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Baby Sleeping Bag and Conventional Bedding Conditions - Comparative Investigations by Infrared Thermography
Abstract
Thermal stress is a risk factor for sudden infant death syndrome (SIDS). Recently, baby sleeping bags have been recommended as a preventive measure against SIDS. The aim of this study was to describe in which way the use of baby sleeping bags might influence thermoregulation of sleeping infants and maybe the incidence of SIDS.
Body surface temperature was recorded by use of infrared thermography in 15 infants (median age 49 days). Recordings were done twice: after sleeping for 60 min under a blanket and after sleeping for 60 min in a baby sleeping bag. Temperature was recorded and compared for defined sites of body surface.
Infants' mean body surface temperature as well as core temperature after sleeping in a baby sleeping bag did not show significant differences when compared to infants sleeping under a conventional blanket.
Under controlled conditions, core temperature and mean body surface temperature are comparable, equally if using a baby sleeping bag or conventional bedding. However, under the more uncontrolled conditions of baby care at home, sleeping bags might provide a more constant temperature profile, while other bedding conditions may lead to significant variations of temperature pattern.
... Sudden infant death syndrome (SIDS) has become a public health issue in both developed and developing countries (Mitchell et al., 2020;Sauseng et al., 2011). In a case study, most of the victims were reported to be overwrapped, and many were abnormally hot and sweaty when found dead (Stanton, 1984). ...
Purpose
The purpose of this study is to determine the temperature ratings of infant bedding.
Design/methodology/approach
Mathematical models were developed for predicting temperature ratings of infant bedding for all age groups based on the thermal balance equation. These models were validated by the published physiological data and the baby manikin tests. The air temperature was compared with the predicted temperature rating, and the skin temperature of infant or baby manikin was used to explain the validation results.
Findings
The models had higher prediction accuracy, especially for the infant bedding with uniformly distributed thermal insulation. The results showed that an increase of 1 clo in thermal insulation caused a decrease of 4.2–6.0 °C in temperature rating. The slope of the model reduced with the increasing month-age, indicating that an older infant had a lower temperature rating than a younger infant.
Practical implications
Suggestions were given for caregivers that younger infants ought to be covered with more bedding than adults; however, older infants were expected to require less bedding.
Originality/value
The outcomes provided scientific guidelines on the selection of bedding for infants at a particular room temperature to ensure the health and safety of infants.
... ambient temperature, air velocity, and humidity). [3][4][5][6][7] The impact of diverse insulation conditions, such as naked or dressed, clothing layers, and mattress types, were also evaluated. 2,8 A mismatch between thermal environment and insulation has been reported as the main cause of overheating. ...
This study aimed to investigate the heat transfer around the infant surface in the indoor environment based on computational fluid dynamics analysis. A three-dimensional numerical model containing a virtual infant manikin was developed in COMSOL software. The high-quality geometry model of the infant was obtained using three-dimensional body scanning technology. Governing fluid flow and energy equations were solved along with the low Re k–ε turbulence model. Real-scale measurements were carried out to determine the accuracy of the developed numerical model. Good agreement was found between the simulation results and the experimental data. The results showed that, at room temperature of 21 o C, the convective heat transfer coefficient was 64.2% greater than the radiative heat transfer coefficient, which demonstrated that the convective heat transfer was the main approach for heat exchange between the infant and its surrounding environment. Moreover, the largest convective heat transfer coefficients were observed at the forearm and calf, indicating the importance of the additional thermal protection at these regions. The findings will be beneficial to provide some instructions on infant thermal care for caregivers.
Body posture affects the heat transfer between infants and surroundings. The purpose of this study was to investigate the air gap thickness as well as the heat transfer at the infant’s body surface when the infant posture changed from standing to lying down (supine). Visual and quantitative air gap distributions were achieved using 3D body scanning technology and reverse engineering software. Global and local heat transfer coefficients were also obtained by baby manikin test. The results showed that the local air gap thickness significantly decreased in supine posture compared to standing, especially at the diaper zone. Moreover, the supine posture reduced the local heat exchange although the corresponding air gap thickness decreased. The different linear regression models between air gap thickness and heat transfer coefficient were therefore built in both standing and supine postures. For the air gap thickness with the range of 4.00-9.05 mm, the coefficient was always lower when lying down than standing. The findings provided useful information for the improvement of infant clothing design and the modelling of heat and mass transfer in infant clothing for different body postures.
Clinical scenario: A mother brought her infant to the hospital with bronchiolitis and incidentally asked if I would recommend the use of infant sleeping bags to protect against Sudden Infant Death Syndrome as several of her friends use them. Structured question: Can infant sleeping bags be recommended by medical professionals as protective against Sudden Infant Death Syndrome?
Methods:
A literature search was performed. Trials were included if they had an English version available and the papers examined the impact that sleeping bag use had on risk of SIDS or its risk factors. Cochrane Library search found eight trials, two of which were found to meet inclusion criteria. MEDLINE was searched using the search terms ((baby sleeping bag) OR infant sleeping bag) OR cotton sleeping sack. Forty-seven papers were found, two of which were found to meet the inclusion criteria, one of which had already been found in the Cochrane Library search. One further paper was found through searching citations of the papers included.
Discussion:
Sleeping bags are used in 48-95% of infants in the UK and advocated for by the Lullaby Trust for their safety in the prevention of SIDS. The case control studies included found that sleeping bags are as safe, if not safer than other bedding when examining SIDS as an outcome. For sleeping bags to be safe they must be well made and appropriately used, which includes the correct size, Tog, clothing and other bedding for bedroom temperature.
The literature survey 2011 is based on 1730 papers found in the databases MEDLINE and EMBASE with the keywords “thermography” or “thermometry” or “thermotherapy” or ‘skin temperature’ or ‘core temperature’ and restricted to “included in the databases between 01.01 and 31.12. 2011”. 36,5 percent of papers of this review are originated from Europe and 96 percent of all papers are written in English. 588 controlled studies using some kind of temperature measurement were included in this survey. Physiology, cardiovascular diseases, neurology, dermatology and clinical & experimental pharmacology were the predominant fields of applications of temperature measurement in medicine. As in previous years, therapeutic hypothermia and hyperthermia treatment was the topic of many papers. Fever attracted also a high number of publications. Some articles were related to sleep or pain. Only few papers were found for intravascular temperature measurement, Raynaud´s phenomenon or breast thermography.
Over the first three months of life the infant's metabolic rate rises, which, together with the rise in ratio of mass to surface area, means that the net heat loss per unit surface area is 50% higher in a 3 month old infant than in a neonate. This, together with the thicker layer of subcutaneous fat and more effective peripheral vasomotor response to cold in a 3 month old infant, means that thermal balance is shifted in favour of heat conservation. The head is the site of 40% of heat production and of up to 85% of heat loss in an infant in bed: covers rising up over the head could therefore result in acute thermal imbalance with a rise in brain temperature not necessarily accompanied by a rise in body temperature. In animal studies relatively small changes in hypothalamic temperature have profound effects on the control of respiration. Alternatively, a rise in metabolic rate (from an acute infection, for example) could result in a significant change in thermal balance. There is anecdotal evidence that heat stress may be associated with sudden infant death or with severe hypoventilation. In the Avon studies infants with SIDS, particularly those over 70 days of age, were more heavily wrapped and were more likely to have had the heating on all night than control infants matched for age, date, and neighbourhood. There was no significant excess of viral infections in the infants with SIDS, but those who had virus infections were much more heavily wrapped than control infants with similar infections, suggesting that the combination of heavy wrapping and virus infection may be more important than either factor alone. There is, therefore, some physiological evidence that infants of 2 to 3 months of age may be more vulnerable to heat stress than younger infants, and limited evidence, from clinical studies, that this may occur and be associated with some sudden deaths. The precise contribution of thermal stress and the mechanism by which it could cause death remain unclear.
In several studies the sudden infant death syndrome (SIDS) has been significantly associated with sleeping in the prone position. It is not known how the prone position increases the risk of SIDS.
We analyzed data from a case-control study (58 infants with SIDS and 120 control infants) and a prospective cohort study (22 infants with SIDS and 213 control infants) in Tasmania. Interactions were examined in matched analyses with a multiplicative model of interaction.
In the case-control study, SIDS was significantly associated with sleeping in the prone position, as compared with other positions (unadjusted odds ratio, 4.5; 95 percent confidence interval, 2.1 to 9.6). The strength of this association was increased among infants who slept on natural-fiber mattresses (P = 0.05), infants who were swaddled (P = 0.09), infants who slept in heated rooms (P = 0.006), and infants who had had a recent illness (P = 0.02). These variables had no significant effect on infants who did not sleep in the prone position. A history of recent illness was significantly associated with SIDS among infants who slept prone (odds ratio, 5.7; 95 percent confidence interval, 1.8 to 19) but not among infants who slept in other positions (odds ratio, 0.83). In the cohort study, the risk of SIDS was greater among infants who slept prone on natural-fiber mattresses (odds ratio, 6.6; 95 percent confidence interval, 1.3 to 33) than among infants who slept prone on other types of mattresses (odds ratio, 1.8).
When infants sleep prone, the elevated risk of SIDS is increased by each of four factors: the use of natural-fiber mattresses, swaddling, recent illness, and the use of heating in bedrooms.
The effect on deep body temperature of infants co-sleeping (with either or both parents) is investigated in this case control study. Overnight continuous recordings of rectal temperature were made from 34 babies co-sleeping with one or both parents throughout the night and 34 infants matched for age, feeding regimen, parental smoking, thermal environment, sleeping position, and sex who slept alone. The co-sleeping infants had significantly higher rectal temperatures from two hours after bedtime, when the initial fall in sleeping body temperature was complete. The mean rectal temperature of co-sleeping infants between two and eight hours was 0.1 degree C higher than that of infants sleeping alone (p < 0.04). Given the very small variance in rectal temperature this probably reflects a considerable physiological difference between the two groups.
In the Netherlands an 18 months case control study into cot death was under-taken as part of the European Concerted Action (ECAS) on sudden infant death syndrome to determine the relative risk of prone sleeping and other sleep practices. Physicians in the Netherlands were asked to report to the study centre all sudden and unexpected deaths of children between 1 week and 2 years of age. Non cot death cases were deleted from further analysis after a consensus was reached by three pathologists, not primarily involved in the post mortem diagnosis. A positive response of families was achieved in 91% of cases registered in the Central Bureau of Statistics. The study comprised 73 cot deaths and 146 controls, two for each case and matched for date of birth. All families were visited at home for completion of a questionnaire. The cot death rate has dropped considerably over the past 10 years after the recommendations on supine sleeping to a low of 0.26 per 1000 live born infants. In addition to the ECAS objective, we wanted to establish whether previously found risk factors are still valid in the present situation or that new factors might have emerged, some of them possibly protective.
Conclusion Placing an infant prone or on side on last occasion, secondary prone position (not placed prone but turned to prone), inexperienced prone sleeping and use of a duvet, leading to head and body being covered, were shown to be risk factors. Preventive factors were using a cotton sleeping-sack and a dummy. Even in a low incidence country, such as the Netherlands, there are indications that further prevention is possible.
The mechanism of sudden infant death syndrome (SIDS) may be linked to an interaction between the SIDS risk factors of hyperthermia and infection, and between their effect on cytokine production and arousal. This study investigated the effects of hyperthermia and a surrogate of infection (muramyl dipeptide or MDP) on cytokine production and mortality in a neonatal rat model. Four temperature groups were studied: 34°C (baseline), 38°C, 39°C, and 40°C. Body temperatures of neonatal rat pups in the hyperthermic groups were raised and maintained at the desired temperature (38°C, 39°C, or 40°C) for 1 h and then returned to the baseline temperature (34°C) for a further hour. The heat source was a covered, heatable aluminum metal plate in a Perspex heating chamber. Intraperitoneal (IP) injection of 0.1 mL normal saline was given 30 min before the start to control for MDP (protocol A). Four equivalent treatment groups were pretreated with MDP (25 nmol/animal) instead of normal saline (protocol B). IP ketamine (55 mg/kg) was used for anesthesia during the experiments and for euthanasia. Blood was collected by direct cardiac puncture immediately after the 2-h experiments and assayed for the cytokines IL-6 and IL-1β by ELISA. Hyperthermia significantly increased the production of IL-6 (p = 0.049) but not IL-1β and significantly increased mortality. Administration of MDP significantly increased the IL-1β production (p = 0.006) but not IL-6. Cox regression analysis showed that MDP in combination with hyperthermia had a significant effect on mortality in the neonatal rat. The risk of experiencing mortality was two and half times higher in the MDP group than in the non-MDP group (p = 0.016) [hazard ratio (95% confidence interval) = 2.66 (1.20-5.92)]. We conclude that hyperthermia and a surrogate of infection (MDP) influence cytokine production and that the combination of heat stress and MDP increases mortality in the neonatal rat.
To examine the sleeping arrangements of sudden infant death syndrome (SIDS) cases on the Wirral. In particular to determine the prevalence of bed sharing with mothers who smoke, a known risk factor for SIDS.
Retrospective study of postmortem determined cases of SIDS from 1995 to 2000 on the Wirral peninsula (population 350 000, 3500 annual births). Ambulance crew reports, case notes, health visitor reports, postmortem reports, and case discussion records were studied for each case.
There were 25 cases of SIDS in the postneonatal age group over the six year period. In nine cases the baby was bed sharing with the mother, of whom seven were smokers. Five of these mothers reported using alcohol or illicit drugs on the night of their infant's death. In two further cases the baby slept on a sofa with a parent.
Bed sharing and smoking remain important risk factors for SIDS. Mothers should be advised ante- and postnatally of this combination of risk factors. Such advice should also include a recommendation not to sleep with their baby if under the influence of alcohol or illicit drugs, and never to sleep on a sofa with their baby. All "Child Health Record" books given to parents on the Wirral now include this advice. "Reduce the Risk" advice leaflets given to parents pre- and postnatally also now carry the recommendation, and health visitors and midwives have been educated with respect to these additions.
Results of case-control studies in the past 5 years suggest that the epidemiology of sudden infant death syndrome (SIDS) has changed since the 1991 UK Back to Sleep campaign. The campaign's advice that parents put babies on their back to sleep led to a fall in death rates. We used a longitudinal dataset to assess these potential changes.
Population-based data from home visits have been collected for 369 consecutive unexpected infant deaths (300 SIDS and 69 explained deaths) in Avon over 20 years (1984-2003). Data obtained between 1993 and 1996 from 1300 controls with a chosen "reference" sleep before interview have been used for comparison.
Over the past 20 years, the proportion of children who died from SIDS while co-sleeping with their parents, has risen from 12% to 50% (p<0.0001), but the actual number of SIDS deaths in the parental bed has halved (p=0.01). The proportion seems to have increased partly because the Back to Sleep campaign led to fewer deaths in infants sleeping alone-rather than because of a rise in deaths of infants who bed-shared, and partly because of an increase in the number of deaths in infants sleeping with their parents on a sofa. The proportion of deaths in families from deprived socioeconomic backgrounds has risen from 47% to 74% (p=0.003), the prevalence of maternal smoking during pregnancy from 57% to 86% (p=0.0004), and the proportion of pre-term infants from 12% to 34% (p=0.0001). Although many SIDS infants come from large families, first-born infants are now the largest group. The age of infants who bed-share is significantly smaller than that before the campaign, and fewer are breastfed.
Factors that contribute to SIDS have changed in their importance over the past 20 years. Although the reasons for the rise in deaths when a parent sleeps with their infant on a sofa are still unclear, we strongly recommend that parents avoid this sleeping environment. Most SIDS deaths now occur in deprived families. To better understand contributory factors and plan preventive measures we need control data from similarly deprived families, and particularly, infant sleep environments.
Background:
With simple prevention measures SIDS (Sudden Infant Death Syndrome) incidence rates can be reduced. A cross-sectional survey in Bavaria in 2005 showed that maternity units fall short in acting as role models and informing parents regarding SIDS prevention and that parents did not sufficiently apply prevention measures. An information campaign in Bavaria was initialized and evaluated after 18 months.
Methods:
Flyers and posters for SIDS prevention using consistent information were developed for dissemination by the relevant occupational groups. The campaign impact was assessed in repeating the cross-sectional survey.
Results:
A response rate of 99% for the maternity units and 60% for the parent questionnaires could be achieved. Significant improvements (p<0.05) in the maternity units regarded a higher proportion of parents informed about SIDS prevention measures (97 vs. 92%) and an increased use of sleeping bags (37 vs. 12%), whereas the proportion of children placed in supine position to sleep was not increased. More parents reported to have obtained advice for SIDS prevention (83 vs. 73%) and to have used sleeping bags (66 vs. 56%). A subgroup analysis revealed poorer information and implementation of the recommendations in families with three or more children and less educated families.
Conclusions:
After initiation of the information campaign reported knowledge about SIDS prevention measures increased. Continuing shortfalls exist regarding maternity units acting as role models and implementation of the recommendations by the parents. Future interventions should focus in particular on the role model function of maternity units and target groups.
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.
Recent years have seen major advances in our understanding of the sudden infant death syndrome (SIDS), including the discovery that the prone sleep position more than triples the risk of SIDS. This finding has led to a worldwide campaign advocating the supine sleep position for infants, which has been associated with a decrease of 50 to 90% in the SIDS rate. This review considers demographic and pathophysiological factors and current concepts about SIDS.
Our goal was to investigate the risk factors for sudden infant death syndrome in the infants' sleep environment for a population in which few infants sleep prone as a result of education campaigns.
This was a population-based sudden infant death syndrome case-control study over 3 years (1998-2001) in Germany.
There were 333 sudden infant death syndrome cases and 998 matched controls. Although only 4.1% of the infants were placed prone to sleep, those infants were at a high risk of sudden infant death syndrome. Those who were unaccustomed to sleeping prone were at very high risk, as were those who turned to prone. Bed sharing (especially for infants younger than 13 weeks); duvets; sleeping prone on a sheepskin; sleeping in the house of a friend or a relative (compared with sleeping in the parental home); and sleeping in the living room (compared with sleeping in the parental bedroom) increased the risk for sudden infant death syndrome; pacifier use during the last sleep was associated with a significantly reduced risk of sudden infant death syndrome.
This study has clarified the risk factors for sudden infant death syndrome in a population where few infants sleep prone. This study supports the current recommendations of the American Academy of Pediatrics. This study has identified several novel risk factors for sudden infant death syndrome: an increased risk if the infants sleeps outside the parental home, death in the living room, and the high risk when sleeping prone on a sheepskin; however, because the numbers of cases in these groups are small, additional studies are needed to confirm these findings.
Southern New Zealnd has one of the highest postneonatal mortality rates in the developed world (8.1/1000 livebirths) and 77% of these deaths are attributed to the sudden infant death syndrome (SIDS). Both hyperthermia and sleeping position have previously been implicated in SIDS. A theoretical model to estimate the thermal balance of infants used here shows that the head, and particularly the face, becomes the main route for heat loss when thick clothing and bedding are used. This thermoregulatory role could be compromised by the prone sleeping position. It is postulated that particular cultural combinations of infant care practices (sleeping position, clothing, bedding, and room heating) may facilitate hyperthermia and explain widely disparate rates of SIDS in different countries and ethnic groups.
To determine whether bundling elevates rectal and/or skin temperature of young infants.
Randomized, prospective study stratified by age.
Clinical Studies Center at a teaching hospital in Los Angeles.
Sixty-four well, full-term infants (ages 11 to 95 days).
Control infants (n = 28) were dressed in a disposable diaper and terry coveralls. Bundled infants (n = 36) were dressed as control infants, plus a cap, a receiving blanket, and a thermal blanket. All infants were monitored in an open crib (room temperature 72 degrees to 75 degrees F). Rectal and skin (anterior mid-lower leg) temperatures and infant states were measured at 5-minute intervals from time 0 to 60 minutes and at 62 and 65 minutes.
The mean skin temperature of bundled infants increased by 2.67 degrees C/hr; mean rectal temperature increased by 0.06 degrees C/hr. The mean skin temperature of nonbundled infants increased by 1.5 degrees C/hr; mean rectal temperature decreased by less than 0.01 degree C/hr. Comparing bundled infants to nonbundled controls, there was a significant rise in skin temperature (P = .0001) but not in rectal temperature (P > .05, Wilcoxon rank sum test). The study had a power > 98% to detect a rise of .5 degrees C in rectal temperature over 60 minutes. The 95% confidence interval for the change in rectal temperature in bundled infants was -0.03 to +0.15 degrees C.
Bundling a healthy infant in a temperate external environment causes an increase in skin temperature, but not in rectal temperature. Elevated rectal temperatures should therefore, rarely if every be attributed to bundling.
In summary, there is evidence that developmental changes in respiratory control and in thermoregulation have effects upon each other. Theoretically, such effects could give rise to failure of the respiratory system and there is some circumstantial evidence to support the concept that on occasions such interactions may be of importance in sudden unexpected death in infancy. Future research in this area should focus on the nature of the interactions between thermoregulation and respiration, and on the effects of infection and infection-related mediators on those interactions.
The heat loss coefficients of a group of infants have been calculated and compared to see if there is a difference in the ability to lose heat between prone and non-prone sleeping infants. For a group of 43 infants aged 4-29 weeks, a simple mathematical model of exponential cooling in a body has been fitted to the fall in rectal temperature which occurs in infants at bedtime. One of the parameters yielded by the fitting process is the coefficient of thermal heat loss. After validation against the estimated heat loss from supine sleeping infants, the heat loss coefficient was compared at different sleep positions and gender. The mean heat loss coefficient, measured from the non-prone sleeping infants (0.269 W/degrees C, S.D. 0.197) agreed well with the value calculated for supine sleepers with the same tog levels (0.4 W/degrees C). Prone sleeping infants were found to have a considerably smaller heat loss coefficient which was approximately 60% of the value for non-prone sleeping infants (P = 0.000097). Female infants were found to have a heat loss coefficient that was approximately 70% of that of male infants but this gender difference was only significant (P = 0.025) for non-prone sleeping infants. These results suggest that infants sleeping in the prone position may be unable to lose heat as rapidly as those infants sleeping non-prone.
Thermography enables the measurement of patients skin temperature profiles without stress caused by direct contact of probes to the skin. In previous incubator studies, frontal recordings were made through a hole in the top wall of the incubator hood. Using this method it is not possible to record the lateral temperature gradient from the back to the abdomen of the infant (in supine position), which is due to very limited heat loss near the incubator mattress. In this study temperature recordings were made from a lateral position. For this purpose a new front door of the incubator (Draeger 8000) was designed, which replaced the standard front door during measurements. In a clinical study thermography was compared to temperature measurements by standard thermistors. The mean difference between thermography and thermistors was 0.16 degree C. These results verify the use of thermography for measuring skin temperature of preterm infants in incubators.
Recommendations to adopt the supine position were followed by a dramatic decrease of SIDS. But no explanation has been given for the association between SIDS and the prone position nor for its decrease in the supine position. We report data on an infant and a mannequin demonstrating an increase in temperature around the head in the prone position. A 4-month-old boy presented an acute life-threatening event related to temperature after febrile otitis despite treatment: 40.5 degrees C, heart rate 280 bpm with circulatory failure and cardiorespiratory arrest requiring resuscitation. There were no seizures. Blood and CSF cultures were negative. The course under antibiotics was favourable. On d 3, we measured temperature at several sites on and around the heat. Temperatures were higher in the prone than in the supine position in pericephalic areas: +1 degrees C (supracephalic), +2.5 degrees C (peritemporal), and +3.5 degrees C (submandibular). In a thermoregulated room, we used a mechanically ventilated mannequin of an infant. The prone position was also associated with an increase in temperature around the head: +3.3 degrees C (supracephalic), +1.8 degrees C (peritemporal), and +1.1 degrees C (submandibular). Changing from the supine to prone position thus increased temperature around the head (infant and mannequin). To our knowledge, this has not been reported before. SIDS is related to factors modifying temperature status and environment. Furthermore, evacuation of heat is mandatory for an infant. We think the increase in temperature around the head in the prone position is due to the absence of convective fluxes, and speculate it could impair thermolysis.
To assess the role of thermal stress in the cause of sudden infant death syndrome (SIDS), and to compare risk factors with those of rebreathing.
Analysis of publications concerning the epidemiology and physiology of thermal stress in SIDS.
A strong association between thermal regulation and ventilatory control was found, specifically for prolonged apnea. Infections, excessive room heat and insulation, and prone sleeping produce significantly increased odds ratios for SIDS. Although some of the risk factors for rebreathing could be explained by the effects of thermal stress, several factors for thermal stress could not reasonably be explained by the rebreathing hypothesis.
Although the risk of thermal stress is widely accepted abroad, it has received relatively little attention in the United States. The incidence of SIDS in the United States can likely be further reduced by educating the public against the dangers of overheating, as an integral part of the back-to-sleep campaign.
The aim of this study was to determine whether infrared thermography before and after challenge of the lower leg in cold water may be a useful tool to detect abnormalities in skin blood flow in adolescent asymptomatic patients with type 1 diabetes mellitus (DM1) and to assess the optimal setting of skin temperature measurements. Twenty-five adolescents (10 female, 15 male, mean age 21.2 +/- 6.2 years, body mass index [BMI] 23.0 +/- 2.1 kg/m2) with a duration of DMI of 13.8 +/- 5.4 years and mean HbA1c levels 8.5 +/- 1.3% were compared to age- and sex-matched controls (BMI 22.9 +/- 2.2 kg/m2). Seven defined sites of the lower leg were assessed by infrared thermography before and for 10 min after exposure of the leg to 14 degrees C cold water. As skin temperature before exposure to cold water differs from individual to individual and basal temperature was significantly warmer in patients at the tip of the first (p < 0.05) and fifth (p < 0.05) toe, the rewarming index was calculated in order to compare data. Rewarming indexes of skin temperature during the whole measurement procedure (0-10 min) were significantly lower at the tip of the first (p < 0.05) and fifth (p < 0.01) toes and from minute 2-10 also at the inner ankle (p < 0.05) in patients compared to healthy controls. Rewarming indexes of the other four sites were not significantly different between patients and controls. Infrared thermography of the lower leg after cold water exposure is an easily applicable method and a useful tool to detect abnormalities of skin blood flow in adolescents with DM1 especially at the tips of the first and fifth toes and the inner ankle.
Sudden infant death syndrome (SIDS) remains a challenge for health professionals despite decreasing rates in recent years. The figures for different areas and time periods are hardly comparable, because of differences in postmortem investigations and classification criteria. In 1992, the European Society for the Study and Prevention of Infant Deaths (ESPID) proposed a classification for any sudden and unexpected death in infancy. This proposal has been used in our study since 1993 to better classify sudden infant death (SID) cases.
56 consecutive SID cases observed between 1993 and 2002 in Styria, the south-eastern province of Austria, were analysed by a multidisciplinary team of health professionals. The study group consisted of pediatricians, forensic pathologists, pathologists, psychologists, nurses, members of the parents' association and health authorities. SID cases were analysed with regard to potential risk factors during pregnancy and early life, the circumstances of death (death scene) and post-mortem findings. From the latter, every SID was classified as either 1) classic SIDS, 2) borderline SIDS, 3) non-autopsied SID or 4) explained death.
Of the 56 SID cases, 22 were assigned to category 1, 19 to category 2, four to category 3, and in 11 cases death could be explained by major post-mortem findings. For 17/22 cases in category 1 and 11/19 cases in category 2, the death scene investigation showed the typical risk profile of manner of bedding and/or environmental conditions. In three cases, child abuse or infanticide was considered possible but could not be proven despite careful autopsy. In recent years, SIDS incidence in Styria has decreased to approximately 0.18/1,000 live-born infants, and the few deaths still occurring mainly present with the typical risk profile.
An extensive analysis of SID events is a prerequisite for reliable and comparable SIDS statistics. Our data show that in several SID cases careful post-mortem examinations led to an explanation of death. In other cases, minor alterations may have contributed to the lethal event. These findings should therefore be considered in the classification of SIDs. The ESPID classification of 1992 appears to be very useful for this purpose and its use may therefore be recommended.
In 1989, a scoring system that aimed to identify infants at risk of sudden infant death syndrome (SIDS) by a structured questionnaire [SIDS risk questionnaire (SRQ)] consisting of 25 items was introduced in Styria (Austria). It was the aim of the study to compare SIDS rates in the population that had access to the SRQ with the population that had no access. Furthermore, for the population receiving the SRQ, the responding (compliant) and non-responding (non-compliant) groups were compared concerning the incidence of SIDS.
Within the study period, 53 865 births and 57 SIDS cases were recorded (incidence 1.06/1000) and analysed retrospectively.
The incidence of SIDS was significantly higher in the non-responding population (2.36/ 1000) than in the responding group (0.81/1000, p < 0.001). However, the incidence of SIDS was not significantly different in the population that had access to the risk questionnaire (1.29/1000) and the group without access (0.86/1000, p = 0.145).
The value of any questionnaire used for SIDS prevention may be limited by the existence of a non-compliant population which represents a risk group and should be targeted by other preventive measures.
To determine the role of heat stress in sudden infant death syndrome (SIDS) by examining the SIDS rates during periods of extreme environmental temperatures in a period when most infants were placed prone for sleep.
A retrospective study of SIDS rates and mortality rates attributable to excessive environmental heat in relationship to climatologic temperature was performed. Data were collected for each of 454 counties in 4 states (Arkansas, Georgia, Kansas, and Missouri) from May 1 to September 30, 1980, and were then summed to yield the mortality rates for each 5 degrees F (2.8 degrees C) temperature range.
chi2 analyses revealed significant relationships for heat-related mortality rates and both the maximal daily temperature and mean daily temperature but demonstrated no such relationships for SIDS rates. No association between SIDS rates and heat-related mortality rates was found with Spearman's ranked correlation, for either the maximal daily temperature or the mean daily temperature.
On the basis of our findings of no significant association between SIDS and either measure of temperature during periods of high heat stress-related death rates, it seems unlikely that the heat stress associated with the combination of prone sleep positions and elevated environmental temperatures has a significant role in the development of SIDS.
The physiological mechanisms that might be involved in an association between heat stress and sudden infant death syndrome (SIDS) are obscure. We tested the hypothesis that a combination of acute hypoxia and elevated body temperature (T(B)) might prevent autoresuscitation from hypoxic apnea (AR). We exposed 21-day-old mice (total = 216) to hyperthermia (40.5-43.5 degrees C), hypoxia, or a combination of the two. Neither hyperthermia alone (40.5-42.5 degrees C) nor hypoxia alone was found to be lethal, but the combination produced failure to AR during the first hypoxic exposure with increasing frequency as T(B) increased. The ability to withstand multiple hypoxic exposures was also reduced as T(B) increased. In contrast, heat stress causing moderate T(B) increase (40.5 degrees C) had no effect on survival. Increased T(B) (43.5 degrees C) reduced gasping duration and number of gasps. It increased heart rate during anoxia but did not alter gasping rate. Furthermore, the oxygen-independent increase in heart rate observed before gasping failure was usually delayed until after the last gasp in hyperthermic animals. Mild dehydration occurred during T(B) elevation, but this did not appear to be a primary factor in AR failure. We conclude that a thermal stress, which by itself is nonlethal, frequently prevents AR from hypoxic apnea. This may be due, at least in part, to decreased gasp number and duration as well as to hyperthermia-related asynchrony of reflexes regulating heart and gasping frequencies during attempted AR.
Differences in the incidence of SIDS between 'Western' and 'Eastern' countries has been attributed to cultural practices, which may affect the infants care and thermal environment.
The purpose of this work was to estimate for selected 'commonly' used bedding, sleep positions and practices in Japan, Korea and New Zealand, the intrinsic 'dry' thermal resistance of bedding. Insulation levels are also discussed in the context of published information about the thermal environment in which the bedding is likely to be used.
Selected Japanese, Korean and New Zealand bedding was loosely tucked over an infant manikin in the lateral, prone and supine sleep positions. Thickness in use was measured, and intrinsic 'dry' thermal resistance estimated using the Wilson Laing model which accommodates the effect on insulation of the three-dimensional arrangement of bedding combinations during use.
Thickness of under- and upper-bedding varied among countries with thickness and estimated 'dry' thermal resistance of the upper-bedding affected by the type/combination of bedding and the infants sleep position. Insulation levels are discussed in relation to environmental conditions within and among countries and between seasons. Further information on thermal environments, bedding combinations used and care practices within both Asian and Western countries is needed.
'Eastern' infants appear likely to be generally covered in bedding combinations of greater insulation than those used to cover 'Western' infants in comparable seasons. Differences existed between insulation of the Japanese and Korean bedding combinations investigated. Lower rates of SIDS apparent in 'Asian' populations do not appear attributable to use of lower levels of bedding insulation only.
Sudden infant death syndrome (SIDS) continues to be the most common cause of postneonatal infant death. SIDS is a complex, multifactorial disorder, the cause of which is still not fully understood. However, much is known now about environmental risk factors, some of which are modifiable. These include maternal and antenatal risk factors such as smoking during pregnancy, as well as infant-related risk factors such as non-supine sleeping position and soft bedding. Emerging evidence also substantiates an expanding number of genetic risk factors. Interactions between environmental and genetic risk factors may be of critical importance in determining an infant's actual risk of SIDS. Although no practical way exists to identify which infants will die of SIDS, nor is there a safe and proven prevention strategy even if identification were feasible, reducing exposure to modifiable risk factors has helped to lower the incidence of SIDS. Current challenges include wider dissemination of guidelines to all people who care for infants, dissemination of guidelines in culturally appropriate ways, and surveillance of SIDS trends and other outcomes associated with implementation of these guidelines.
Heavy wrapping and head covering are risk factors for Sudden Infant Death Syndrome. A new mattress construction, PurFlo, has extremely low thermal resistance, and when used with an infant sleeping bag minimizes the risk of head covering.
To investigate the thermal balance and metabolic rate of infants sleeping on a conventional mattress or a Purflo mattress in infant sleeping bags.
A longitudinal study of thermal balance of infants during day-time sleep on both mattress types in thermoneutral and cool conditions at ages 3 weeks (n = 24), 3 months (n = 22) and 5 months (n = 18).
In thermoneutral conditions axillary temperatures in quiet sleep were lower on the conventional mattress than on the PurFlo mattress (p < 0.05, Wilcoxon test). On lowering room temperature to 15-16 degrees C axillary temperatures fell, particularly in the older babies, and at each age were lower on the conventional mattress than the Purflo (differences 0.14-0.72 degrees C, p < 0.05, Wilcoxon test).
In both thermoneutral and cool conditions, infant temperatures were higher on the PurFlo than the conventional mattress. The more deformable surface of the PurFlo mattress may lead to more effective insulation by the sleeping bag despite a lack of mattress insulation.
It was the aim of this study to investigate the surface temperature in newborns within the first hour after delivery. Furthermore, the influence of different environmental conditions with regard to surface temperature was documented.
Body surface temperature was recorded under several environmental conditions by use of infrared thermography. 42 newborns, all delivered at term and with weight appropriate for date, were investigated under controlled conditions.
The surface temperature immediately after birth shows a uniform picture of the whole body; however, it is significantly lower than the core temperature. Soon after birth, peripheral sites become cooler whereas a constant temperature is maintained at the trunk. Bathing in warm water again leads to a more even temperature profile. Radiant heaters and skin-to-skin contact with the mother are both effective methods to prevent heat loss in neonates.
Infrared thermography is a simple and reliable tool for the measurement of skin temperature profiles in neonates. Without the need of direct skin contact, it may be helpful for optimizing environmental conditions at delivery suites and neonatal intensive-care units.
Despite declines in prevalence during the past two decades, sudden infant death syndrome (SIDS) continues to be the leading cause of death for infants aged between 1 month and 1 year in developed countries. Behavioural risk factors identified in epidemiological studies include prone and side positions for infant sleep, smoke exposure, soft bedding and sleep surfaces, and overheating. Evidence also suggests that pacifier use at sleep time and room sharing without bed sharing are associated with decreased risk of SIDS. Although the cause of SIDS is unknown, immature cardiorespiratory autonomic control and failure of arousal responsiveness from sleep are important factors. Gene polymorphisms relating to serotonin transport and autonomic nervous system development might make affected infants more vulnerable to SIDS. Campaigns for risk reduction have helped to reduce SIDS incidence by 50-90%. However, to reduce the incidence even further, greater strides must be made in reducing prenatal smoke exposure and implementing other recommended infant care practices. Continued research is needed to identify the pathophysiological basis of SIDS.