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Current Pediatric Reviews
ISSN: 1573-3963
Current Pediatric Reviews
Volume 6, Number 1, February 2010
Contents
Sudden Unexpected Death in Infancy – Amazing
Progress but Still Unanswered Questions
Guest Editor: Edwin A. Mitchell
Editorial
Pp. 1-4
Sudden Unexpected Death in Infancy and the Dilemma of Defining
the Sudden Infant Death Syndrome Pp. 5-12
Henry F. Krous
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Article]
Do
we Need a New Definition for SIDS?
Commentary on ‘Sudden Unexpected Death in Infancy and
the Dilemma of Defining the Sudden Infant Death Syndrome’
by Henry Krous Pp. 13-14
Peter Sidebotham
English Multi-Agency Approach to the Investigation of Sudden
Unexpected Deaths in Infancy and the Care of Bereaved Families
Pp. 15-18
Peter J. Fleming
[Abstract] [Purchase
Article]
Commentary on the Multi-Agency Approach
to the Investigation of SUDI Pp. 19-20
Torleiv Ole Rognum
[Abstract] [Purchase
Article]
Sudden Unexpected Death in Infancy (SUDI) – The Role
of the Pathologist Pp. 21-26
Roger W. Byard
[Abstract] [Purchase
Article]
The Death-Scene Investigation
Pp. 27-29
Martin Schlaud
[Abstract] [Purchase
Article]
Sudden Infant Death Syndrome: Implications
of Altered Physiological Control During Sleep
Pp. 30-38
Rosemary S.C. Horne, Nicole B. Witcombe, Stephanie R. Yiallourou
and Heidi L. Richardson
[Abstract] [Purchase
Article]
Potential Mechanisms of Failure in the Sudden Infant
Death Syndrome Pp. 39-47
Ronald M. Harper and Hannah C. Kinney
[Abstract] [Purchase
Article]
Sudden Unexplained Death in Infancy and Long QT Syndrome
Pp. 48-55
Jonathan Robert Skinner
[Abstract] [Purchase
Article]
Gene and Gene-Environment Risk Factors in Sudden Undexpected
Death in Infants Pp. 56-62
Carl E. Hunt and Fern R. Hauck
[Abstract] [Purchase
Article]
Bed Sharing and the Risk of Sudden Infant Death: Parents
Need Clear Information Pp. 63-66
Edwin A. Mitchell
[Abstract] [Purchase
Article]
Perspectives on Bed-Sharing Pp.
67-70
Peter S. Blair
[Abstract] [Purchase
Article]
Never Sleep with Baby? Or Keep Me Close But Keep Me
Safe: Eliminating Inappropriate “Safe Infant Sleep”
Rhetoric in the United States Pp. 71-77
Lee T. Gettler and James J. McKenna
[Abstract] [Purchase
Article]
Some Controversial Theories for SIDS
Pp. 78-81
Mechtild M.T. Vennemann, T. Fracasso and Edwin A.
Mitchell
[Abstract] [Purchase
Article]
Role of Voluntary Organisations Pp.
82-85
Joyce Epstein
[Abstract] [Purchase
Article]
Creating Change: How Knowledge Translates into Action
for Protecting Babies from Sudden Infant Death?
Pp. 86-94
Stephanie Cowan
[Abstract] [Purchase
Article]
International Trends in Sudden Infant Death Syndrome
and Other Sudden Unexpected Deaths in Infancy: Need for Better
Diagnostic Standardization Pp. 95-101
Fern R. Hauck and Kawai O. Tanabe
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Article]
Abstracts
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Sudden Unexpected Death in Infancy and the Dilemma
of Defining the Sudden Infant Death Syndrome
Henry F. Krous
Sudden unexpected death in infancy (SUDI) is an umbrella
label that some employ to encompass all sudden unexpected
infant deaths, whether or not explained, while others restrict
its use to cases in which the cause of death is uncertain,
but possibly due to asphyxia as may occur, for example, with
sleeping prone, face down on a soft sleep surface, and/or
being found with the head covered. Since sudden infant death
syndrome (SIDS) is a diagnosis of exclusion, there is an inevitable
interface between it and those cases whose deaths are potentially
caused by unsafe sleep environments. This interface is especially
blurred given the lack of definitive, easily identifiable
postmortem marker(s) for SIDS. Therefore, present SIDS definitions
are imprecise and its diagnosis remains one of exclusion.
Improved death scene investigation has resulted in a diagnostic
shift away from SIDS towards other causes of death such as
positional asphyxia or undetermined. Unfortunately incomplete
death scene investigation has hampered evaluation of the real
circumstances of death in too many of the cases further contributing
to confusion. In this report, the purposes for and primary
definitions of SIDS are delineated. Subsequent discussion
focuses on the increasing challenge to incorporate risk factors
and the underlying pathology germane to the pathophysiology
of SIDS into future definitions. This challenge is matched
by the need to develop affordable and widely available testing
that will identify pathology relevant to medical examiners
and others charged with certifying the cause and manner of
death.
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English Multi-Agency Approach to the Investigation of Sudden
Unexpected Deaths in Infancy and the Care of Bereaved Families
Peter J. Fleming
Experience of the investigation of unexpected infant
deaths in several countries has identified recurring instances
of two types of error in such investigations – both
equally destructive and undesirable –
1) inadequate investigation failing to identify child neglect
or abuse, or
2) innocent parents being wrongly accused of harming their
child.
Studies of the use of multiagency investigation of unexpected
infant deaths have shown that the needs of bereaved parents
for help and support and the need for statutory agencies to
investigate unexpected infant deaths need not be seen as conflicting
or incompatible.
The implementation in England of a co-ordinated multiagency
approach to the investigation of unexpected deaths in infancy
has led both to improved care and support of families and
to higher standards in the investigation of such deaths, making
optimal use of all available forensic, clinical and epidemiological
skills and evidence.
This chapter describes the rationale behind the English approach
and the preliminary effects of its implementation over the
past few years.
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Commentary on the Multi-Agency Approach to the Investigation
of SUDI
Torleiv Ole Rognum
To use the diagnosis SIDS, investigation of the
death scene is a prerequisite. In some countries death scene
investigation is performed by ordinary police, in some states
in the US it is performed by the medical examiner, but in
many countries no death scene investigation is done at all.
There is general agreement in the SIDS community that the
death scene should be investigated by a specialist team including
medical and forensic experts. This requirement has been a
challenge for the legislators and legal experts who claim
that entering homes without consent is violation of human
rights. This challenge has been overcome in the UK where after
a new law was passed on April 1, 2008, professor PJ Fleming
and his co-workers successfully have developed a multi-agency
approach which may be a model for other countries.
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Sudden Unexpected Death in Infancy (SUDI) –
The Role of the Pathologist
Roger W. Byard
The involvement of a pathologist with forensic and pediatric
training in all stages of the assessment of sudden and unexpected
infant death (SUDI) is crucial as pathologists are among a
limited group of medical practitioners who have been trained
in evaluating the interaction of injuries, disease processes,
and post-mortem changes. However problems exist, with variations
in the quality of pediatric autopsy practice and in diagnostic
categories that are applied. While the development of standard
definitions and protocols has improved this situation, use
of the term SUDI as an umbrella term has also assisted in
evaluating trends and reducing the impact of diagnostic shift.
The following paper reviews the contributions that may be
made by pathologists in cases of SUDI, from an initial evaluation
of a death scene, through the autopsy process, discussions
with families, research and participation in multidisciplinary
death review committees.
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The Death-Scene Investigation
Martin Schlaud
The death-scene investigation is an important and increasingly
recognized step in the process of diagnosing Sudden Infant
Death Syndrome (SIDS). According to current definitions, information
from death-scene investigations is required when SIDS diagnoses
are made. Due to differences in national jurisdictions, however,
there are differences in the methods used and the professions
involved in routinely performed death-scene investigations.
Therefore any international comparability of death-scene data
is limited.
Only a few epidemiological studies have used thorough death-scene
investigations in a systematic way, including a standardized,
objective observation of the scene in cases and reference
data from the general population. These studies gave close
insights into the circumstances of infant death, but their
complex protocols are mostly not feasible for routine use.
For that purpose, manageable death-scene investigation protocols
need to be distilled from the ones used in complex studies,
taking into account their results.
Whilst protocols for post-mortem examinations and definitions
for SIDS have been largely standardized and agreed internationally,
this step is still missing for death-scene investigations.
If routinely obtained death-scene data were standardized and,
thus, comparable, this would have a potential of generating
new hypotheses that eventually lead to a better understanding
of the underlying mechanisms and to more effective measures
of prevention.
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Sudden Infant Death Syndrome: Implications of Altered
Physiological Control During Sleep
Rosemary S.C. Horne, Nicole B. Witcombe, Stephanie R. Yiallourou
and Heidi L. Richardson
A failure of cardiorespiratory control mechanisms, together
with an impaired arousal from sleep response, is believed
to play an important role in the final event of the Sudden
Infant Death Syndrome (SIDS). The ‘Triple Risk Model’
describes SIDS as an event that results from the intersection
of three overlapping factors: [1] a vulnerable infant, [2]
a critical developmental period in homeostatic control, and
[3] an exogenous stressor. In an attempt to understand how
the Triple Risk Hypothesis is related to infant cardiorespiratory
physiology many researchers have examined how the known risk
factors for SIDS alter infant physiology and arousal particularly
during sleep. This review discusses the association between
the three components of the Triple Risk Hypothesis, the major
risk factors for SIDS (prone sleeping and maternal smoking),
together with three “protective” factors (breastfeeding,
pacifiers and swaddling), and cardiovascular control and arousability
from sleep in infants, and discusses their potential involvement
in SIDS.
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Potential Mechanisms of Failure in the Sudden Infant
Death Syndrome
Ronald M. Harper and Hannah C. Kinney
Current evidence suggests that multiple neural mechanisms
contribute to the fatal lethal event in SIDS. The processes
may develop from a range of otherwise seemingly-innocuous
circumstances, such as unintended external airway obstruction
or accidental extreme flexion of the head of an already-compromised
structure of the infant upper airway. The fatal event may
occur in a sleep state which can suppress muscle tone essential
to restore airway patency or exert muscle action to overcome
a profound loss of blood pressure. Neural processes that could
overcome those transient events with reflexive compensation
appear to be impaired in SIDS infants. The evidence ranges
from subtle physiological signs that appear very early in
life, to autopsy findings of altered neurotransmitter, including
serotonergic, systems that have extensive roles in breathing,
cardiovascular regulation, and thermal control. Determination
of the fundamental basis of SIDS is critical to provide biologic
plausibility to SIDS risk reduction messages and to develop
specific prevention strategies.
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Sudden Unexplained Death in Infancy and Long QT Syndrome
Jonathan Robert Skinner
After more than 30 years of research into the hypothesis
that long QT syndrome (LQTS) might be a cause of arrhythmic
sudden infant death, we are now at the point where we can
state with certainty that some sudden unexplained deaths in
infancy, about 10%, are indeed due to long QT syndrome. The
evidence for this lies in large population ECG screening programmes,
post-mortem molecular genetic testing of sudden infant death
victims, and some informative case reports. The cardiac sodium
channel gene SCN5A (LQTS type 3) is the most common
culprit, but LQTS types 1,2, 6, 9 and 12 have also been found.
There is also new evidence that other arrhythmic syndromes
sometimes cause SUDI, in particular short QT syndrome, and
catecholaminergic polymorphic ventricular tachycardia (CPVT).
These conditions are also due to disordered cardiac ion channel
function like LQTS, and are usually inherited in an autosomal
dominant fashion. There remain, however, many unanswered questions,
most particularly whether all populations are affected equally,
and what should clinicians do with this knowledge? Should
newborn ECG screening become mandatory? How should we best
investigate SUDI at post mortem in order to diagnose LQTS?
This review summarises the evidence to date and addresses
these questions.
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Gene and Gene-Environment Risk Factors in Sudden Undexpected
Death in Infants
Carl E. Hunt and Fern R. Hauck
Sequencing of the human genome has expanded our understanding
of the molecular basis of many diseases and the complexity
of genotype-phenotype relationships. Knowing the genotype
does not define the clinical characteristics or phenotype,
however, since phenotype is also influenced by gene-gene and
gene-environment interactions. Studies in SIDS infants have
now identified polymorphisms in 25 genes that are present
in increased frequency compared to controls. These include
polymorphisms in 8 cardiac channelopathy genes, 3 genes related
to serotonin (5-HT), 7 genes related to autonomic nervous
system development, 6 genes related to inflammation, and 1
gene related to energy production. The polymorphisms related
to cardiac channelopathies and 5-HT have been confirmed in
several reports. Confirmation is less robust, however, for
the polymorphisms in other genes, in particular as related
to energy production. We still know very little about the
associated clinical phenotypes and the environmental perturbations
required to unmask antemortem phenotypes having increased
risk for sudden unexpected death in infants (SUDI). The recent
identification of multiple genetic risk factors for SIDS and
enhanced understanding of gene-environment interactions are
contributing to our knowledge related to SUDI. The challenge
now is to capitalize on these hypothesis-generating studies
to identify opportunities for effective assessment and intervention
in infants who will otherwise die suddenly and unexpectedly.
This review summarizes current knowledge regarding gene and
gene-environment risk factors that interact to yield phenotypes
susceptible to SUDI.
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Bed Sharing and the Risk of Sudden Infant Death: Parents
Need Clear Information
Edwin A. Mitchell
Bed sharing is a major risk factor for sudden infant
death syndrome. This risk is increased when the mother smokes
or smoked in pregnancy, or when the parent has drunk alcohol
or taken drugs. This risk is further increased in younger
infants. The mechanism of sudden infant death with bed sharing
is unknown, but airway obstruction, thermal stress and head
covering have all been suggested. The benefit from bed sharing
has only been established for breastfeeding, although other
benefits are claimed. There is a small group of infants that
has been shown to be at no increased risk of SIDS with bed
sharing, namely infants of mothers who do not smoke, who are
aged 3 months or more, and whose mothers have not taken alcohol
or drugs and do not co-sleep on a sofa. Recommendations on
how to bed share safely are not evidence based. Without this
knowledge parents cannot make an informed choice on whether
or not to bed share. Parents should be advised to place the
baby to sleep in its own cot next to the parents’ bed
for the first six months.
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Perspectives on Bed-Sharing
Peter S. Blair
The successful and dramatic reduction in cot deaths has
come about not so much because of a better understanding of
causal mechanisms of sudden death but rather from identifying
risk factors in the infant sleeping environment; in particular
placing young infants on their front to sleep.
More recently bed-sharing has been identified as a potential
risk factor and similar efforts are being made in some countries
to advise against this care practice. However prone sleeping
is not a culturally widespread behaviour; introduced in the
20th century partly based on observations showing how premature
infants thrived (and still do) when placed in this position
in incubators. If we are going to advise against a behaviour
such as bed-sharing that is common to many cultures over many
thousands of years we need to address some basic questions.
This review asks i) Is there any benefit to bed-sharing? ii)
Is bed-sharing in itself a 'risk-factor' for SIDS? and iii)
By advising against bed-sharing will we do any harm?
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Never Sleep with Baby? Or Keep Me Close But Keep Me
Safe: Eliminating Inappropriate “Safe Infant Sleep”
Rhetoric in the United States
Lee T. Gettler and James J. McKenna
Creating public health messages regarding how mothers
should sleep close and safely with their babies is tricky
and complex. It requires an appreciation of what exactly the
term “sleeping with baby” and “co-sleeping”
can mean. It also requires sensitivity to what parents will
or can do if told emphatically “never sleep with your
baby.” In the United States, well-intentioned public
health messages from prominent government agencies about safe
infant sleep have increasingly used language that equates
“safe infant sleep” with the absence of the mother.
Many messages seemingly imply that all forms of “co-sleeping”
are dangerous and that those parents that practice it are
acting irresponsibly. Messages such as “babies sleep
safest alone” conflict with both laboratory and epidemiological
findings as well as with recommendations from most medical
organizations, including the American Academy of Pediatrics,
who state that mothers and babies should sleep on separate
surfaces close together in the same room. Moreover, studies
reveal that breastfeeding and forms of co-sleeping, including
both roomsharing and bedsharing, are functionally interdependent
and that many mothers worldwide find that they can manage
their own and their infant’s needs more easily by adopting
at least intermittent bedsharing. Hence, simple, unqualified
recommendations against ever bedsharing are not likely to
be followed. According to recent studies the most effective
public health recommendations are likely to be those that
educate parents and facilitate parents in implementing bedsharing
safeguards alongside their own choices. This approach does
not exclude informing parents of what we know can be dangerous
about some bedsharing practices, nor where and when it should
be avoided altogether. Rather, it acknowledges that while
separate surface co-sleeping in the form of roomsharing should
always be recommended, nonetheless, many parents will appreciate
and benefit from the opportunity to learn how to reduce the
risks associated with bedsharing.
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Some Controversial Theories for SIDS
Mechtild M.T. Vennemann, T. Fracasso and Edwin A.
Mitchell
Almost 20 years ago prone sleeping position was established
as a risk factor for sudden infant death syndrome (SIDS) and
with risk reduction campaigns which largely focused on this
one factor, the incidence of SIDS has declined by 50-80% in
most of the countries where campaigns were conducted. However,
the pathophysiological cause or causes of SIDS are not yet
known, although many theories have been proposed. This paper
examines several of the more controversial theories for SIDS
causation.
In 1997 a link between Helicobacter pylori and SIDS was proposed.
Initial positive results were not confirmed. More recently
there is new evidence that H. pylori may play a role
in some cases but these results need to be confirmed by others.
Anaphylaxis caused by milk is an older theory, which has its
merits, but needs to be verified with new methods. The toxic
gas theory was interesting but had flaws. “Toxic gases”
have not been produced in an environment remotely resembling
that found in a cot. Proponents of the theory have recommended
wrapping the cot mattress in polythene to prevent the postulated
gases reaching the baby, but there is no evidence that this
has had any effect. The proponents have been very vocal in
the lay media despite evidence that disproves this theory.
No further evidence is needed for the final rejection of this
theory. The harm and benefits of immunisations are a controversial
topic in the lay press, although seldom in the scientific
literature. As the age of infants dying from SIDS is similar
to that when immunisation is given, it has been postulated
that there is a causal link. Several large case-control studies
have shown that immunisations are not a risk factor for SIDS
and recent a Meta analysis in fact reported that immunisation
halve the risk for SIDS compared with infants who had not
been immunized.
In conclusion, while the cause or causes of SIDS remains unknown
new theories will be proposed and this is to be welcomed.
These theories should be first discussed within the scientific
community. Debating theories and preliminary findings in the
lay media risks confusing parents of young infants and takes
attention away from established risk factors and recommendations.
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Role of Voluntary Organisations
Joyce Epstein
Voluntary organisations, working closely with scientists
and doctors in some 15 countries, play a key role in promoting
research into Sudden Infant Death, providing support for bereaved
families, disseminating infant care messages to help prevent
deaths and improving investigations when a baby dies. This
paper provides an overview of the role of voluntary organisations
including giving examples of innovative projects and programmes
to tackle the problems of sudden infant death.
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Creating Change: How Knowledge Translates into Action
for Protecting Babies from Sudden Infant Death?
Stephanie Cowan
We know how to protect babies from sudden infant death
syndrome (SIDS) and have had considerable success in doing
so. Yet babies continue to die in non-supine positions, unsafe
sleeping environments and exposed to smoking. Why? Understanding
what underpins the success to date is essential to the design
of strategies for the final stage of prevention. This paper
reviews influences on changing SIDS mortality, describes the
practice of creating change as it relates to protecting babies
from sudden infant death, and presents three principles that
emerge from the success to date to focus the design of research
and intervention programmes for ending the SIDS story.
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International Trends in Sudden Infant Death Syndrome
and Other Sudden Unexpected Deaths in Infancy: Need for Better
Diagnostic Standardization
Fern R. Hauck and Kawai O. Tanabe
Purpose: The aim of this paper is to compare international
trends in sudden infant death syndrome (SIDS) and postneonatal
mortality (PNM) since the introduction of SIDS risk reduction
and safe sleep campaigns, offer possible explanations for
differences, and to provide recommendations to improve consistency
in classifying and reporting sudden unexpected deaths in infancy
(SUDI) internationally. Methods: SIDS and postneonatal
mortality rates were obtained for 15 countries from 1990 through
the year for which most recent data were available. Results:
SIDS rates have declined in all countries, with reductions
well over 50% for most countries. These declines are attributed
to SIDS risk reduction campaigns, which achieved success primarily
in reducing rates of prone sleeping among infants. The largest
declines generally occurred in the first few years after initiation
of national campaigns, and there are concerning indications
that these rates have reached plateaus in many countries.
Conclusions and Recommendations: Diagnostic accuracy
is essential to monitor and compare trends in SIDS and other
sudden unexpected infant deaths. This requires establishing
sudden infant death definitions and diagnostic categories
that are agreed upon widely. National and local campaigns
need to be re-energized to continue the early successes made
in reducing SIDS incidence. Finally, data collection needs
to be easy to access and this would best be accomplished by
national vital statistics agencies posting data in a uniform
way on their websites.
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