Changes in pulmonary function after bullectomy

Changes

in Pulmonary After

Function

Bullectomy*

S. F. BOUSHY, M.D., D. M. BILLIG, M.n.t ano! R. KOHLN, M.D.

Houston,

Texas

The results of changes in pulmonary function after bullectomy are reported in fifteen patients, eleven of whom had bronchospirometry. Changes toward normal occurred after operation; however, these were slight except when the bullae occupied most of a hemithorax, and even in these patients not all tests showed improvement. This is in contrast to the consistent improvement in dyspnea observed in patients with significant symptoms prior to operation. Postoperatively, maximum static negative intrathoracic pressure increased, the elastic work of breathing increased and the nonelastic component decreased, residual volume decreased, forced flow rates and seven minute nitrogen washouts returned toward normal, and airway resistance decreased when it was elevated preoperatively.

MPRovEMENT in clinical symptoms after bullectomy have not been reported to accompany similar improvement in pulmonary function studies consistently [I-?]; however, changes in function toward normal after bullectomy have been recorded and occasionally such changes have been spectacular [4]. For the most part previous reports included a limited number of tests in each individual patient. In this report we analyze the studies performed before and after bullectomy in fifteen patients, and in eleven this included bronchospirometry. The clinical data, with limited function studies, have been reported previously [5], with the exception of one patient operated on since then.

(TLC) were measured by the closed circuit helium method. Diffusing capacity for carbon monoxide (DLCO) was measured by the single breath method. Esophageal pressure, flow and tidal volume were recorded simultaneously, and compliance was measured at points of zero flow. Pulmonary resistance was measured at mid-inspiration and mid-expiration. Maximal static negative intrathoracic pressure (MIP) was recorded after full inspiration. The work of breathing was calculated from pressure volume loops recorded on an X-Y recorder. Arterial oxygen and carbon dioxide tension (PO, and PCO,) were measured with their respective electrodes. Bronchospirometry was carried out using the Gaensler-Collins bronchospirometer. All function studies were performed shortly before and two to four months after operation. In ten patients a second postoperative study was carried out one to two years after the first postoperative study.

I

METHODS AND MATERIAL Studies before the first operation and after the second operation are recorded. The data were paired prior to analysis, and the dependent “P” value was calculated [6]. The methods have been described in detail previously [7,8]. Vital capacity (VC), forced expired volume in one second and max(FEV,) J maximal mid-flow (FEF,,_,,) imal voluntary ventilation (MVV) were measured from recordings on 13.5 L. Collins spirometer. Residual volume (RV) and total lung capacity

RESULTS Changes in function studies in three cases are illustrated in Figures 1 and 2. In two patients the postoperative studies showed the FEV, to be within normal limits; in the third it was severely reduced, indicating severe obstructive pulmonary disease. Thus, Figures 1 and 2 illustrate the changes in two patients

*From the Veterans Administration Hospital and Baylor University College of Medicine, Houston, Texas. Requests for reprints should be addressed to Dr. S. F. Boushy, Pulmonary Function Laboratory, Veterans Administration Hospital, 2002 Holcombe Blvd., Houston, Texas 77031. Manuscript received January 23, 1969. tPresent address: New England Medical Center Hospital, 171 Harrison Avenue, Boston, Massachusetts. 916

AMERICAN

JOURNAL

OF

MEDICINE

C

H

A iUNcl

VOLUME:; 0

Normal

ka Pre-op

c E

E‘K,. 1. Changes in lung volumes after I~ull~~ctorn~ ax illuctmtctl ill th>cc patients. The bullac in patient 4 occupied moj-e than 90 per cent of the I-ight hemithorax (Fig. 3) ; in patient B the bullac~ occupied 50 per cent of the right hemithorax; and in patient C it occupied 30 per cent of tlw right henrithorax.

A

C

B FORCED

FLOW

RATES

(FEV,Ol

0

Normal

q Pre-op

INSPIRATORY

MAXIMUM

NEGATIVE

PULMONARY

RESISTANCE

INTRATHORACIC

PRESSURE

FIG. 2. Representative function studies in the same patients 1. Patients A and C had normal FEV, after operation. \<>I.

47,

DFCEMRI-R 1969

shown

in Figure

30 30 70 40 difference

260 130 270 220 27511 -1 40 II

-1,115 - 1,222 316 190 53411

12 10 2

13 9 1 5 10

!I

219 - 1,908 -1,422 167 _ 323

35 15 45 40 22

10 15 20 7

-1

751 682 64 817 469 910

10 32 154 91 99 28

2 5 22 18 20 4 -

(CC.1

(L./min.)

Xl00

TLC

Fl?FZ.?j

VC

FEVl

-

-

-

_

-

664 800 270 1 62211

1,063 689 870 230 1,275

1.3 2.5 -6.7 -2.5 -0.6

per

2 4 17 3

-20

to incrc;tse

-4.40 -1.83 4.01 -2.16 -2.8511

Nornzal-Less

-13 5 2

. .. : : :

-1.3 0.8 FEV,.o%

19 7

Norllzal~

2 19 12 -11 4 2

Hg)

(mm.

PO?

1.26 -5.41

FEV,.s%

:9.96 -7.44 -3.75

-1.38 -0.29

N?““%,$

7 min.

I

9 1 1 9 4 6

500

-

-

-0.011 0.007 . . .

0.027 -0.017

2 3 3 4 2

cc

0’00s’ --O.OOR -0.027 0.003

than 50

-18 1 91 11

0.015 0.020 0.009 0.002 0.035 0.017

.

-4

61

2 8 0

17 2

17 5 18 1

6

HnO)

(cm.

MIPS

BULLECTOMY

pliance

Com-

Specific

AFTER

-50 to 70

-

-

Hg)

(mm.

PC02

OF CHANGE

TABLE

-0.2 0.8

-0.2 0.3 -1.3 -2.0 0.5 -0.2

750 RVt

(cc.)

725 1,553 1,120 660 387 481

SBNn

RV

AND QUANTITY

* Expressed as per cent of hemithorax. t Single breath nitrogen washout. Per cent nitrogen inct-ease 750.RV converted $ Per cent nitrogen in alveolar air at end of seven minutes of breathing oxygen. D Maximum negative static intrathoracic pressure. 11Significant at 5 pzr cent level.

12 13 14 15 Mean

451 422 586 189 92

270 199 450 100 -220

-

1,282 1,219 522 63 952

40 30 40 30 30

7 8 9 IO 11

-

100 80 1,610 610 450 0

26 891 1,056 157 82 429

30 20 90 30 30 30

1 2 3

z 6

(cc.)

(cc.)

Bulla*

FEV1.o

No.

vc

of

Case

Size

DIRECTION

-0.002 0.004 0.007

ioo;

.

0.017 0.017

0.001 -0.014 -0.009 0.007 0.014 0.031

Elastic

0.00;

-0.059 0.010

0.019 -0.008 -0.009 -0.013 0.018 0.013

elastic

iAd

-0.053 0.009

0.016 -0.011 -0.012 -0.004 0.016 0.029

Total

-0.047 -0.003 -0.005

Breathing M./L.)

Non-

of

-0.047 -0.005 -0.007

km.

Work

.. -2.1 -4.5 0.1 -0.9

4.8 -12.1 0.3 2.2

...

0.1 0.6 1.1 1.3 0 1 8.8

tory

Expira-

0.2 0.1 -0.7 -0.2 0.9 -0.3 -

tory

Inspira-

HzO/L./sec.)

Resistance (cm.

RV

-55t

-2 -9

--_’ -3 -16

-16

-3 -16 -6 -3 -4

TLC

1

I

2

8

x 100

DLCO

-1

-2 -1

-10

-9 -7 -1

-2

/mm.

2

0

5

1

4 2 4 0

Hg)

(cc./min.

‘I. 1~1.oncI,ospi~ot~~etric tracing of tlie SJIIIC patictlt shawl in Figure 3. ‘lhr bpacc IJetweCn the horimntal lines represents 1 I.. The space between the Lcrtical lines rrprcsents one minute. ‘l‘here was market1 improvement in oxygen uptake and wntilation after operation. 1;lL.

Pulmonary

920

Function

After

Bullectomy-Boushy

et ~2.

TABLE II CHANGESIN FUNCTIONTESTS

AFTER

BULLECTOMY

RELATED

TO

DURATION

AFTER

OPERATION

24 Months After Operation

14-26 Months After Operation

Test

No. of Patients

Mean

S. D.

Mean

Specific compliance MIP (cm.H,O) Work of breathing (gm.M./L.) Elastic Nonelastic Total Resistance (cm.H,O/L./sec.) Inspiratory Expiratory RV:TLC x 100 DLCO (cc./min./mm.Hg) FVC (cc.) FEV,., (cc.) FEV,., -xl00 FVC FEF,,_,, (L./min.) TLC (cc.j RV (cc.) SBN, 750-RV 7 min. N, PO, (mm.Hg) PCO, (mm.Hg)

9 8

0.038 28

0.012 12

0.046 25

0.015 9

8 8 8

0.020 0.038 0.046

0.010 0.023 0.021

0.013 0.053 0.056

0.009 0.028 0.026

9 9 IO 10 10 10

2.48 3.90 47 23 3,255 2,210

1.10 2.27 10 800 843

3.79 5.05 43 24 3,575 224’3

1.55 2.16 8 4 975 845

10

66

15

61

15

10 10 10 9 8 10 10

115 6,003

64 1,356 1,038 2.23 3.75 12 3

105 6,369 2,764 3.29 4.83 81 38

57 1,451 829 1.26 7.54 9 3

NOTE:

For explanation

of symbols refer to Table

2,921 3.70 3.41 78 40

s. D.

I.

ment in all tests. In some tests there were marked changes toward normal; in others there were no changes. The one patient with the most marked improvement (Case 3) had bullae that occupied over 90 per cent of a hemithorax (Fig. 3)) and preoperatively his bronchospirometric data showed significarrt impairment in the function of the right lung (Fig. 4). In ten patients pulmonary function studies were performed on two occasions after bullectomy, the first two to four months after operation and the second one to two years later. These studies showed slight change during this interval in the group as a whole (Table II) . The bronchospirometric data are summarized in Table III. The side of the bullectomy contributed less after than prior to the operation to the total ventilation, oxygen uptake and vital capacity. Exceptions to this are illustrated for one patient (Fig. 4) who had bnllae occupying 90 per cent of the right hemithorax. The capacity of the lung to increase function in a dependent position as compared to an upright position is illustrated by variation in the rotation index used by Autio and Lahesmaa [S]. If the right lung contributed 60 per cent

of total oxygen uptake in the right lateral decubitus position and 50 per cent in the left lateral decubitus position, the rotation index would be 10. Expressed in this way the capacity of the lung to increase oxygen uptake and ventilation was probably slightly increased after bullectomy. COMMENTS

Changes in pulmonary function after bullectomy depend on the extent to which the bullae contributed to the tests used, to what extent the intrathoracic space occupied by the bullae was replaced by lung tissue, and the presence of generalized lung disease. Theoretically, the thorax can expand and accommodate a cyst filled with air with little interference with many of the common pulmonary function studies such as after pneumothorax [IO]. Thus, results after operation would vary from patient to patient. This was the case in this series, and in presenting the data we considered qualitative as well as quantitative differences by indicating the differences between the pre- and postoperative studies and the number of patients in each direction of change (Tables I and III) . AMERICAN

JOURNAL

OF

MEDICINE

l‘o~al lung capacity was reduced after bulle( tomy, for tile most part due to reduction in residual volume with no change in the vital c:~~I;Ni ty. ‘I‘ert patients had second postoperali~c studies one to two years later, and total lklng cal)acil)- sllowed an increase over the first stlidl. 111 some patients this increase in lung \,olumc later after operation was explained by (11~ l~rcsencc of pleural thickening subsequent which showed gradual clearance 10 StIrget’) O\YI-;I period ol one to two years. It should be ~~mphasi/etl that removal of bullae implies remo\ al of alq)reciable lung tissue since bullae visually invol\,e one and often two or more 1ullg se~rrlerlts, and this factor must have pl;t~c(I ;I 1);““ in reducing lung volume. _Another I’actol- which could have contributed to this I-etluction in residual volume is reduction in tile si/c of the thorax. The size of the thoracic cavity is determined by the outward pull oi t11(~tllor;~x and incvard pull due to lung recoil 1I / j. Increase in lung recoil would result in ~cducetl tlloracic cavity, and decrease in lung recoil would have the opposite result. In 1II is &es the maxitnum negative intrathoracic 1” assure incl~eased after operation in most I,at ients. Ch;rnges in intrathoracic pressure, however, ww not proportional to changes in lung volumcs or to the size of the bullae. This is not rlnexpected. .,1mong the factors which can inIlt~ence the change in intrathoracic pressure is 1l1c presence of disease in the lung tissue that eapndctl to fill the space. In one patient with“0,.

47,

DFCE.\IBER

1969

evidence of obstructive disease Xl 1P changed from 18 to 35, and in another (Fig. 2) the change was minimal even though the si7e of the removed bullae was not markedly different. In some patients total lung capacity increased postoperatively. The presence of communicating or noncommunicating b~illae would c,ertainly influence the direction of change in volumes after bullectomy. Others I/_‘] have reported predominant increa~c: in total lung capacity after resection of I~ullous lesions. In normal subjects and in patients ,with chronic 0l)structive pulmonary disease, intratltoracic pressure is a significant determinant of airway resistance [13]. In this study the pulmonary inspiratory resistance was measirred and the results are comparable to rne;u;uremen6 of airway resistance measuretl lq body plethysmography [14]. Changes in XIII’ and airway resistance correlated pnorly (Table I and Fig. I!) . In four patients with increased preoperative pulmonary inspiratory resistance [IS], greater than 4 cm. H,O per 1.. per second, considerable decrease in resistance occurred after bullectomy (Table I) whereas the change in MIP was variable (Cases 5. IO, 13 and 14). In other patients with lesser clevation in airway resistance, this measurement showed little change regardless of changc:s in MIP. Thus, decrease in airway resistance was not proportional to increase in nqative intrathoracic pressure. The responsiveness of airway resistance to changes in intrathoracic pres-

OllL

922

Pulmonary

Function

After

sure varies [I’]. In patients with bullous emphysema the mechanism of elevated airway resistance could vary from patient to patient and could be caused by additional factors to those usually present in chronic obstructive These additional factors pulmonary disease. might include tortuosity of airways adjacent to enlarging bullae, of airways leading to the bullae or to compression of the lung where it is functioning at low lung volume. In the four patients who had marked decrease in airway resistance this decrease was proportional to the level of airway resistance prior to operation. Forced flow rates improved in almost every case. This occurred in cases in which there was no change in MIP or in airway resistance, which are major determinants of forced flow rates [I6,17]. The decrease in airway resistance and increase in lung recoil referred to would decrease the nonelastic work of breathing and increase the elastic component. This was the case after bullectomy. As expected the total work of breathing, which includes elastic and nonelastic components, showed little change. Specific compliance was practically unchanged even though it was measured at the functional residual capacity level, as was the work of breathing. Increase in the elastic work of breathing is expected after resection of bullae that are characterized by high compliance [18]. The slight change in this measurement is probably a reflection of the limited participation of these air cysts during spontaneous quiet breathing. The improvement in seven minute nitrogen washout supports this and indicates much greater participation during full inspiration and expiration. Laurenzi et al. [29] reached similar conclusions from nitrogen washout measurements made during spontaneous and deep breathing. The data on airway resistance and seven minute nitrogen washout indicated the greatest improvement in patients who showed the most abnormality prior to operation. Postoperative bronchospirometric da t a showed a decrease in the contribution of the side of the bullectomy to the vital capacity, oxygen uptake and minute ventilation. This decrease was noted also in the absolute change in vital capacity (Table III) . It is possible that the interval between bullectomy and the postoperative study (two to fobr months) was too short and the reduction in function was sec-

Bullectomy-Boushy

et al.

ondary to pleural thickening after surgery; however, a great change could not have occurred one to two years after operation since in ten patients the increase in vital capacity was minimal over this period (Table II) . In general, changes toward normal occurred after bullectomy, but these were not marked except in patients with bullae occupying most of a hemithorax. This has also been reported previously [20]. Even in patients with large bullae some tests showed no change whereas other tests did. The more extensive the examination, the more likely to detect improvement. This is in contrast to the usually obvious clinical improvement in dyspnea in this series [5] and in those reported by others [1,?,20-Z?]. That changes in function studies and improvement in dyspnea were not proportional is not surprising. The cause of dyspnea is poorly understood and correlation between the degree of impairment in pulmonary function studies and dyspnea in bullous emphysema and chronic obstructive pulmonary disease is usually low [7,24]. Patients with severe impairment in function studies can experience marked improvement in their dyspnea with slight changes toward normal whereas patients with much lesser degree of impairment may not experience any change in dyspnea with similar improvement in function studies. Marked changes in clinical symptoms accompanied by what is expected to produce minor change in pulmonary function tests have been demonstrated in patients with lung disease and diminished pulmonary reserve [25,26]. When bronchospirometry shows marked impairment on the side of the bullae as compared to the other side, dramatic improvement in pulmonary function after operation can be expected. In a large group of patients with bullous emphysema marked differences in the function of the two sides were present when the bullous lesion occupied most of the In most patients, however, the hemithorax. bullae fill less than 60 per cent of the hemithorax [7]. Knowledge of the natural course of bullous emphysema is important in deciding whether operation is indicated or not. The natural course of this disease is characterized by slow but consistent and gradual enlargement of the bullae and increase in the severity of chronic obstructive pulmonary disease with time and increasing age 171. After resection bullae are AMERICAN

JOURNAL

OF

MEDICINE