Unexpected sudden death due to recreational swimming and diving in men in Croatia in a 14-year period

The article deals with 17 sudden deaths which occurred during recreational swimming and diving in men in Croatia in a 14-year period: from January 1, 1998 to December 31, 2011. The sample is taken out from the total number of 61 sudden deaths in men during or immediately after sport or recreational exercise. Included are also sudden deaths of 8 foreigners spending holidays at the Croatian Adriatic Coast. In all of them forensic medicine autopsy was done. Thirteen males from Croatia died during recreational swimming. Three of them were aged 15-29 yrs: one had signs of hypertrophic cardiomyopathy, the second suffered from chronic myopericarditis with left ventricular aneurysm, and the third had cardiomegaly and blood alcohol level of 1.7 per thousand. Five were aged 30-64 yrs: four of them have suffered from coronary atherosclerosis and left ventricular hypertrophy of 15-18-18-22 mm, and one with left ventricular hypertrophy drowned suddenly, probably because of malignant ventricular arrhythmia. The fifth suffered stroke and drowned. Five elderly men, aged 65-85 yrs, have suffered from coronary atherosclerosis, myocardial fibrosis or myocardial scars, and three of them had left ventricular hypertrophy of 19 mm. Four males died during recreational diving. One aged 26yrs drowned, at autopsy he had left ventricular hypertrophy of 17 mm. Three males were middle-aged: two had coronary atherosclerosis, two of them had a severe degree of coronary atherosclerosis and one had coronary atherosclerosis of medium degree but with myocardial fibrosis and left ventricular hypertrophy of 18 mm. Seven male foreigners died, five of them during swimming: two aged 30-64 and two aged 65-85. They all have had coronary atherosclerosis: one of them had an acute myocardial infarction of the posterior wall, and one hypertrophic cardiomyopathy as well. One middle-aged and one elderly man died during diving, and both had an acute myocardial infarction of the posterior wall. One elderly foreign woman died during swimming, she had coronary atherosclerosis and a myocardial scar. In Croatia, death rate during both swimming and diving in men aged 15-29 years amounted to 0.63/1,000.000 (p=1.0000); in those aged 30-64 it reached 0.56/1,000.000 (p=0.3698), and in those aged 65-85 it was 1.41/1,000.000 (p=0.1849). The death rate during swimming in men aged 15-29 amounted to 1.47/1,000.000 (p=0.9864), in men aged 30-64 it reached 0.35/1,000.000 (p=0.2245), and in those aged 65-85 it was 1.41/1,000.000 (the difference is significant, p=0.0472). The death rate during diving in men aged 15-29 was 0.16/1,000.000, and in men aged 30-64 the observed rate was 0.21/1,000.000 (p=1.0000).     

Sudden Death in Hospital after Discharge from Coronary Care Unit

In a group of 339 patients with acute myocardial infarction treated in a coronary care unit, 273 left the unit while improving and were expected to leave hospital alive; 23 had a cardiac arrest or died suddenly while still in hospital—17 died immediately or after temporary resuscitation and six were resuscitated to leave hospital alive. Ventricular fibrillation was found in 13 of the 20 patients attended by the cardiac arrest team. The incidents were scattered from the 4th to the 24th day after the onset of infarction. Risk factors in these “late sudden death” patients were compared with the 250 patients who left the unit while improving and did not die or suffer cardiac arrest. The patients susceptible to late sudden death were characterized early in their hospital course by the findings of severe, predominantly anterior infarction, left ventricular failure, persistent sinus tachycardia, and frequent ventricular arrhythmias. It is suggested that such patients be chosen for prolonged observation in a second-stage coronary care unit.     

Lung immunoglobulins in the sudden infant death syndrome.

The incidence of the sudden infant death syndrome parallels that of respiratory tract infections in the paediatric community. On the basis that the aetiology of the sudden infant death syndrome may lie in an unusual response to a trivial intercurrent respiratory infection a necropsy study was carried out investigating pulmonary immunoglobulins in 16 victims of the syndrome and a series of infants (controls) who had died of non-pulmonary causes. Compared with the controls victims of the sudden infant death syndrome had grossly raised concentrations of IgG, IgM, and to a less extent IgA in lung lavage samples. In addition, pulmonary interstitial and terminal airway cells expressing these immunoglobulins were identified far more often in victims than controls. The study failed to determine whether the increased immunoglobulin concentrations were a consequence of an unusual response to a trivial infection or an expression of otherwise altered immunological control in the respiratory tract. Epidemiological evidence and the findings of this study suggest that the respiratory tract is the prime target organ in the sudden infant death syndrome.     

One year's treatment with propranolol after myocardial infarction: preliminary report of Norwegian multicentre trial.

A prospective, randomised, double-blind study was performed to compare the effects of propranolol and placebo on sudden cardiac death in a high-risk group of patients who survived acute myocardial infarction. Altogether 4929 patients with definite acute myocardial infarction were screened for inclusion: 574 (11.6%) died before randomisation, and 3795 (77%) were excluded. Five hundred and sixty patients aged 35 to 70 years were stratified into two risk groups and randomly assigned treatment with propranolol 40 mg four times a day or placebo. Treatment started four to six days after the infarction. By one year there had been 11 sudden deaths in the propranolol group and 23 in the placebo group (p less than 0.038, two-tailed test analysed according to the "intention-to-treat" principle). Altogether there were 25 deaths in the propranolol group and 37 in the placebo group (P less than 0.12), with 16 and 21 non-fatal reinfarctions respectively. A quarter of the patients were withdrawn from each group. Withdrawal because of heart failure during the first two weeks of treatment was significantly more common among propranolol-treated patients than among the controls, but thereafter the withdrawal rate was the same. The significant reduction in sudden death was comparable with that after alprenolol, practolol, and timolol, which suggests that the mechanism of prevention is beta-blockade rather than any other pharmacological property of the individual drugs.     

Sudden death in epileptic rats exposed to nocturnal magnetic fields that simulate the shape and the intensity of sudden changes in geomagnetic activity: an experiment in response to Schnabel, Beblo and May

To test the hypothesis that sudden unexplained death (SUD) in some epileptic patients is related to geomagnetic activity we exposed rats in which limbic epilepsy had been induced to experimentally produced magnetic fields designed to simulate sudden storm commencements (SSCs). Prior studies with rats had shown that sudden death in groups of rats in which epilepsy had been induced months earlier was associated with the occurrence of SSCs and increased geomagnetic activity during the previous night. Schnabel et al. [(2000) Neurology 54:903–908) found no relationship between SUD in human patients and geomagnetic activity. A total of 96 rats were exposed to either 500, 50, 10–40 nT or sham (less than 10 nT) magnetic fields for 6 min every hour between midnight and 0800 hours (local time) for three successive nights. The shape of the complex, amplitude-modulated magnetic fields simulated the shape and structure of an average SSC. The rats were then seized with lithium and pilocarpine and the mortality was monitored. Whereas 10% of the rats that had been exposed to the sham field died within 24 h, 60% of the rats that had been exposed to the experimental magnetic fields simulating natural geomagnetic activity died (P<.001) during this period. These results suggest that correlational analyses between SUD in epileptic patients and increased geomagnetic activity can be simulated experimentally in epileptic rats and that potential mechanisms might be testable directly.     

Can the fall in Avon's sudden infant death rate be explained by changes in sleeping position?

OBJECTIVE--To examine the impact of changing practice with regard to infant sleeping position on mortality from the sudden infant death syndrome. DESIGN--A population based study of all infants dying suddenly and unexpectedly during February 1990 to July 1991, and two groups of controls; one comprising every 125th baby born to Avon residents and the other comprising pairs of infants matched to each index case for age, neighbourhood, and date of study. Information about sleeping position was collected at home visits soon after the index baby''s death or, for the population based controls, on several occasions in the first six months of life. The design was comparable to that of an earlier study of the same population. SETTING--County of Avon. SUBJECTS--35 infants who died suddenly and unexpectedly (32 of the sudden infant death syndrome), 70 matched controls, and 152 population based controls. RESULTS--The prevalence of prone sleeping in the matched controls was much lower than that found in an earlier study in Avon (28% (18/64) 1990-1 v 58% (76/131) 1987-9; p less than 0.001) and was comparable with the prevalence in population based controls (29%). This would be expected to lead to a reduction in the incidence of the sudden infant death syndrome to 2.0/1000 live births (95% confidence interval 1.8/1000 to 2.5/1000). The actual mortality fell from 3.5/1000 in 1987-9 to 1.7/1000. CONCLUSION--The fall in mortality can be almost entirely accounted for by the reduction in prone sleeping, suggesting a causal relation exists between them. Side and supine positions confer protection but the side position is unstable and the infant may roll prone. We therefore recommend supine as the safest sleeping position for babies.     

Thermal environment and sudden infant death syndrome: case-control study.

OBJECTIVE--To compare the thermal environment of infants who died of the sudden infant death syndrome with that of age matched control infants. DESIGN--Case-control study. Infants who died were matched with two controls, one for age and one for age and birth weight. Thermal measurements were conducted at the death scene for cases and at the scene of last sleep for control infants, who were visited unexpectedly within four weeks of the index infant''s death on a day of similar climatic conditions. A follow up questionnaire was administered to parents of cases and controls. SETTING--The geographical area served by the professional Tasmanian state ambulance service, which includes 94% of the Tasmanian population. SUBJECTS--41 infants died of the sudden infant death syndrome at home; thermal observations at death scene were available for 28 (68%), parental questionnaire data were available for 40 (96%). 38 controls matched for age and 41 matched for age and birth weight. RESULTS--Cases had more excess thermal insulation for their given room temperature (2.3 togs) than matched controls (0.6 togs) (p = 0.009). For every excess thermal insulation unit (tog) the relative risk of the sudden infant death syndrome was 1.26 (95% confidence interval 1.05 to 1.52). The average thermal bedding value calculated from parental recall was similar to that observed by attendant ambulance officers (mean difference = 0.4 tog, p = 0.39). Cases were more likely to have been found prone (odds ratio 4.58; 1.48 to 14.11). Prone sleeping position was not a confounder or effect modifier of the relation between excess thermal insulation and the syndrome. CONCLUSIONS--Overheating and the prone sleeping position are independently associated with an increased risk of the sudden infant death syndrome. Further work on infant thermal balance and sudden infant death is required and guidelines for appropriate infant thermal care need to be developed.     

"Natural cause of death or not?" How do nursing home physicians act when in doubt of natural cause of death?

The objective of the study was to explore if nursing home physicians act by law, when they doubt the natural cause of death. In May 1999, a questionnaire was sent to 153 nursing home physicians in the region of Utrecht and Nijmegen. They were asked if they consult the coroner when they have doubts about the natural cause of death. Eighty-six percent (104) returned the questionnaire. Thirty-two percent of the nursing home physicians always consult the coroner and 52% does so most of the time. Only 12% does not consult the coroner most of the time and 2% never does. The main reasons for not consulting the coroner were that nursing home physicians judge a death after a fall as an incident that fits in the descending lifeline of patients and that some nursing home physicians had bad experiences consulting the coroner. We conclude that this policy may lead to underregistration of unnatural deaths. Changing the definition or changing the law may reduce this problem. Education and information can also contribute to change in physician's attitudes.     

Interaction between bedding and sleeping position in the sudden infant death syndrome: a population based case-control study.

OBJECTIVE--To determine the relation between sleeping position and quantity of bedding and the risk of sudden unexpected infant death. DESIGN--A study of all infants dying suddenly and unexpectedly and of two controls matched for age and date with each index case. The parents of control infants were interviewed within 72 hours of the index infant''s death. Information was collected on bedding, sleeping position, heating, and recent signs of illness for index and control infants. SETTING--A defined geographical area comprising most of the county of Avon and part of Somerset. SUBJECTS--72 Infants who had died suddenly and unexpectedly (of whom 67 had died from the sudden infant death syndrome) and 144 control infants. RESULTS--Compared with the control infants the infants who had died from the sudden infant death syndrome were more likely to have been sleeping prone (relative risk 8.8; 95% confidence interval 7.0 to 11.0; p less than 0.001), to have been more heavily wrapped (relative risk 1.14 per tog above 8 tog; 1.03 to 1.28; p less than 0.05), and to have had the heating on all night (relative risk 2.7; 1.4 to 5.2; p less than 0.01). These differences were less pronounced in the younger infants (less than 70 days) than the older ones. The risk of sudden unexpected death among infants older than 70 days, nursed prone, and with clothing and bedding of total thermal resistance greater than 10 tog was increased by factors of 15.1 (2.6 to 89.6) and 25.2 (3.7 to 169.0) respectively compared with the risk in infants of the same age nursed supine or on their side and under less than 6 tog of bedding. CONCLUSIONS--Overheating and the prone position are independently associated with an increased risk of sudden unexpected infant death, particularly in infants aged more than 70 days. Educating parents about appropriate thermal care and sleeping position of infants may help to reduce the incidence of the sudden infant death syndrome.     

Are geomagnetic disturbances a risk factor for the sudden unexplained death of epileptic children?

The relationship between geomagnetic disturbances (with amplitudes above 50 nT) and the sudden unexplained death (SUD) of epileptic adults has been controversial up to now. In an autopsy-based cohort study (from 1964 to 1992) 15 epileptic children with SUD aged 1-14 years were compared to 63 epileptic children whose cause of death was known (KCD). The time of death as well as two international geomagnetic indices were assessed: Bartels' planetary 3-h signs (Kp) for the time of death and 2 h before, and the mean planetary daily amplitudes (Ap) on the day of death and on the 4 critical days before (and on the 4 post-mortem days as a control). Among the 15 SUD patients 9 died between 6 a.m. and 9 a.m. (universal time) whereas the KCD group showed an approximately uniform distribution of the time of death ( P = 0.026, Kolmogorov-Smirnov test). The Kp signs at death and 2 h before as well as the Ap indices at death and for the 4 pre-mortem days or after were not different in comparisons between the SUD and the KCD group ( P > 0.2, Mann-Whitney test). Furthermore the frequency of sudden storm commencement at death and for the 4 days before revealed no deviation of the SUD (26.7%) from the KCD group (23.8%) ( P > 0.2, Fisher test). The results do not support the hypothesis that geomagnetic disturbances are a risk factor for the sudden unexplained death of epileptic children.     

Hybrid approach for complex coronary artery and valve disease: a clinical follow-up study

For patients suffering from complex coronary artery disease (CAD) with or without concomitant valve disease, no evidence is available in the current guidelines to propose a predefined treatment regimen. We sought to assess the clinical impact of an unconventional or extended definition of the hybrid approach that combines percutaneous coronary intervention (PCI) and cardiac surgery in subjects suffering from severe solitary CAD or combined with valve disease. Between July 2002 and August 2004, 18 consecutive patients with complex CAD with or without significant valve disease who qualified for a hybrid approach were enrolled in a clinical follow-up study. Four patients eventually did not complete the proposed interventions. One patient refused treatment after inclusion, one patient died before treatment could be undertaken and two patients died after surgery but before PCI. In the other 14 cases combined treatment was technically successful. After a mean follow-up period of 15±5 months two patients had died, one due to sudden cardiac death and one of a noncardiac cause. No other major adverse clinical events were reported. A marked increase in quality of life was reported in those alive. Hybrid approach had a favourable long-term outcome in patients with complex cardiovascular disease undergoing successful treatment; however, this was observed at the expense of significant periprocedural mortality in these high-risk subjects. Therefore we believe that hybrid approaches may provide an alternative for selected cases. (Neth Heart J 2007;15:329-34.)     

The Journey from Traffic Offender to Severe Road Trauma Victim: Destiny or Preventive Opportunity?

Background

Road trauma is a leading cause of death and injury in young people. Traffic offences are common, but their importance as a risk indicator for subsequent road trauma is unknown. This cohort study assessed whether severe road trauma could be predicted by a history of prior traffic offences.

Methodology and Principal Findings

Clinical data of all adult road trauma patients admitted to the Western Australia (WA) State Trauma Centre between 1998 and 2013 were linked to traffic offences records at the WA Department of Transport. The primary outcomes were alcohol exposure prior to road trauma, severe trauma (defined by Injury Severity Score >15), and intensive care admission (ICU) or death, analyzed by logistic regression. Traffic offences directly leading to the road trauma admissions were excluded. Of the 10,330 patients included (median age 34 years-old, 78% male), 1955 (18.9%) had alcohol-exposure before road trauma, 2415 (23.4%) had severe trauma, 1360 (13.2%) required ICU admission, and 267 (2.6%) died. Prior traffic offences were recorded in 6269 (60.7%) patients. The number of prior traffic offences was significantly associated with alcohol-related road trauma (odds ratio [OR] per offence 1.03, 95% confidence interval [CI] 1.02–1.05), severe trauma (OR 1.13, 95%CI 1.14–1.15), and ICU admission or death (OR 1.10, 95%CI 1.08–1.11). Drink-drinking, seat-belt, and use of handheld electronic device offences were specific offences strongly associated with road trauma leading to ICU admission or death—all in a ‘dose-related’ fashion. For those who recovered from road trauma after an ICU admission, there was a significant reduction in subsequent traffic offences (mean difference 1.8, 95%CI 1.5 to 2.0) and demerit points (mean difference 7.0, 95%CI 6.5 to 7.6) compared to before the trauma event.

Significance

Previous traffic offences were a significant risk factor for alcohol-related road trauma and severe road trauma leading to ICU admission or death.     

Is there a link between cot death and child abuse?

Forty five babies delivered in Oxford obstetric units who subsequently died unexpectedly in infancy were compared with 134 controls matched for maternal age, social class, parity, and year of birth to see whether five factors identified in an earlier study as predictive of subsequent child abuse would also predict the sudden infant death syndrome. Epidemiological findings had suggested certain similarities between the two events. In contrast with babies who were abused, four of the five factors did not distinguish between babies who died suddenly and unexpectedly and their controls, but there was a slight increase in the proportion of mothers of babies who died suddenly and unexpectedly for whom nursing staff thought that support and advice on feeding the baby were needed. Factors predictive of child abuse did not predict sudden infant death in this study.     

Acoustic Characteristics of Stridor in Multiple System Atrophy

Nocturnal stridor is a breathing disorder prevalent in patients with multiple system atrophy (MSA). An improved understanding of this breathing disorder is essential since nocturnal stridor carries a poor prognosis (an increased risk of sudden death). In this study, we aimed to classify types of stridor by sound analysis and to reveal their clinical significance. Patients who met the criteria for probable MSA and had undergone polysomnography (PSG) were recruited. Patients were then assessed clinically with sleep questionnaires, including the Pittsburgh Sleep Quality Index, and the Hoehn and Yahr scale. Nocturnal stridor and snoring were analyzed with the Multi-Dimensional Voice Program. Nocturnal stridor was recorded in 22 patients and snoring in 18 patients using the PSG. Waveforms of stridors were classified into rhythmic or semirhythmic after analysis of the oscillogram. Formants and harmonics were observed in both types of stridor, but not in snoring. Of the 22 patients diagnosed with stridor during the present study, fifteen have subsequently died, with the time to death after the PSG study being 1.9 ± 1.4 years (range 0.8 to 5.0 years). The rhythmic waveform group presented higher scores on the Hoehn and Yahr scale and the survival outcome of this group was lower compared to the semirhythmic waveform group (p = 0.030, p = 0.014). In the Kaplan Meier’s survival curve, the outcome of patients with rhythmic waveform was significantly less favorable than the outcome of patients with semirhythmic waveform (log-rank test, p < 0.001). Stridor in MSA can be classified into rhythmic and semirhythmic types and the rhythmic component signifies a poorer outcome.     

Are pre-hospital deaths from accidental injury preventable?

OBJECTIVE--To determine what proportion of pre-hospital deaths from accidental injury--deaths at the scene of the accident and those that occur before the person has reached hospital--are preventable. DESIGN--Retrospective study of all deaths from accidental injury that occurred between 1 January 1987 and 31 December 1990 and were reported to the coroner. SETTING--North Staffordshire. MAIN OUTCOME MEASURES--Injury severity score, probability of survival (probit analysis), and airway obstruction. RESULTS--There were 152 pre-hospital deaths from accidental injury (110 males and 42 females). In the same period there were 257 deaths in hospital from accidental injury (136 males and 121 females). The average age at death was 41.9 years for those who died before reaching hospital, and their average injury severity score was 29.3. In contrast, those who died in hospital were older and equally likely to be males or females. Important neurological injury occurred in 113 pre-hospital deaths, and evidence of airway obstruction in 59. Eighty six pre-hospital deaths were due to road traffic accidents, and 37 of these were occupants in cars. On the basis of the injury severity score and age, death was found to have been inevitable or highly likely in 92 cases. In the remaining 60 cases death had not been inevitable and airway obstruction was present in up to 51 patients with injuries that they might have survived. CONCLUSION--Death was potentially preventable in at least 39% of those who died from accidental injury before they reached hospital. Training in first aid should be available more widely, and particularly to motorists as many pre-hospital deaths that could be prevented are due to road accidents.     

36 例心源性猝死尸检的临床病理学研究*

目的:分析心源性猝死的临床病理学特征,为心源性猝死的诊断和预防提供理论依据。方法:收集36例心源性猝死病例的尸检解剖资料,进行病理组织学检查。结果:36例心源性猝死者中,冠心病21例,占心源性猝死者总数的58.33%;心律失常性右心室心肌病猝死者3例,占心源性猝死者总数的8.33%。结论:科学系统的尸检可以明确猝死原因,为医疗纠纷鉴定提供可靠依据,同时,对提高医疗质量,早期诊断、治疗心血管系统疾病和减少猝死发生起有重要作用。     

Role of respiratory viruses in childhood mortality.

Respiratory viruses have been identified at necropsy in the lungs of 13 out of 24 children who died with observed acute respiratory illness. The histological appearances of the lungs supported the association between virus and death in each of these 13 children and suggested an unidentified virus aetiology in a further five cases. Histological appearances compatible with bacterial infection were found in the lungs of only two of the 24 children. Similar virus and histological findings have been reported in about one-third of victims of the sudden infant death syndrome (cot deaths), indicating a rapid unobserved respiratory virus infection as the most likely mode of death in this group. Evidence that respiratory viruses may be involved in a larger proportion of sudden unexpected deaths, perhaps as antigens in a hypersensitivity reaction, is discussed. Respiratory viruses seem the major identifiable agents contributing to the maintenance of the postneonatal mortality rate since acute respiratory illness and the sudden infant death syndrome together account for about two-thirds of deaths at this age.     

Community study of the causes of "natural" sudden death.

Three hundred and fifty cases of "natural" sudden death within six hours of onset of symptoms in people ranging in age from 18 to 69 years in Wandsworth were studied using a detailed necropsy protocol to determine the cause of death. Sudden death occurred in 28 (8%) Asians and blacks, but because of the small number they were excluded from the study, leaving 322 cases. Ischaemic heart disease accounted for 189 (59%) of the 322 sudden deaths (155 (65%) men; 34 (41%) women) and no proportional increase in instantaneous compared with non-instantaneous sudden death was found. Non-ischaemic cardiac disease was the cause of sudden death in 24 cases (7.5%). Non-cardiac disease included pulmonary emboli, aortic aneurysms, and intracerebral haemorrhage and caused 89 (27.6%) deaths. Alcohol was the cause of nine deaths (2.8%) and in 11 (3.4%) cases (six men and five women) no cause of death was found. This study shows that although ischaemic heart disease is the single largest cause of sudden natural death there are other major causes.     

Bed sharing,smoking, and alcohol in the sudden infant death syndrome. New Zealand Cot Death Study Group.

OBJECTIVES--To investigate why sharing the bed with an infant is a not consistent risk factor for the sudden infant death syndrome in ethnic subgroups in New Zealand and to see if the risk of sudden infant death associated with this practice is related to other factors, particularly maternal smoking and alcohol consumption. DESIGN--Nationwide case-control study. SETTING--Region of New Zealand with 78% of all births during 1987-90. SUBJECTS--Home interviews were completed with parents of 393 (81.0% of total) infants who died from the sudden infant death syndrome in the postneonatal age group, and 1592 (88.4% of total) controls who were a representative sample of all hospital births in the study region. RESULTS--Maternal smoking interacted with infant bed sharing on the risk of sudden infant death. Compared with infants not exposed to either risk factor, the relative risk for infants of mothers who smoked was 3.94 (95% confidence interval 2.47 to 6.27) for bed sharing in the last two weeks and 4.55 (2.63 to 7.88) for bed sharing in the last sleep, after other confounders were controlled for. The results for infants of non-smoking mothers were inconsistent with the relative risk being significantly increased for usual bed sharing in the last two weeks (1.73; 1.11 to 2.70) but not for bed sharing in the last sleep (0.98; 0.44 to 2.18). Neither maternal alcohol consumption nor the thermal resistance of the infant''s clothing and bedding interacted with bed sharing to increase the risk of sudden infant death, and alcohol was not a risk factor by itself. CONCLUSION--Infant bed sharing is associated with a significantly raised risk of the sudden infant death syndrome, particularly among infants of mothers who smoke. The interaction between maternal smoking and bed sharing suggests that a mechanism involving passive smoking, rather than the previously proposed mechanisms of overlaying and hyperthermia, increases the risk of sudden infant death from bed sharing.