Consequences of getting the head covered during sleep in infancy

Prematurity, the diagnosis of bronchopulmonary dysplasia, and maturation of ventilatory control

Infants born before 32 weeks gestational age and receiving respiratory support at 36 weeks postmenstrual age (PMA) are diagnosed with bronchopulmonary dysplasia (BPD). This label suggests that their need for supplemental oxygen (O₂ ) is primarily due to acquired dysplasia of airways and airspaces, and that the supplemental O₂ is treating residual parenchymal lung disease. However, emerging evidence suggests that immature ventilatory control may also contribute to the need for supplemental O₂ at 36 weeks PMA. In all newborns, maturation of ventilatory control continues ex utero and is a plastic process. Among premature infants, supplemental O₂ mitigates the hypoxemic effects of delayed maturation of ventilatory control, as well as reduces the duration and frequency of periodic breathing events. Nevertheless, prematurity is associated with altered and occasionally aberrant maturation of ventilatory control. Infants born prematurely, with or without a diagnosis of BPD, are more prone to long-lasting effects of dysfunctional ventilatory control. This review addresses normal and abnormal maturation of ventilatory control and suggests how aberrant maturation complicates assigning the diagnosis of BPD. Greater awareness of the interaction between parenchymal lung disease and delayed maturation of ventilatory control is essential to understanding why a given premature infant requires and is benefitting from supplemental O₂ at 36 weeks PMA.

Types of Objects in the Sleep Environment Associated With Infant Suffocation and Strangulation

OBJECTIVE

To investigate the circumstances of death and types and roles of objects present in the sleep environment at the time of death for infants who died from suffocation or strangulation during sleep.

METHODS

This study analyzed 1736 reported incidents of accidental suffocation and strangulation in bed (ASSB) of infants younger than 1 year of age. These fatalities occurred from 2000 through 2012 and were reported to the United States Consumer Product Safety Commission.

RESULTS

The mean age of ASSB death was 3.76 months (SD, 2.51). Infants younger than 5 months accounted for 67.3% (1168 of 1736) of all reported fatalities and 58.3% (1009 of 1731) were male. Deceased infants were often found in a crib or bassinet (30.6%; 383 of 1253) or in the prone orientation (84.9%; 595 of 701). The most common objects associated with infant ASSB were pillows (24.5%; 425 of 1736), mattresses (21.0%; 364 of 1736), blankets (13.1%; 228 of 1736), and walls (11.5%; 199 of 1736). Wedged (43.3%; 616 of 1424) or positioned on top of an object (25.9%; 369 of 1424) were the most common positions associated with death. Infants were often found wedged between a mattress and wall (30.2%; 181 of 599) or oriented face-down or prone on top of a pillow (52.2%; 187 of 358). Sleep surface sharing was associated with 6.5% (112 of 1736) of ASSB deaths.

CONCLUSIONS

Pillows and blankets are objects in sleep environments frequently associated with unintentional suffocation and strangulation of infants. Increased efforts should be made to remove these and other objects from sleep environments of infants.

Hypoxic and hypercapnic events in young infants during bed-sharing

OBJECTIVES

To identify desaturation events (arterial oxygen saturation [Sao(2)] <90%) and rebreathing events (inspired carbon dioxide (CO(2)) >3%), in bed-sharing (BS) versus cot-sleeping (CS) infants.

METHODS

Forty healthy, term infants, aged 0 to 6 months who regularly bed-shared with at least 1 parent >5 hours per night and 40 age-matched CS infants were recruited. Overnight parent and infant behavior (via infrared video), Sao(2), inspired CO(2) around the infant's face, and body temperature were recorded during sleep at home.

RESULTS

Desaturation events were more common in BS infants (risk ratio = 2.17 [95% confidence interval: 1.75 to 2.69]), associated partly with the warmer microenvironment during BS. More than 70% of desaturations in both groups were preceded by central apnea of 5 to 10 seconds with no accompanying bradycardia, usually in active sleep. Apnea >15 seconds was rare (BS infants: 3 events; CS infants: 6 events), as was desaturation <80% (BS infants: 3 events; CS infants: 4 events). Eighty episodes of rebreathing were identified from 22 BS infants and 1 CS infant, almost all preceded by head covering. During rebreathing, Sao(2) was maintained at the baseline of 97.6%.

CONCLUSIONS

BS infants experienced more oxygen desaturations preceded by central apnea, partly related to the warmer microenvironment. Rebreathing occurred mainly during bed-sharing. Infants were at low risk of sudden infant death syndrome and maintained normal oxygenation. The effect of repeated exposure to oxygen desaturation in vulnerable infants is unknown as is the ability of vulnerable infants to respond effectively to rebreathing caused by head covering.

Airway covering during bed-sharing

BACKGROUND

Parent-infant bed-sharing is a common practice in Western post-industrial nations with up to 50% of infants sleeping with their parents at some point during early infancy. However, researchers have claimed that infants may be at risk of suffocation or sudden infant death syndrome related to airway covering or compression in the bed-sharing environment. To further understand the role of airway covering and compression in creating risks for bed-sharing infants, we report here on a sleep-lab trial of two infant sleep conditions.

METHODS

In a sleep-lab environment 20 infants aged 2-3 months old slept in their parents' bed, and in a cot by the bed, on adjacent nights. Infants' oxygen saturation and heart rate were monitored physiologically while infant and parental behaviours were recorded via ceiling-mounted infra-red cameras. Infants served as their own controls. Continuous 8-h recordings were obtained for covering of infant external airways, levels of infant oxygen saturation, infant heart rate, evidence of parental compression/overlying of infant, circumstances leading up to potential infant airway obstruction, and parental awareness of and responses to infant airway covering.

RESULTS

The majority of infants (14/20) spent some part of the bed night with their airways (both mouth and nose) covered, compared with 2/20 on the cot night; however, no consistent effect on either oxygen saturation levels or heart rate was revealed, even during prolonged bouts of airway covering. All cases of airway covering were initiated by parents; 70% were terminated by parents, the remainder by infants. Seven bouts of potential compression were observed with parental limbs resting across infant bodies for lengthy periods, however, in only two cases was the full weight of a parental limb resting on an infant, both events lasting less than 15 s, both being terminated by infant movement.

CONCLUSION

Although numerous authors have suggested that bed-sharing infants face risks because of airway covering by bed-clothes or parental bodies, the present trial does not lend support to this hypothesis.

The German case-control scene investigation study on SIDS: epidemiological approach and main results

The present study, which was part of the German SIDS Study (GeSID), enrolled sudden infant death syndrome (SIDS) cases and population controls and obtained objective scene data via specifically trained observers shortly after discovery of each dead infant. Infants who had died suddenly and unexpectedly at ages between 8 and 365 days were enrolled in five regions of Germany between November 1998 and October 2001. Shortly after discovery of each dead infant, a specially trained doctor of legal medicine visited the bereaved family at home. Data were obtained by measurements and observations. Dead infants underwent a standardised autopsy, additional information being obtained by standardised parent interviews. Investigation of the sleep environment and wake-up scene in matched controls followed the same protocol. A total of 52 SIDS cases and 154 controls were enrolled, 58% were boys, and median age of cases vs. controls was 126 vs. 129 days. Risk factors in the sleeping environment were pillow use (adjusted OR 4.3; 95%CI 1.6-11.6), heavy duvets (OR 4.4; 1.5-13.3), soft underlay (OR 3.0; 1.1-8.7), face covered by bedding (OR 15.8; 2.5-102.1) and entire body covered by bedding (OR 35.5; 5.5-228.3). Using a standardised protocol, including objective measurements of the sleep environment and a case-control design, this study was able to confirm many risk factors for SIDS.

Head covering and the risk for SIDS: findings from the New Zealand and German SIDS case-control studies

OBJECTIVES

The aim of this investigation was to identify risk factors for being found with the head covered in sudden infant death syndrome cases and determine whether head covering was likely to be an agonal event or potentially part of the causal pathway in some cases. By using the data from 2 sudden infant death syndrome case-control studies, consistency of the findings could be assessed.

METHODS

Two case-control studies were assessed: (1) the New Zealand Cot Death Study (1987-1990, 393 sudden infant death syndrome cases) and (2) a German SIDS case-control study (1998-2001, 333 sudden infant death syndrome cases).

RESULTS

The proportion of sudden infant death syndrome cases in which infants were found with their head covered was 15.6% in the New Zealand study and 28.1% in the German study. Being found with head covering was associated with older infant age. In both studies, being found with head covering was associated with being very sweaty when found. Head covering was also associated with the incidence and severity of thymic petechiae in both studies. Both the position in which the child was placed to sleep and the position in which the child was found were not associated with head covering.

CONCLUSIONS

The finding that sudden infant death syndrome cases in which infants were found with their heads covered were often very sweaty suggests that head covering was not an agonal event and that it preceded the death and may have been causally related to the death. Infants who were found with their head covered were older, which probably reflects motor development.

Is the mattress important in helping babies keep warm?--Paradoxical effects of a sleeping surface with negligible thermal resistance

BACKGROUND

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.

AIM

To investigate the thermal balance and metabolic rate of infants sleeping on a conventional mattress or a Purflo mattress in infant sleeping bags.

METHODS

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).

RESULTS

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).

CONCLUSION

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.

Sleep arrangements and behavior of bed-sharing families in the home setting

OBJECTIVES

We aimed to provide a quantitative analysis of the sleep arrangements and behaviors of bed-sharing families to further understand the risks and benefits as well as the effects of infant age and room temperature on bed-sharing behaviors.

METHODS

Forty infants who regularly bed shared with > or = 1 parent > or = 5 hours per night were recruited. Overnight video of the family and physiological monitoring of the infant was conducted in infants' homes. Infant sleep position, potential for exposure to expired air, head covering and uncovering, breastfeeding, movements, family sleep arrangements, responses to the infant, and interactions were logged.

RESULTS

All infants slept with their mother. Fathers were included in 18 studies and siblings in 4. Infants usually slept beside the mother, separated from the father/siblings (if present), facing the mother, with head at mothers' breast level, touching, or with mother cradling. Median overnight breastfeeding duration was 40.5 minutes. Mothers commonly faced their infant, but infants were rarely in a position that potentially exposed them to maternal expired air. Fathers were seldom in contact with the infant during sleep. Of the 102 head-covering episodes observed in 22 infants, 80% were because of changes in adult sleep position. Sixty-eight percent of head uncovering was facilitated by the mother; half of these events were prompted by the infant. A 1 degree C increase in room temperature decreased infant head covering by 0.2 hours.

CONCLUSIONS

The mother-infant relationship is of prime importance during bed sharing, whether the father is present or not. The focus around breastfeeding often dictates the sleep position of the infant and mother, though room temperature may also influence this. In colder rooms infants tend to spend more time with their face covered by bedding. Frequent maternal interactions rely on the ability of the mother to arouse with little stimulation. Mothers, perhaps impaired by alcohol, smoking, or overtiredness, may not be able to respond appropriately.

Decreased arousals in infants who sleep with the face covered by bedclothes

OBJECTIVE

The risk of becoming a victim of sudden infant death syndrome is increased in infants who sleep with their face under bedding items. The present study was designed to evaluate auditory arousal thresholds of infants who sleep with their face covered by bedclothes.

METHODS

Twenty healthy infants with a median age of 11.5 weeks (range: 4-22 weeks) were recorded polygraphically for 1 night. Although they slept in their usual supine position, a bed sheet was placed over their face for 60 minutes. Fifteen of the 20 infants were chosen at random and were exposed to white noises of increasing intensities to determine their auditory arousal thresholds. All infants were challenged with the face covered and with the face free during both rapid eye movement (REM) and non-REM (NREM) sleep. Seven infants were first challenged with the face covered, and 8 were challenged with the face free. The following variables were recorded simultaneously: electroencephalogram, breathing and heart rates, and rectal and pericephalic temperatures. In 5 infants who were not exposed to the auditory challenges, end tidal CO2 was recorded for 30 minutes while sleeping with the face covered.

RESULTS

During REM sleep, arousals occurred for significantly more intense auditory stimuli when the infant's face was covered than when free. No significant difference was seen in NREM sleep. Compared with the face-free periods, the face-covered sleep periods were characterized by greater rectal and pericephalic temperatures, a greater density of body movements, and a decrease in NREM sleep. Respiratory frequency was increased during the face-covered periods in both REM and NREM sleep. No differences were seen in the frequency or duration of apnea. There was a tendency for heart rate to increase during both sleep stages when the face was covered, compared with the face-free periods, but the changes were not statistically significant. A positive correlation was found between pericephalic temperatures and arousal thresholds (r = 0.60) during REM sleep. End tidal CO2 values increased when the face was covered, reaching a maximum value during the first 5 minutes of the experiment. No fall in oxygen saturation was seen.

CONCLUSIONS

Covering the infant's face with a bed sheet was associated with a significant increase in auditory arousal threshold. The finding could be related to an elevation in temperatures within the infant's microenvironment.

A review of the anatomy of the upper airway in early infancy and its possible relevance to SIDS

BACKGROUND

Since the danger of prone sleeping in the first 6 months of life has been publicised, there has been a dramatic and consistent reduction in the incidence of sudden infant death syndrome (SIDS). However, unexpected infant deaths and apparent life-threatening events (ALTEs) continue to occur that are clearly not associated with known epidemiological risk factors.

AIMS

To review the unique features of the anatomy and function of the upper airway of the young infant which contribute to increased vulnerability to hypoxia in this age group. We discuss the clinical identification of those infants at risk of obstruction or restriction of the upper airway and the management of the 'at risk' infant.

CONCLUSIONS

In the era after the "back to sleep" campaigns, it is likely that an increasing proportion of cases of ALTEs and SIDS will be related to obstruction or limitation of upper airway size leading to sleep hypoxia/asphyxia. This type of problem may be anticipated by evaluation and investigation of infants with signs or a clinical history consistent with possible upper respiratory tract compromise, including micrognathia.

Computational simulation of accumulation of expired air in the infant cot

Accumulation and re-breathing of CO2 in expired air has been suggested as one possible explanation for the strong association between prone sleeping position and sudden infant death syndrome (SIDS). This preliminary study applying a modern computational fluid dynamics (CFD) program to simulate the aerodynamics in an infant cot supports the idea that accumulation of expired air may occur in the prone position. The literature dealing with the potential association between re-breathing of accumulated CO2 and SIDS is briefly reviewed.

CLINICAL REVIEW ARTICLE: Is changing the sleep environment enough? Current recommendations for SIDS

Sudden infant death syndrome (SIDS or cot death) was the major cause of post-neonatal infant death in many countries in the late 1970s and 1980s. There is now very strong evidence that public intervention campaigns targeting the prone sleeping position, which had been identified by epidemiological studies as a major risk factor, were followed by substantial falls in the rate of SIDS. In the present review we discuss the evidence on which current recommendations for the prevention of SIDS are based. The prone sleeping position is now clearly causally associated with SIDS. Further reductions in SIDS may be produced by recommending the back sleeping position as opposed to the side position. Maternal smoking in pregnancy and bed sharing by infants of mothers who smoke are also strongly associated with SIDS, but have been harder to influence. Paternal smoking has also been implicated, although the magnitude of the reported risk is small. Finally, breastfeeding, pacifier use and having the infant sharing the parents bedroom, but not the bed, may also reduce risk. Continued reductions in SIDS mortality will require innovative public health education to target these major risk factors, while building on the "back to sleep" approach.