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Airway article Airway article Document Transcript

  • Child: care, health and developmentOriginal Article doi:10.1111/j.1365-2214.2009.00979.xAirway covering during bed-sharingH. BallParent–Infant Sleep Lab and Medical Anthropology Research Group, Department of Anthropology, Durham University, Durham, UKAccepted for publication 9 March 2009 Abstract 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 (bothKeywordsinfant sleep, suffocation, mouth and nose) covered, compared with 2/20 on the cot night; however, no consistent effect onSIDS, cosleeping 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,Correspondence:Helen Ball, Parent–Infant the remainder by infants. Seven bouts of potential compression were observed with parental limbsSleep Lab and Medical resting across infant bodies for lengthy periods, however, in only two cases was the full weight of aAnthropology Research parental limb resting on an infant, both events lasting less than 15 s, both being terminated byGroup, Department ofAnthropology, Durham infant movement.University, Dawson Conclusion Although numerous authors have suggested that bed-sharing infants face risksBuilding, South Road,Durham, DH1 3LE, UK because of airway covering by bed-clothes or parental bodies, the present trial does not lendE-mail: h.l.ball@dur.ac.uk support to this hypothesis. time (Tuohy et al. 1998; Rigda et al. 2000; Willinger et al. 2003;Introduction Blair & Ball 2004; van Sleuwen et al. 2005; Bolling et al. 2007). ItParent–infant bed-sharing is a common night-time infant care has been emphasized by a variety of researchers that infants maypractice in Western post-industrial nations; regional and be at risk of sudden and unexpected death in the bed-sharingnationwide surveys conducted in the UK, USA, Australia, New environment because of accidental suffocation and rebreathingZealand and the Netherlands have consistently found that (e.g. Byard et al. 1994; Beal & Byard 1995; Blair et al. 1999; Bealaround 50% of infants under 3 months of age have bed-shared & Byard 2000; Corbyn 2000; Flick et al. 2001; Galland et al.with one or both of their parents for at least some of their sleep 2002). Several published reports using data from cohorts of © 2009 The Author728 Journal compilation © 2009 Blackwell Publishing Ltd
  • Airway covering during bed-sharing 729sudden infant deaths drawn from the records of the US Con- hypothesis was reviewed by Guntheroth and Spiers (1996) whosumer Product Safety Commission also emphasize hazards such concluded that although it may be possible for certain sus-as suffocation from overlaying or head covering when bed- ceptible infants to suffer rebreathing suffocation by virtue ofsharing (Scheers et al. 1998; Drago & Dannenberg 1999; Naka- abnormalities in ventilatory control, rebreathing was unlikely tomura et al. 1999; Kemp et al. 2000). It is often recommended occur for the majority of infants who slept in the prone posi-that parents who wish to sleep with their infants should take tion. Research into the mechanism(s) via which prone sleepcare to avoid duvets/comforters (Blair et al. 1999) soft bedding might increase the sudden infant death syndrome (SIDS) riskand loose covers (AAP 2000; Willinger et al. 2003). Because the ceased to explore suffocation and rebreathing hypotheses in thecovering of external airways by bedding or bed-partner would late 90s as attention turned to other potential explanations forappear to happen relatively easily in a bed-sharing situation, the link between SIDS and prone sleep (e.g. infection and over-airway occlusion has become a cause for concern regarding heating). Although the causal mechanism(s) for its successbed-sharing-related sudden infant deaths (Beal & Byard 2000; remains unknown, the supine infant sleep strategy imple-Byard & Krous 2001; Flick et al. 2001; Galland et al. 2002). In mented via national campaigns in many industrialized coun-order to further explore this issue, this paper summarizes the tries was hugely successful in reducing the rate of unexpectedfindings of previous research conducted into the effects of infant deaths (Blair et al. 2006) with the rate of SIDS in the UKairway covering (e.g. suffocation, and the related issue of falling from 2/1000 in 1985 to 0.3/1000 in 2003 (Office forrebreathing) among solitary sleeping infants and presents new National Statistics 2004).data from a sleep-lab study regarding the propensity for, and The impact of airway covering on the breathing of supinecircumstances of, airway covering in the parent–infant bed- sleeping infants has been subjected to much less scrutiny thansharing environment compared with cot sleeping. for prone infant sleep; however, it is clear that the two situations In the early 1990s, epidemiological studies examining the are very different. Physiological trials indicate that the risks ofconditions associated with sudden unexpected death in infancy airway obstruction in the supine position are much lower thanrevealed the majority of cases to have been discovered in the those when infants sleep prone (Kemp 1996, citing Gallandprone position, often with their heads covered (Mitchell et al. et al. 1994). Even under a 13-tog infant duvet the weight of the1992; Fleming et al. 1996; Scheers et al. 1998; Skadberg et al. bed-covers themselves are insufficient to completely occlude1998; Beal et al. 2000; Hauck 2001). Popular mechanisms pro- an infant’s nose and mouth (Skadberg & Markestad 1997).posed to explain these associations involved mechanical suffo- Rebreathing of exhaled CO2 was also found to be an unlikelycation resulting from the infant’s face being pressed against soft risk for supine sleeping infants whose faces were covered withbedding (Abramson 1944; Carpenter & Shaddick 1965; Beal bedding because of the effect of body movements on CO2 accu-2001; Galland et al. 2002) and hypercapnia resulting from mulation. Experiments showed that when an infant aroused orrebreathing exhaled CO2 pooled around the infant’s face (Kemp moved in their sleep, the duvet lifted from the mattress and aet al. 1993, 1998). These speculations prompted various physi- sudden drop in CO2 was observed. ‘Visible temporary or per-ological ‘reconstruction’ studies (using mechanical and animal manent air channels were commonly created after such move-models) which investigated the combination of prone infant ment and resulted in low and stable CO2 levels throughout thesleep position and sleep surface on both airway obstruction and rest of the study’ (Skadberg & Markestad 1997, p. 3).CO2 rebreathing (e.g. Kemp et al. 1991, 1993, 1998; Bolton et al. In the bed-sharing environment a number of additional vari-1993; Kemp & Thach 1995; Kemp 1996; Campbell et al. 1997). ables must be considered. Parental movements may cause repo-These studies identified numerous hazardous sleep surfaces for sitioning of both infants and bed-clothes in ways that are notsimulated prone-facing infants but attracted criticism because encountered by infants sleeping alone (Baddock et al. 2007),of the use of artificial mannequins which had rigid nares, and while parental bodies are themselves considered to be hazardousthe use of anaesthetized animal models that were unable to to infants by some researchers/commentators (Byard 1994). Itperform normal arousal behaviours (Johnson 1994; has been argued by some authorities (e.g. Thogmartin et al.Guntheroth & Spiers 1996). Researchers who examined the 2001) that adult beds, unlike cots and cribs, are not ‘designed’effects of the face-down prone position on the breathing of for infant sleep, and therefore carry at least a theoretical risk ofliving infants (e.g. Chiodini & Thach 1993) concluded that accidental entrapment and suffocation. An anthropological per-airway occlusion was rare in the face-down position and ‘overt spective points out that infants were not ‘designed’ to sleepobstruction of the airway may be less likely than has been specu- alone in cribs or cots, and that sleep contact with a caregiver haslated’ (pp. 690–691). Evidence in support of the rebreathing important physiological and behavioural ramifications for © 2009 The Author Journal compilation © 2009 Blackwell Publishing Ltd, Child: care, health and development, 35, 5, 728–737
  • 730 H. Ballinfant development (e.g. McKenna et al. 1993; Ball & Klinga- 2 Examine the circumstances leading up to potential airwayman 2007), but it is true that Western-style beds and bedding obstruction.would not have formed part of the environment in which 3 Examine parental awareness of and responses to infant airwayhuman infants evolved – therefore the Western bed-sharing covering.environment requires evaluation and modification in terms ofrisks posed to infants (e.g. Beal & Byard 1995). Methods In the UK bed-sharing is a common practice of both SouthAsian ethnic groups (Gantley et al. 1993; Farooqi 1994) and As infants are known to develop at different rates, and there arebreastfeeding mothers (Ball 2002, 2003; Ball & Klingaman 2007; individual differences in physiological parameters (e.g. WailooBolling et al. 2007). Among both groups infants are normally et al. 1989), subjects in this study served as their own controlsplaced in a supine position (Ball 2003); however, placing the across the two sleep environments monitored. Within-infantinfant in a prone position while bed-sharing appears to be more developmental changes were minimized as infants were moni-frequent in the USA (Thogmartin et al. 2001), among African tored over a short and limited time period (three consecutiveAmericans (Flick et al. 2001) but not among Hispanic or White nights). Ethical approval was obtained from both the UniversityUS breastfeeding mothers (McCoy et al. 2004). Surveys of of Durham Ethics Committee, and the Local NHS Researchinfant sleep environments also suggest that the use of duvets/ Ethics Committee (North Tees and Hartlepool NHS Trust)quilts when bed-sharing is common practice (Willinger et al. prior to the commencement of the study. In order to ensure2003). infant safety, an intervention policy was agreed with staff at the Studies involving video observations of adult–infant bed- Paediatric Department at North Tees Hospital, providing crite-sharing behaviour have found that the way in which parents ria for intervention by research staff in any situation where anbed-share may affect their infant’s chances of having their infant appeared to be at risk on a monitoring night. All researchairways covered by bedding. Ball (2006) reported that breast- staff involved in overnight monitoring were trained and certi-feeding bed-sharing infants in the UK are not placed on or fied in infant resuscitation, and parents remained with theirbetween pillows, nor placed prone, but are covered by duvets, infants at all times.and are in close proximity to adult bodies. In contrast, formula- Participants were recruited from the town of Stockton-on-fed bed-sharing infants are commonly placed on or between Tees and the surrounding region via health visitors, baby clinicsparental pillows, but because they are positioned at their moth- and local publicity using purposive sampling. Parents whoer’s face height they are unlikely to have their faces covered by volunteered were contacted by telephone and the study wasduvets or quilts (Ball 2006). In a study of night-time behaviour explained verbally. Eligibility criteria for recruitment were:among 40 regularly bed-sharing parents and infants in com- breastfed term infant under 3 months, non-smoking mother,parison with 40 age- and season-matched cot-sleeping infants both parents willing to participate, baby bed-shared regularly oraged 0–6 months, Baddock and colleagues (2007) found that occasionally and otherwise slept in a cot by the bed. Eligible80% of infant head-covering episodes resulted from adult posi- volunteers received written information on the study by post,tional changes during sleep, and that 68% of uncovering of together with a participant consent form. Parents who wereinfant faces occurred by intentional and unintentional parental willing to participate in the study returned the completedclearing of the covers, with infants clearing their own faces in consent form and subsequently received and completed a series32% of cases. In order to further illuminate the behavioural of three infant sleep logs. Arrangements were made for parentsfeatures of bed-sharing which may either contribute to, or ame- to bring their infant to the Durham University sleep lab on theliorate, airway covering during bed-sharing, we describe below Queen’s Campus, Stockton-on-Tees for three consecutivethe results of a two-condition sleep-lab trial comparing etho- nights. The first night served as a habituation night: monitoringlogical and physiological data obtained for infants sleeping in an took place while participants followed their normal sleepadult bed with their parents versus in a cot by their parents’ bed. practices; however, the data from these initial nights were notThis study specifically aimed to: included in the analyses. On the following two test nights, allo- cated in random order (via a coin toss conducted in the parents’1 Compare the two infant sleeping conditions for: presence), parents and infants were monitored sleeping in the a. covering of external airways; bed-sharing and the cot-by-the-bed conditions. Following each b. levels of oxygen saturation and infant heart rate; night of monitoring, parents were offered the opportunity to c. compression/overlying of infant. view the videotape of the previous night prior to providing their© 2009 The AuthorJournal compilation © 2009 Blackwell Publishing Ltd, Child: care, health and development, 35, 5, 728–737
  • Airway covering during bed-sharing 731final consent for the tapes to be analysed. A member of the 1996; Morielli et al. 1996). Proximity and orientation of parentsresearch team interviewed parents during their stay in the lab to and infant to one another, body positions of all three subjects,obtain background demographic data and further information position of the infant’s face relative to each parent, height ofregarding night-time infant care practices and normal sleeping covers relative to all three individuals, and position of pillowsarrangements. (and other soft bedding) relative to infant’s head and face were The sleep lab is arranged in the manner of a normal domestic coded using 3-min interval scans. Frequency data were recordedbedroom with en-suite bathroom facilities and a kitchenette. for all interactions between parents and infant (e.g. visuallyBoth blankets and quilts (polyester and down filled) were pro- checking, patting, re-blanketing, repositioning), for gross limbvided for bedding and parents were asked to use the bedding movements and changes in position, for feeding bouts andmost similar to that used at home. Parents were able to bathe other waking activity. Duration data were recorded for feedingtheir baby, watch TV, make refreshments and generally follow a events and episodes of waking. All bouts of infant airway cov-‘normal’ preparatory routine for sleep. Before the infant was ering were identified visually and coded from video. Data fromdressed for sleep, monitoring sensors were applied. Data utilized the pulse oximeter channel was exported via the Win-visi®in this report were obtained using two paediatric respiratory monitoring system and converted to Excel® spreadsheet files forplethysmography bands placed around the infant’s chest and analysis. Oxygen saturation and heart rate was recorded onceabdomen, and a wrap-around pulse oximeter (recording both per second and averaged (median) across 1-min epochs for theoxygen saturation and heart rate) attached to the infant’s big whole 8-h monitoring period on both cot and bed nights. Alltoe. Infants wore thin stretch-suits to help keep the instruments movement artefact and periods where the oximeter was dis-in place. The sensor leads were taped to the infant’s skin and lodged were removed from the physiological record.gathered into a single ‘umbilical cord’ which conveyed signalsfirstly to a header box, positioned above the head of the bed or Resultscrib, and then to the computer monitoring equipment (WinVisiSleep System – Stowood Scientific Instruments) in the adjacent Twenty families participated in this study; socio-demographiccontrol room. Leads could easily be detached from the header characteristics are given in Table 1. All but one infant was low-box to facilitate movement around the room. risk for SIDS according to established criteria (Conroy & Smith Video recordings were made from a ceiling-mounted low- 1999); the exception was the sibling of a SIDS infant who lackedlight intensity camera positioned to capture an image of the bed any other SIDS risk characteristics.or bed and cot. Ceiling-mounted infra-red lights allowed videorecordings to be made in the dark. The video signal was Covering of airways by bedding for bed and cot infanttransmitted to the adjacent monitoring room where it was sleep locationscontinuously recorded to an 8-h videotape. The camera couldbe panned and zoomed remotely from the monitoring room. The majority of infants (14/20) spent some part of the bed nightPhysiology traces were superimposed on the video signal, thus a with their airways (both mouth and nose) covered, comparedcontinuous recording of respiration, heart rate and O2 satura- with 2/20 on the cot night; infants also spent a significantlytion was synchronized with the video image. Video and physi-ological recordings commenced when the parents prepared for Table 1. Socio-demographic characteristics of study sample (n = 20)sleep and a researcher remained in the monitoring room for the Mean maternal age 30 yearsduration of the night. Recording was terminated when parents Mean paternal age 32 yearsand infant arose the following morning, or after 8 h, whichever Mean infant age on 1st monitoring night 9 weeks 3 daysoccurred sooner. Videotapes were coded by three trained Mean gestational age at birth 40 weeks 1 day Mean birth weight 3.6 kgobservers using a behavioural taxonomy for parent–infant bed- Mean maternal parity 2.3sharing developed and used in previous studies (Hooker 2001; Mean household income £24 939Ball 2006). Observers were trained for inter-observer reliability Proportion homeowners 66.6%via repeated coding of video excerpts by all observers until Proportion of fathers employed 80.5% Proportion of mothers employed 66.6%kappa scores in excess of 90% were achieved. Proportion of fathers with HE quals 57.1% Sleep states were coded minute by minute for all three sub- Proportion of mothers with HE quals 47.6%jects using respiratory movements and observational data Proportion of parents married 76.1% Proportion of infants with father who smoked 23.9%(Anders & Keener 1985; Keefe et al. 1989; Kirjavainen et al. © 2009 The Author Journal compilation © 2009 Blackwell Publishing Ltd, Child: care, health and development, 35, 5, 728–737
  • 732 H. BallTable 2. Description of bouts of airway covering on bed nightInfant Test night Duration (min) How was airway covering terminated?002 bed 85 mother’s sleep-related movement aroused baby, infant altered orientation, bringing about uncovering of airways004 bed 57 mother aroused and removed duvet from over infant’s face012 bed 30 mother’s sleep-related movement uncovered baby013 bed 309 mother, awake and talking to infant’s sibling, moved duvet from infant’s face014 bed 184 mother’s sleep-related movement uncovered baby015 bed 351 baby aroused, waved arms and independently moved covers away from face018 bed 240 infant movement caused mother to move, shifting covers019 bed 104 baby moved and grunted under covers, mother woke and moved baby021 bed 312 father aroused and removed covers from infant’s face022 bed 72 father, on waking, removed covers from infant’s facegreater proportion of the bed night (median = 21%; range 99 970–89%) with their airways covered by bedding, compared with 95the cot night (median = 0%; range 0–100%; Wilcoxon sign 93 %ranks test: P = 0.006); however, the ranges testify great variabil- 91ity. Eight of the 20 infants experienced airway covering for 30% 89or more of the bed-sharing night; all instances commenced with 87covers being pulled over the infant’s face by a parent, or a parent 85positioning the infant under the covers. On the cot night one 2 4 12 13 14 15 18 19 21 22infant spent 20% and another 100% of the night with airways Covered Uncovered Infantcovered by bedding; both commenced when parents tucked the 160bed-clothes across the infant’s face. 140 120 100 Heart rateParental response to external airway covering 80Ten bouts of airway covering were actively terminated during 60the observation period and were individually examined to 40determine how airway covering was terminated (Table 2). 20 Seven of the 10 bouts were terminated by parents altering the 0 2 4 12 13 14 15 18 19 21 22position of the covers and consciously or unconsciously uncov- Infant Covered Uncoveredering their infant’s airways. In three cases infants initiatedremoval of the covers, two by arousing a parent and one by Figure 1. Overall median SatO2 (top) and heart rate (bottom) foraccomplishing movement of the covers unassisted. matched bouts with airways covered and uncovered on bed nights. heart rate values were calculated. Wilcoxon signed ranks testsEffects of airway covering on oxygen saturation and heart were used to compare the median oxygen saturation and heartrate rate values during covered and control bouts for all infants withIn order to examine the effects of prolonged periods of airway paired data (see Fig. 1). In no cases were any significant differ-covering on oxygen saturation and heart rate, 30-min bouts of ences found between covered and uncovered periods for eitherairway covering were paired with control bouts from the same oxygen saturation or heart rate using Wilcoxon signed ranksnight when airways were uncovered, matched for sleep state. tests.Where airways were covered by bedding for periods longer than Further analysis was conducted comparing oxygen satura-30 min, the terminal portion of the period was chosen as the tion (SatO2) and heart rate for periods of airway covering ontest bout (i.e. when the infants’ airways had been covered for bed nights (covered bed bout) with control periods (matchedthe longest period). For each covered and control bout the for duration since sleep onset) from each infant’s cot nightminute-by-minute and overall median oxygen saturation and (control cot bout). Figure 2 shows median SatO2 and heart© 2009 The AuthorJournal compilation © 2009 Blackwell Publishing Ltd, Child: care, health and development, 35, 5, 728–737
  • Airway covering during bed-sharing 733 99 chest or face and potentially restricting breathing) lasting 97 1–9 min, occurred on bed nights. In one case a father’s arm rested across his infant’s chest; all other cases involved mothers. 95 Each incident was independently examined by two observers to 93% determine whether the weight of a parental limb rested on the 91 infant and thus could be considered actual compression. 89 Descriptions of each case are provided in Table 3. 87 Although episodes were recorded for seven infants where 85 2 4 12 13 14 15 18 19 21 22 parental limbs rested across an infant’s chest or face on the bed Covered (bed) Uncovered (cot) night, in only two of these bouts did the full weight of the parents’ limb (arm) appear to rest upon the infant. In both cases a 160 parental arm rested across the infant’s face for a brief period (less 140 than 15 s) and both bouts were terminated by infant movement 120 that triggered the parent removing their arm. Oxygen saturationHeart rate 100 data were compared for all periods of potential compression with 80 an immediately preceding period of the same duration; no sig- 60 nificant differences in percentage of SatO2 were detected. 40 20 0 Discussion 2 4 12 13 14 15 18 19 21 22 Infant Concern has been expressed that airway covering or obstruction Covered (bed) Uncovered (cot) may present a suffocation, overlying or rebreathing risk for theFigure 2. Median SatO2 (top) and heart rate (bottom) for matched bouts bed-sharing infant. The results of the present study do notwith airways covered on bed night and uncovered on cot night. support concerns regarding suffocation and overlying. The situ- ation regarding rebreathing was not examined directly in this study; however, it is discussed below in terms of indirect evi-rate for each of the infants for whom covered bed bouts dence and the reports of other researchers.and control cot bouts were available. Wilcoxon signed ranks The present study replicates the findings reported bytests found no significant differences between either SatO2 or Baddock and colleagues (2007) that babies experienced moreheart rate for covered bed bouts and their matched control airway covering by bedding when bed-sharing than when sleep-bouts. ing in a cot, but that this airway covering did not compromise infants’ ability to maintain normal levels of circulating oxygen, even when airway covering by bedding was prolonged. In theCompression/overlaying of infant in bed-sharing vs. case of compromised oxygen supplies, it would be expected thatby-the-bed infant sleep locations infant heart rate would increase in order to more efficientlyCompression was defined as a parent’s limb(s) lying across a circulate available oxygen around the tissues. In the presentpart of an infant’s body that might restrict the infant’s ability to study, airway covering was not associated with significantlybreathe. Overlaying was defined as an adults’ torso lying against lower oxygen saturation, nor with significantly increased infantor across an infant in such a way as to restrict the infant’s ability heart rate, and although bed-sharing infants were frequentlyto breathe. No instances of overlaying were observed. One observed to have their airways covered, they also frequently gotinfant on the cot night, and seven on the bed night experienced uncovered, sometimes as a consequence of the infant’s owna parental limb lying across their bodies. Two lengthy periods of actions, but more commonly as a consequence of parental con-potential compression were identified – one on a bed night scious or unconscious intervention.where the mother’s arm was observed to rest across the infant’s Mechanical obstruction of breathing via overlaying or com-body for 108 min – and another on a cot night (with the cot by pression of an infant’s body by a parental limb has also beenthe bed) where a mother’s hand was observed to rest across the postulated as a risk of the bed-sharing environment that may beinfant’s face for 21 min. In addition, five shorter potential com- responsible for infant deaths (whether designated SIDS or acci-pression bouts (with a parent’s limb resting across an infant’s dental suffocation). This study found no evidence that sharing a © 2009 The Author Journal compilation © 2009 Blackwell Publishing Ltd, Child: care, health and development, 35, 5, 728–737
  • 734 H. BallTable 3. Termination of bouts of potential compression that may restrict infant’s breathingInfant Test night Duration (min) Description Termination001 bed 5 father’s forearm on infant’s chest terminates when father moves002 bed 4 mother’s forearm on infant’s abdomen terminates with infant movement005 cot 21 mother’s arm across infant’s chest weight of mother’s arm not supported by infant010 bed <1 father’s arm on infant’s face for few seconds baby initiates removal011 bed 108 mother’s forearm rests across infant’s chest weight of mother’s arm not supported by infant012 bed 9 mother’s arm resting on infant’s chest weight of mother’s arm not on baby020 bed <1 mother’s hand resting on baby’s cheek for few seconds baby initiates removal022 bed <1 baby turns face into mother’s arm mother moves to terminatebed with non-smoking parents who were not under the influ- Mosko and colleagues (1997) assessed the accumulation ofence of alcohol or drugs was a suffocation or compression CO2 around an infant’s face that might be contributed by thehazard to a sleeping infant. trapping of its mother’s exhaled air under a blanket in a recon- The possibly fatal consequences of rebreathing are often structed bed-sharing scenario using an adult female and aninvoked when infant airway covering is discussed. In their review infant-sized doll. After applying the blanket to form an air pocketregarding airway covering of solitary sleeping infants in the around the doll’s head, both CO2 baseline and peak concentra-supine position, Thach and Lijowska (1996) concluded that ‘the tions measured at varying distances from the mother’s facehuman infant frequently encounters situations in which ventila- increased. The highest peak levels attained were between 1.5%tion is compromised by airway obstruction of the nose or mouth. and 2% CO2, occurring at a distance of 9 cm. These levels wereA . . . common example is when loose bedding covers the within the range that is known to increase infants’ ventilatoryinfant’s face creating a situation in which expired air is response (Schafer et al. 1993), but not high enough to attainrebreathed. Such events usually have minimal adverse conse- lethal levels. It seems unlikely, therefore, that covering of thequences’. In the present study we were unable to measure either airways of a bed-sharing infant with adult bedding could lead toend-tidal CO2, or the transcutaneous CO2 of infants, because of lethal levels of CO2 rebreathing in normal infants who show antechnological constraints, which means that our conclusions appropriate response by increasing ventilation or moving in suchremain limited. However, other studies indicate that the frequent a way that releases trapped CO2. In the bed-sharing environmentmovement of bed-partners and bedclothes on bed nights where bed-partners also cause movement of the bedding, itappears to prevent a build-up of expired CO2 and therefore would appear even less likely that an infant would experienceameliorates the effects of rebreathing; furthermore, in the pres- sufficient CO2 accumulation that would normally cause death. Itence of adult bodies air channels are present in the bedding may be the case, however, that rebreathing contributes to SIDSaround the infant. Skadberg and Markestad (1997) observed that infant deaths in situations where normal rebreathing responsesfor solitary sleeping infants, body movements or arousals during are impaired (Bolton et al. 1993; Chiodini & Thach 1993); it issleep caused regular lifting of duvets from mattresses that were now suspected that such babies have an intrinsic medullary 5-HTassociated with sudden drops in accumulated CO2; with bed- abnormality that inhibits a normal ventilatory response to thepartners the effect is likely to be even greater. An examination of rebreathing of CO2 (Paterson et al. 2006) and such babies may bethe physiological effects of bed-sharing on infants in the home vulnerable to the periodic airway covering that is experiencedenvironment conducted in New Zealand (Baddock et al. 2006) during bed-sharing.confirmed that bed-sharing infants were more commonlyexposed to rebreathing situations than cot-sleeping infants, andthat infants often remained in these positions for extended Conclusionperiods of time. Infants were able to maintain SatO2, in partbecause of an increased rate of breathing, and did not suffer any Numerous authors have suggested that bed-sharing infants faceadverse consequences. Because of our inability to extract respi- an increased suffocation or SIDS risk because of airway cover-ratory movement data from our overnight recordings, we are ing by bed-clothes or parental bodies. The present review andunable to confirm this finding in the current study; however, in the limited data available from this sleep-lab trial do not lendthe present study heart rate was not found to be significantly support to the hypothesis that normal bed-sharing infants are atgreater during airway covering than during control bouts. risk as a result of airway covering, overlying or compression.© 2009 The AuthorJournal compilation © 2009 Blackwell Publishing Ltd, Child: care, health and development, 35, 5, 728–737
  • Airway covering during bed-sharing 735 Ball, H. L. & Klingaman, K. P. (2007) Breastfeeding and Key messages mother–infant sleep proximity: implications for infant care. In: Evolutionary Medicine and Health: New Perspectives (eds • Infants regularly experience airway covering and uncover- W. Trevathan., E. O. Smith & J. J. McKenna), pp. 226–241. ing during bed-sharing. Oxford University Press, New York, NY, USA. Beal, S. M. (2001) The rise and fall of several theories. In: Sudden • Airway covering during bed-sharing did not result in Infant Death Syndrome: Problems, Progress and Possibilities (eds R. increased infant oxygen saturation or heart rate. W. Byard & H. F. Krous), pp. 236–242. Oxford University Press, • The results of this trial did not reinforce the view that New York, NY, USA. airway covering or obstruction is a risk for normal infants Beal, S. M. & Byard, R. W. (1995) Accidental death or sudden infant bed-sharing with parents whose sleep awareness is not death syndrome? Journal of Pediatric Child Health, 31, 269– impaired. 271. Beal, S. & Byard, R. (2000) Sudden infant death syndrome in South Australia 1968–1997. Part 3: is bed sharing safe for infants? Journal of Paediatrics and Child Health, 36, 552–554. Beal, S., Baghurst, P. & Antoniou, G. (2000) Sudden infant deathAcknowledgements syndrome (SIDS) in South Australia 1968–1997. Part 2: the epidemiology of non-prone and non-covered SIDS infants. JournalSpecial thanks are due to all parents and their babies who of Paediatrics and Child Health, 36, 548–551.volunteered to participate in this study and to Dr Ian Verber, Blair, P. S. & Ball, H. L. (2004) The prevalence and characteristicsConsultant Paediatrician at North Tees Hospital who assisted associated with parent–infant bed-sharing in England. Archives ofin drafting intervention guidelines for this study. 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