LUNG
VOLUMES
OF
NORMAL
AND
ASTHMATIC
CHILDREN
By John F. Andrewes, M.B., D.C.H., and Daniel H. Simmons, M.D., Ph.D.
Departments of Pediatrics, Medicine and Physiology, Universmty of California Medical Center,
and the Veterans Administration Center, Los Angeles
(Accepted Septemiiber 23, 1958; submitted June 17.)
Assisted in part by gramits from the American Heart Associatiomi and the Los Angeles County Timber-culosis and Health Association.
ADDRESS: (I).H.S.) Department of Medicine, University of California Medical Cemiter, Los Angeles 24, Cahiformiia.
PEDIATRICS, March 1959
507
LTHOUGH
the
measurement
of lung
voi-umes is an established clinical and
re-search tool in the investigation of
respira-tory disease in the adult, little use has been
made of it in the study of children. This is
unfortunate because such study might
well
throw light on the pathogenesis and
natural
history of lung disease, particularly chronic
emphysema.
Such neglect has probably been due to
the absence of reliable normal standards,
and this, in its turn, to the difficulty in ob-taming sufficient co-operation for carrying
out the older techniques. Since the
intro-duction of the closed-circuit helium-dilution
method of Meneely and Kaltreiderl and its use by Engstrom et al.2 in studying nor-mal children, these difficulties ilave
con-siderably decreased.
Using the open-circuit method of Darling
et al., Lukas4 investigated six asthmatic children between 11 and
16 years
of
age,
and Beale et included three children in
a larger series of adults. They found
con-siderable increases in the residual volume
(1W)
and
ftmnctional
residual
capacity
(FRC), and they observed improvements in
maximal breathing capacity and vital
capac-ity (VC) after the umse of bronchodilators,
sumggesting that a persistent, unrecognized
bronchial obstruction is, at least in part,
responsible for the hyperinflation of the
chest of the asthmatic subject.
The purpose of the present investigation
was to find out to what degree these
changes are present in a younger age group
amid to attempt to correlate these findings
witil clinical history. In addition, a number
of normal children were examined with the
object of comparing the values so found with those of Engstr#{246}m et al.’ as a
check
on the
present
method.
PATIENT
MATERIAL
The 21 asthmatic children investigated were from among those attending the Pediatric
Al-lergy Clinics of the U.C.L.A. Medical Center and St. John’s Hospital, Santa Monica. It was found that if a child was having even a mild asthmatic attack, high values for functional residual capacit’ and residual volume were obtaimied, and that evemi though bronchodilators reduced these valumes considerably, they still remained high and variable. It was the
inten-tion to study all the children of this series at a time when they were free of symptoms; some of the children with more severe asthma had
to be exelumded because they were never asvmp-tomatic omi an appropriate occasion. The only other factors involved iii the selection of pa-tients were their willingness, co-operatiomi and
availabihity.
The 27 miormal childremi, 6% to 13 years of age, were from the University of California Elementary School, except for a few children
attendimig the Pediatric Ciimiic for unrelated
condtions.
Four childremi with allergic rhimiitis were also
examincil.
METHODS
AND
PROCEDURE
The closed-circuit helium dilution method of Meneebv and Kaltreiderl was used. The appara-tus amid procedure differed only in detail from
that used by Engstr#{246}ni et al.2 amid will not be described here. The concemitration of the helium was recorded omi a kvmograph tracimig
throughout the procedure using the method
508 LUNG VOLUMES
Although helium was used as the test gas, the comicemitratiomis iii use
(
10 to 15) were not great enough to ehamige appreciabl’ there-sistamice to air flo’ through obstructed path-ways imi the lung.7
The volume of the apparatus was determined by addimig to the closed system increments of
oxygemi amid measuring the resuitamit
eomieen-tratiomis of oxygemi i)’ the Scholander technique
of
gas-amialvsis. This gave a volume of 3,476 ml (3,415 to 3,510 ml), imiehudimig the tubing to the mouthiu)iece.A total of thiree deterrninatiomis was carried out with each child. Iii seven of the asthmatic subjects audi two of the normals, the third determiiumiatiomi was carried out after the imihala-tiomi of isopropvi miorepimiephrimie spray, 1:400. This as adhmimiistered from a plastic nebuhiser
(Isuiprel NIistometer’-) designed to deliver a comistant dose-one delivery being given to each
child before examilimlation . Each determimiation was comicluded b’ encoumraging the child to
miiake a maximal expiratiomi followed
immedi-ately by a maximal imispiration amid another maximal expiratiomi. This was done because iii the asthmatic subjects there seemed to be coIl-siderable variatiomi iii the restimig endl-expiratory
position; a full inspiratorv excursion was de-sired from which to calculate the vital
Ca-pacitY. The secondi forced expiratiomi was to determimie whether air-trapping was occuirning.
The residual volume was calculated for each single determiiumiation b’ subtracting from the functional residumal capacit’ the correspomiding expiratorv reserve amid averaging the values.
In addition, the continuous plot of the
con-centratiomi of heliumn on the tracing was
meas-ured for the time takemi for the concentratiomi to fail half way to the final equilibriumm level,
be-ginning from the momemit it started to fall
(umsu-ally about 9 secomids after the patient was comi-nected to Use apparatus). This valume will be referred to as half-equilibration time (t%). Fig-umre 1 demomistrates how this appeared on the record in relation to the spirometer tracing and how t% was derivedl from it.
-J Id
‘I
Fic. 1. Cumrve of the decline in hiehitmni comicentration as recorded withi the kymograph. The ruled lines indicate htow the
RESULTS
Variation in Individual Determinations
For the purpose of tiiis analysis, instances where there was only one value for a given estimation were excluded. The calculation of the standard deviation of the values for
eacil imidividuial’s mean was carried out
umsimig the formula,
Most writers seem to agree that the
vari-ous lung volumes correlate best with the
third power8 or near the third power2 of
tile height. However, over the small range of observations of height recorded here,
these functions deviate little from straight lines, and for the purpose of this study it
was considered sufficient to derive simple
-
)‘ + (x, - X22 + . . . +(x-N-p-i
where N total number of determinations
and! p = number of children.
The results are given in Table I, where
it carl be seen that the variation between
tile two or three values for each individual is nuutchi greater in
tue
case of the asthmatic sul)jects thami for the normals; we believethat this rel)resents a real variation from momemlt to moment of the functional re-sidlihul ca)acity and resid!uai volume, though
it might be accounted for in part by
al)-normalities in dhistribumtion of gas.
Group A. Normal Children
This part of the investigation was
umnder-taken miot so mumch to obtain furtiler data
for statistical amialysis and! the contribution of amiother set of normal stamld!ard!s, but rather to determine whether the present
niethiods would give resumits comparable to
those of othiers. The nummber of cases is certainly insufficient for the former puirpose
hut adequate for the latter.
TABLE I
\uitmu’riox mx Ixm)lvmm)u AL h)ETEIuIINvrmoxs
Total
,
\ umber of \ umber of(/iildren Determmna-. tioiis Standard . Deem-lion \orma1s Functional residual
capacity 7 75 7 ml
Residual volume 6 73 80 ml
Asthmatics
Fumnctiom,al resi(lual
capacity 0 50 160 ml
Residual volume 0 50 158 ml
linear regressions. Values for functional residual capacity, vital capacity and total
lumng capacity (TLC) correlate well withl the findings of Engstr#{246}m et al.2 This is demon-strated in Figure 2 which shows the normal values for functional residual capacity with
the regression lines calculated from our data and from those of Engstrom et a!. and includes one standard error of the estimate
above and below the regression line. Our values for residual volume are slightly
greater than those of Engstr#{246}m et al. as
shown in Figure 3. This seems to be due to some extent to the inability of three
cliii-dren to demonstrate mucil expiratory
re-serve.
The values for RV/TLC and FRC/TLC are also slightly higher than those of Eng-strom et a!.:
RV/TLC 23.9% Standard deviation 4.5%
FRC/TLC 44.3% 4.7%
The time for equilibrium of gas to be reached during the determination of func-tional residumal capacity was from 2 to 4
minutes, and the value of t% from 11 to 21 seconds with a mean of 13.9 seconds and a standard deviation of 2.4 seconds.
During the washing out of an inert gas from a uniformly ventilated lung, its con-centration should fall off exponentially, and if the logarithm of the concentration is
plotted! against time, the result silotmid be a
straight line. When the results were treated! this way it was apparent that there was a
sudden change in slope after a time, sumch as might be expected from a two-compart-ment system. In such a system the washouts
independ-V
-1SD Engstrom
V
V V
‘Mean
Engstrorn
. .
2000
1800
1600
E
. l400
1200
1000
800
0 120
HEIGHT
(cm)Fmc. 2. Values for functional residual capacity (FRC) of normal children (Croump A) plotted agaimist height, together withi regression line amid standard error of the estimate of the regression equation for the present
data (solid lines) and those of EngstrOm et al.2 (dotted hines).
1000
900
800
130 140 150 160
S
S
E
U
> TOO
600
500
400
Mean Engstrom
SD.Engstrom S
_-#{149}
--
.---- - S
_---__.
---- SS
12G 130 140 ISO
1 60
HEIGHT
(cm)FIG. 3. Values for residual volume (RV) of normal childremi plotted against height. Regressions are shown
asthmatic
---normal
a) I
I
0 0 -J
‘S
- ‘S
‘S
\ \\
- #{188}
S
#{149}‘
-\
#{149}\
\
S
0
o \O
0 60 120
I I I
-
______
TIME
(sec) 180I I I 1
_____
240 300
ARTICLES
Fic. 4. Plot of the logarithm of the dechimie in concentration of hehiumni (the concentration at time t minus the concentration at time of final equilibrium) against time t for two normal children and two asthmatic
children, showing the biphasic character described in the text.
ent exponential curves. This is shown in Figure 4 where the logarithm of helium
concentration at time t minus helium con-centration at time of final equilibrium is plotted against t, the time from the moment the helium concentration began to fail. This
biphasic character has been observed in
open-circuit washout curves 9,10 and in the
closed-circuit helium method.hu The signifi-cance of this is discumssed by these authors, who considered that the hatter part of the curve represented the washout of a “poorly ventilated space.” Others,12 using an open-circuit method, have demonstrated
single-component washotmt curves with women and children, and suggest that the two-component curve described here is a char-acteristic of results obtained from a closed
lung-spirometer system which incorporates
a comparatively slowly reacting
katharom-eter. This would account for the fact that
a biphasic curve was obtained from both normal and asthmatic subjects, and means that no conclusion can be drawn as to the presence of the “poorly ventilated space” in either group.
No correlation was observed between the
values for t3 and height, any of the lung
volumes, or volume ratios, althoumgh a
re-lationship to initial volume of the spirom-eter to that of the lung should theoreti-cally exist. Any increase in t% as a result of increase in residual volume or functional
residual capacity due to greater height
512 LUNG VOLUMES
* For abbreviatiomis iii Tables see text. t Allergic rhinitis.
Group B. Asthmatic Children present throtmghout the age ramige stuldiedi.
Findings in this group are presented in The increase in residlumal volume was ac-Table II, and tile changes are demonstrated companied by a decrease in the expiratory in Figures 5-9. In addition to the lung vol. reserve but not necessarily by a change in ummes plotted against height, the regression functional residumal capacity so that, in germ-line derived from the data of the normal eral, the changes in residlumal volume were
groumi is shown together with one standard more striking than those in the fumnctional
error of the estimate above and below the residual capacity. This is more apparent in
regression equation. the chamlges in volumme ratio to be discumssed.
FUNCTIONAL RESIDUAL CAPACITY AND VmTAL CAPACITY: Althoumgh most of the
RESIDUAL VOLUME: A considerable increase resumits fell iml the normal range, five chil-in both of these values over the normal was dren had! grossly d!iminished vital capacities
TABLE II
RESULTS \ViTII ASTIIMATI(’ (iIILmnmEN
lslhmatic, -
,
,
,
ItL’/ FR(/, Age height (* RJ iR( fL(
(ase No. (rroup FL( TL( 14 (see)
(yr) (cm) (ml) (ml) (ml) (ml)
I) /o) 7o
1 K.K. 64 123 1,214 7t7 1,065 1,941 37 55 13
2 1)13. 74 P21 1,570 1,065 1,704 ,635 40 65 19
3
.u;.
8 132 t,117 8’23 1,359 ‘2,94() 8 46 154 .J.s. 81 17l 1,718 785 1,27() ‘2,503 31 51 15
5 MO. 9 1354 1,127 1,179 1,561 .?,306 51 68 II)
6 Ml!. I) 136 ,476 8t’t 1,474 3,utOS 5 45
7 LN. 9 138 ‘2,01() 767 1,32I) ‘t,777 8 18 H
8 P.K. #{190} 137 ‘2,43() 1,003 1,709 3,433 :.?I) 50 16
9 .J.M. 10 H5 1,657 1,368 1,741 3,05 45 58
10 $.C. 10 127 1,758 898 1,437 t,656 34 54
11 R.M. 10 13’2 1,614 616 1,147 ‘2,6(I t9 51 13
H A.F. 10 141 1,994 582 1,16 ,576 .H 17 11
13 CS. 104 14() 2,106 1,411 ‘2,067 3,517 40 59 18
14 KG. 11 1384 1,87u2 734 1,431 2,6()6 ‘28 55 16
15 I.S. H 154 1,1)33 1,795 ‘2,’287 3,7t8 48 61
16 A.L. lut4 1424 1,091 2,0u5 ,33() 3,116 63 75
17 ,J.V. 13 153 2,608 1,398 2,496 4,006 35 6’2 21
18 11.0. 13 160 3,445 1,127 2,0I)5 4,57t t5 46 19
19 .LL. 13 161 3,115 1,818 ,956 4,933 37 60
2() M.S. 14 146 1,406 2,O4I ,300 3,450 59 67
21 B.M. 15 159 1,849 1,768 28() 3,617 49 63
Mean values for asthmatics Mean values for normals
37 .4 23.9
56 .5 44.3
19.1 13.9
Miscellan-eons,
Gronp C
MS. S H4 1,536 776 1,2l9 2,312 34 53
‘23 RB. 7 1344 ,04S 7’23 1,118 ,771 ‘26 40 16t
,4 A.B. 10 149 u,24I) 716 1,39() ,I)65 i4 47 16f
5 (‘.N. H 1464 2,31S 1,554 ,319 3,872 40 60 lOt
ARTICLES
#{149}
Normal
o Asthmatic
0
0
000
0 0
0
U
0
0
28 - 0
24
20- S 0
S
6 - S 0 550
S 500
- S SS
S S 0SSS
2 - 55 5 5 c
S S
500 1000
RV
(cm)1500 2000
Fmc. 5. Plot of t against residual volume (RV) for normals (Group A) and asthmiiatic subjects (Group B). The values for time asthmatic subjects are correlated iii a roughly linear fashion, while those for the
normiials seemii to have no such relationship.
-children who also had! considlerably in-creased! residumal volummes.
TOTAL LUNG CAPACITY: Most of the vahimes for total lumng capacity fell withimi the expected normal range, but taking the groump as a vhiole, there was ii significant
imicrease in this measurement as compared to the normal groump. (p < 0.01, using
niethod of analysis of covariance).
VOLUME RATIOS:
RV/TLC 37.4% Standard deviation 11.7%
FRC/TLC 56.5% 8.4%
Both of these valuies are statistically
differ-ent from tile normahs (p < 0.01). The in-crease in RV/TLC over normal was greater than the increase imi FRC/TLC, being 56% and 27% highier than tile average normal ratio, respectively. A greater increase in residumal volume than in functional residual
capacity was previously noted.
INTRAPULMONARY MIXING OF GASES: The
time taken for equihibrium of the gas to be
reached was from 4 to 8 minutes. The
valumes for t% varied! from 13 to 28 seconds with a mean of 19.1 seconds and a standard deviation of 4.6 seconds. This represents a significant increase over the valumes obtained
in studies of the normal children (p 0.01). The value for t% seemed to depend on
many factors and in particumiar on the rate
and depth of respiration whicii in turn de-pended on the state of excitement of the child at the time. The respiratory rate of most of the children was about 18/mm, but some would ilyperventilate at the start. The figure of 28 seconds was obtained from a child with very slow respiratory rate (9/mm) and prolonged expiration with trap-ping of air.
0 asthmatic (GpB)
S miscellaneous (Gp C)
0
0
0 S 0 0
0
0
0
0
0
0 0
3000
2500
- 2000
U-500
000 I30 140 150 60
HEIGHT
(cm)F.c. 6. Values for fumnctional residual capacity (FRC) of asthmatic children (Group B) amid others (Group C) plotted against height, together with the regression line and the standard error of the
estimate of time regression equation calcumlated from data for normal children.
0 asthmatic (Gp B)
2000 - S miscellaneous (GpC) 0 0
0
0 0
S
500
-0 o
E 0
U
>
0
0
0
000- 0
20 130 140 150 160
HEIGHT
(cm)0 asthmatic (GpB)
Smiscellaneous (Gp C)
0
0 0
0
0
0
0
0
130 40 50 160
ARTICLES
E
U
U >
3500
3000
asoo
2000
500
000
120
HEIGHT
(cm)FIG. 8. Values for vital capacity (VC) of Groups B and C, with regression lines for normal children.
seemed to he some relation between t3 and
iumng volummes or volume ratios. This was to
be expected because the increase in lung
volumes of an asthmatic subject is
inde-pendent of height, and the consequent
in-crease in t3 is not compensated for by in-creased ventilation. In fact, it is increased further as a result of disturbed
intrapul-monary mixing. This relationship was most
marked between t3 and residual volume
(Fig. 5).
Semilogarithmic plots of the washout curves on two of the asthmatic children are
shown in Figure 4. These demonstrate the same type of biphasic curve as the normals,
the only difference being the slower
equili-bration rate, both phases of the process seeming to be delayed to the same extent.
No conclusions are made as to the signifi-cance of this at the present time.
Group C. Patients with Allergic Rhinitis, etc.
One girl with allergic rhinitis (C.N.) but
the asthmatic children in the series, was examined and showed a considerable in-crease in residual volume and functional residual capacity, but no evidence of
pro-longed expiration or air trapping. This prompted us to consider whether, in allergic
rhinitis, there is another significant factor
in the development of emphysema.
Conse-quently, three additional children with
al-lergic rhinitis were studied; these were nor-ma! in every respect.
One other child (M.S.) who could not be
included in either Group A or Group B
was an 8-year-old boy, supposedly normal, but who tended to wheeze on rare occa-sions with respiratory infections. The func-tional residual capacity and residual
vol-ume were above the normal range and the RV/TLC ratio was 34%.
Effect of Bronchodilators
0 asthmatic (Gp. B)
S miscellaneous (GpC)
0
S
0
0
0
130 40 ISO 60
HEIGHT
(cm)516 LUNG VOLUMES
E
U
U
-J
I-5000
4000
3000
2000
120
FIG. 9. Valumes for total lung capacity (TLC) of Groups B and C, with regression lines for normal children.
be to diminish the fuinctional residual
capac-ity and residumal volume. That this occurs during the acute attack is well known,1 but this has never been clearly
demon-strated in quiescent periods. Unfortunately,
we were somewhat overcauitious in dosage
of isopropyl norepinephrine, and there was
a marked decrease (more than 200 ml) in
only two of the seven asthmatic children so
stuidied. Fumrther, one of the two normal childremi demonstrate! as great a decrease. A more extensive stuidy of normal children
should be undertaken before any conclu-sion can be drawn.
Correlation with History
The history of the asthmatic child is, of course, one of episodes of exacerbation and remission, severe short-lived attacks or pro-longed mild wheezing, and it has proved impossible to find any kind of numeric
fig-ure (e.g., length of history or frequency of
attacks at the time of examination) whichi
would correlate with the findings. However,
consideration of the cases individumaily leads
us to believe that the lung volumes are
more dependent on the state of the asthma at the time of examnination than on tile past history. It seems likely that this is truer in
the pediatric age groump than in oldler
mdi-viduals, wilere changes have becomne
irre-versible. This can best be demonstrated by
consideration of the case histories.
Case 2
CASE
REPORTS
D.B., a 73-year-old girl, was well until the
age of 53 ears when she began to have
fre-quent nasal discharge and smieezing imi the suim-mer and fall. At 63& years of age, after an
at-tack of whooping cough, she began to have
nocturnal attacks of wheezing and coughing.
517
TABLE 111
REsULTS IN (ksE i
L
S
lit II
-
II’
i’m I
I
,1
started on hvposensitizatiomi and was still hay-imig frequemit attacks (Table III).
These findings vere grossly abnormal amid were comisistent with an active asthmatic process.
Case 12
A.F. , a lO-vear-okl girl, hiadl frequemit
respira-tory imifections diuring earh chi hdhhiood
umi-affected b a tonsihhectoniv at 3 ears of age. At ears of age she developed dermiiatitis of the hiandls amid begami to have attacks of
coumgh-imig, w’heezing audi occasn)mial voniiting about two to three timnes a month. History (flidi skin
testimig sumggested allergies to certain pollemis
and foods.
She hadl beemi receiving pollemi hvposensitiza-tiomi for 2 years. Durimig the last year she had
Obser,’ed
‘
Iahmies
1’ /) ‘ 1
.lfler
In/ia-#{149} lation (If
,
I5O/)ropyl .\
or-epinephirine
Expected
‘5ormal- Ranqe.. (9.7 (1)iifl-dence limits)
FRC I,701 1,330 5(15)- 1,30()
RV I 065 474 300- 700
\-c I,570 1,t)6.? S5() i,000 TLC t ,o1s _),436 1 3(H)- 7(H)
R’/TLC 40% t0% 15-33
ti II) secomm(ls 9-19
Spirograrn : slightly proloimge(I expiration vitlm no air-trapping.
Fmc. 10. Spirograms niade in two of the cases discussed. Time position of the resting, emid-expiratory position (horizomital hue) is used in calcumlating the fuinctiomial residual capacity. The record of subject A.F. is normiial; that of SIml)ject P.S. shows prolonged expiration
518 LUNG VOLUMES
TABLE IV
RESULTS IN CASE H
,
Obserred I ahmies (ml)
Expected Normal Range
.
(9.1% confidence lmmmts)
(ml)
FRC 1,16 900-1,700
RV 5S2 450- 900
\‘C 1,944 1,650-2,80()
‘I’LC t,576 2,l50-3,600
RV/TLC ‘i’.i% 15-33
t4 14seconds 9-19
Spirogrmum : Nornial.
Effect of isopropyl norepineplirine-little change (
Ex-amples of spirogranms are showim iii Fig. 10).
beemi almost symptom-free except for two or three attacks during the 2 months before the studies. These findings are all within normal limits and substantiate the impression of clini-cal improvement (Table IV).
Case
15
P.S., a 12-year-old boy, was attending the clinic for psychiatric reasons amid not in connec-tion with asthma.
At 4 months of age he had developed atopic dermatitis which responded to dietary manage-ment. From 2 to 7 years of age he had attacks of asthma about every 2 months. At the time of these studies he had been free of asthma for 5 years except for one severe attack 33 months previoumslv. Physical examination on one
occa-sion 3 weeks previousis’ had revealed a few high-pitched rhonchi. Roentgenograms of the chest showed “mild peripheral emphysema
con-TABLE V
ltEsuTLTs IN CASE 15
Obserred Values
( 1)
m
Expected Normal Range
.
(9.1% confIdence 1mmits) (ml) FRC RV Vc TLC ‘2,287
I,795 1,933 3,7R 1,’00-2,O00 600-1 ,000 ,100-3,30O 2,S0O-4,100 RV/TLC t4 48% seconds 15-33 9-19
Spirogram: Greatly prolonged expiration with
air-trapping.
sistent with chronic asthma.” Results are shown in Table V. The residumal volume and functional
residual capacity were defimiiteiv imicreased amid
the spirogram sumggested the presence of
bronchospasm.
DISCUSSION
AND
CONCLUSIONS
It is apparent from these findings thiat the imicreases in functional residumal capacity
and residlual voluime that have been
re-ported in adumits and older children can occur as early as 63 years of age amid after
asthmatic histories as short as 6 montlls
(Case 2). We prefer to call this change
hy-perinfi :ition rather than emphysema, and
reserve the latter term for an irreversible
degenerative change in the lummlg structure. That this ilypermfiatiOn is reversible is in-dicated by the following: 1) the slight
van-ations in degree from moment to nioment
discumssed above; 2) its diminumtion in some
cases in response to bronchodilators; 3) the
finding of normal valumes in patients who have been symptom-free for some time or
whose asthma is largely under control.
Because the decrease in fumnctional
resi-dual capacity and residumal volumme as a re-suit of inhalation of bronchodilators was a
variable finding, we cannot at the present time suibstantiate our belief that the
hyper-inflation is a direct consequmence of the presence of bronchial obstrumction. Humrtado
and! Kaltreidlerl1 describe an adult patient
in whom the residual volumme dlecreased dramatically d!umring an asthmatic attack with the administration of epinephnine, but no change was demonstrated when he was
subsequently given epinephnine during a
symptom-free period. It is possible that
while tile hypeninflation in children is due to bronchospasm and is reversible, that in the older patient it is to a greater extent due to structural change. The presence of
hypeninflation in two cases in Group C
could be accouinted for on the basis of a mild unrecognized bronchospasm, such as
might vell occur in cases of allergic rhini-tis.
519
had been present hut unrecognized for the
last 5 years, and if it were as severe as the
spirogram and prolonged time for mixing
of gas suggest, then we would expect him
to have had an even more severe degree of
hyperinflation than we in fact found. A
more probable explanation would be that
he ilad been suiffening a relapse for 4
months.
In conclusion, the chest of a child ap-pears to respond to the asthmatic process
by an increase in functional residual
capac-ity and residumal voluime, the increase in residual volume being the most marked.
This response is a sensitive one and may be
brought about by clinically unrecognized
bronchospasm and may be reversed with the patient’s recovery from asthma. What
part these changes play in the development of emphysema is uncertain, but a
longitudi-nal study with periodic measurements of
luirig volume of a number of normal and
asthmatic children might be revealing.
SUMMARY
Measurements of the various lung
vol-umes were carried oumt with 27 normal chil-dren, 21 asthmatic children and 4 with al-lergic rhinitis. The asthmatic children had
increases in functional residutal capacity
and resid!ual volumme.
There was a significant increase in the
time required for intrapulmonary mixing of
gas in the asthmatic subjects.
A biphiasic character to the “wash-otmt” curves in both normal and asthmatic sub-jects was shown.
It was consid!ered, though not proved,
that the increases in lung volume were due
to the presence of bronchial obstruction.
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