Hernia (zooo)4:lO5-111

Hernia 9

2000

Use of progressive pneumoperitoneum in the repair of giant hernias

S. Willis and V. Schumpelick Department of Surgery,TedlnicalUniversityAachen,Germany

Summary: Preoperative progressive pneumoperitoneum is a well-known, but sporadically used procedure in preparing patients with giant inguinal or incisional hernias for operation. The technique requires the frequent insufflation 4 of air into the abdominal cavity in order to make room to accommodate herniated viscera and facilitate fascial repair with minimal tension. In 11 patients with giant inguinal and incisional hernias a preoperative progressive pneumoperitoneum was performed. Due to a lack of compliance it had to be terminated without operation in one patient. Minor complications appeared in almost all patients, but after pneumoperitoneum a tension-free closure of the fascial defect was successful in all patients. The direct suture of the defect was successful in 4 patients with primary hernias, while in all cases of recurrent hernias an additional fascial augmentation by alloplastic meshes was required. Until now no recurrences have appeared. We conclude that the progressive pneumoperitoneum is a useful adjunct in the preoperative preparation of patients with giant hernias. It is not a competing, but a complementary procedure to mesh repair in patients with huge defects or fascial weakness.

Correspondence to: S. Willis, Chirurgische Universitiitsklinik und Poliklinik der R WTH Aachen, Pauwelsstrasse 3o, 52o57Aachen, Germany

Key words: Hernia - Tension-free repair - Pneumoperitoneum - Mesh - Preoperative preparation Received December 7, 1999 Accepted in final form April 17, 2000

The operative treatment of giant inguinal or incisional hernias is a challenge for every surgeon. The intraabdominal pressure leads to an e v e n t r a t i o n of intraabdominal organs into the hernial sac. Due to the retraction of the abdominal wall muscles and relaxation of the diaphragm, the eventrated viscera have ~ forfeited their right of domicile ~>in the abdominal cavity (Fig. 1). Often obesity, renal and cardiopulmo-

nary diseases are predisposing factors for the development of those monstrous hernias. Forced reposition under general anesthesia with direct closure of the defect often leads to bad results with suture dehiscence, cardiac failure due to venous obstruction or respiratory decompensation due to atelectasis and pneumonia [Rives 1973, Flament 1998]. Several strategies, such as phrenicectomy, transverse incisions, mus-

culo-skeletal flaps or even intestinal resections have been proposed to solve this problem [Willis 1996]. In 194o the Argentine surgeon Goni Moreno was the first to use intraperitoneal injections of oxygen to reduce an incarcerated epigastric eventration and to prepare the patient for repair under local anesthesia [Goni Moreno 1947]. Despite m a n y reports of successful treatment of giant hernias by progressive

106

S. Willis and V. Schumpelick: Progressive pneumoperitoneum in hernia surgery

Fig. I

Fig. 2

A. Pathophysiologyof hernia formation: relaxation of the diaphragm and retraction of abdominal wall muscles.B. Principleof progressivepneumoperitoneum:elevation of the diaphragm and distensionof the abdominal wall by inflation of air

Placementof the catheter under localanesthesiaand inflation of air. The intraabdominal pressuremust not exceed18 cm H20

p n e u m o p e r i t o n e u m , the p r o c e d u r e d i d n o t g a i n g e n e r a l acceptance, especially since the introduction of alloplastic m e s h e s p r o m i s e d s u r g e o n s the p o s s i b i lity to close e v e n large defects w i t h o u t problems. However, in view of their effects on abdominal wall mobility

[Miiller 1998], the u n k n o w n l o n g - t e r m histologic tissue r e s p o n s e [Klosterhalfen 1999] a n d the p r o b l e m of d u r a b l e m e s h f i x a t i o n to p r e v e n t d i s l o c a t i o n and fistula formation [Schumpelick 1999], m e s h i m p l a n t a t i o n s h o u l d b e r e s t r i c t e d to p a t i e n t s i n w h o m m e s h -

free t e c h n i q u e s are n o t available. F u r thermore, meshes do not solve the u n d e r l y i n g p r o b l e m , i.e. to re-establish room in the abdominal c a v i t y to contain the eventrated viscera after r e p o s i t i o n . This has led to a revival of preoperative progressive pneumoperi-

Table 1. Patient characteristics Patient

Gender/age

CA

M / 57

K]

M / 68

TN

M / 75

BE

W [ 72

MS

M / 67

ED

M / 67

RA

W / 75

BP

M / 68

AH

Type of hernia / previous operation Scrotal / Primary hernia Scrotal / 1. recurrence Incisional-cystotomy/ Lrecurrence Umbilical / Primary hernia

Duration of Pneumoperitoneum

Follow-up

Operation

Concomitant diseases

15 days

50 months

Shouldice repair

Obesity, COLD

2 days (abort) Stoppa repair Direct suture

Obesity, COLD, coronary heart disease Obesity, coronary heart disease, hypertension Obesity, diabetes, cardiac insufficiency NYHA II, arrhythmia Obesity

14 days

41 months

6 days

32 months

Scrotal / Primary hernia Scrotal bilateral / 3./1.recurrence Incisional - Billroth-1 Primary hernia Scrota1 / Primary hernia

5 days (local infection)

26 months

8 days

18 months

lO days

18 months

lo days

16 months

Shouldice repair

Obesity, hypertension, COLD

M / 74

Incisional-gastrectomy/ 1. recurrence

lo days

14 months

Vypro | sublay

Obesity, diabetes, cardiac insufficiency NYHA III,coronary heart disease

SH

M / 74

12 days

14 months

TB

M / 41

Incisional-umbilicalhernia / 6. recurrence Incisional-adrenalectomy /2. recurrence

lO days

1 months

Vypro | sublay Vypro * sublay

Obesity, severe COLD, diabetes, hypertension Obesity

Shouldice repair Stoppa repair Atrium* -sublay

Obesity, diabetes, hypertension Obesity, hypertension

S. Willis and V. Schumpelick:Progressivepneumoperitoneumin hernia surgery toneum in the m a n a g e m e n t of giant hernias in our department.

Material and methods

Since 1995 progressive pneumoperiton e u m has b e e n p e r f o r m e d in 11 patients with giant inguinal and incisional hernias. Four patients had primary hernias without previous operations, while the o t h e r patients had recurrent hernias with 1 to 6 previous o p e r a t i o n s . The m e a n age o f the patients was 67 (41-75) years. All were obese and 9 had further concomitant diseases such as hypertension, chronic obstructive lung disease (COLD), cardiac i n s u f f i c i e n c y , c o r o n a r y h e a r t disease or diabetes (Table 1). The clinical impression of <> was decisive for the indication in all patients. The progressive pneumoperitoneum was performed if a complete reposition of the hernia seemed impossible at clinical examination. A CTscan for e v a l u a t i o n o f the loss o f domain was not performed. Besides standard laboratory tests all patients underwent a pulmonary function test and an a b d o m i n a l u l t r a s o n o g r a p h y before the start of the procedure and again before operation.

Technique The abdominal cavity was punctured with a Veress n e e d l e u n d e r sterile c o n d i t i o n s s u p r a u m b i I i c a l l y . The pneumoperitoneum was established by use of a laporoscopy unit, which allowed measurement of the inflated volume and intraabdominal pressure. The i n f l a t i o n was s t o p p e d w h e n the intraabdominal pressure reached 18 cm HzO (15 m m H g ) or w h e n the patient complained of discomfort or pain. The initial volume varied between l o o o ml a n d 4 o 0 0 ml o f air. Afterwards, an indwelling s t a n d a r d u r i n a r y c a t h e t e r was p l a c e d in the upper left abdominal quadrant under local anesthesia (Fig. 2). The site of placement of the catheter should be at a distance from the hernia and from previous incisions. Intraoperative ultrasonography of the abdominal wall

107

facilitated the proper placement of the catheter. The outflow of air showed the correct position of the catheter afterwards. The p n e u m o p e r i t o n e u m was maintained by daily injections of 500 ml to 2ooo ml of air. Pain referred to the shoulder, signifying diaphragmatic irritation, indicated the end-point of injections. The intraabdominal pressure was measured additionally to avoid renal or circulatory complications. To reduce the risk of vomiting and aspirat i o n we r e q u e s t e d the p a t i e n t s to remain upright and not to eat for several hours before and after the procedure. Low dose h e p a r i n was given for thromboembolic prophylaxis during the whole procedure. During maintenance of the p n e u m o p e r i t o n e u m the abdominal circumference was determined daily. Additionally, in 2 patients the abdominal surface was reconstructed by three-dimensional stereography and the a b d o m i n a l c u r v a t u r e was d e t e r m i n e d every two days [Klinge 1998].

moperitoneum at the 5th day. However, the procedure had progressed far enough to perform a Shouldice repair in this patient. Localised hematomas and emphysema of the abdominal wall a p p e a r e d in 7 patients and did not require any therapy. Pulmonary function did not deteriorate during the progressive pneumoperitoneum. There was even a slight increase of the vital capacity from initially 2,56 -- 0,45 1 to 2,61 -+ 0,57 1 after pneumoperitoneum and 2,8o -+ o,6a 1 after th e operation (n=lo> Wilcoxon test not significant) (Fig. 3). In the first two patients the pneumoperitoneum was terminated after 2 weeks. Reconstruction of the abdominal surface in these patients by threedimensional stereography revealed no further flattening of the curvature after the 6 th day. Therefore, in the subsequent patients the abdominal circumference was m e a s u r e d daily and the progressive p n e u m o p e r i t o n e u m was terminated when the abdominal circumference remained constant for two days. Under these conditions, the average duration of the p n e u m o p e r i t o neum was lo,2 (5-15) days. Operations were performed under general anesthesia. In all patients, reposition of the hernial contents and fascial closure were possible with minimal tension. In 3 patients with giant scrotal hernias a conventional Shouldice repair was possible. In one patient with bilateral recurrent scrotal hernias a Stoppa repair with a Marlex| was p e r f o r m e d . Four patients with

Results

There were no severe complications due to the p n e u m o p e r i t o n e u m . All patients complained of intermittent nausea. In one patient the procedure had to be terminated after two days due to insufficient patient compliance and operation on the hernia was refused. In another patient with giant scrotal hernia a localized infection of the abdominal wall at the catheter site led to premature termination of the pneu-

voi. {rod

vco]

14000

OP vifcll capacity (VC} ,.

12OOO

Fig.3 Respiratory function of a patient during progressive pneumoperitoneum in relation to the insufflated volume. Vital capacity does not decrease during pneumoperitoneum or after operation

~"

,. - " " lnsufflated air volume (vol.) tt"

6000

i -,'+" ...................

... ............

8000

2.5

2,0

1

1,5

1i

/ /

1,0 12

2000 # 0

o

i

~

5

7

9

...... i7 .....

i~

x I I 15

!

0,5

0

108

recurrent incisional hernias required alloplastic mesh reinforcemet in sublay situation (Table 1) [Flament 1999, Schumpelick 1996]. With one exception the p o s t o p e r a t i v e course was uncomplicated. Only one patient with severe obstructive pulmonary disease developed a critical pneumonia which required respiratory therapy in the intensive care unit for lO days. In 2 patients with massive scrotal hernias a secundary scrotal plasty was performed due to surplus skin. Patients were regularly monitored by clinical investigation and ultrasound in our unit. Until now, no patient has developed a r e c u r r e n t h e r n i a (follow-up 1-5o months).

l

Discussion Originally, intermittent percutaneous puncture of the abdominal wall was used for the frequent insufflation of air into the abdominal cavity [Moreno 1947]. In 1965 Steichen described the placement of an indwelling catheter for daily injections of air [Steichen 1965]. To reduce the likelihood of complications from multiple p u n c t u r e s we adopted this technique by using an indwelling standard urinary catheter which can be inserted u n d e r local anesthesia. The site of placement of the catheter should be at a distance from the hernia and from previous incisions. Adhesions from the intestine to the abdominal wall can be excluded by the use of ultrasound [Conze 1996]. Alternatively, the catheter can be placed at the left McBurney point or supra- or infraumbilically. In doubtful cases, puncture of viscera can be excluded by radiography after injection of radiopaque fluid. For maintenance of the pneumoperitoneum normal air should be used, because CO2 and oxygen are absorbed 4 times more readily in the peritoneal space than air [Mason 1995]. The principle of the progressive pneumoperitoneum consists of gradual stretching of the abdominal wall by intermittent insufflation of air into the abdominal cavity. It facilitates operative reduction of the hernial contents

S. Willis and V. Schumpelick: Progressive pneumoperitoneum in hernia surgery

Fig. 4 Chest radiograph during pneumoperitoneum. Note the elevation of the diaphragm by subphrenic air and the concomitant skir emphysema

and allows fascial repair under minimal tension. Although the immediate result is distension of the hernia sac and the overlying skin, over time a gradual increase of the size of the abdominal cavity becomes apparent. This has been proven additionally by an experimental study, which showed dilatation of all structures of the abdominal wall including muscles, fascias and aponeuroses d u r i n g p n e u m o p e r i t o n e u m [Willis 1996]. The skin and hernial sac have a limited capacity even when they are s t r e t c h e d , and a d d i t i o n a l air stretches the diaphragm and the abdominal wall. The elevation of the diaphragm is the most important effect of the pneumoperitoneum, because it not only contributes to the increase of the abdominal cavity, but also to an improvement of the patient's respiratory function. Due to the eventration, patients with giant hernias have a decreased intraabdominal pressure with a disequilibirium between intraabdominal and intrathoracic pressures. As a result the diaphragm is weak and relaxed, leading to a deterioration of respiratory function. Pneumoperitoneum leads to an increase of the intraabdominal pressure, thereby causing elevation of the diaphragm with restitution of its physiological tension and function (Fig. 4) [Champetier 1978, Rives 1973]. By this way the patient can adapt stepwise to the postoperative situation.

Patients who cannot tolerate the stepwise inflation of air must be denied for any surgical t r e a t m e n t . T h e r e f o r e pneumoperitoneum can be considered diagnostically as well as therapeutically. The infation of air allows the surgeon to increase the abdominal volume gradually while observing the reaction of the conscious and alert patient. Contraindications to the use of the p n e u m o p e r i t o n e u m are those that would make the patient a poor candidate for hernia repair even after completion of the p n e u m o p e r i t o n e u m , such as major cardiac and respiratory insufficiency. The inflation of 500 ml of air may be the best way to determine candidates for such a treatment and to exclude patients with limited cardiac and pulmonary reserves [Raynor 1989, Mason 1995]. Other advantages of the pneumoperitoneum are the gradual preoperative lysis of adhesions between the intestines and the hernial ring, the unmasking of additional areas of fascial weakness and potential sites of recurrent herniations, and a decrease of the chronic edema of the mesentery. Furthermore, the stretching of the hernial sac has been found to be helpful in skin cleansing before the operation and potentially decreases the incidence of infection [Moreno 1978]. Incarcerated hernias are a contraindication to p n e u m o p e r i t o n e u m in our opinion and require immediate surgery.

S. Willis and V. Schumpelick:Progressivepneumoperitoneumin hernia surgery

109

Fig.S A. 67-year old patient with bilateral scrotal recurrent hernias. B. Postoperative picture after 8-days pneumoperitoneum and Stoppa repair with a Marlex-mesh

In the literature no concrete recommendations concerning the duration of the pneumoperitoneum can be found. Moreno stops the procedure when bulging of the flanks is noted, signifying adequate stretching of the abdominal wall [Moreno 1978]. Others r e c o m m e n d a lateral chest radiograph for estimation of the volume created [Raynor 1989]. Depending on the author, the progressive pneumoperitoneum is maintained for between 7 and 60 days with a volume inflated between 5ooo ml and 15ooo ml [Koontz 1958, Pingree 1968, M o r e n o 1978, R a y n o r 1989, Mason 1995]. M e a s u r e m e n t s of the abdominal circumference and curvature by stereoradiography and repeated m o n i t o r i n g of r e s p i r a t o r y f u n c t i o n during the progressive pneumoperitoneum in our department indicate that there is no further benefit after 6 to lo days. Due to these preliminary results we decided to shorten the duration of the pneumoperitoneum. We assumed the proper time for surgery was when the abdominal circumference did not further increase during two consecutive inflating sessions. However further experience is required with this regime. Complications of progressive pneum o p e r i t o n e u m are often associated with the p u n c t u r e of the abdominal wall. Nevertheless, perforation of viscera, peritonitis and air embolism are rare complications [Hamer 1972, Ray-

nor 1989, Caldironi 199o, Mason 1995]. The use of an indwelling catheter rather than intermittent puncture to induce pneumoperitoneum should reduce the likelihood of these complications. Skin e m p h y s e m a a p p e a r s in a l m o s t all patients and normally requires no specific therapy, while related emphysema of the mediastinum or pericardium is rare. In a series of 587 patients Goni Moreno described 11 local infections of the catheter site, 9 cases of pneumonia, 4 cases of lung embolism due to deep vein thrombosis and 3 heart infarctions. 6 of his patients died because of complications from the pneumoperiton e u m [Goni M o r e n o 1978]. In o u r experience patients always complained of nausea and vomiting during pneum o p e r i t o n e u m . This i n c r e a s e s the often preexisting immobilization of the patients due to their desease and leads to an increased risk of severe thromboembolic complications. Therefore, in our department patients were admitted to hospital and received low-dose heparin and regular physiotherapy during the procedure. However, good results have been published by others using ambulatory pneumoperitoneum [Goni M o r e n o 1978, R a y n o r 1989, Mason 1995]. Until now, no r e c u r r e n c e s have appeared in our patients. Long-term results based on controlled trials are not available in the literature. Controlled r a n d o m i z e d studies do not exist

because patients with giant hernias are rare and often exhibit unique qualities caused by their disease. Despite these systematic difficulties, H a m e r et al. compared lO patients with progressive p n e u m o p e r i t o n e u m with ao patients with immediate direct closure. After e years there were no recurrences after pneumoperitoneum, while direct closure led to 3 recurrences [Hamer 1972]. Koontz et al, reported one recurrence in 8 patients with preoperative progressive pneumoperitoneum [Koontz 1958]. Raynor et al. described 3 recurrences in 7 patients during 36 months [Raynor 1989] while Caldironi et al. had only 2 recurrences in 4o patients during 25 m o n t h s [Caldironi 199o]. Over the years M o r e n o r e p o r t e d 14 recurrences in 487 patients without indicating the types of hernia and the follow-up time [Moreno 1978]. Calculated recurrence rates are between o and 43% with a mean of 3,6%. Compared with recurrence rates for conventional repair with ao to 49 %, or alloplastic r e p a i r with 7 to 15%, these results are impressive [Schumpelick

1996]. At this point it has to be emphasized that p r e o p e r a t i v e p r o g r e s s i v e p n e u m o p e r i t o n e u m and alloplastic fascial augmentation are no competing, but complementary procedures. Progressive p n e u m o p e r i t o n e u m is a useful adjunct in the preoperative preparation of patients with giant hernias

110

S. Willis and V. Schumpelick:Progressivepneumoperitoneumin hernia surgery

Fig. 6 A. 41-year old patient with recurrent incisional hernia after adrenalectomyand previousalloplasticrepair with a Marlex-rneshin onlay technique. Intraoperatively,the mesh was torn offat 3 cornersand showed significant shrinkage.B. Postoperativepicture after lO-days pneumoperitoneum, explantation of the previous Mesh,and repair by Vypro-sublay

when conventional operations promise not to be successful. It facilitates the r e p o s i t i o n of h e r n i a t e d viscera and improves the respiratory function of the patients at the same time. However long term results and recurrence rates depend primarily on the quality of the fascial reconstruction and only to a slight extent on the use of the pneumoperitoneum. While meshes, on the one hand, cannot create room to accomm o d a t e the h e r n i a t e d v i s c e r a , the pneumoperitoneum on the other cannot compensate for the fascial weakness of the patient. Especially in giant hernias with a large hernial orifice or multiple defects, the combination of preoperative progressive pneumoperitoneum and mesh repair seems to be

useful (Figs. 5, 6). The availability of improved alloplastic materials enables s u r g e o n s to close e v e n v e r y large defects with low recurrence rates. Due to t h e i r d i s a d v a n t a g e s (shrinkage, abdominal wall stiffness, visceral perforation, durable fixation) meshes cannot be applied unrestrictedly [Klosterhalfen 1999, Schumpelick 1999]. In our department the indications for an alloplastic repair are incisional hernias with an orifice of more than 4 cm or recurrent inguinal hernias with a weak e n e d s u r r o u n d i n g fascia, w h e n a stable Shouldice repair seems doubtful. Mesh-free repairs after pneumoperiton e u m have b e e n e m p l o y e d o n l y in umbilical or primary unilateral inguinal hernias. However even patients

where mesh repair without pneumoperitoneum seems to be technically feasible m a y p r o f i t f r o m the p o s i t i v e effects of the p n e u m o p e r i t o n e u m on respiratory function. That is why the progressive p n e u m o p e r i t o n e u m has been established as an additional preoperative p r o c e d u r e in patients with extremely large hernias in our department. We use this p r o c e d u r e in all patients, where a tension-free reposition of the hernia seems doubtful or even impossible. In this circumstances this ~ antiquated ~ procedure is in our o p i n i o n , a u s e f u l a d j u n c t to ~ m o d e r n ~ m e s h r e p a i r s in giant inguinal and incisional, primary and recurrent hernias.

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References Caldironi MW, Romano M, Bozza F (199o) Progressive pneumoperitoneum in the management of giant incisionaI hernias: a study of 41 patients. Br J Surg. 77:306-308 Champetier ], Laborde Y, Letoublon Ch, Durand A (1978) Traitement des 6ventrations abdominales postop~ratoires: bases biom~caniques ~lementaires. I Chit (Paris) 115: 585591 Chevrel JP, Flament JB (1995) Traitement des ~ventrations de la paroi abdominale. Techniques chirurgicales. Appareil digestif. Encycl Med Chir Paris, pp. 4o-165 Conze J, Truong S, Willis S, Schippers E, Schumpelick V (1996) Vermeidung iatrogener Verletzungen bei laparoskopischen Eingriffen durch pr~ioperative perkutane Sonographie. Endoskopie heute 9:124 Flament JB, Rives I, Palot JB, Burde A, Avisse C (1998) Major incisional hernia. In: Chevrel IP (ed) Hernias and surgery of the abdominal wall. Springer-Verlag, Berlin Heidelberg New York, pp. 128-~57 Flament IB, Avisse C, Palot JP, Delattre JF (1999) Biomaterials - principles of implantation.. In: Schumpelick V, Kingsnorth AN (eds) Incisional hernia. Springer-Verlag, Berlin Heidelberg New York, pp. 217-23o Goni Moreno IG (1947) Chronic eventrations and large hernias. Surgery 22:945-948

Goni Moreno IG (1978) The rational treatment of hernias and voluminous chronic eventrations: Preparation with progressive pneumoperitoneum. In: Nyhus LM, Condon RE (eds) Hernia. 2nd edition, JB Lippincott, Philadelphia, pp 536-560 Hamer DB, Duthie HL (1972) Pneumoperitoneum in the management of abdominal incisional hernia. Br J Surg 59:372-375 Klinge U, Miiller M, Brficker C, Schumpelick V (1998) Application of three dimensional stereography to assess abdominal wall mobility. Hernia 2:11-14 Klosterhalfen B, Klinge U (1999) Biocompatibility of biomaterials - histological aspects. In: Schumpelick V, Kingsnorth AN (eds) Incisional hernia. Springer-Verlag, Berlin Heidelberg New York, pp 198-216 Koontz A (1958) Hernias that have forfeited the right of domicile: Use of pneumoperitoneum as aid in their operative cure. South Med J 51:165-169 Mason EE (1995) Pnenmoperitoneum in giant hernia. In: Nyhns LM, Condon RE (eds) Hernia. 4th edition, JB Lippincott, Philadelphia, pp 515-524 Mfiller M, Klinge U, Conze J, Schumpelick V (1998) Abdominal wall compliance after Marlex mesh implantation for incisional hernia repair. Hernia 2:113-117

Pingree JH, Clark IH (1968) Pneumoperitoneum. A neglected procedure for the repair of large abdominal hernias. Arch Surg 96:256-258 Raynor RR, Del Guerico L (1989) The place for pneumoperitoneum in the repair of massive hernia. World J Surg 13:581-585 Rives J, Lardennois B, Pire J, Hibon i (1973) Les grandes ~ventrations: importance du ,,volet abdominal >7et des troubles respiratoires qui lui sont secondaires. Chirurgie 99:547-551 Schumpelick V, Conze I, Klinge U (1996) Preperitoneal mesh repair of incisional hernias - a comparative retrospective study. Chirurg 67:lo28-1o35 Schumpelick V, Klinge U (1999) Intermediate follow-up results of sublay polypropylene repair in primary and recurrent incisional hernias. In: Schumpelick V, Kingsnorth AN (eds) Incisional hernia. Springer-Verlag, Berlin Heidelberg New York, pp 312-326 Steichen FM (t965) A simpte method for establishing, maintaining, and regulating surgically induced pneumoperitoneum in preparation for large hernia repairs. Surge~ 58:lo31-1o32 Willis S, Conze I, Mfiller S, Klosterhalfen B, Schumpelick V (t996) Progressives Pneumop e r i t o n e u m in der B e h a n d l u n g yon Leisten- und Narbenhernien - Tierexperimentelle Ergebnisse und ldinische Anwendung. Langenbecks Arch Chir 381:132-137