previous chest trauma were excluded, there was a significantly greater number of cases with pulmonary interstitial hemosiderin in the SIDS infants with histories of ALTEs compared with the subgroup of control infants with no previous chest trauma (n = 1 of 20, 5%) (P < .05). No relationship could be established between the timing of the ALTEs, the type of resuscitation or age of the infant at death, and the presence of hemosiderin. None of the sections of thymus gland stained positively for hemosiderin. Positive staining for pulmonary interstitial hemosiderin, therefore, differentiated a group of SIDS infants with histories of previous ALTEs from a subgroup of control infants with no histories of previous chest trauma. However, pulmonary interstitial hemosiderin staining could not be used with certainly to confirm or exclude previous ALTEs in individual SIDS cases as not every SIDS case with a history of an ALTE stained for pulmonary interstitial hemosiderin. In addition, positive staining occurred for SIDS infants without histories of ALTEs and also for control infants who died of other causes.

Mesh-sided cots--yet another potentially dangerous infant sleeping environment.

Two cases of accidental asphyxia involving an 11.5 month old boy and a 3.5 month old boy who each died after being trapped between the elastic mesh side of their cots and the cot mattress are reported. In both cases the original cot mattress has either been replaced or augmented by a less well fitting, thicker mattress. Particular problems that exist with these type of mesh sided cots are the potential for considerable stretching of the side of the cot admitting the relatively larger, poorly supported infant head, with elastic recoil of the mesh holding the head in potentially dangerous positions. To help determine whether accidental asphyxia has occurred, death scene examination in cases of sudden infant death during sleep should include reconstruction of the position of the body in the cot or bed, with careful examination of the structure of the cot/bed.

Accidental infant death and stroller-prams.

A three-month-old boy and an eight-month-old boy died from accidental positional asphyxia and hanging, respectively, after being placed to sleep unsupervised in stroller-prams. Both infants had moved down towards the fronts of the stroller-prams. The younger infant fell out when the footplate collapsed and he was found hanging from a metal bar on the side. The older infant had partly slipped through the front and was suspended with his head and arms within the stroller-pram and with his face pushed firmly into the mattress by a horizontal metal bar. Stroller-prams are a potentially dangerous sleeping environment unless infants are closely supervised, gaps in the front of stroller-prams closed and upright footplates stabilised.

Accidental death or sudden infant death syndrome?

OBJECTIVE: To describe the reasons why it is difficult to decide whether to attribute some infant deaths to accidents or to SIDS. METHODOLOGY: To extract from infant deaths data in South Australia those where the cause of death is debatable. RESULTS: The risks associated with rocking cradles, bed sharing, bedclothes, couch sleeping, unsafe cots or beds and the prone position are presented. CONCLUSIONS: Uniform worldwide death scene investigations for all infant deaths should help identify unsafe sleeping conditions for infants.

Has changing diagnostic preference been responsible for the recent fall in incidence of sudden infant death syndrome in South Australia?

OBJECTIVE: An apparent decrease in deaths attributed to sudden infant death syndrome (SIDS) has been noted in a number of diverse geographical areas during the past several years. At the same time the definition of SIDS has been in a state of flux and some observers have raised the possibility that the fall in SIDS deaths is due to diagnostic transfer rather than to a genuine decrease in numbers. The present study was undertaken to investigate this possibility. METHODOLOGY: All sudden and unexpected deaths in infants under 1 year of age in South Australia during a 10 year period from 1984 to 1993 were reviewed. RESULTS: The number of deaths due to SIDS fell from 40 in 1984 to 17 in 1993, with a maximum of 52 cases per year in 1987. In contrast, the number of cases of sudden death not due to SIDS remained under 10 per year. The overall infant death rate also fell, while the total number of births per year remained relatively unchanged. CONCLUSIONS: The lack of major change in sudden infant death rates from other causes, combined with the fall in SIDS deaths, is not supportive of diagnostic transfer being a major determinant of the declining SIDS death rate. Therefore, other factors are likely to be responsible for the falling SIDS rate in this population.

The danger of freely rocking cradles.

OBJECTIVE: To assist the Adelaide State Coroner with his inquest into the death of two infants in South Australia, and to assist the Department of Public and Consumer Affairs develop Australian Standards for rocking cradles. METHODOLOGY: A sample of each brand of new cradle commercially available in South Australia was examined. Videotapes were made of 11 healthy infants in rocking cradles to examine how they moved and how they reacted in different positions. RESULTS: Many cradles had insecure locking pins. Infants in a cradle tilted at 10 degrees greater, face down with the side of the face against the bars, and an aim trapped between the body and bars or through the bars, were unable to obtain a clear airway unless a dummy was in the mouth. CONCLUSIONS: Infants should never be left unattended in freely rocking cradles. Australian Standards should recommend locking pins be bolted into place and that cradles cannot tilt to greater than 5 degrees.