Download Sensorineural Hearing Loss in ECMO Survivors

J Am Acad Audiol 9 : 367-370 (1998)
Sensorineural Hearing
Loss in ECMO Survivors
Toni Mann*
Karen Adamst
Abstract
Survivors of extracorporeal membraneous oxygenation (ECMO) treatment are at risk for §erious neurodevelopmental disorders or neurologic sequelae, but little has been reported about
the prevalence of sensorineural hearing loss in these patients . Of 123 ECMO survivors born
between 1987 and 1996, at least 30 survivors have confirmed sensorineural hearing loss .
Progressive hearing loss has been confirmed in 10 subjects .
Key Words:
Extracorporeal membraneous oxygenation
Abbreviations : ABR = auditory brainstem response, ECMO = extracorporeal membraneous oxygenation, NICU = neonatal intensive care unit
ECMO AND HEARING LOSS
E
xtracorporeal membrane oxygenation
(ECMO) is a form of cardiopulmonary support for full-term or near-term neonates who fail
to recover from life-threatening pulmonary illnesses despite conventional medical management (Hofkosh et al, 1991 ; Robertson et al, 1995).
The extracorporeal membrane oxygenator is
essentially a simplified heart-lung machine. Cannulas draw blood from the right atrium and
return it to the aorta, thereby functionally bypassing both the lungs and the heart for prolonged
periods of time. The extensive course of treatment
can result in severe neurologic sequelae and sensorineural hearing loss. Newborn diagnoses leading to ECMO treatment in this study included
respiratory distress syndrome secondary to persistent fetal circulation, congenital diaphragmatic
hernia, meconium aspiration, respiratory syncytial virus, blood aspiration, and persistent pulmonary hypertension of the newborn (Table 1) .
The purpose of this study was to examine the
occurrence and time of onset of sensorineural
'Texas Tech University Medical Center, Hearing &
Speech Care Center, Lubbock, Texas ; tHendrick Medical
Center, Hearing Health Center, Abilene, Texas
Reprint requests : Toni Mann, Texas Tech University
Medical Center, Hearing & Speech Care Center, 3502 9th
Street, Suite 410, Lubbock, TX 79415
hearing loss in ECMO survivors . Of 123 ECMO
survivors born between 1987 and 1996 and
treated at Texas Tech University Medical Center (TTUMC), 30 survivors were identified with
sensorineural hearing loss (Table 2) . Eight subjects with birth dates in 1988 and 1989 were
studied retrospectively, while all others were
prospectively investigated . Previous research
investigations have yielded a highly variable
prevalence of hearing loss (4-75%) in ECMO
survivors, possibly due to the limited number of
hearing-impaired subjects identified (Table 3) .
SUBJECTS AND METHODS
T
he TTUMC infant hearing assessment protocol required audiologic screening of ECMO
infants prior to discharge from the neonatal
Table 1 Primary Associated
Diagnoses for Subjects in this Study
Diagnoses
Respiratory distress syndrome secondary
to persistent fetal circulation
Congenital diaphragmatic hernia (left or right)
Meconium aspiration
Respiratory syncytial virus pneumonia
Persistent pulmonary hypertension of the
newborn
Blood aspiration
Number
8
367
Journal of the American Academy of Audiology/Volume 9, Number 5, October 1998
Table 2 Degree and Prevalence
of Sensorineural Hearing Losses
in Study Subjects
Degree
Table 4
Prevalence
Unilateral mild
Bilateral mild
Bilateral moderate
Bilateral severe
Bilateral profound
1
1
12
7
9
esearch Team
Year
Reported
Number
of HearingHearing Impaired
Loss
Subjects
of
Cheung et al (1996)
Hofkosh et al (1991)
Kawashiro et al (1996)
1996
1991
1996
14 .3
21
75
9
7
6
Schumacher et al (1991)
1995
4
4
Robertson et al (1995)
368
1995
8
3
1-Minute
Apgars/
5-Minute
Apgars
Total
Time on
ECMO
in Hours
ex
1
2
3
M
F
F
3 .4
2 .5
2 .1
7/7
0/0
6/6
93
154
73
5
M
3 .7
5/6
199
6
Table 3 Previous Reports of Sensorineural
Hearing Loss Subsequent to ECMO
Birth
Weight
in Kg
When on ECMO
ubjects
4
intensive care unit (NICU) using automated
auditory brainstem response (ABR) techniques .
The screenings were conducted on the day of discharge or within the week prior to discharge.
Infants born in 1987 and 1988 did not receive a
screening in the NICU because their births predated the infant screening program. Not all
infants born in 1989 or later were screened. Following a long distance transfer for ECMO treatment, several patients were transported to the
home hospital prior to the level of health stabilization required for ABR screening. Following
normal screenings, parents were advised to
schedule serial audiologic assessments to rule out
subsequent hearing loss .
Follow-up testing included otoscopy and
combinations of the following techniques dependent upon age appropriateness : ABR, visual
reinforcement audiometry, play audiometry, traditional earphone techniques, tympanometry,
and otoacoustic emissions . Medical record
reviews were conducted in order to confirm or
complete case history reports and confirm initial audiologic screening results. Eighteen of
the patients studied were male while the remaining 12 were female . Twenty-eight of the 30 hearing-impaired children had gestational ages
between 32 and 43 weeks when placed on ECMO
immediately after delivery, while two were placed
on ECMO at the chronological ages of 3 months
Relevant Subject Data
7
8
9
10
11
12
13
14
15
M
M
18
19
20
21
22
F
M
F
M
F
24
25
26
27
28
29
30
3 .0
3 .3
4 .0
NA
3 .0
3 .7
2 .8
3 .1
F
M
23
3.7
M
M
F
M
F
M
F
F
16
17
3.2
4.4
3 .1
M
3 .5
M
4/6
1/2
8/9
1/3
NA
2/3
6/8
1/4
8/8
1/5
8/9
1/4
150
182
105
125
92
653
123
138
141
119
115
96
110
NA
3 .4
4 .1
2 .3
3 .2
NA
6/8
4/6
5/7
9/10
397
131
130
118
100
2 .6
3 .7
1 .8
3 .3
3 .7
3 .8
3 .6
4/6
5/7
2/5
2/5
6/8
5/8
5/7
106
69
111
292
51
97
104
2 .8
F
M
M
F
M
M
M
3/6
5/7
76
NA -- not applicable .
and 13 months . Birth weights ranged from
1 .81 kg to 4.4 kg . For the newborn patients,
1 minute Apgar scores ranged from 0 to 9, while
5-minute Apgar scores ranged from 0 to 10. The
ECMO run time was 51 to 292 hours for all subjects with one exception, who remained on
ECMO for 653 hours (Table 4) . Mean ECMO
run time for the 30 hearing-impaired subjects
was 148 .3 hours . Family history of hearing loss
was ruled out for 29 patients . Subject number
6 did have a family history of congenital hearing loss . Patients with conductive hearing losses
were referred to otolaryngology for treatment.
RESULTS
T
en subjects had a normal ABR screening
prior to discharge from the NICU and were
subsequently identified with a hearing loss . Of
the 30 cases with confirmed sensorineural hearing losses, 20 did not receive an automated ABR
Sensorineural Hearing Loss in ECMO Survivors/Mann and Adams
screening prior to discharge from the NICU .
Late-onset hearing loss could not be ruled out
for the 20 unscreened patients . The typical configuration of hearing loss was precipitously sloping in the high frequencies. Degree of hearing
loss ranged from mild to profound and amplification was required for all 30 patients . A bilateral hearing loss was recorded for 29 subjects ;
the remaining one subject presented a right
unilateral loss . Exact onset of hearing loss could
not be ascertained but was noted to be as late
as 30 months after ECMO treatment in some
cases. ECMO survivors show a high prevalence
of hearing loss, 24 percent in this study.
DISCUSSION
he high prevalence of sensorineural hearT ing loss in the post-ECMO population, at
least 24 percent in this study, is critically important . This is remarkably higher than the prevalence reported in the general NICU population,
2 to 10 percent (Cox et al, 1981 ; Galambos et al,
1984). A higher pervasiveness of hearing loss cannot be ruled out since many of the 123 survivors
were lost to follow-up.
Another primary issue is the progressive
manifestation of hearing loss noted in at least
10 of the 30 subjects studied . At least one-third
of the subjects were identified with late-onset
hearing loss . The age of onset was noted to be
36 months for one subject, indicating the need
for long-term serial testing. This subject was
tested routinely every 3 months after NICU discharge and found to have completely normal
results until age 36 months . It is probable that
the prevalence of progressive loss is even higher
and possibly 100 percent in that every hearingimpaired infant that was screened before discharge passed the initial ABR screening. Despite
early detection efforts from screening in the
NICU, an insidious hearing loss may go undetected if late onset is not monitored aggressively. Frequent serial testing is needed to detect
hearing loss at the earliest stage of development. Significant prevalence of progressive hearing loss is a concern presented by numerous
researchers when investigating hearing loss in
NICU graduates surviving ECMO, persistent
fetal circulation, and persistent pulmonary
hypertension of the newborn (Naulty et al, 1986 ;
Nield et al, 1986 ; Hendricks-Munoz and Walton,
1988 ; Walton and Hendricks-Munoz, 1991 ; Cheung and Robertson, 1994 ; Robertson et al, 1995 ;
Cheung et al, 1996 ; Kawashiro et al, 1996 ;
Fujikawa et al, 1997).
These findings indicate that an audiologic
screening prior to discharge from the NICU
alone is not sufficient audiologic management .
Conscientious follow-up audiologic care is
required for ECMO graduates at least through
the age of 3 years. Parent education is also an
important issue. Parents must be informed of the
risk of progressive hearing loss, symptoms of
hearing loss, and symptoms of speech and language delay.
The use of ECMO is decreasing as a result
of the introduction of nitric oxide treatment,
but many medical centers may not yet have
access to this new treatment approach . Future
research efforts should include audiologic findings of nitric oxide cases to delineate the source
of the hearing loss as the actual underlying
medical disorder or the ECMO treatment . Further longitudinal scientific investigation is
needed to compare treatment variables and indicators for hearing loss between normal hearing
and hearing impaired groups and to provide
further description of the time course of progressive hearing loss .
Acknowledgments .
We are grateful to Dwayne
Paschall and Jane Goldthom for their assistance with this
study and to Mary Ann Rogers for her assistance in locating, contacting, and scheduling audiologic evaluations for
the subjects of this study through the years. This study
is dedicated to her memory.
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Journal of the American Academy of Audiology/Volume 9, Number 5, October 1998
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