Joan E. Hodgman, Toke Hoppenbrouwers, Susan Geidel, Anthony Hadeed, Maurice B. Respiratory Behavior in Near-Miss Sudden Infant Death Syndrome.
Respiratory Behavior in Near-Miss Sudden Infant Death Syndrome Joan E. Hodgman, Toke Hoppenbrouwers, Susan Geidel, Anthony Hadeed, Maurice B. Sterman, Ronald Harper and Dennis McGinty Pediatrics 1982;69;785
The online version of this article, along with updated information and services, is located on the World Wide Web at: http://pediatrics.aappublications.org/content/69/6/785
PEDIATRICS is the official journal of the American Academy of Pediatrics. A monthly publication, it has been published continuously since 1948. PEDIATRICS is owned, published, and trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk Grove Village, Illinois, 60007. Copyright © 1982 by the American Academy of Pediatrics. All rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275.
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Respiratory Behavior in Near-Miss Sudden Infant Death Syndrome Joan E. Hodgman, Toke Hoppenbrouwers, Susan Geidel, Anthony Hadeed, Maurice B. Sterman, Ronald Harper and Dennis McGinty Pediatrics 1982;69;785 Updated Information & Services
including high resolution figures, can be found at: http://pediatrics.aappublications.org/content/69/6/785
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PEDIATRICS is the official journal of the American Academy of Pediatrics. A monthly publication, it has been published continuously since 1948. PEDIATRICS is owned, published, and trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk Grove Village, Illinois, 60007. Copyright © 1982 by the American Academy of Pediatrics. All rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275.
Downloaded from pediatrics.aappublications.org at UCLA Digital Coll Svcs on October 9, 2013
Respiratory Behavior in Near-Miss Sudden Infant Death Syndrome Joan E. Hodgman, MD, Toke Hoppenbrouwers, PhD, Susan Geidel, RN, MS, Anthony Hadeed, MD, Maurice B. Sterman, PhD, Ronald Harper, PhD, and Dennis McGinty, PhD From the Newborn Division of the Los Angeles County-University of Southern California Medical Center; Department of Pediatrics, University of Southern California School of Medicine; Sepulveda Veterans Hospital, Departments of Anatomy and Psychiatry; and Brain Research Institute, University of California, Los Angeles
ABSTRACT. Seventeen infants with unexplained pro longed apnea that has been designated near-miss sudden infant death syndrome were monitored for sleep and cardiorespiratory
variables
during
a 12-hour,
all-night
recording session. Infants were matched for gestational age, sex, and age at recording with control infants. Res piratory
variables
studied
included
respiratory
rate, res
piratory variability, apnea duration, apnea density, and periodic
breathing.
No statistically
significant
differences
were found in sleep state or respiratory variables between near-miss recurrence
and control infants. Eight infants (47%) had no ofprolonged
apnea,
whereas
three
(17.6%) had
recurrent apneic episodes for six weeks to eight months following the original episode. No clinical or polygraphic finding predicted which infant would exhibit recurrent apnea. None of the infants was monitored at home. All infants were developing
normally
when examined
at 1 to
2 years of age. Pediatrics 69:785—792, 1982; sudden infant death syndrome, near miss, apnea, periodic breathing, sleep.
the clinical history, polygraphic findings, and sub sequent course of infants with unexplained apnea referred to us as a part of a study of development of cardiorespiratory reflexes during sleep. An inte gral part of the study was collection of normative data with particular emphasis on respiratory behav ior during sleep states in infancy. Data on physio
logic behavior in infants with unexplained apnea will be compared with that in control infants.
METHODS Subject Selection Infants were referred following an episode of pro longed apnea with color change requiring active intervention
to terminate
who were included
the apnea.
The
met the following
17 infants
criteria:
(1)
All infants were at least 2 weeks old at the time of
An infant with unexplained prolonged apnea as sociated with pallor or cyanosis has been designated a “¿near miss― for sudden infant death syndrome (SIDS),' and in this paper these terms will be used interchangeably. Some authors think that there is a close connection between unexplained apnea and SIDS, whereas others remain skeptical.2@ Poly graphic monitoring of sleep and cardiorespiratory variables has been carried out in these infants in an effort to identify physiologic changes that may be associated
Received
with
risk for SIDS.5'6
for publication
March
We wish to report
3, 1981; accepted
Nov 5, 1981.
Reprint requests to (J.E.H.) 1240 Mission Rd, Los Angeles, CA 90033. PEDIATRICS (ISSN 0031 4005). Copyright ©1982 by the American
Academy
of Pediatrics.
the first apneic episode. Premature infants were included only if the first episode occurred at 38 weeks or older postconceptional age in order to exclude apnea of prematurity. (2) No clinical find ings were present that could explain the occurrence of apnea. (3) A control infant matched for gesta tional age (GA) and sex was available for compari son. Control infants were part of a larger study and were selected before birth from a low-risk popula tion with no family history of SIDS or unexplained apnea. For the purpose of the present study each of the 17 infants with unexplained apnea was matched and compared with a control infant of like GA, sex, and postnatal age. Three premature infants be tween 34 to 36 weeks GA with unexplained apnea could be matched; however, three others of 28 to 33 weeks GA could not and were excluded from the study.
PEDIATRICS Vol. 69 No. 6 June 1982
785
Clinical Data
6
Maternal and infant characteristics are presented in Table 1. Gestational age was based on the mother's history. The pregnancy, labor, and deliv ery histories
@
were uniformly
benign in both groups.
The only abnormality was prolonged rupture of the fetal membranes in one mother of a near-miss in fant. All birth weights were appropriate for gestational age (AGA). When available, Apgar scores of infants with ur.explained apnea were 8 to 10, and no infant had a history suggesting birth asphyxia. Nursery problems
were limited
to the preterm
infants
and
were those associated with prematurity. One pre term infant had transient grunting for which he received supplementary oxygen, and another devel oped physiologic jaundice and required early gavage feedings at 34 weeks' gestation. A family history of SIDS was present in four of the near-miss infants. No history of unexplained apnea in family members was reported. Apgar scores of control infants were 8 to 9 at I minute
and 9 to 10 at five minutes
for the premature Apgar
twins. The first-born
except
twin had
scores of 6 and 8, and the second-born
had
scores of 1 and 4. Problems in the nursery were also
limited to the pretermtwins,bothof whomdevel oped mild respiratory distress syndrome requiring supplemental oxygen but no ventilatory assistance.
Description of Apneic Episode The age at first apneic episode for all infants is shown in Fig 1. All of the infants exhibited cyanosis or pallor
and all required
z
stimulation.
The
first
apneic episode in three infants was observed by medical personnel; in the other infants the first episode was observed by a parent or caretaker.
z 1@1@ 6
2
8
10
12
14
16
18
@o 22
24
26
AGE IN WEEKS
Fig 1. Ageat firstapneicepisoderequiringintervention for 17near-missinfants.Note that medianageis 5 weeks. personneL In eight of the infants (47%) mouth-to mouth resuscitation was performed. Four infants were awake, and the remainder were either oh served asleep or presumed asleep in their cribs. Vomiting just prior to the apnea was described in
two infants. Rigidity and stiffnesswere present in another
two whereas
blood was found
in the naso
pharynx in an additional two. Four infants (23.5%) of the total series had a history of mild upper respiratory infection at the time of the apnea. Irri tability and noisy breathing on the day before the episode were described for one additional infant, and another had a chronic stuffy nose. Results of physical examinations were normal
exceptfor hypotonia in four infants (23.5%).Labo ratory tests of blood count, urinalysis, chest radi ogram, electrocardiogram, and capillary blood gas analysis were obtained at the time of our initial contact. The results of the majority of these studies were normal. The exceptions were one infant with
a wandering
atrial pacemaker
demonstrated
by
more detailed than those obtained from hospital
ECG and two with questionable increased pulmo nary markings on chest radiograph. One infant had gastroesophageal reflux demonstrated by barium swallow.
TABLE 1.
Data Collection
Parenthetically,
histories
from
the
parents
were
MaternalandInfantCharacteristics
MissControlMaternal
Near
yrMaternalage range19-31 educationFinished school1417Attended high
yr20-35
were donefor each infant. Growth wasrecordedas
college1011Primigravida71PresentationVertex1716Breech01Low
weight22Male/Female10/710/7RaceWhite1211Black. birth
.3Mexican52Oriental.
.1Breast-fed68
Physical and developmental examinations using the Denver Developmental Screening Test (DDST)
.
.
percentile of expected growth for age corrected for prematurity, using the growth charts from the Na tional Center for Health Statistics.7 Rate of growth was evaluated by comparing the percentile at time of apnea with the percentile at birth and three patterns
to the
786
of growth
identified:
the rate
of growth
was constant with less than 25 percentiles' change, accelerated or decelerated based on a change of more than 25 percentiles in either direction. All but two infants were monitored four days or longer after the apnea in order to exclude acute changes related apnea.
Interval
histories
RESPIRATORY BEHAVIOR IN NEAR-MISS SUDDEN INFANT DEATH
were
obtained
for
all infants for at least the first six months, and all infants but one were followed up for one to two years. Physical and developmental examinations were done in the infants' homes by one of the authors (S.G.) at ages 8 months, 1 year, and 2 years.
MonitoringProcedure Each infant was admitted to the sleep laboratory at 5 PM for 12-hour monitoring sessions.Monitoring procedures
have been reported
in detail elsewhere.8
The sleep variables recorded included two EEG derivations,
a chin electromyogram
(EMG),
and eye
movements. Thoracic or abdominal excursions were monitored
by impedance
pneumography.
In addi
tion, a Beckman Pco2 monitor sampled expired gas through a miniature cannula which was taped under the infant's nostrils and which also contained a thermistor. The ECG was recorded with two dis posable electrodes placed symmetrically beneath the clavicles. A ground electrode was applied above the umbilicus. Additionally, a skin temperature probe was applied to the abdomen below the right costal margin. Electrodes on the mattress surface under the crib sheet registered the infant's gross body movement. Data were recorded on a 16-chan nel Grass model 76 polygraph and simultaneously stored
on a 14-channel
Honeywell
analog tape re
corder together with an IRIG E time code.8'9
Data Analysis Each minute of the record was coded as either active sleep (AS), quiet sleep (QS), awake (AW),
or
indeterminate (IN), according to criteria reported elsewhere.'°The entire data set for each infant was digitized on a PDP-12 laboratory computer and the
Pco2signalsubmittedto a breath-to-breathinterval
identified in four infant pairs. The problems asso
ciatedwith the identification of mixedandobstruc tive apnea are discussed elsewhere.'2 Second, the recordings of these subjects were submitted to a computer program which attempted to identify breathing pauses equal to or longer than two seconds' duration in each sleep state. Duration categories were divided into short, two to five sec onds, medium, six to nine seconds, and long, equal to or in excess of ten seconds. Inasmuch as the Pco2 signal was used, this computer strategy did not differentiate between, but included central, mixed, and obstructive pauses.'3 Apnea density was calculated by dividing the number number
of apneic of minutes
episodes in each state by the spent in each state. The result
ing value was multiplied by 100 to obtain a density score in percent. A paired t test was used to examine differences between study groups. Periodic breathing was defined using the criteria of Parmelee et al'4 as two cessations of breathing each >3 seconds but
