A CONTROLLED
STUDY
OF THE USE OF
THE BLOXSOM
AIR
LOCK
By Thomas E. Reichelderfer, M.D., and Harold M. Nitowsky, M.D.
Deptrtmeeits of Pediatrics of Jolirms Hopkins ‘tIcdical Institutions and Sinai hospital of Baltinmore, 071(1
Dici.sion of Maternal and Child Health, School of Hygiene and Public health, Jo/ins Hopkins Universiti,
(Submitted June 1, accepted Jcmne 15, 1956.)
Dr. Reichebderfer was a Postdoctoral Fellow, National Foundation of Infantile Paralysis.
PRESENT ADDRESS: (T.E.R.) Ancken Hospital, Saint Patmi 1, Minnesota.
918
T
HE Bhoxsom air lock was introduced in1950 as a resuscitator for newborn
in-fants.’ Since then, much controversy has
arisen as to its effectiveness.2 The device
consists of a chamber into which a pressure control is bumilt allowing for the application of alternating and variable pressures at
dif-ferent rates. The pressures suggested were
approximately those of umterine contrac-tions, ranging from 50 to 150 mm mercury
(
1
to 3 lb/in.2) above atmospheric pressure, with a cycle duration of 40 to 45 seconds. The rationale for the umse of such an appa-ratums was based upon the hypothesis thatthe back of conditioning of the respiratory center by imterine contractions was one
fac-tor in the high incidence of difficulty in initiating respirations in infants delivered by cesarean section and not subjected to a
trial of labor. Other advantages of the air
lock were stated to be removal of fluid
from the infant’s lungs by “expansion of
gases,” better absorption of oxygen through
the skin, prevention of pulmonary edema, more efficient aeration of atelectatic lungs amid increased rate of morphologic change
of cells lining the alveoli from a cuboidal to a flattened type allowing for more
effi-cient exchange of oxygen and carbon
di-oxide.23
After the introduction of the air hock into
a maternity hospital, the over-all mortality
rates for both term and premature infants
(lumring the first 48 hours of life were low-ered approximately 25%.1, 3 4 Whether the
observed reduction in mortality rates
be-tveen 1949 and 1952 is related primarily or solely to the effect of the air lock is not
convincingly demonstrated by the data pre-sented. Alterations in the care of the
new-born infants unrelated to the use of an air
hock may have improved their chances for
sumrvival. It is of imiterest that a change of the physical facilities at the hospital imi qumestion to improve care of the newborn
infant with distress was reported about
the same time that the air bock was
intro-duced for u5 The clinical impression
ex-ists in many obstetrical services that the
condition of some infamits with respiratory
distress is improved by placing them in
the air lock.6
It
seemed important to obtain further evidence relating to the clinical umsefumbnessof the apparatums. A controlled clinical trial
was undertaken at the Johns Hopkins
Hos-pital among a groump of infants with
in-creased risk of mortality who were
ran-domly alternated between the air bock as
an added resuscitative device and the Iso-hette#{174}ordinarily umsed ifl the routine care
afforded prematumre and distressed infants.
There was no difference in over-all
mor-tality or in the relief of respiratory distress
in the groups stumdied. No evidence was
obtained that the air lock was an
effec-tive resumscitator in this groump of infants.
METHODS
ALTERNATION SCHEDULE : Time assigmimemit of
infants to the Bloxsom air bock or to the
Isobette was determined
by
the evemi or oddcharacter of the mother’s hospital miumber. It
was hoped
by
this means to achieve a randomdistribution of the series amid to eliminate factors of bias rebated to maternal age, parity,
complications of pregnanc, birth weight, and
general conditiomi of the imifant at the time of
delivery. In the event of multiple births, the
accor(h-ing to the mother’s hospital miumber; all
sue-ceeding infants were altermiateci relative to the
(hiSpositiomt of the first. Once assigned to a
1)mrtictmitr apparatus, the infant remained
thereimi for a predetermined period or tmntil
(leath occtmrred with the exception of two
cases, the details of which will be presented
later.
IMMEDIATE CARE AFTER DELIVERY: All
in-famits received routine resuscitative measures
which included l)ulb suctiomi of the oropharynx
and miasal passages, amid oxygen b mask at a
flow of 1 h/mimi. Infants delivered by cesarean
section also received gastric aspiration in most
instances. At times, additional resuscitative
measures were employed, imicludimig oxygen
with positive pressure, amid on a few occasions
tracheal intubation amid parenteral analeptics
(
caffeine soditmm benzoate and epinephrine)depending upon the condition of the infant at
birth.
All infants received 2.5 mg of vitamin K
(
Hvkimiomie ) subcutamieously and 20,000 units/kg of pemiicilhin and 25 mg/kg of streptomvcin
intramusctmlanhv imi a combined preparation.*
Antibiotics were umsed in an attempt to reduce
morbidity amid mortality due to infectiomis
see-omidamy to complicatiomis of pregnancy and
de-livery which were frequent imi this group.
This use of antibiotics regardless of the
condi-tion of the infant seemed justified only as part
of a controlled stumd. All infamits were weighed
and given a preliminary physical examination
to detect amiv conditiomis which might
necessi-tate immediate treatment or comitraindicate an
umnimiterrtmpted exposumre of 12 hours in the air
lock or Isohette’.
Following the initial postnatal care, infants
assigned to the air lock were placed therein
almost immediately after delivery. The
appa-ratus was operated with an oxygen flow of
al)out 6 i/mimi to yield an oxygen
comicentra-tion between 45 amid 50 volummes/ 100 ml,
de-termined at intervals with a Beckman oxygen
analyzer. The decision to limit oxygen
concen-tration to this range imistead of 60% as
onigi-mialhy recommended by 3 was based
on the desire to make the oxygen tensions
comparable to those employed in the Isolette#{174}
and to minimize insofar as possible the risk
of retrohental fibrophasia. It was necessary to
run compressed air into the air lock at a flow
0 Comhiotic#{174}, supplied through the generosity
of Pfizer Laboratories, Brooklyn, New York.
of 13 1 mimi
ut
order to achieve a pressure cyclebetween 50 and 150 mm merctmrv above
at-mosphenic iresstmre at a frequemicv of 1.2
ccies,’min. ilie temperature within the
appa-ratus was maintaine(l at 32.2#{176}C and, by means
of bubbling the incoming gases through
per-forated tubes completely immersed in a
trough of water, a relative humidity of
ap-proximately 90 to 95% was attained.
Infants were kept in the Bloxsom air hock
for ami uninterrumpted period of 12 houmrs
dun-ing which time regular observations were
made 1))’ the nursing and house staffs. This
time pemiod was selected for two reasons. First,
the majonit’ of neomiatal deaths among
prema-tumne infants occtmns during the first 12 hours of
hife. Second, iii an earlier report on the use
of the Bboxsom air hock, 98 of a group of 50
full-term infants and 58% of 50 premature
in-fants who required resuscitatiomi were kept in the air lock for 12 hours on less. It was felt
in the present study that an exposure period of
this duration would be adequate to determine its effects as a nesumscitaton. The pressure
cy-chimig was discomitinued at the termination of the
12-hour period and during the succeeding 60
minutes a stepwise decompression was carried
out. Following this, the infants were removed from the air hock and transferred to Isolettes#{174} in the nurseries for premature or fimll-term infants.
Arm infant assigned to an Isolette#{174} was
ad-mitted to the premature or full-term nursery
shortly after birth. The Isolette#{174} was
main-tamed at a temperature of 32.2#{176}C and
super-saturated with moisture by use of a
Vapor-jette. The flow of oxygen was regulated to
yield a concentration between 45 and 50%#{176}
as determined at regular intervals with a
Beck-man oxygen anahzen. Periodic observations
similar to those recorded for the infants in
the air lock were made by nursing personnel
and house staff.
LATER CARE: All infants, including those
transferred at the end of the exposure imi the
air lock were kept imi the 1sohette umntih 48
hours of age. After the age of 48 hours, a
de-cisioti for removal to a bassinet, another
incu-bator or retention in the Isolette#{174} was made. During the second 24 hours of life, the
physi-cal examimiation was repeated and a second
injection of penicillin amid streptomycin was
0 Oxygen concentrations of 30 to 40% are now
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5’‘FABLE I
(‘o%lm-.su.tBII.mT’v ()} INFANTS IN .mu IA)(K NI)
(‘oNTImoL (;mmom
Air Lock
No. %
72
(‘ontrol
No. %
71
‘l’otalNumber of Infants
Sex:
Male
Ft-tunIc
33 48.7 36 50.7
37 31.3 35 49.3
54 75.0 58 81.7
18 ‘25.() 13 18.3
36 77.8 47 66.2
16 22.2 24 33.8
3 5 8 7 13 12 3 6 7 5 5 3 13 17 28 30
66 91.7 66 93.0
6 8.3 4 5.6
1 1.4
ARTICLES
givemi. When the size amid condition of the
in-fammt permitte(h, feedimigs with a 5% solution of
ghmcose iii water were begumi at this time.
OBSEHVATIONS : Regular periodic
observa-tiomts of the imifammt’s colon, respiratiomis, body
movememmts and pnesemice or absence of oral or
nasal secretions were made and recorded
dumn-ing the first 48 hours of life. These findings
were recorded on a special form prepared for
this stumdv, a sample of which is shown (Fig. 1).
Pathologic stumdies were carried oumt b Dr.
Ceorge W. Anderson of the Women’s Clinic of
the Johmis Hopkimis Hospital omi all bumt 1 of the
42 imifamits \Vh() died.
PATIENT
MATERIAL
The study was limited to those newborn
infants for viiom one might anticipate higher
morbidity and mortality rates because of
pre-maturity amid vanioums complications of
preg-namicv amid (leliverv.” ‘ Because of the
con-servative use of sedatives amid anesthetics at
the Woman’s Clinic, the problem of the
miarcotized neWl)Orfl imifamit is au infrequent one
and it was impractical to restrict this study to
sumchi infamits. The infamits selected were those
delivered on the ward service of the Woman’s
Clinic of the Johns Hopkins Hospital a) with
a birth weight of 2000 gm or less, and
b) where delivery was b nonehective cesarian
sectiomi regardless of birth weight.
All imifants born to diabetic or Rh negative,
semisitized mothers were exclumded because the
postmiatal care of these newborns ulsuahly
pre-eluded the possibility of contimiuoums
uninter-ru1)ted observations in the Bhoxsom air hock or
in the Isobette.#{174}
A total of 171 imifants delivered at the
\Vomami’s Clinic of the Johns Hopkins Hospital
from October 5, 1953, to March 16, 1955, met
the criteria for inclusion in this investigation.
Of
these, 28 were subsequently excluded for reasomis which will be presemited later. Thepresent analysis, therefore, is restricted to the
remaimiimig 143 imifamits.
Seventy-two infamits were assigmied to the air
bock amid 71 infants were placed imiitiabhy imi the
Isolette.
A comparison of these two groups of infants
is presented in Tables I amid II. There is a
stnikimig similarity in the distributions by sex,
race amid maternal complications of pregnancy
and delivery. Some differences were noted in
the distributions
by
birth weights, althoughthese differences were not statistically
signifi-Color: Nommwhite
White
‘rype of 1)elivery:
Vaginal
Cesarean
Complications of Pregnancy
aml(l l)elivery: Multiple pregnamicy ‘roxeiiiims
I’lacent iii l)revia amm(I mmli-ruptio Prolapsed cord Infect ion ITterimme imiertiit Other5 Nomme Breathing Tniie: ‘fsvo minutes or
Greater thami t wo mnimmutes Not reeorde(l
A Imicludes antel)artmmmn hemiiorrhage, heart disease,
endommiet riosis, polyhydramim nios, ahnornmzml fetal
posi-tion, an(l CephaIo)elVic disproportion.
‘FABLE II
BIIITII WEIGhTS OF INFANTS IN Ama Locx
ANI) (‘oNTuoL GiCoips
JI’esg/zt
(grit)
.‘lir Lock
-No. % (‘ant rol
iv.
______
300-1000 1001-1500 1501-2000 2000plus 14 16 32 10 19.5 22.2 44.5 13.8 6 17 29 19 8.4 24.0 40.8 26.8Control Total
‘\O. % %O. %
25
18
28
72
58
13 45
‘3’)
78
TIME DISTRIBUTION OF DEATHS,
AIR LOCK AND CONTROL GROUPS
L:J Ar lock El Control
0 0
a Ui
z
TIME IN HOURS
Fic. 2.
cant. Amomig imifants assigned to the air lock,
14 (19.5%) had birth weights of 1000 gm or
less; this compares with 6 (8.4%) infamits
as-sigmied to die Isohette#{174} in this birth weight
category (X2 = 2.73, p = .10). Furthermore,
10 (13.8) infants placed in the air lock
weighed more than 2 kg at birth, whereas 19
(26.7%) infants in the Isolette#{174} were in this
category (X2
=
2.32, p = .10). Becaumsemor-tabity rates were determined on a weight
specific basis, i.e., for each individual birth
weight category, it was felt that the observed
differences iii distnibumtion of birth weights did
not imivalidate a comparison between the air
bock amid comitrol groups.
RESULTS
Although an attempt was made to evaltm-ate the clinical course of the infants
dur-ing the first 48 hours of life by serial
oh-servations of rate, rhythm, and depth of
respiration and by the color of the skin,
this proved difficult. Only a rough
assess-ment of the presence or absence of
mod-crate to severe respiratory distress during
the first 12 hours of life was made and the effect thereon of continued exposure in the
air bock or Isohette was noted. On the
basis of detailed records of behavior, a
diagnosis of respiratory distress, either
moderate or severe, was made only in the
presence of peripheral or generalized
cy-anosis, and some degree of intercostal,
sumb-sternal or sumpraclavicular retractions. Most
of these infants also had irregularities of
respiratory rhythm, tachypnea and periodic
episodes of apnea.
A total of 58 infants had moderate or
severe respiratory distress during the first
12 houmrs of life. The outcome of this
diffi-culty during continued observation in the
air hock or Isobette#{174} is summarized in Table III. Of 25 infants with respiratory
diffi-cumbty in the control group, 7 (28%), showed
improvement during the first 12 hours,
whereas, of 33 infants in the air lock, who
also presented signs of respiratory distress,
6 (18%) demonstrated clinical improvement dumring this same period. These proportions did not differ significantly (X2 .325).
Ex-pulsion of secretions from the oropharynx
TABLE III
OUTcoME OF INFANTS WITh Mom)Eim3TE To SF:vEmmi: RESPIICATOmCY I)NTIII5S l)1muNu FmmmsT 12
Ilotmis om.’LIF’E
Air
Lock
____
NO. %‘rotal infants with
dis-tress ‘33
Improved 6 18
Not imnprOVe(I 27 82
occumrred as frequmently in the control groump
as among those in tile air lock.
Death was adopted as an additional
en-tenon of comparison. Because it seemed
that the effects of the air lock as a
nesumsci-tator shoumhd be most apparent dumning and
shortly after its umse, an analysis of deaths
(lumning the first 24 houmrs of life was carried
ouit. In order to evabumate any more remote
effects of exposure in the air lock, arm
analy-sis was also made of total deaths in both
groups. The frequency distributions of
deaths by age at death for 12-hour
inter-vahs from birth to the second day and
there-after by 24-hour intervals through the
.1ir Lock
.Vurnber
‘1
I’ifa,its
J)eathx
(No.)
flirt/i H’eiyht
(U”,)
301 -bOo
10)0)1-15(101
I 301-200() 2001 amid larger
‘b’ota 1
.bfortality
Rate
(%)
(‘out rol
Number
Deat/,. of
U o.)
Infants
14 16
32
10
H
4
3
0
.1!ortality
Rote
(%)
x2of
Differences
‘3d
25
9
0)
72
6
17
29
19
15
3
Oi ‘7
0)
50) 35
7 0)
20.8
.0)38
.069 .003
7b lb 15.5 .372
‘I)TcL I)E.cTiiS TABLE IV
I)cTIIs w!Tmmmx FIRST 24 lIotims
the 17 deaths among the controls, 10
(59%)
occumrred imi the first 12 houmrs and 11 (65%)
durmg the first day. These percentages are
in close agreememit with the percentage of
deaths (56.5%) which occurred during the
first 24 houmrs of life among infants in the
1000 to 2000 gm category of birth weight
at the Johns Hopkins Hospital from 1937
to 1949.
The death rates for the first 24 hours by
specific weight groups are presented in
Table IV. Ahthoumgh cruide death rates were
20.8% and 15.5% for the air lock and control
groups, respectively, the difference is not
statistically significant (X2 .372). For
in-fants weighing between 1 and 1.5 kg at
birth, the mortahity rates were 35% and 25%
(X2 = .069), and for those weighing
be-tween 1.5 and 2 kg, mortality rates were
7% and 9% (X2 .013). No deaths occurred
among iiifants with birth weights greater
than 2 kg.
A comparison of over-all death rates,
including those infants whose deaths took place during and after the first 24 houmrs
of life, is presented in Table V. No
signifi-cant differences in over-all or
weight-spe-cific mortality rates were noted between infants assigned to the Isolette#{174} and those
Placed in the air lock. It is surprising that
the death rate among the smallest infants
assigned to the control groump was only 67%,
since the mortality rate for infants with
this birth weight is umsumally
90%
or greater.9However, this may he related to the small number of infants involved.
In Table VI are presented the caumses of
death as determined by necropsy of 41
infants who sumecumbed, 25 of whom died
within the first 24 hours of life. While
the number of infants in each category is
small, it can be seen that there are no
stnik-imig differences in the distribution of deaths
by specific cause of death among the air
Cause of Death
Deaths -within 24 Hours Total Deaths
-.1ir Lock Control .4 ir Iock Control
Unknown
Anoxia Atelectasis
Ilyaline membrane
Pneumonia
(‘ongenital mnalformnatiomi
Intracrammial hemorrhage amid trauma
Sepsis
2
4
1 4 1 1
I
-2
2
‘3 1
-1
2
-2 2
8 5
3 4
4 2
2 I
2 I
2 i 2
-
1lotal
TABLE VI
(‘.u-sas OF l)EATH-PATllomjxac DiAGNosms
14 Ii 23 18
S No necropsy WaS (lOtte on an infant in the air lock group who (lied at 4 hours of age.
lock and control groups. It is of interest
that more infants had pathologic findings indicating anoxia as the primary cause of
death among the air lock groump than
among the controls, both dumning and foh-bowing tile first 24 hours of life. If a com-panison of mortality rates is made between
control and air hock groups for deaths due
primarily to some respiratory cause, i.e.,
anoxia, atehectasis, pneumonia and hyabine
membrane, no significant differences are
mioted. Thums, among 72 infants assigned to the air lock, 10 (14%) of the total, died
be-caumse of some primary respiratory cause
during the first day of life. In the control groump, the comparable mortality rate was 9%. Over-all mortality rates for deaths due
to respiratory causes during and following
the first day of life were 24% and 17% for the air lock and control groups,
respec-tively.
In two instances it was decided to termi-nate prematurely the period of exposure
in the air bock becaumse of the poor condition
of the infant. One infant who weighed
1140 gm at birth, was removed from the
air lock and placed in the Isolette#{174} at 8
hours of age. He died 73 hours later and at
necropsy a sumbarachnoid hemorrhage was
foumnd. Another infant with a birth weight
of 850 gm was transferred to the Isolette#{174}
after % hour exposumne in the air lock and
died at 4 hours of age. Necropsy revealed
no obvious cause of death except for the
factor of prematumnitv. Both infants were
included in the series even though
cx-posuire in the air lock was not for the
pre-scribed period of 12 houmrs since the
appa-ratus had failed to alleviate their
diffi-cubties. Their exebumsion woumbd not have
altered the findings.
Twenty-eight infants who met the
en-tenia for admission to the stumdy were
cx-eluded for a variety of reasons which are listed in Table VII. Ten infants, seven of
whom had been assigned to the air hock,
were excluded because the apparatus was
in use at the time of their birth. No
Iso-lette#{174} was available in the case of three
infants and another type of incumbator was
employed. The air hock coumhd not be
op-crated in two instances becaumse of mechani-cal failure. Six other infants were exchumded
TABLE VII
REASONS FOR EXCLUSION FROM STImY FOit 28 INFANt’S
Air Lock
Reason
---A(). lnfants
(‘out ml
---\o. Infants
Apparatus miot available 7 3
1\leehamiical failure 2
--Incorrect alternation 2 4
Immadvertemitly ex(’lu(led 5 3
925
TABLE VIII
MOUT.-% LITY RATES AMONG INFA NTS ExcLvnEn FROM STInY
1ir Lock (‘out rol
Nimitiher of imifatits 16 12
I)eaths 3 4
Over-all niortalitv rate 18.8% 33.3%
x2of (lifferemices for over-all immortality rates = .196.
l)ecaulse they were assigned incorrectly to
the air bock or to the Isobette#{174}. Finally,
after reviewing the roster of deliveries at
the Woman’s Clinic from October 5, 1953,
to Niarcil 16, 1955, dumring which time this
stu(IV vas in progress, it was foumnd that
10 infants who met the criteria for
inchut-sion had been inadvertently omitted from
the investigation.
Imi an effort to determine whether
omis-sion of these 28 infants from the stumdy
biased the results in any way, an analysis
of deaths was made in this groump. It was
found that among 12 infants who were
exebumded from the control groump, 4 deaths
occurred and among 16 exclumsions from the
air lock, 3 deaths oeeumrred. The mortality
rates of 33% amid
19%
for the control and airlock groups, respectively, are not different
(X2 = .196). These data are presented in
Table VIII. It is evident, therefore, that the
exclusion of these 28 infants did not
prejum-dice the findings among the larger groump of
143 infants.
DISCUSSION
Various claims have been macic
concern-ing the efficacy of the Bhoxsom air lock as a
resuscitator for newborn infants. Although
there is comisiderable disagreement aboumt
the physiologic concepts upon which the
a)paratums is based, some physicians are
enthusiastic as to its practical
umseful-ness. 2a, CC Others have questioned the
inter-pretation of the statistics which have been
pul)bished in StmI)port of its 21 The
pres-ent study was undertaken to evaluate more
critically and in a controlled fashion the
effect of tile air bock as a resumseitator.
The results indicate that exposure of
prematumre infants and infants delivered by
nonelective cesanian section in the air bock
for a prescribed 12-hour period does not
alter the mortality risk during or follow-ing the period of exposure. Thus, the
mon-tahity rate during the first 24 hours of life
among infants assigned to the air hock was
21% which does not differ significantly from
the rate of 16% in the control groump.
Simi-hanhy, there were not remote effects of the
apparatus in that over-all mortality rates, which included deaths after the first day
of life, were 33% and 25% for the groump in
the air hock and that in the Isohette,
re-spectivehy. Pathologic studies were carried
ouit on all but 1 of the 42 infants who died
and they revealed a similar incidence of
deaths dume primarily to respiratory
ab-normalities or anoxia in the air lock and control groups.
Ahthoumgh a precise evalumation of
ventiha-tony distress was difficult, serial
observa-tions of infants with obvious moderate to
severe respiratory distress was made. It
was apparent that improvement of 6 of 33
infants with respiratory distress while in the air lock occurred no more frequently
than among the control groump, where it
was noted in 7 of 25 instances. It would
appear that the air hock had no particumlar
therapeumtic merit in the management of
these infants with respiratory difficumlties.
The random placement in the air lock of members of a group of premature infants
with birth weights of 2 kg or less and a
group of infants delivered by nonehective
cesanian section differs to some extent from
its usual restriction to infants with
respira-tory distress secondary to maternal
anes-thiesia or analgesia, intra-umtenine anoxia or
the traumma of delivery. In order to
ehimi-nate factors of bias which might result from
the use of arbitrary criteria for respiratory
difficuilties, it was decided to include ahh
newborn infants in the aforementioned categories withoumt waiting for symptoms whiebl woumld require more than the umsumai
resumseitative measumres. This was vell borne
oumt by the pathologic stumdies which
pni-manly or secondarily from respiratory
ab-normahities, and included such causes as
llyaiine membrane, pneummonia, atehectasis
and anoxia.
In order to make conditions in the air
lock comparable to those prevailing in the Isobette#{174}, the umse of the former was further
modified in that the rate of flow of oxygen
was reduced to provide concentrations
be-tween 45 and
50%
and the relative humiditywas increased to 90 to 95%. There was no
alteration in the rhythmic pressure cycling. Becaumse claims for the efficacy of the air lock have rested largely on this barospiro-metric feature, it was felt that other
op-crating conditions in the air hock such as
oxygen concentration and relative
humid-ity shoumbd be kept comparable to those
maintained for the control group of
in-fants.
Among other advantages of the air bock
have been the claims of removal of fluid
from the infants’ lungs by the cyclic
pres-sure variations and improvement of
oxy-genation by absorption of oxygen through
the skin. The investigation of Apgar and
Kreiselman1’ showed that the air bock was ineffective in expelling secretions from the apneic dog’s trachea or in improving oxy-genation in these animals.
The claims of the clinical response of
some apneic, narcotized or cyanotic infants
to exposure in the Bboxsom air lock are of
some 2a61 C The reports of Lee12 and
of Wihson’ on the response of cyanotic in-fants to the Eve tilt table or the Drinker
apparatums suggest that rhythmic
stimumla-tion, regardhess of its nature, may, under
certain circummstances, improve respiration
or circulation. How effective cyclic
pres-sumne variations are in this respect may be
questioned in the bight of the absence of any effect on mortality rates or respiratory
distress as observed in this study. It is
pos-sible that other types of rhythmic
stimula-tion, such as that provided by the Rock-ette’#{176}or the tilt tal)he may be more
bene-ficial as respiratory and circumlatory
stimum-lants. This remains to be evaluated by
con-trolled stumclies in the fumture.
The sumccessfuml care of infants with
ne-spiratory distress demands attention to mi-nute detail on the part of the medical and
nursing staffs. All too often the availability
of such a device as the air bock furnishes
a panacea for the management of all
in-fants with respiratory difficumbty. It may at
times be sumbstitumted in place of a carefuml diagnosis of the nature of the difficumlty and for the umse of well established resumscita-live procedures sumch as providimig a clear
airway for the onset of respiration. The
inacessibility of infants in the air bock makes it difficult to follow their course with
repeated physical examinations and often
provides a false sense of secumnity that
“something is being done” for the baby.
These are definite and important
disad-vantages which we have encountered in the
use of the apparatus.
SUMMARY
A controlled study of the response of
premature infants and infants delivered by
nonelective cesanian section to exposumne in the air lock was undertaken. Seventy-two infants were placed in the air lock and 71
received the routine care in an incumbator. There were no significant differences noted in over-all mortality rates, in mortality rates
during the first day of life on in the mci-dence of relief of respiratory distress
be-tween the group of infants exposed in the air lock and those placed in the Isolette#{174}.
No evidence was adduced for the
effec-tiveness of the air bock as a resumscitator in this group of infants.
ACKNOWLEDGM
ENT
The authors wish to thank Dns.
Nichola-son
J.
Eastman, George W. Anderson andHarry H. Gordon, and the houmse staffs of
the Woman’s Clinic and the Harriet Lane
Home of the Johns Hopkins Hospital for
their assistance in carrying out this study.
REFERENCES
1. Bhoxsomii, A. : Resuscitation of the
new-bonmi infant.
J.
Pediat., 37:311, 1950.2a. Bhoxsom, A. : Newer therapeutic
ptmlmnomiam’v ventilation in the mle\vI)Ormi iimhtnt. j. Pediat., 45::37:3, 1954. 2b. \Vilsomi, j. L. : IC/oft. In discussion.
3. Bloxsom, A. : As1-)hyxia mmeonatontimii mmev
method of resuscitation. J.A.\i.A., 146:
1120, 1951.
4. Bloxsom, A., and Amigehique, Sister M.:
Neonatal imifant mortality; i)efore and
after the use of the air lock for the
treatment of newborn infants in a large
matermiitv hospital. Am.
J.
Obst., 67:647,1954.
5. Bloxsom, A. : The function of a recovery
nursery imi a large maternity hospital.
J.
Pediat., 38:618, 1951.6. Townsemicl, E. H. : The oxygen air
pres-sure bock I. Clinical observations on its
use during the neonatab period. Obst. &
Cvnec., 4: 184, 1954.
Towmisend, E. H. : The oxygen air pressure
hock II. Antiatebetatic action in the
neo-natal period. Obst. & Cvmiec., 5:678,
1955.
7. Zebenik,
J.
S., amid Prstowskv, H. : Astudy of 153 infamits placed in the
posi-tive pressure oxgen air lock. Am.
J.
Obst. & Gynec., 64:1.316, 1952.
8. Cordon, H. H. : Editoniah-Ox’gen
adminis-tration anti retrohental fibroplasia .
PEDI-ATmucs, 14:543, 1954.
9. Dunham, E. C. : Premature Infamits, 2nd
Ed. New York, Hoeber, 1955.
10. \Vinfield, T. H., and Ward, E. j. : The
intrimisic fetal mortality of cesanian
see-tiomi. Am.
J.
Obst. & Cvnec., 65:1276,1953.
-1 -1. Apgar, V., amid Kreiselmami,
J.
: Studies omiresumscitation . Au experimental
evalua-tion of the Bloxsom air lock. Am.
J.
Obst. & Gynec., 65:45, 195:3.
12. Lee, H. F. : A rocking bed respirator for
umse with premature imifamits imi
imicul)a-tors: a descriptiomi of apparatus.
J.
Pediat., 44:570, 1954.
1:3. Wilson,
J.
L. : 15th M & R PediatricRe-search Comiference-Respiratorv
Prob-hems in the Prematumne Infant. Columbums,
NI & R Laboratories, 1954, p. 44.
SUMMARIO
IN
INTERLINGUA
Studio
Controlate
del
Aeroclausura
de
Bloxsom
Imiter 195:3 e 1955 un studio controbate
es-seva execumtate al Hospital Johns Hopkins pro
determinar be valor de periodos de 12 horas de
expositiomi al aeroclausura de Bhoxsom como
medio resumscitatori in infantes prematur e in
imifantes nascite per non-elective section
cesa-m’ian. Un serie comisecutie de 14:3 casos esseva
alternate al basard() secummido Ic mmumeros
regis-tratori tid niatres. Scptanta-duo infammtes csseva
phaciate in Ic aerochausura e 71 esseva
sumb-jicite ah tractamento routinani in incubatores.
Un comparation del duo gruppos-stumdiate
se-cundo he distribution del sexos, del racias, del
comphicationes imi pregnantia e partunition, e
del lesiones pathologic de constatation
necrop-tic-demonstrava que un bomi grado de
com-parabilitate habeva essite attingite. Esseva
notate nuhle significative differemitias del
mor-talitate general, del mortalitate dumrante be prime
(lie del vita, o del incidentia de alleviamento
del amigustia respiratori inter he grumppo de
in-fantes expomlite dimrante 12 horas ah
aeroclaum-sura e he infantes placiate in un Isoletta.
Le imifantes (liii moriva durante Ic prime 24
horas hah)eva mortalitates grossier qume nomi
differeva sigmiificativemente inter he duo
grump-p05. Le mortabitate grossier del gruippo a
aero-clausura esseva 20,8 . Imi Ic grumppo de
Coii-trobo, illo esseva 15,5%. Quando be mortahitates
del prime 24 horas hi be duo gruppos esseva
referite al peso, be differentias esseva de novo
simi significatiomi statistic. Post Ic prime 24 horas,
Ic mortalitates in he dumo gruppos manifestava
simile conformationes. Amigustia
respiratori-demonstrate imi he comportamento del infamites,
cyanosis gemieralisate o periphenic, retractiones
imitercostal o suprachavicular o sul)stermial,
apmiea, 0 irregumbanitates del rhthmo respiratori
durante Ic prime 12 horas del vita-exhibiva immi
melioration de 1 8% in be gruppo a aerochausura
sed de 28% in he gruppo de controho. Iste
diffe-rentia es statisticamente mion significative.
Mor-tahitate per caumsas specific monstrava nuble
dif-ferentia frappamite de distnibimtion in Ic casos
del infamites qui moniva in be aeroclaumsura e in
be grumppo de controbo, jumdicate super Ic base
del constatationes necroptic. Umi plums grande
numero de imifantes habeva comistatationes
pathologic que indicava anoxia como causa
primani del morte in Ic grumppo a aenochaumsura
cjue iii be gruppo de controho. Isto vabeva pro
he prime die e pro be periodo sumbsequente.
Plure infantes qui satisfaceva he criterios del
presente studio esseva excludite a causa de
paminas mechanic del apparatura, de
alterna-tion incorrecte, 0 de errores del personal. Le
inclusiomi de iste casos norm haberea cambiate le
resuhtatos.
respiratoni requmire he plus striete e he plus
de-tahiate attention del parte del personal
medi-cal e infirmerial. Le aeroclausura non
repre-senta umi panacea pro be tnaetamento de omne
infamites con difficuhtates respiratoni. In certe
casos ihho pote prender be pbacia de un exacte
diagnose del natura del difficultate con
initia-tion de estabhite mesuras specific de
resuseita-tioti. Le inaccessibihitate del infantes in be
aerochausura rende difficile he survehiantia de
hon curso per medio (be repetite examines
ph’-sic e frequmentemente genera umn false 5tiS() de
secumnitate proqume “post toto, be infamite recipe omne he sobhicitude possibihe.” Istos es senie dis-avantages que nos ha miotate in Ic uso del aero-clausura.
Nubbe prova esseva trovate pro be efficacia del
aeroclausura como resuscitator in iste gruppo de infantes, e be assertiones de Dr. Bboxsom fool
