Influence of bulla volume on postbullectomy outcome

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O R I G I N A L

A R T I C L E

1 _{tstitrto di Fisiotogia Ctinica}

Influence

of bulla

volume

on

postbu

I lectomy

outcome

S Baldi wo1

, A Palla

MD2,

A Mussi

MD2,

F Falaschi

Mo3, L Carrozzi

MD2,

C Giuntini

MD2,

CA Angeletti

Ivto2

CNR,

2 Dipartimento Cardio Toracico,

3 Dipartimento di tmmagine,

Università di Pisa, Pisa, ltaly

S Baldi, A Palla, A Mussi, et al.Influence of bulla volume on postbullectomy outcome. Can Respir J 2001;8(4): 233-238.

OBJECTIVE: To quantify the contribution of the resected volume and the presence of associated, functionally signifì-cant emphysema to the postoperative improvement of pul-monary function after resection of giant lung bullae. DESIGN: Patients undergoing elective surgery for giant bullae who had had complete pulmonary function and radio--qraphic studies performed were reviewed retrospectively. SETTING: All 25 patients underwent surgery at the thoracic surgery unit of the University of Pisa. Pisa. Italy.

MITTHODS: Pulrnonary function was assessed befbre and l2 nronths afìer surgery. On the chest radiograph, the lclcation of bullae, and the signs of compression and ernphysema were evaluated. The radiographic total lung capacity lTLC'-.ay) and the volume of bullae were measured according to the el-lipse method. Postoperatively, functional iind ra<.lio-qraphic changes were analyzed. The percentage change in forced expi-ratory volume in I s (AFEV t7o) after surgery was the main outcome measure. The influence of factors related to em-p h y s e m a a n d b u l l a v o l u m e o n t h e f u n c t i o r r a l i m p r o v e m e n t postbullectorny was assessed by stepwise rnultiple regres-s i o n .

RESULTS: Before sursery, the TLC*-1xy overestimated the TLC measured by nitrogen washout, with a rnealj dil't'crence between the two measurements of 1.095 L. A close re lation-ship was found between the TLC*-ray lrnd the plethysnro-graphic TLC (n=6; r=0.95). After surgery. dyspnea lessetted ( P < 0 . 0 5 ) a n d F E V t i n c r e a s e d ( P < 0 . 0 1 ) . S t a t i s t i c a l l y . t h e radiographic bulla volume was the single most itnportant f a c t o r d e t e r m i n i n g t h e A F E V t7c (r-0.80, P<0.000l ) .

CONCLUSIONS: These findings suggest that the preop-erative size of bullae is the most important contributor to the improvement in ventilatory capacity after bullectorly. and that it is possible to predict the expected increase of postop-erative FEVr from preoperative bulla volume.

Key Words: Bullous errtpht'senut: Chronic: ohstructive pulmonurt

di,sease ; Otttt'ttnte : Rudiogrupltic bu||u v'o\uma : Srrlgen'

Incidence du volume des bulles sur les

résul-tats post-bullectomie

O I I J E C T I F : Quantifier I'incidencc du voluntc réséqué e t l a p r - é s e n e c d ' e m p h y s è n r e a s s o c i é , 1 < l n c t i o n n e l l e r n e n t s i g n i f i c a t i f s u r l ' a n r é l i t l r a t i o u d e s r é s u l t a t s d e I ' e r p l o r a t i o n l b n c t i o n n e l l e re s p i l a t o i r e a p r ò s la r é s e : c -l i o n c -l e b u -l -l e s p u -l m o n a i r e s g é a n t e s . P L A N D ' E T U D B : O n a p r o c é c l é ì r u n e ra m e n r é t r o s p e c t i f c l c s p l t r e n t s q u i a v a i e n t é t é o p é r é s p o u r u n e r é s e c t i o n n o n u r - s e n t e d e b u l l e s g t i a r r t e s e t q u i a v a i e n t s u b i a u p r é a l a b l e u n e e x p l o r a t i o n lì r n c t i o n n e l l e r c s p i r a -toire comple\te et des radiographies.

N T I L I E U : ' f o u s l e s p a t i e n t s ( 2 - 5 ) o n t é t é o p é r é s à l ' u r r i t é c l e s o i n s th o n r -c i q u e s d e l ' u n i v e r s i t é d e P i s e , e n I t a l i e .

METHODB : Il y a eu exploration fbnctionnelle respiratoire avant et l 2 m o i s a p r è s I ' i n t e r v e n t i o n c h i r u r g i c a l e . O n a é v i i l u é , s u r l e s r a d i o g r a -p h i e s -p u l m o n a i r e s , l a p o s i t i o n d e s b u l l e s . le s s i g n c - s c l e c o m p r e s s i o n e t I ' e m p h y s è n r e . L a c a p a c i t é p u l m o n a i r e t o t a l e 1CPTs1) à la radiographie e t l c v o l u m e d e s b u l l e s o n t é t é m e s u r é s s e l o n la t b r m u l e d e l ' e l l i p s e . L e s v a r i a t i o n s f o n c t i o n n e l l e s e t r a d i o g r a p h i q u e s o n t f ' a i t l' o b j e t d ' a n a l y s e s a p r è s l' o p é r ' a t i o n . L a p r i n c i p a l e m e s u r e d e r é s u l t a t s c o n s i s t a i t d a n s le s é c a r t s d e p o u r c e n t a g e c l u v o l u r n e e r p i r a t o i r e r n a x i n r u n r e n u n e s e c o n c l e ( V E M S ) a p r è s I' i n t e n , e n t i o n . A é g : r l e m e n t é t é é v a l u é e I' i n c i d e n c e d e s factcurs liés à l'emphysème et au volume des bulles sur l'arnélioration fbnctionnelle post-bullectornie à I'aide de la régression multiple graduelle. RESULTATS : Avant I'interventiorr. rl y a eu surévaluation. par la CPTnx.de la CPT mesurée par l'élirnination de l'azote; l'écart rnoyen était de 1.09,5 | entre les deux mesures. Une relation étnrite a été établie entre la

voir page suivante

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CPTRX et la CPT par pléthysmographie (n=6; r=0.9-5). Après l'inten'en-t i o n . o n a o b s e r v é u n e d i m i n u t i o n d e l a d y s p n é e ( P < 0 . 0 5 _{) e t u n e a u g m e n} -t a -t i o n d u V E M S ( P &l-t; 0 , 0 1 ) . S u r l e p l a n s -t a -t i s -t i c l u e . s e u l l e r , ' o l u r n e c l e s bulles à la radiographie s'est avéré un facteur intportant cl'écart dLr V E M S ( r = 0 , 8 0 ; P < 0 . 0 0 0 I ) .

C O N C L U S I O N S : L e s r é s u l t a t s c l o n n e n t i ì p e n s e r q u e la t a i l l e d e s b u l l e s avant l'opérution es1 le facteur le plus inrporlant cle I'arrélioration de la c a p a c i t é r , e n t i l a t o i l e a p r è s Ia b r - r l l e c t o r n i c e t c 1 u ' i l c - s t p o s s i b l e d e p r é r , o i r I'au-rrnrr'rrtatiorr clu VEMS après l'opération à pafiir dll t,olunte des hLrlles a v i t r t t l ' r l p c < r ' l r t i o n .

T n . s u r g i c a l r e m o v a l o l ' g i a r r t b u l l a e . i e . r h o s e o c c u p y i n g

T '

I rnore than one-third of the hemithorax on chest radio--sraph, improves dyspnea and airflow limitation (.1.2). There is little improvement in lung function for bullae that occupy less than one-third of the hemithorax and when lung func-t i o n is m i n i m a l l y im p a i r e d ( 2 , 3 ) . A l s o , th e o u t c o r n e i s p o o r in the presence of very low forced expiratory volume in I s (FEVI) with hypercapnia and cor pulmonale, unless com-pressed lung adjacent to a bulla is released by operation (4,5). Thus, the assessment of function in the nonbullous paren-chynla, which is expected to re-expand afÌer surgery, is also helpful in patient selection (6).

Previous studies support the use of pulmonary finction tests in patients with giant bullae to cletect those witlr tinction-ally significant emphysema and to predict their postoperative improvement (7-9). A reappraisal of the role of radiological techniques in the clinical assessment of emphysema has shown that the chest radiograph helps to identify patients with functionally significant entphysema ( 10). Furthermore, the radiographic method originally described by Barnhard et al ( I I ) for the determination of total lung capacity (TLC) also enables the volumetric analysis of discrete thoracic segnlents, and may be applied to the measurement of bulla volume.

ln the present study, we examined the reliability of the chest radiograph in quantifying the contribution of the re-sected volume of giant bullae to the postoperative recovery of pulmonary function in patients with and without func-t i o n a l l y s i g n i f i c a n t e m p h y s e m a . T h e s t u d y w a s d e s i g n e d t o i n v e s t i g a t e t h e r e l a t i o n s h i p b e t w e e n v o l u m e o f b u l l a . a s a s -sessed by Barnhard's method, and postoperative change in F E V r . C l i n i c a l , r a d i o g r a p h i c a n d f u n c t i o n a l p o s t s u r g i c a l results were also analvzed.

P A T I E N T S A N D M E T H O D S

Between l9l7 and 1994, 153 patients with radiographic evidence of unilateral or bilateral giant bullae underwent elective surgery for giant bullous emphysema at the Thoracic Surgery Unit of the University of Pisa, Pisa. Italy. Among them, 25 patients who had had cornplete physiological and radiographic studies were reviewed retrospectively. All of the pulmonary resections were performed through a unilateral thoracotomy under general anesthesia. When bilateral bullae were present, the hemithorax showing the largest bulla and/or radiographic signs of compression was operated on. Preoperatively and postoperatively, dyspnea was graded according _{to the British Medical Council Qr,restionnaire}( l2), and pulmonary function tests were measured according to standard techniques (13). Functional residual capacity was measured by nitrogen washout. In six of 25 patients, thoracic gas volume at end-tidal expiration was measured in a

con-234

stant r olume body plethysnrograph by panting at slow fie-qLrenc\ (approrirnately 0.5 Hz) against a closcd shutter. Carbon monoxide ditfusing capacity (Dco) was determined b y t h e s i n g l e b r e a t h t e c h n i q u e ( l4). All of-the n r e a s u r e d d a t a were expressed iìs a percentage of preclictecl values according to the respective reference equations. Refèrence values for slow vital capacity and expiratory flclw rates were derived f r o m P a o l e t t i e t a l ( 1 5 ) . F o r s t a t i c lu n g v o l u m e s o t h e r th a n vital capacity, the predicted values were derived from Gold-man and Becklake ( l6). For single breath DCo, the refèrence data of Cotes (17) were used. Also. the arterial tensions of oxygen and carbon dioxide were obtained. A chest radio-graph and a computed tomogriiphy (CT) scan. whenever available. completecl the investigation.

A stanclard 2 m focus-to-film distance was used. To re-duce rnotion artifact. the exposure time was kept as short as p o s s i b l e a n d w a s u s u a l l y w i t h i n 0 . 0 5 s . T h e k i l o v o l t a g e w a s adjusted to each patient's bocly build.

The chest radiographs were independently read by two readers - olre who was a chest radiologist and the other who was a chest physician. The reading file included the evalua-tion of unilateral or bilateral location of bullae, signs of com-pression (ie, mediastinal shift and/or herniation), and signs of overinflation and pulmonary vascular abnormalities known to be associated with ernphysemiì ( l0;. On the preoperative c h e s t r a d i o g r a p h , t h e r a d i o g r a p h i c T L C ( T L C * - r a y ) w a s measured and the bulla volume was calculated with the as-sumption that both were ellipticiil cylindroids according to the method of Barnhard et al ( I l). In the posteroanterior and lateral views. the outer borders of bullae were outlined with a wax pencil; on the posteroanterior view, the longest diameter of this area (height), and the perpendiculars fiorn this line to the furthest point to the lefi and right borders of the bulla, were measured. The surn of these two lines was used as the anteroposterior diarnefer; orì the lateral view, the longest possible line roughly perpendicular to the long diameter (transverse diameter) was traced. The measurements were comected for the clivergence of the x-ray beam by subtracting lo7o. The bulla volume (V) was calculated by the following equation:

V = lqn x transverse diameter x anteroposterior diameter x height

Also, in the l5 patients who underwent the exarnination, the hard copies of CT scans were analyzed according to the ellipse method (l l). The longest transverse and anteropos-terior diarneters were identified and measured. The height w a s c a l c n l a t e d b y s u m m i n g t h e t h i c k n e s s o f t h e s l i c e s i n which the bulla was visible. The radiographic and CT scan volurnes of bullae were then compared in this subset of pa-t i e n pa-t s .

Postoperatively. functional and radiographic changes

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Giant

bullous

emphysema:

Postsurgical

improvement

TABLE

I

Radiographic

qualilative evaluation,

operative

findings and surgical procedures

in 25 patients who underwent

elective surgery for giant bullae

Chest radiography qualitative evaluation Operative findings Signs of Overinflation plus Site and aspect

Patient Age (years) compression* vascular destruction of bullae Size of bullaet 1 2 3 4 E 6 7 8 I 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 20 2 1 22 23 24 25 1 7 27 6 1 77 48 69 4 1 54 4 b 42 45 O J 2 1 +z 37 40 20 47 66 43 59 6 1 32 60 47 s . _

;S ; S ; S ;

-

;S ; -S ; H S ; H S ; H S ;

-

;S ;

-

-;-S ; H S ; H

;S ; S ;

-

;S ; S ; S ;

-

-;-E E E E E E E E E E E E R U L , m u l t i p l e b u l l a e L U L . m u l t i o l e b u l l a e LLL, giant bulla R U L . m u l t i o l e b u l l a e L U L , m u l t i p l e b u l l a e LLL, multiple bullae R U L , g i a n t b u l l a L U L , m u l t i p l e b u l l a e R U L , m u l t i p l e b u l l a e R U L , g i a n t b u l l a RUL, multiple bullae

LLL, giant bulla R U L , g i a n t b u l l a R U L , m u l t i p l e b u l l a e R U L , g i a n t b u l l a R U L , m u l t i p l e b u l l a e R U L , g i a n t b u l l a R U L , m u l t i p l e b u l l a e L U L , m u l t i p l e b u l l a e L U L , m u l t i p l e b u l l a e R U L , g i a n t b u l l a R U L , g i a n t b u l l a R U L , g i a n t b u l l a LUL, giant bulla R U L , m u l t i p l e b u l l a e Operation Lobectomy Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Plication and packing

Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Plication and packing Plication and packing

Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Bullectomy Plication T T +++

îî

++ +++ ++ + +++ +++ +++ T

î

++ ++ +++ + T ++ T

î

++ + + ++ +

'Signs of comprcssion are tisted in the fotlowing odet: 1) mediastinal shift (S); 2) nediastinat herniation (H);tThe sizes ol bullae werc evaluated by the suryeon at the opening oÍ the chest: + Less than one-half oÍ the hemíthorax; ++ Greater than one-half of the hemithorax; +++ Hemithorcx. E Prcsence ol emphysema in peibullous parcnchyma; LLL Left lowet lobe; LUL Left uppet lobe; RUL Right uppet lobe

were analyzed. The percentage change in FEVr (AFEVrTo) after bullectomy was expressed by the following equation:

AFEVr% = (postoperative value - preoperative value) x 1 00/preoperative value

The relationship of the postoperative AFEV t%o withradio-graphic and functional measurements was investigated to predict the contribution of the resected volume of bullae, the compression signs and the several physiological indexes to the increase of postoperative ventilatory function.

Statistical analysis: The reproducibility of radiographic chest signs was evaluated by assessing interobserver varia-tion using Spearman rank correlation coefficients. For vari-ables scored in a dichotomous fashion (present/absent), the interobserver agreement was tested by means of the kappa statistic (18). The parametric paired r test and the nonpara-metric Wilcoxon's signed rank test were used to analyze dif--ferences before and after surgery. Stepwise multiple regres-sions of AFEV 17o wrth radiographic measurements of bulla volume, TLCx-13y, residual volume, FEVr and radiological signs of compression were derived to identify the predictors

of improvement in ventilatory function. P<0.05 was ac-cepted as indicating statistical significance. Data through-out the text are given as mean + SD.

R E S U L T S

Clinical and physiological assessments were obtained be-fore and at a mean of 12.1 months after surgery. There were 23 men and two women with an average age of 47 yearc (range 17 to 17 years).

Preoperative radiographic findings, operative findings and surgical procedures are listed in Table l. The surgical proce-dures, performed through unilateral thoracotomies. comprised bullectomy in 20 patients, plication and packing in four patients, and lobectomy in one patient. Three of the 25 pa-tients died due to respiratory failure at four months, one year and two years, respectively. Postoperatively, incomplete re-expansion with high hemidiaphragm occurred in one of 25 patients, and mediastinal herniation of the opposite lung oc-cumed in two of 25 patients.

Before and afier surgery, the chest radiograph readings were highly reproducible. When bulla dimensions were

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con-J

E

o

J F .g CL

g

U'

.9

t,

g

12000 10000 8000 6000 4000 2000 0 2000 4000 6000 8000 10000 12000 TLC N2-washout, mL

Figure l) Comparison of the radiographic' total lung capucitt' (fLC) (measured according to the method of Barnhard et ul fl ll) with the nitrogen washout TLC (TLC N2-washout) tech-nique (opert circles). Radiographic TLC overesîinntecl TLC Nz-washout (r=0.36, not signiJ'icant). The dotted line is the line of itlentin,. Tlte solid trfungles represeilt measurenrenfs (n=ó) obtoined by means of body plethysmography. The relationship be-tween radiographic TLC and plethv-smogruphic TLC is strong ( r = 0 . 9 5 , P < 0 . 0 0 1 )

sidered, Spearman rank corelation coefficients were statisti-cally significant (P<0.001 ). Values of kappa coefficients for variables scored in a dichotomous fashion (location of bul-lae, signs of compression and signs of emphysema) were also statistically significant (P<0.01). The average of the readings made by the two reviewers was used for the analyses.

On chest radiography, bilateral bullae were present in eight of 25 patients (32Ea).In these patients, the bullae con-tralateral to the operated side occupied less than one-half of the hemithorax. Radiographic signs of emphysema were present in 12 of 25 patients (48Vo), and signs of compression of peribullous parenchyma - ie, mediastinal shift and medi-astinal herniation - were present in 17 patients (68Vo) and five patients (207o), respectively (Table I ).

The TLC*-ray waS 1963+1322 mL. The radiographic vol-ume of bullae that were resected was I 448t159 mL (range 5 6 6 t o 4 1 8 1 m L ) . F i g u r e I s h o w s T L C x - r a y p l o t t e d a g a i n s t nitrogen-washout TLC (TLCN1-washour) and the line of iden-tity (r=0.36, not significant). Th; total lung volume measurecl by the ellipse method tended to overestimate the measure-m e n t s o f T l C p r - w a s h o u r . H o w e v e r , a c l o s e r e l a t i o n s h i p was founcl betwéen TLCx-ray ancl plethysmographic TLC (r=0.95, P<0.001) in the six patients who underwent this measurement (shown as solid triangles in Figure l).

Figure ? shows the close relationship between bulla vol-ume measured by CT scan and the corresponding value measured on the chest radiograph (r=0.79, P<0.01) in a sub-set of l5 patients.

In Table 2, changes in dyspnea and pulmonary function

236

Figure 2) Comparison of hulla volumes meas'urecl on chest rudio-graplt w'itlt tho.se meusurecl bt' thoracic computed lornogruph), (CT) scan (r=0.80, P<0.001) in a subset of I5 potients

TABLE 2

Ghanges (mean t SD) in dyspnea, tobacco consumption and lung function in 25 patients who underwent elective surgery for giant bullae

Dyspnea (grade)

Before After oq9l"t,on o3e11tion

1 . e ( 1 . 0 ) 1 . 0 ( 1 . 0 )

Pack-years 25 (19) 26 (20) NS Vital capacity (% pred) 95 (23) 101 (24) NS R e s i d u a l v o l u m e ( % p r e d ) 1 4 5 (6 7 ) 1 2 8 (6 0 ) N S FRC (% pred) 122 (35) 1 18 (39) NS Total lung capacity (% pred) 114 (16) 128 (17) NS Forced vital capacity (% pred) 81 (21) BB (20) Î FEVI (% pred) 57 (29) 67 (29) T FEVr/vital capacity (%) Dco (% pred) PaOz (mmHg) PaCOz (mmHg) 4 e ( 1 7 ) 5 6 ( 1 7 ) + 67 (26) 71 (28) NS 8 1 ( 1 2 ) 8 4 ( 1 4 ) N S 42 (4) 44 (5) NS *P<0.05 _{by Wilcoxon's}_{signed rank test;T}_P<0.05;+

P.0.01 . Dco Singte breath carbon monoxide diffusion capacity; FEVr Forced expiratory volume in 1 s; FRC Functional residual capacity;NS Not significant; % pred Percentage of the predicted normal value; PaCOz Afterial carbon dioxide tension;PaOz Arterial oxygen tension

tests afier surgery are reported. Dyspnea lessened signifi-cantly (P<0.05) and the percentage of the predicted normal value of FEV 1 increased signifìcantly (P<0.01 _).

T h e A F E V l T c w a s p o s i t i v e in a l l p a t i e n t s , w i t h t h e e x -ception of patient nunrber 19, in whom there was incomplete re-expansion with a hìgh hemidiaphragm postoperatively. In this patient, the AFEY to/o tellby 39c/o; this patient was not irì-cluded in the subsequent analyses. The AFEV to/o in the other 24 patrents was 34+31. J

E

qi

E

:f o

g

:'

.cl c aú o o F (J 4000 3000 2000 1000 0 1000 2000 3000 4000

radiographic bulla volume, mL

(5)

Stepwise rnultiple linear regression analysis showed that the AFEVIc/c was related mainly to the volume of bullae re-sected (Figure 3); the inclusion of additional variables such as preoperative arterial tension of carbon dioxide, residLral volume, FEV r, DCo, TLCx-ray and signs of compression did not significantly improve the correlation, which took the fol-lowing form:

-rFEVr% = -5.82 + 0.028 x bulla volume (mL)

On chest radiography, no new bullae were seen in the op-erated lung during the year of follow-up. The compression signs caused from bullae disappeared in all patients afier b u l l e c t o m y , i n d i c a t i n g d e c o r n p r e s s i o n o f ' t h e p e r i b u l l o u s p a r e n c h y m a .

D I S C U S S I O N

The results of the present study confirm that bullectorny irnproves dyspnea and airflow obstruction in patients with giant bullae. with or without the association of functionally significant ernphyserna ( 1,9.19-25).

The fìncling that the volunre of the resected bLrlla is statis-tically the single most important contributor to the LFEY f/c leads to the conclusion that a bulla contributes to airflow ob-struction that is reversible after bullectoÍny, independent of the presence of coexisting emphysema. Also, the relationship between AFEVr o/c and bulla volume may enable postopera-tive improvement in ventilatory function to be predicted with a simple and clinically useful formula.

The volurnetric analysis of bulla volurne was perforrned according to the method described by Barnhard et al ( I l) f o r d e t e r m i n a t i o n o f T L C . I n t h e p r e s e n t s t u d y . T L C x - r . a y tended to overestimate TLC5r-wnshout. The mean difference of 1.095 L is similar to a previously reported _{value ( l I ). This} difference is not surprising in patients who have between 566 mL and 4187 mL of gas trapping (26). Also, the TLCx-pny was closely related to plethysrnographic TLC (r=0.95) in six patients who underwent this measurement. Thus, our find-ings tend to validate the radio_qraphic rnethod for measuring both the TLC and the volurne of giant bullae.

Thoracic CT has been recognized as the method of choice to measure the total lung volurne (27) and the volunre of bul-lae (28) accurately, and to quantify emphysema in the non-bullous parenchyma (29,30). Thus. we believe it should be added to the preoperative functional evaluation of bullous emphysema. In the present study, we did not perform a densi-tometric analysis of CT scans because only the hard copies of CT scans from 15 patients were available to us. In the re-maining l0 patients. CT scans were performed at different hospitals.

Although the measurements from chest radiographs would have underestimated the presence of some small bLrllae (31,32) and subclinical emphyserna in nonbullous paren-chyma (30), our findings confirmed the value of the chest ra-diograph in the quantitative evaluation of well localized areas of compressed lung in giant bullous emphysema. Moreover, in the l5 patients who had a CT scan. we found a close relation-ship between the volume of bullae measured by the ellipse

Giant bullous emphysema: Postsurgical improvement

Figure 3) Lineur regre,s.sion analysis of'percentuge chunge in forc'ed e.rpiratrtrt yrtltune irt I s'(LFEVlclc)versus bullu yttlLune as'u.tses.setl

bt'g,eonrcf rir: rneu,surentent,s.from chest rttdiograph (ellipst'nteÍfuttl) itt 21 puriertts. I-lte re{r(,.t.\ion equuti()tt lr'rrs r'=--5.82+0.028"r, and tlrcre v'as u ,s'Íttti.stic'allr .:igrùfit'tutt corrclatiott t'oe.fJ-icient (r=0.80, P<0.0001). The open circle in bruc'kets refèrs to putienî nuntber 19, w'ho w'tts not included in the correlution bec'ctu.;e tf incomplete re-e rpu n s i rnt vt' i t h u lt i g h lt e t n id i a p h ru g m po.s t op e ru t i ve I t

method on both CT scan hard copies and chest radiographs ( r = 0 . 7 9 , P < 0 . 0 1 ) ( F i g u r e 2 ) .

C O N C L U S I O N S

W e f o u n d a p o s t o p e r a t i v e i n c r e a s e i n F E V l o f a p p r o x i -mately 20t/o over the preoperative value in patients under-g o i n under-g b u l l e c t o r n y . T h e e x t e n t o f i m p r o v e l n e n t r t r a y b e p r e d i c t e d b y m e a n s o f q u a n t i t a t i v e a s s e s s m e n t o f t h e c h e s t r a d i o g r a p h , w h i c h m a y b e o f p r a c t i c a l v a l u e w h e n e l e c t i v e surgery is under consideration for patients with giant bullous emphysema.

R E F E R E N C E S

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(6)

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