Chest Wall Constriction After Too Extensive and Too Early Operations for Pectus Excavatum J. Alex Haller, Jr, MD, Paul M. Colombani, MD, C. Thomas Humphries, MD, Richard G. Azizkhan, MD, and Gerald M. Loughlin, MD Divisions of Pediatric Surgery and Pediatric Pulmonary Medicine, The Johns Hopkins Children's Center, Baltimore, Maryland

Background and Methods. Since 1990 we have evalu- ated 12 children and teenagers in whom severe cardiore- spiratory symptoms have developed due to failure of chest wall growth after very extensive pectus excavatum operations (removal of five or more ribs) at very early ages (<4 years).

Results. Apparently these extensive procedures have removed or prevented growth center activity, which resulted in restriction of chest wall growth with marked limitation of ventilatory function. The forced vital capac- ity ranged from 30% to 50% of predicted and the forced expiratory volume in 1 second from 30% to 60%. All

patients are symptomatic with mild exercise and cannot compete in running games. Our protocol for critical evaluation includes exercise pulmonary function studies and axial computed tomographic reconstruction.

Conclusions. This report is an alert to recognize such patients and also to recommend delay in operative repair in small children until at least 6 to 8 years of age. The younger the patient the more limited the chest wall resection for pectus excavatum should be. Five of these patients have had a chest cavity expansion operation with encouraging early results.

(Ann Thorac Surg 1996;61:1618-25)

I n the past 5 years (1990 to 1995) we have evaluated 12 chi ldren and teenagers with severe symptoms of re-

spiratory distress with exercise who had extensive pectus excavatum repair in early chi ldhood and who have dem- ons t ra ted failure of chest wall growth. All of these chil- dren had operat ive procedures with the removal of five or more rib carti lages on each side and all were opera ted on at very early ages (before 4 years of age). As older chi ldren and teenagers , all of these pat ients are symp- tomatic with mild exercise and cannot compete in run- ning games and sports.

The purposes of this repor t are: (1) to alert pediatr i - cians and surgeons to recognize pat ients with this com- plication of pectus repair , (2) to descr ibe the symptom- atology and descr ibe the physical f indings in this group of chi ldren and teenagers, (3) to r ecommend rest ing and exercise pu lmonary function studies in the evaluat ion of these patients, (4) to offer a possible explanat ion for this failure of chest wall growth and development , (5) to describe an operat ive technique for relief of chest wall constriction by thoracic cavity expansion, and (6) to repor t early, pre l iminary postopera t ive s tudies that doc- ument part ial relief of pu lmonary functional abnormal i - ties.

Patient Group

As noted in Table 1, all 12 pat ients had been opera ted on for pectus excavatum deformit ies before 4 years of age;

Presented at the Forty-second Annual Meeting of the Southern Thoracic Surgical Association, San Antonio, TX, Nov 9-11, 1995.

Address reprint requests to Dr Haller, Division of Pediatric Surge~, Johns Hopkins Children's Center, 600 N Wolfe St, CMSC 7-113, Balti- more, MD 21287-3716.

the majori ty (7) were 3 years of age or younger. All had very extensive rib carti lage excision as a part of their repair, usually the whole cartilage of five or six ribs on each side. Parents typically repor ted that their child 's chest did not appear to enlarge after the operat ion with general body growth. The children became progress ively short of breath with mild to modera te exercise and eventual ly they all sought advice because of growth re tardat ion accentuated by this progressive decrease in exercise tolerance. None of the pat ients could compete in running games or sports. Several of the pat ients had repea ted bouts of pneumonia , which were difficult to treat and had pro longed durat ion, suggest ing some in- terference with normal pu lmonary dynamics.

Physical Findings

The universal physical f indings were a small, immovable anterior chest wall, a very long torso, p r imary d iaphrag- matic breathing, and no evidence of recurrence of the excavatum deformity (Fig 1). These findings immedia te ly brought to mind the characteristic features of the pro- totype of chest wall growth retardat ion, namely, the congenital abnormal i ty of asphyxiat ing thoracic chondro- dys t rophy or Jeune 's syndrome [1-3]. This congenital pu lmonary and chest wall growth abnormal i ty usually causes death of the newborn infant because of respira- tory insufficiency due to hypoplas ia of the lungs and a very small chest. A few of these babies will survive with less severe forms of this congenital abnormali ty, and as shown in Figure 2, they may present with increasing respira tory distress and l imitation of activity in early childhood. Most of these children ul t imately succumb to repea ted upper respira tory infections and are severely

© 1996 by The Society of Thoracic Surgeons 0003-4975/96/$15.00 Published by Elsevier Science Inc Pll S0003-4975(96)00179-8

Ann Thorac Surg HALLER ET AL 1619 "1996;6l:1618-25 EARLY PECq-US EXCAVATUM REPAIR

~t

0

,.b.

= "8

2 ~ ~

= J ' S ~

,>.,

>...

p,.,

= ° t ' S ' ~

0

~ + ~ ' ~

©

0

B ~ ~ "~ ~- ~ .~ ~ ~ ,~ '~.

o

.~=

.2 ° .~

o . ~

• ~ ~-~

~. ,.-, ~ " ~ . , ~

o. ~. o. ~ , .

n

0

,.o ~ ' ~ ' ~ = >. -,-- ~ ~ "~ ~

" U

,~ ~ ~ ~ ~ ,-, ~ ~ -~ 6 x o =

o O ' ~

r-,

II

D

b" , i

"y>

,.2o ,J

r d

,~ ,..%

o .~

il II

r..r,.

r., iI ~

[,-,

. . 8

,,..,

.-2. LI

1620 HALLER ET AL Ann Thorac Surg EARLY PECTUS EXCAVATUM REPAlR 1996;61:1618-25

A B

Fig 1. This 12-year-old patient had pectus repair at age 2 years. He had no chest wall growth, and is unable to compete as a little league baseball pitcher because of shortness of breath. (Reprinted by per- mission of The Society of Thoracic Surgeons [Ann Thorac Surg 1995;60:1857-81.)

l imited in their exercise tolerance. Often they become unsa tura ted with exercise.

Because the findings in this group of postoperat ive children are so similar to this congenital abnormali ty , we have labe led this condit ion of restrictive complicat ions of extensive pectus excavatum repair "acqui red Jeune 's synd rome" (Figs 1, 3).

L a b o r a t o r y Tes t s

Representat ive chest roen tgenograms and computed to- mographic scans of some of these chi ldren are shown in Figure 4. We have also found that spiral computed tomographic reconstruct ion of the chest is helpful for three-d imens ional evaluat ion of these children. These spatial scans are useful in es t imat ing pu lmonary volume and compar ing postoperat ive results (Figure 5).

The most critical tests in evaluat ing these chi ldren are

A B Fig 3. This 19-year-old patient had pectus repair at 3 years 3 months. He is unable to work because qt shortness of breath climb- ing stairs. There is no anterior chest wall movement on respiration.

pulmonary function studies at rest and with maximal exercise [4-6]. The findings of these pu lmonary function studies are shown in Table 2. Basically, these chi ldren and teenagers show a marked decrease in functional vital capacity and forced expiratory volume in 1 second. They also show marked decreases in exercise pu lmonary func-

A B Fig 2. Six-year-old boy with congenital asphyxiating chondrodystro- phy or ]eune's syndrome. He had marked limitation of exercise abil- ity and desaturation while running.

A

B

Fig 4. Computed tomograms of 2 patients with severe chest wall constriction (acquired Jeune's syndrome). Note rib regrowth behind sternum.

Ann Thorac Surg HALLER ET AL 1621 1996;61:1618-25 EARLY PECTUS EXCAVATUM REPAIR

tion. In severa l chi ldren, desa tu ra t ion occur red d u r i n g these exercise p u l m o n a r y funct ion studies.

Explanation f o r " A c q u i r e d Jeune's Syndrome"

It s eems ve ry l ikely that an ex tens ive opera t ive p r o c e d u r e at a ve ry y o u n g age has s ignif icant ly a l te red the g rowth po ten t ia l of the ches t wall. W e would , therefore , p ropose the fo l lowing exp lana t ion for g rowth re tardat ion . These ch i ld ren were o p e r a t e d on at m u c h y o u n g e r ages (less than 4 years of age) than usua l ly r e c o m m e n d e d (6 to 8 years) [7, 8]. At this y o u n g age, the var ious opera t ive steps m a y have in te r fe red m o r e wi th the del ica te g rowth centers of the ches t wall, i nc lud ing the s t e rnum, than w o u l d be t rue in la ter ch i ldhood and the ear ly t e e n a g e years. M a n y m o r e rib car t i lages and m u c h la rger seg- m e n t s of these car t i lages w e r e r e m o v e d in these ch i ldren than is s t anda rd [7, 9]. Resec t ion was of ten three to e ight ribs on each side or five to six total rib car t i lages bi la ter-

A

B

Fig 5. Examples of spatial computed tomographic reconstruction qf patients with acquired Jeune's syndrome.

Table 2. Pulmonary Function Studies in 12 Patients With Acquired ]eune' s Syndrome"

FVC (L) FEV 1 (L) TLC (L) Age (y) Pre Post Pre Post Pre Post

11 1.33 No operation 1.16 No op 1.72 No operation (51%) (57%) (58%)

17 1.55 1.78 1.06 1.04 2.19 2.51 (32%) (35%) (26%) (24%) (36%) (39%)

12 1.33 1.58 1.25 1.41 2.02 2.08 (41%) (46%) (46%) (49%) (49%) (46%)

13 1.59 2.07 1.31 1.59 2.56 2.69 (43%) (45%) (42%) (40%) (32%) (43%)

19 2.52 2.51 1.74 1.82 4.09 4.34 (47%) (47%) (38%) (40%) (48%) (56%)t

12 1.47 1.66 1.13 1.40 2.17 ND (56%) (44%) (46%) (44%) (57%)

19 2.84 ND 2.40 ND 4.71 ND (49%) (49%) (64%)

18 2.2 ND 2.0 ND 4.09 ND (38%) (42%) (36%)

21 2.29 ND 2.00 ND 3.48 ND b (35%) (37°'o) (43%)

20 1.85 ND 1.75 ND ND ND c (33%) (37°,.)

16 1.58 ND 1.31 ND 2.60 ND b (50%) (47%) (58%)

12 1.42 1.44 ND ND 2.05 2.09 (52%) (47%) d (55°) (51%) e

a Six of 6 (all) measured FVC increased postoperatively. Four of 5 FEVj increased postoperatively. Five of 5 (all) TLC increased postoperative- ly. b No return yet. ~ Too soon postoperatively, a 1.63 (46%) at 2 years postoperatively. 1.85 (48%) at 3 years postoperatively. ~ 2.09 (47%) at 2 years postoperatively. 2.81 (60%) at 3 years postoperatively.

FEV l - forced expiratory, volume in 1 second; FVC - forced vital capaci~; ND = not done; op - operation; TLC - totallung capacity.

ally. The usua l r e c o m m e n d a t i o n for the basic opera t ive p r o c e d u r e is resec t ion of 2.5-cm s e g m e n t s of th ree to four car t i lages on each side, p r e se rv ing the p e r i c h o n d r i u m [8].

In a s u b g r o u p of ch i ld ren w h o w e r e o p e r a t e d on by a s ingle surgeon , the rib car t i lage and p e r i c h o n d r i u m of the s econd rib were r e m o v e d and at that level a t rans- ve rse o s t eo tomy comple t e ly t h r o u g h the s t e r n u m b o n e was car r ied out. Possibly the g rowth cen te r of the ster- n u m was t ransected . In a s t anda rd opera t ive p r o c e d u r e only the anterior cortex of the s t e r n u m is t ransected , not both, so this m o r e ex tens ive p r o c e d u r e m a y have in ter - fe red wi th the b lood supp ly of the s t e r n u m and i m p e d e d g rowth and d e v e l o p m e n t .

Finally, in comp le t i ng recons t ruc t ion of the lower ches t wall, m a n y of the ch i ld ren had the pe r i chondra l shea ths of rib seven, and of ten rib eight, su tu red toge the r bi lat- eral ly and b r o u g h t b e n e a t h the s t e r n u m to give addi - t ional suppor t . This subs te rna l pe r i chondra l b r idge was then su tu red to the s te rnum. In so doing, w h e n the car t i lage r e g e n e r a t e d and u l t imate ly was r ep laced by bone, the re w o u l d be m a r k e d res t r ic t ion of the lower ches t wal l because of this semic i rcu le r b a n d of car t i lage- b o n e (see Fig 4). This exp lana t ion is theoret ical , because

1622 HALLER ET AL Ann Thorac Surg EARLY PECTUS EXCAVATUM REPAIR 1996;61:1618-25

Fig 6. Figures 6 through 11 show the proposed operative procedure to correct chest wall constriction in patients with acquired Jeune's syndrome.

specific dynamics of growth of the anterior chest wall, including the growth centers for the sternum and costal cartilages, have not been well established.

Proposed Operative Correction

Assuming that our understanding of this complication of very early extensive pectus excavatum repair was correct, we reasoned that it might be possible to improve pulmo- nary function, although we could not enhance pulmo- nary parenchymal growth at this late time in childhood and the teenage years. We developed an operative pro- cedure that will expand the anterior chest wall and increase the volume of the chest cavity. In this way the

Fig 8. Extensive mobilization of the sternum.

trapped lung, which can only function by diaphragmatic excursion, might be freed for better diaphragmatic func- tion. Characteristically, all of these children had very low-lying diaphragms.

As shown in Figures 6 through 11, we removed the regenerated cartilage/bone of the anterior ribs along the sternum, which allowed the sternum to be freed and brought anteriorally. Modified Rehbein splints (which have been used for decades to treat primary pectus excavatum in Europe) were modified and used as ele- vated bridges to hold the sternum in the new position and expand the anterior chest wall. The ends of the Rehbein splints were inserted in the marrow cavity of an

Re sF

W r e ~ c h

Fig 7. Resection of abnormal costal cartilages. Prophylach'c antibiot- ics are given. Sutured 7-8 rib perichondrium can be recognized be- hind the sternum. Fig 9. Insertion qf Rehbein splints into appropriate bony ribs.

Ann Thorac Surg HALLER ET AL 1623 1996;61:1618-25 EARLY PECTUS EXCAVATUM REPA1R

Fig 10. Construction of Rehbein splint bow with attachment to ele- vated sternum.

Fig 12. Gusset of woven silicone material to expand anterior chest wall fascia.

appropriate pair of ribs and the two halves were brought together in front of the sternum. With various means of fixation to the sternum, this bow of stainless steel was constructed.

In the initial operative procedure a transverse skin incision was used, but with extensive mobilization of the chest wall, it was impossible to bring together the ante- rior pectoral-rectus fascia without using prosthetic mate- rial as a gusset (Fig 12) Therefore, the incision was changed in the later children to a vertical incision be- cause the pectoralis major muscle mass could be stretched and brought over the expanded sternum with- out the use of foreign material (Fig 13).

These children as a group have had remarkably smooth postoperative recoveries in spite of our concern about their basic lack of pulmona~ functional reserve. We believe this rapid recovery may represent immediate improvement in pulmonary function, which is possibly best explained by the mechanical relief of diaphragmatic displacement, which permits better excursion.

Fig 11. Realignment of perichondral sheaths to sternum, and place- ment of deep and subcutaneous drains.

Postoperative Studies

Early postoperative studies in 6 patients show no change in resting functional vital capacity, which is not surpris- ing if our theoretic explanation of the functional abnor- mality is correct, namely, interference with diaphrag- matic function (see Table 2). All of the children are symptomatically improved and preliminary exercise pul- monary function studies show mild to moderate im- provement 3 to 6 months after operation. It is far too soon to evaluate the total effect of chest wall expansion, but our early results are encouraging.

Conclus ions

Extensive operative procedures for repair of pectus exca- vatum in very early infancy and childhood can interfere with chest wall growth and result in severe pulmonary dysfunction. This complication can be prevented by de- laying repair until 6 to 8 years of age and by limiting the operative procedure to the resection of short segments of three or four cartilages on each side combined with a minimal sternal osteotomy.

We would strongly recommend that children with pectus excavatum deformities not be operated on in early infancy and childhood because there are no obvious advantages, and in rare instances, chest wall growth may be impaired [10].

We believe the mechanism of pulmonary functional improvement after operation in these children with ac- quired Jeune's syndrome is expansion of the thoracic cavity, which allows for better excursion and function of the diaphragm. The preliminary results of our recon- structive procedure suggest improved function. This op- eration may be the prototype for a corrective operative procedure for acquired Jeune's syndrome.

Addendum Since this report was written (October 1995) 6 more (total, 11) children and teenagers with acquired leune's syndrome have

1624 HALLER ET AL Ann Thorac Surg EARLY PECTUS EXCAVATUM REPAIR 1996;61:1618-25

~ . , , Pre-o~er. . ~ 2

"Cf seventh r [b S[ru~

/

C I)

Fig 13. Second generation of proposed operative procedure for acquired Jeune's syndrome.

T r a n s v e r S e cross-sec~;~on~l Vie'W"

had chest wall expansion operations. There were no immediate postoperative complications, but the Rehbein splints broke in 2 patients (at 5 months and 6 months) and required removal. In 2 patients the splint eroded through very thin chest skin with very little muscle coverage. Both required removal of the bar. In 1 patient the Rehbein splint pulled loose from the s ternum and had to be reattached. Clearly, the operation is still in evolution.

We thank Ms Karen Jelus for her careful measurements of exercise pulmonary function, which were performed with her characteristic sensitive professional techniques.

References

1. Jeune M, Carron R, Beraud C, et al. Polychondrodystrophie avec blocage thoracique d'volution fatale. Pediatric 1954;9: 390-2.

2. Kaufman HJ, Kirkpatrick JA. Jeune's thoracic dysplasia: a spectrum of disorders? In: Bergsma D, ed. Birth defects: original article series. Miami: Symposia Specialists, 1974; 10(9):101-16.

3. Pirnar R, Neuhauser EBD. Asphyxiating thoracic dystrophy of the newborn. AJR 1966;98:358-64.

4. Polgar G, Promadhat V, eds. Pulmonary function testing in children: techniques and standards. Philadelphia, Saunders: 1971.

5. Wasserman K, Hansen JE, Sue DY, Wipp BJ. Measurements of the physiological response to exercise. In: Principles of exercise testing and interpretation. Philadelphia: Lea & Febiger, 1987:27-46.

6. Cahill JL, Lees GM, Robertson HT. A summary of preoper- ative and postoperative cardiorespiratory performance in patients undergoing pectus excavatum and carinatum re- pair. J Pediatr Surg 1984;19:430-3.

7. Ravi tch MM. Depress ion deformit ies . In: Welch KJ, Randolph JG, Ravitch MM, O'Neill JA, Rowe MI, eds. Pediatric surgery (4th ed). Chicago: Year Book Medical, 1986:568 -78.

8. Hailer JA, Scherer LR, Turner CC, Co |omban i PM. Evolv- ing m a n a g e m e n t of pectus excavatum based on a single inst i tut ional experience of 664 patients. Ann Surg 1989; 209:578-83.

9. Haller JA. Operative management of chest wall deformities in children: unique contributions of Southern thoracic sur- geons. Ann Thorac Surg 1988;46:4-12.

10. Nathanson I. Chest wall abnormalities. In: Loughlin GM, Eigen H, eds. Respiratory disease in children: diagnosis and management. Baltimore: Williams and Wilkins, 1994:533-43.

Ann Thorac Surg HALLER ET AL 1625 1996;61:1618-25 EARLY PECTUS EXCAVATUM REPAIR

D I S C U S S I O N

DR HAROLD C. URSCHEL, JR (Dallas, TX): This is a l andmark paper and I think probably one of the most impor tan t on the program. There is virtually no l i terature about this disease, and I have never seen a case personally. I would be in teres ted to poll the audience to see if anybody has seen a personal case. I have seen one referred to me for medical- legal reasons that was opera ted on before the age of 4 years in which this developed, and then subsequen t ly another case that never healed and had a total flail chest with excessive use of the cautery. These cases r ep resen t the two ends of the spect rum.

This is like volume reduction in reverse. When I came to Texas 35 years ago, Shaw and Paulson had operated on many of the young kids with tracheoesophageal fistulas, pectuses, and so on. I found 38 cases that were operated on at age 4 years or younger, and there were no cases in which this complication subsequently developed. Doctor Hailer sent me this manuscript to review.

The possible explanat ions are, as he po in ted out, you ei ther injure the rib or s ternal growth centers someplace, whe reve r they are, or the resect ion of the pe r i chondr ium totally could fail to regenera te any pe r i chondr ium and the pat ient would heal by fibrous tissue that was solid not flail. I th ink that this is an excellent repor t and an excellent solution.

Spiral com pu te d tomography and th ree -d imens iona l mag- netic resonance imaging are extremely valuable in these cases. I th ink this is an ingenious therapeut ic operat ion and should be called the Haller procedure .

DR FRANCIS ROBICSEK (Charlotte, NC): Doctor Haller, as usual, p r e sen ted a very interest ing paper. However , I can agree only with par t of it; namely, that you have to do the operation well. If you do it well, ie, not too radically, and you do not extirpate radically the costal cartilages with the pe r i chondrum on both sides, this complicat ion will not occur.

I especially disagree, that age creates even a relative contra- indication. Naturally, if you make a mistake in a small person, your mistake becomes a "b ig" mistake! With my late partner , Paul Sanger, we did approximate ly 850 pectus repairs, close to 300 of t h e m were in chi ldren less than 31/2 years of age. We have not seen this complicat ion once! My prefe r red t ime is still a round 3 years. But you have to do it well!

A n d as far as the technique is concerned, in the early 1970s we deve loped a m e t h o d that consists of sternal os teotomy, bilateral costal cartilage resection, de t achmen t of the xyphoid process, substernal Marlex m e s h support , and pres ternal approximat ion of the pectoralis muscles. Our long- term results remain consis- tently very good.

DR HALLER: Doctor Robicsek, I think you asked me someth ing about the age, and I would only say that you are correct, a good operat ive procedure done delicately in a small child is probably all right. But because we do not know why these few chi ldren have had this growth r e t a rda f ion - - and certainly it 's t rue that the younger the pat ient ' s chest, the more likely you could interfere with g r o w t h - - m y point is why opera te on them at 3 years of age? (unless you're just afraid they will get out of town to some other thoracic surgeon if they are allowed to be followed up!) I think you can follow them up until they are school age; they handle their operative procedure better and also their hospitalization. But your point is a good one; the procedure needs to be done properly.

DR CONSTANTINE MAVROUDIS (Chicago, IL): I would like to follow up on one of the issues that Dr Urschel touched upon. Where do you think the growth center is in the rib? We know that if you do an above- the -knee amputa t ion in a little child, the femur will s top growing. Do you think that is wha t happens here? Should we leave a little piece of that cartilage behind where the rib is? I would be interested to hear what you have to say.

DR HALLER: I tr ied to find out where the growth centers of the costal cartilages lie, and there are not very good data on that, Dr Mavroudis. I th ink that it is likely to be at the cart i laginous bony junction laterally, because that certainly is the most active growth center in the chest wall. We have just luckily, by the grace of God, s tayed away from it by removing a shor t s egmen t next to the s te rnum. You certainly do not need to r emove all of the cartilage; that may be one of the reasons we have b e e n lucky in not having this complication.

DR JOEL D. COOPER (St. Louis, MO): I was excited w h e n I saw this paper on the program, because it explained a pat ient I saw recently, and I previously had no knowledge of this entity. The pat ient was a 35-year-old man sent to me with a severe restric- tive deficit. I had my secretary fax me my record today. His vital capacity was 19% of predicted, his f i rs t-second vital capacity was 17% of predicted, and his total lung capacity was 33% of predicted. At the age of 4 years this pat ient had had a pectus deformity repaired. W h e n I examined him I said I had never seen anything like this; he s e e m e d to have a hypoplast ic chest. We did dynamic magnet ic resonance imaging and there was noth ing that moved other than his d iaphragm. In this part icular case his ribs were very horizontal, and so moving the s t e rnum forward would not help him. On the roen tgenogram, the entire r ibcage looked like that of a dog. The ribs from tb.eir poster ior joint to the front were very horizontal and fixed, with a 4-cm distance be tween the front and back of his chest. I do not think for him just moving the s t e rnum forward would do anything. We decided there was nothing that we could possibly offer him. If you come up with something, I would love to send him to you. My question is: Have you seen any of these patients in w h o m the entire ribcage was involved, not just the front plate? Thank you for the opportunity of comment ing on this interesting report.

DR HALLER: Doctor Cooper , you were kind enough to ment ion that in the hall to me before the meeting, l think each surgeon who does a n u m b e r of pectus repairs may have one or two such complications. I bel ieve that the whole anter ior chest wall is failing to grow, which may extend out to the midaxillary line.

Your point about d iaphragmat ic function is an impor tan t one. If this operat ive p rocedure we are p ropos ing does help, it can only help by rel ieving the d i aph ragm to funct ion better, because we are only expanding the volume of the chest cavity. We are obviously not increasing lung growth; these patients have al- ready passed the lung growth stage. So I th ink this is like a box that you make bigger; the d iaphragms are p u s h e d far down before; they may function bet ter if they have more volume in which to expand. W h e t h e r in a 35-year-old man you could expect to do that or not, I am not sure.