Home monitoring for infants at risk of the sudden infant death syndrome

Abstract This study evaluates the effectiveness and social implications of home monitoring of 31 infants at risk of sudden infant death syndrome (SIDS). Thirteen siblings of children dying of SIDS, nine near miss SIDS infants and nine preterm infants with apnoea persisting beyond 40 weeks post conceptual age were monitored from a mean age of 15 days to a mean of 10 months. Chest movement detection monitors were used in 27 and thoracic impedance monitors in four. Genuine apnoeic episodes were reported by 21 families, and 13 infants required resuscitation. Apnoeic episodes occurred in all nine preterm infants but in only five (38%) of the siblings of SIDS (P<0.05). Troublesome false alarms were a major problem occurring with 61% of the infants and were more common with the preterm infants than the siblings of SIDS. All but two couples stated that the monitor decreased anxiety and improved their quality of life. Most parents accepted that the social restrictions imposed by the monitor were part of the caring process but four couples were highly resentful of the changes imposed on their lifestyle.
The monitors used were far from ideal with malfunction occurring in 17, necessitating replacement in six, repair in six and cessation of monitoring in three. The parents became ingenious in modifying the monitors to their own individual requirements
Although none of these 31 'at risk' infants died the study sample was far too small to conclude whether home monitoring prevented any cases of SIDS.     

Metal content of the liver in sudden infant death syndrome

Abstract The metals zinc, iron, copper, manganese, calcium, magnesium, potassium and sodium were analysed in the livers of 67 Australian infants who had died from Sudden Infant Death Syndrome (SIDS) and 29 infants who had died from other causes (non-SIDS). The results were evaluated in relation to medical data and fatty acid composition of the livers. In infants less than 6 months old the liver potassium levels were significantly lower in SIDS than in non-SIDS infants. No other significant differences in metals between the SIDS and non-SIDS livers were found. Zinc, iron and copper levels in infant liver fell with age during the first year.     

Growth and the sudden infant death syndrome

Objective : To compare the growth curves based on measurements of body weight for male and female infants dying of sudden infant death syndrome (SIDS) with those of male and female controls. Methods : The data were drawn from a large case control study of SIDS carried out in New Zealand between 1987 and 1990. Results : The mean birthweight for the cases was 3049 g and for the controls 3526 g. The mean growth curves for the male and female controls were close to the 50th centile of growth charts used in New Zealand. The growth curve for the male cases diverged from that of the controls, being closer to the 25th percentile. The differences between the female cases and controls were less pronounced. The differences in weekly weight increments derived from the curves for the cases and controls for nine 4-week periods were not statistically significant after taking into account race, manner of feeding and maternal smoking for any 4-week period. Conclusions : SIDS cases were lighter at birth, but their growth velocity was normal postnatally.     

Pre- and postnatal medical care and risk of sudden infant death syndrome

The current study investigated whether sufficient attendance at prenatal and postnatal checks affects the risk of sudden infant death syndrome. A case-control study in the Tyrol enrolled 99 infants with sudden infant death syndrome that occurred between 1984 and 1994, and 136 randomly selected control cases. The risk of sudden infant death syndrome was higher in infants whose mothers attended less than five antenatal health checks than in the group with at least five or more visits (OR 5.1; p < 0.01). Babies who received medical help beyond routine health controls had a lower risk than those who did not (OR 0.32; p < 0.001). These differences persisted when social and demographic variables (mother's age at delivery, educational level, marital status, parity and gestational age) were taken into account. Our study identified inadequate antenatal and postnatal care as a risk indicator for sudden infant death syndrome and as a potential target for further educational work. Clinical recommendations should await the results of further evaluations.     

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.     

Epidemiology of sudden infant death syndrome in Japan

An epidemiological survey was carried out to examine the present situation with respect to sudden infant death syndrome (SIDS) in Kanagawa Prefecture. Questionnaires on sudden unexpected death of infants aged < 1 year in 1990-91 were sent to the hospitals and clinics in Kanagawa Prefecture which may take care of such infants. By analysing information from 10 485 replies, 48 out of 73 reported sudden infant deaths were confirmed to be SIDS, although autopsy was not performed in 13 cases (27%). The incidence of SIDS per 1000 live births in Kanagawa Prefecture was 0.29 in 1990 and 0.31 in 1991; and if limited to autopsy cases 0.19 and 0.25, respectively. Sudden infant death syndrome cases in Japan were found to occur more frequently when infants were < 6 months old, at home and sleeping alone, but less in the winter and between midnight and early morning. There was little difference between the numbers in prone and supine sleeping positions at discovery. It was not clear whether SIDS occurred more often to babies sleeping prone than supine, because there were no controls matched with the SIDS cases. In future, continuous epidemiological surveys of SIDS in Japan should be carried out.     

Gender and the sudden infant death syndrome

Abstract A nationwide case-control study compared the prevalence and magnitude of risk factors for sudden infant death syndrome (SIDS) in male and female infants. The risk factors of SIDS and their magnitude for males and females are very similar. After adjustment for potential confounders male infants had a 1.42-fold (95% CI = 1.04, 1.94) increased risk of SIDS compared with females. Risk factors identified in most epidemiological studies are not the reason for the increased SIDS mortality seen in male infants.     

Issues in diagnosis following the sudden infant death syndrome intervention campaigns

Abstract: The fall in numbers of sudden infant death syndrome (SIDS) deaths in recent years has resulted in questions being asked as to whether changes in the pathological assessment and diagnosis of such cases have influenced reported death rates. Specific concerns have been raised about possible changes in diagnostic criteria, differences in the evaluation of these infants and the possibility of changes in the pathological findings at autopsy. However, no major changes in either diagnostic criteria or in pathological features appear to have occurred, despite some changes in the epidemiological characteristics of cases.     

Seasonality of sudden infant death syndrome (SIDS) by age at death

Seasonality of sudden infant death syndrome (SIDS) is a well-established epidemiological finding. The purpose of the study was to determine whether this feature varied significantly with age at death. In total, 13 990 cases of SIDS in Scotland, England and Wales during 1982–1992 were studied by age group at death. Seasonality was established by fitting a sinusoidal curve and for each set of monthly data the peak position in the year and its magnitude were determined. Weighted regression revealed significant differences in peak position and amplitude of seasonal variation between those dying at ≤ 4 months and those aged ≥ 5 months at death. Those infants in the younger age group were more likely to die earlier in the winter months and had a smaller variation in seasonality. The peak (acrophase) months were January for ≤ 4 months and February for ≥ 5 months at death. Weighted regressions of peak position and amplitude on age at death had p-values of < 0.001 and < 0.01, respectively. A log linear model relating SIDS incidence to month of birth, month of death and age was able to explain some of these findings. The findings support the hypothesis that in SIDS there may be more than one infant cohort, each of which passes through a vulnerable developmental window at different ages.     

Well health care and the sudden infant death syndrome

The aim of this study was to examine whether poor attendance at routine antenatal and postnatal 'well child' health services was associated with a higher risk of sudden infant death syndrome (SIDS, or cot death). A nationwide case-control study of SIDS in New Zealand enrolled 485 postneonatal deaths due to SIDS and 1800 control infants who were selected randomly. The risk for SIDS was found to be higher for infants whose mothers attended their first antenatal check later than 3 months into the pregnancy, made fewer antenatal visits, and did not go to antenatal education classes. However, this increased risk was largely explained by high parity, maternal smoking, the mother not being married, mother being <20 years old at the birth of her first child, and delivery during the winter months. Infants not attending a 6 week postnatal check had an almost three-fold increased risk of SIDS compared with those who did attend (odds ratio [OR] 2.86; 95% confidence interval [Cl] 1.93, 4.24). Similarly, infants not attending well child clinics were at increased risk of SIDS (OR 2.75; 95% Cl 2.09, 3.62). These differences persisted when adjusted for likely confounders. This study demonstrates that infants who miss child health nurse clinics are those most at risk for SIDS and are those who warrant increased surveillance.     

Overview of sudden infant death syndrome in Japan

In spite of rapid medical advancement in the care of infants and children, not only the general public but also many medical personnel have remained unaware of sudden infant death syndrome (SIDS) until very recently in Japan. In 1981, a research project team on SIDS financed by the Ministry of Health and Welfare was founded. Current incidence of SIDS is estimated to be about 0.5 per 1000 live births. The SIDS Family Association was organized in 1993 in Japan and began to publicize the social importance of SIDS and to support SIDS families by training befrienders. A series of articles on current achievements from SIDS research projects and from the SIDS Family Association are submitted to this issue. The present paper summarizes the status of SIDS in Japan by overviewing the activities of the research team and the SIDS Family Association.     

Near miss sudden death in an infant with Wolff-Parkinson-White syndrome

A 6 month old infant with known Wolff-Parkinson-White syndrome presented with an out of hospital cardiac arrest. An electrocardiogram in the emergency department demonstrated atrial fibrillation with rapid ventricular response. The child subsequently was resuscitated and underwent successful interruption of an accessory connection after failing medical therapy. This case underlines the need to reassess the indications for invasive electrophysiologic testing in young children.     

Developmental brain-stem pathology in sudden infant death syndrome

The brain-stems of control and sudden infant death syndrome (SIDS) infants were examined developmentally with Golgi and immunohistochemical methods. The development of dendritic spines changed dramatically from the prenatal to postnatal period in the ventrolateral medulla as well as in the reticular formation and vagal nuclei in controls, but persisted in SIDS infants. These observations suggest a delay in maturation of the meduallary respiratory neurons and transneuronal connection between the central chemoreceptor and neural respiratory center in SIDS. In addition, substance P (SP)-positive nerve fibers were increased in the pons of SIDS infants. An increased activity in the afferent SP neurons in SIDS may be due to chronic hypoxia as in brain-stem gliosis, and may be involved in cardiorespiratory regulation.     

Child care practices and the sudden infant death syndrome

Abstract Southern New Zealand has one of the highest reported rates of the sudden infant death syndrome (SIDS) in the world. Data were collected on 49 infants who died from SIDS in the Dunedin and Invercargill Health Districts of southern New Zealand. Forty-two of the families were interviewed at home following the loss of their infant. In the week prior to death, 17 infants (40%) had an upper respiratory tract infection, although in 11 of these infants their infection had apparently resolved at least 24 h prior to death. Thirty infants (71%) had their faces down into the bedding or their heads covered with bedding. Thirty-four infants (81%) were found dead in the prone position, whereas 49% of New Zealand infants aged 3 months would be expected to sleep prone. Sleep position and the terminal position of the head in relation to SIDS requires further study.     

The airway occlusion test as a screening for sudden infant death syndrome (SIDS)

The airway occlusion test was carried out as a screening test for sudden infant death syndrome (SIDS). To obtain the normal values for use as control values, the relationship of the airway occlusion test with various variables was determined in 234 infants. The result shows that the best correlation was seen between percentage prolongation and the corrected gestational age. Percentage prolongation increased with the progression of age up to about the 40th week of corrected gestational age. Subsequently, there was no remarkable change in percentage prolongation. In six out of eight cases with apparent life threatening events, percentage prolongation was reduced. These results indicate that the determination of percentage prolongation can be used for screening of high risk babies for SIDS.     

Interactions between maternal smoking and other prenatal risk factors for sudden infant death syndrome (SIDS)

Abstract In numerous investigations, maternal smoking increases the risk of sudden infant death syndrome (SIDS). In the present study we investigated whether prenatal risk factors for SIDS modify the effect of maternal smoking on SIDS mortality. We analysed data from a population-based cohort study (222 cases, 260,604 infants at risk) within the Westphalian Perinatal Inquiry in Germany between 1990 and 1994. In the stratified analysis, smoking was classified into non-smoking, moderate (1–10 cigarettes/d) and heavy smoking (> 10 cigarettes/d). Multiplicative interactions between smoking and other prenatal risk factors were assessed in a logistic regression model. The relative risk (RR) for maternal smoking was 2.4 (95% confidence interval 1.7-5.4) for moderate and 7.2 (5.3, 9.7) for heavy smokers. Previous established risk factors for SIDS, such as preterm birth, low birthweight, and number of prenatal visits did not increase the risk of SIDS among non-smokers, but became important risk factors among smokers. In preterm infants (< 37 weeks) of heavy smokers, the RR was 19.6 (10.4, 36.8) compared to term infants of non-smokers. Low birthweight infants (< 2500 g) of heavy smokers had a RR of 16.3 (8.4, 31.2) compared to normal weighted infants of non-smokers. Adjustment for occupational status did not change the crude estimates. The RR of < 6 prenatal visits in the heavy smoking subgroup was 14.8 (7.2, 29.6) compared to > 9 prenatal visits in the nonsmoking strata. Heavy smoking potentiates other prenatal risk factors for SIDS suggesting an increased susceptibility towards the adverse effects of tobacco smoke in utero. In infants born to non-smoking mothers, prenatal risk factors are absent and postnatal factors may be of major importance.     

Interpretation of recent sudden infant death syndrome rates in Western Australia

The diagnosis of sudden infant death syndrome (SIDS) has undergone several changes in definition since first being recognised as a cause of death. Linked total population data from Western Australia enable investigations to determine changes in classifications of mortality for the infants of Aboriginal and non-Aboriginal mothers (Aboriginal and Torres Strait Islander people are referred to throughout this report as 'Aboriginal'). Data for recent years show a shift away from a classification of 'SIDS' towards a classification of 'unascertainable', particularly for Aboriginal infants. This has implications for the accurate translation of data into policy and practice.     

Pathophysiology of overheating in a piglet model: Findings compared with sudden infant death syndrome

Objective : To examine the nature of hyperthermia-induced pathophysiological changes in an animal model including effects on lung compliance.
Methodology : Piglets were randomly assigned to heated or non-heated groups. Heated animals were warmed to 4°C above normal body temperature while sedated and breathing spontaneously. Cardiorespiratory variables were recorded serially and haematological assessments and blood cultures taken at 0 and 6 h. After 6 h the animals were killed and a limited postmortem was performed. Control animals had all procedures without heating.
Results : Heated piglets developed tachycardia, hypotension and a metabolic acidosis in addition to tachypnoea, hypocapnic alkalosis and a neutrophil leucocytosis. Rectal temperature after death fell at the same rate in both groups. Lung histology revealed an excess of lung haemorrhage and alveolar oedema in the heated group. No significant group differences in dynamic lung compliance were demonstrated.
Conclusions : The pathological changes that occur during hyperthermia are non-specific but not incompatible with those found in sudden infant death syndrome. There was no confirmation of the thesis that hyperthermia causes death by altering lung compliance.     

Increased number of substitutions in the D-loop of mitochondrial DNA in the sudden infant death syndrome

The purpose of the present study was to investigate substitutions in the D-loop of mitochondrial DNA (mtDNA) in sudden infant death syndrome (SIDS) and controls, since several observations indicate the involvement of mtDNA mutations in SIDS. These include elevated levels of vitreous humour hypoxanthine in SIDS victims, familial clustering without mendelian traits, and observations of increased sleepiness and a lower activity score in infants who later succumbed to SIDS. Eighty-two cases of SIDS and 133 controls were investigated and the D-loop sequences were recorded in the base-pair range 16 055-16 500 in the mtDNA sequence. The sequencing was carried out using the Applied Biosystems Sequenase dye terminator method and a ABD373A sequencer. The recorded D-loop sequences were compared with the Cambridge sequence and differences were recorded as substitutions. The SIDS cases had a tendency towards a higher substitution rate in the D-loop than the controls ( p = 0.088). This observation makes it interesting to search for deleterious mutations in other locations in the mtDNA.