Apparent life-threatening event: a neurologic perspective

Of 46 infants who were investigated for apparent life-threatening events, central nervous system disorders were diagnosed in seven (15%). Convulsive disorders, intraventricular hemorrhage and hydrocephalus, absent corpus callosum, and development deficits were found. In four of the seven, no neurologic deficit was suspected before the event. Electroencephalographic studies (overnight in two) would have identified the disorder in all four. Electroencephalography is therefore a recommended routine procedure in investigation of apparent life-threatening events. Central nervous system disorders should be routinely ruled out in cases of apparent life-threatening event, even in the absence of clinical clues.

Is cardiorespiratory failure induced by bacterial toxins the cause of sudden infant death syndrome? Studies with an animal model (the rabbit)

Recent studies have implicated various toxigenic bacteria and their toxins in the aetiology of sudden infant death syndrome (SIDS). Therefore the effect of six bacterial toxins on the cardiorespiratory system of the rabbit was studied as a model for SIDS. The toxins' effect on the heart rate, arterial blood pressure, and breathing of anaesthetized rabbits was determined and their action compared to that of endotoxin. Intravenous injection of Clostridium perfringens enterotoxin and alpha-toxin, Staphylococcus enterotoxin B, Escherichia coli heat-stable toxin (STa), Clostridium difficile toxin A and B reduced heart rate, blood pressure, respiration and increased, slowed and prolonged thorax expansion, and at higher concentrations caused sudden death without visible stress or trauma. A combination of a low concentration of enterotoxins caused a greater reduction of these activities and sudden death. These effects were generally similar to those produced by endotoxin. In non-anaesthetized rabbits, the toxins slowed metabolism until death occurred without agitation, spasms, visible distress or prolonged illness. Intestinal production of these toxins by toxigenic strains, when conditions are suitable, and their systemic absorption, could therefore cause SIDS by an endotoxin-like shock mechanism.

Effect of maternal cigarette smoking on pregnancy complications and sudden infant death syndrome

BACKGROUND

The purpose of this study was to estimate the annual morbidity and mortality among fetuses and infants that can be attributed to the use of tobacco products by pregnant women.

METHODS

Published research reports identified by literature review were combined in a series of meta-analyses to compute pooled risk ratios, which, in turn, were used to determine the population attributable risk.

RESULTS

Each year, use of tobacco products is responsible for an estimated 19,000 to 141,000 tobacco-induced abortions, 32,000 to 61,000 infants born with low birthweight, and 14,000 to 26,000 infants who require admission to neonatal intensive care units. Tobacco use is also annually responsible for an estimated 1900 to 4800 infant deaths resulting from perinatal disorders, and 1200 to 2200 deaths from sudden infant death syndrome (SIDS).

CONCLUSIONS

Tobacco use is an important preventable cause of abortions, low birthweight, and deaths from perinatal disorders and SIDS. All pregnant women should be advised that smoking places their unborn children in danger. The low success rate of smoking cessation among pregnant women suggests that efforts to reduce the complications of pregnancy attributable to tobacco use by pregnant women should focus on preventing nicotine addiction among teenaged girls.

[Arterial oxygen saturation monitoring of sleeping infants by pulse-oximeter--effect of sleeping position on arterial oxygen saturation in infants]

Monitoring of the arterial oxygen saturation (SaO2) in two sleeping infants was reported. They were a couple of female twins and had grown up normally after admission to NICU (Neonatal Intensive Care Unit) for a month. We investigated their SaO2 with the puls-oximeter at the terms between the 2nd and the 10th month. There was no significant difference between SaO2 in prone positions (n = 29) and that in supine positions (n = 30). In the infant with the sniffing conditions, however, SaO2 in prone positions seemed to be slightly lower than that in the healthy conditions. The slightly low SaO2 would give no effects on the healthy infants, but it may cause ALTE (Apparent Life Threatening Event) or death from SIDS (Sudden Infant Death Syndrome) to some infants who are not in good health and/or who are prone to get into ALTEA or SIDS. Especially, in the sniffing condition with hyperthermia, as the oxygen dissociation curve sifts to right and SaO2 degradation appears easily, sudden infant death may be possible to happen in prone position.

Arterial oxygen saturation in infants at risk of sudden death: influence of sleeping position

To study the possible influence of sleeping position on arterial oxygen saturation, measured by pulse oximetry (SpO2), 7-h overnight recordings of breathing movements and ECG were performed in 43 infants (median age 2.4 months, range 0.2-11 months) at increased risk of sudden infant death syndrome (SIDS). Infants were randomly allocated to start sleeping either in their usual sleeping position or in the opposite position. After 3.5 h, all infants were gently turned over. Thus, each infant served as their own control. Recordings were analysed for sleep time, baseline SpO2 (only during regular breathing), and the number and duration of desaturations (a decrease in SpO2 to < or = 80%). In the prone position, a significantly higher proportion of time was spent asleep (median 79% versus 70%; p < 0.05). Median baseline SpO2 was 98.8% (91.7-100%) in the prone and 99.0% (92.0-100%) in the supine position (ns). A total of 191 desaturations were found in 29 recordings; 96 in the prone and 95 in the supine position (ns). One infant subsequently died of SIDS while sleeping in the prone position. He had a relatively high number of desaturations (n = 12) which all occurred in the prone position. These results confirm earlier studies which could not find a significant influence of sleeping position on baseline oxygenation. The occurrence of desaturations in the prone position only in the infant who subsequently died requires further investigation.

Sudden infant death and maternal cigarette smoking: results from the Lower Saxony Perinatal Working Group

Maternal smoking has long been identified as a risk factor for sudden infant death (SID). However, only few studies analysed the biological plausibility of the relationship between maternal smoking and SID. In Lower Saxony (North Germany), detailed information concerning the perinatal period is routinely obtained for almost all infants born in this region. The perinatal data sets from 190 SID cases who had died between 1986 and 1990 and in whom a full autopsy had been performed were identified and compared to data sets from 5920 random controls, frequency matched to cases on year of birth. After adjusting for potential confounders (socio-economic status, birth weight, maternal age and nationality), smoking during pregnancy was still associated with a significantly increased risk of SID (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.7-4.5). There was a clear dose-effect relationship between the number of cigarettes smoked and the risk of SID: adjusted ORs were 2.6 (1.5-4.4) for 1-10 cigarettes/day, 2.8 (1.8-6.0) for 11-20 cigarettes/day, and 6.9 (1.9-25.5) for > 20 cigarettes/day. There also appeared to be an interaction between smoking during pregnancy and maternal anaemia: the risk of SID almost doubled if mothers not only smoked, but were also anaemic (haemoglobin < 100 g/l). These results support the concept that smoking during pregnancy has direct biological effects on the fetus which are associated with an increased risk of SID later in life. The exact mechanism(s) whereby smoking increases the risk of SID, however, remains to be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

[Sudden death in a 4-month-old infant associated with anomalous origin of the left coronary artery]

We describe the autopsy findings of a 4 months-old boy, who died suddenly after an episode of high airway infection of 3 days time. Autopsy examination showed cardiomegaly (80 g) with widening of the left cavities and thick and white endocardial surface, besides a severe thinning of the cardiac apex at the level of the left ventricle. Left coronary origin was in the pulmonary artery trunk. Histologically, the myocardium shows endomyocardial fibroelastosis and also multiple and extensive areas of old and recent infarcts in the left ventricle. The collateral coronary arteries, were increased in number, and branches showed a marked intimal oedema and a reduction of the luminal diameter.

The oxygen-conserving dive reflex re-examined as the principal contributory factor in sudden infant death

This hypothesis and overview of sudden infant death syndrome (SIDS) literature is an extension of a previously published hypothesis by the author, which linked the prone sleeping position and other triggers to the oxygen-conserving dive reflex as a primary cause of SIDS. Recent prospective epidemiologic and biochemical studies, together with other data, seem to lend support to the theory that this reflex, either induced or occurring spontaneously, may lead to an irreversible pathophysiologic mechanism resulting in respiratory failure and cardiac arrest. It will also be argued that SIDS is multifactorial and tri-phasic and that several other well-known hypotheses may form a previously unrecognized part of the theory.

Sleeping position and sudden infant death syndrome (SIDS): effect of an intervention programme to avoid prone sleeping

The proportion of prone sleeping among sudden infant death syndrome (SIDS) victims and infants in general, and the rate of SIDS were prospectively studied in the county of Hordaland, Norway, three years before (1987-89) and three years after (1990-92) a campaign to discourage prone sleeping. Before the campaign, 64% of random reference infants were put prone versus 8% after (p < 0.0001). Concurrently, the rate of SIDS decreased from 3.5 to 1.6 per 1000 live births (63 infants before and 30 after the campaign, p = 0.0002). Prone sleeping was not considered a statistically significant risk factor for SIDS before (OR 2.0, 95% CI 0.8-4.5), but was highly significant (OR 11.3, 95% CI 3.6-36.5) after the campaign. Prone sleeping is an important risk factor for SIDS, but the association may be missed in epidemiological studies if prone is the predominant sleeping position. Behaviour with regard to sleeping position may be changed rapidly by means of a simple campaign.

[Fear paralysis--still a possible cause of crib death]

There is overwhelming evidence that prone sleeping entails more risk of sudden infant death than supine sleeping does. However, no generally accepted biological explanation of this phenomenon has been found. In a viewpoint article in Acta Paediatrica in 1994 the author has re-emphasized that the fear paralysis reflex (tonic immobility) could be a cause of sudden infant death. The response consists of immobility, apnea, profound bradycardia and vasoconstriction. The bradycardia may proceed to irreversible asystole and silent death within a few minutes. In infant monkeys, this innate, atavistic reflex, which is prompted by aversive environmental fear-producing events, has the same age distribution as sudden infant death syndrome between the 2nd and 5th month of life. Main triggering stimuli are: restraint of movement (preventing flight) and sudden exposure to unfamiliar environments and persons, events for which the organism appears to be unprepared. Movements of the extremities are more restrained in the prone than in the supine position with greater chance of eliciting fear paralysis responses and death in prone sleepers. This biological mechanism presumably also applies to the winter peak (restraint due to overwrapping), sleeping outdoors (overwrapping) and co-sleeping in the same bed as another (parent).