Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_731_Библиотеки_им_академика_М_И_Перельмана.pdf
Chapter 17 • Managing Pediatric and Neonatal Abdominal Wall Defects 311
Undermining of
subcutaneous layer
Figure 17-11.
Transverse closure
of fascia
Figure 17-12.
Figure 17-13.
312 Section V • Other Abdominal Wall Procedures
s
Sutureless repair, developed by Sandler et al. (2004), allows the defect to naturally heal
4. Postoperative Care
s
s
s
s
s
Postoperative care requires the neonatal intensive care unit (NICU). Larger defects require
After repair, ileus is common, resolving more quickly in patients with omphalocele than
Gastroschisis also is associated with morbidity and mortality related to gastrointestinal
With omphalocele, the long-term outcome is most dependent on the associated chromo-
The long-term outcome for patients with gastroschisis has dramatically improved over the
over the reduced bowel. The bowel is first manually reduced into the abdominal cavity
(Fig.17-14, A, B). The umbilical cord is wrapped into a coil over the defect. The area is cov-
ered with a 2 × 2 gauze sponge and Tegaderm dressing (3M, St. Paul, MN) and allowed to
heal over several days (Fig.17-14, C, D). This type of repair uses no sutures, eliminates the
need for a trip to the OR, and may be cosmetically superior to traditional surgical repair.
mechanical ventilation for days to weeks. It is important to monitor for signs of abdominal compartment syndrome (hypotension, oliguria, acidosis, intestinal ischemia, liver dysfunction) with intragastric or intravesical catheters. The intraabdominal pressure should
not be above 15 to 20 mm Hg.
those with gastroschisis. A nasogastric tube is necessary initially and total parenteral nutrition is started early. In fact, many surgeons place a central venous catheter at the time of
operation for this purpose. Once bowel function has returned, enteral feedings can begin.
Elemental formula is best tolerated and once the infant’s caloric intake is adequate (usually
around 3 to 4 weeks without complications) the patient is ready for discharge to home.
dysfunction, such as short bowel syndrome and sepsis from intraabdominal, wound, or
central line infection.
somal/structural abnormalities with an overall mortality of 10% to 30%. Long-term complications include gastroesophageal reflux disease, feeding disorders, and adhesive bowel
obstruction, but most of these issues improve over time. Most individuals without severe
associated anomalies grow up to live normal lives.
past few decades because of improved surgical technique and perioperative management,
such as the use of staged closure and the availability of total parenteral nutrition. Overall
mortality is now <10%, and is most often associated with intestinal atresia. Prognosis is
most dependent on the condition of the exteriorized bowel. Those patients with intestinal
atresia undergo additional surgical procedures, delayed enteral feedings, and have prolonged hospital stays.
Chapter 17 • Managing Pediatric and Neonatal Abdominal Wall Defects 313
A
C
Figure 17-14.
B
D
314 Section V • Other Abdominal Wall Procedures
5. Pearls/Pitfalls
s
s
s
s
If a fetus is discovered to have an abdominal wall defect, there is no evidence to sug-
gest that early delivery or cesarean-section is beneficial. The mode and timing of delivery
should be determined by fetal well-being and obstetric considerations. Serial ultrasound
exams during pregnancy can aid in evaluating the condition of the bowel and whether the
fetus is at risk.
It is important to differentiate omphalocele from gastroschisis because this distinction
greatly affects clinical management. A membranous sac covering the viscera is present
in omphalocele (unless ruptured) and absent in gastroschisis. Omphalocele is a central
defect, whereas gastroschisis is lateral to (usually to the right of) the umbilicus. The herniated viscera in omphalocele may include bowel, stomach, and liver, whereas gastroschisis
may involve bowel, stomach, bladder, and gonads.
Omphalocele can be repaired electively, while the presence of associated abnormalities is
investigated. However, gastroschisis (and ruptured omphalocele) require urgent surgical
repair because these entities leave the infant vulnerable to dehydration, hypothermia, electrolyte abnormalities, and infection.
When repairing these abdominal wall defects, care must be taken to avoid too aggressive
of a repair, which can potentially lead to abdominal compartment syndrome, causing more
complications and putting the remaining bowel at risk. Avoidance of abdominal compartment syndrome decreases the risk of intestinal ischemia, necrotizing enterocolitis, and
intestinal perforation, all of which can lead to devastating consequences for a vulnerable
infant.
Selected References
Aspelund GLJ: Abdominal wall defects, Current Paediatrics:192–198, 2006.
Henrich K, Huemmer HP, Reingruber B, Weber PG: Gastroschisis and omphalocele: treatments and long-term outcomes, Pediatr Surg Int
24:167–173, 2008.
Langer JC: Abdominal wall defects, World J Surg 27:117–124, 2003.
Ledbetter DJ: Gastroschisis and omphalocele, Surg Clin North Am 86:249–260, 2006:vii.
Mann S, Blinman TA, Douglas Wilson R: Prenatal and postnatal management of omphalocele, Prenat Diagn 28:626–632, 2008.
Molenaar JC, Tibboel D: Gastroschisis and omphalocele, World J Surg 17:337–341, 1993.
Puri PHM, editor: Pediatric Surgery, New York, NY, 2006, Springer-Verlag Berlin Heidelberg, pp 153–170.
Sandler A, Lawrence J, Meehan J, Phearman L, Soper R: J Pediatr Surg 39(5):738–741, 2004 May.
Biologic Mesh Choices for
1. Indications for the Use of Biologic Mesh Materials
C HAPT E R
18
Surgical Repair
Michael G. Franz, MD
s
s
s
The major indication for the use of biologic meshes during abdominal wall surgery is
improved wound healing. This most often translates into the minimization of wound complications. Studies have reported wound infection rates of 4% to 16% after incisional ventral hernia repair. The application of synthetic mesh to reinforce abdominal wall repairs
significantly reduced recurrence rates, but it introduced an increased risk of complicated
wound infections, synthetic mesh infections and erosion into the bowel. Level one data find
that recurrence rate and wound infection are related, in that a postoperative wound infection significantly increases the incidence of recurrent incisional hernia. Another inherent
limitation with synthetic meshes is shrinkage. It is well measured now in animal models
and with human explants that synthetic meshes lose on the average 20% of their surface area following implantation. This is believed to contribute to high hernia recurrence
rates. The era of managing traumatized patients with open abdomens expanded the use of
biologic mesh based abdominal wall reconstruction. Here there was concern for wound
contamination and exposure of synthetic prostheses to the abdominal viscera. Tenuous or
insufficient skin coverage also is suggested as an indication for the use of a biologic mesh
during abdominal wall repair.
The risk of laparotomy wound complications may be graded and wound outcomes pre-
dicted based on patient comorbidities and level of contamination. Now long-term experience with synthetic meshes in the abdominal wall raises awareness and concern for acute
and chronic infections, as well as intestinal injury. The growing problem of infected mesh
explantation also drove increased use of biologic meshes as replacements. Obesity is now a
measurable risk factor for increased wound complications following ventral hernia repair.
The growing popularity of major reconstructive procedures for large ventral hernias also
expanded the use of biologic meshes. The perceived need for reinforcement following
component separation procedures and the concern for the implantation of synthetic materials into these large surface area wounds led to this adaptation of biologic mesh. Clinical
studies have supported reduced recurrence rates using mesh reinforcement during component separation.
316
Chapter 18 • Biologic Mesh Choices for Surgical Repair 317
Table 18-1. Tissue Source and Properties of Biologic Meshes
PRODUCT MANUFACTURER PROPERTIES
HUMAN DERMIS
Alloderm Lifecell Non–cross-linked
Flex HD Musculoskeletal Transplant
Foundation (MTF)/Ethicon
Allomax Bard/Davol
Permacol Covidien
Strattice LifeCell Non–cross-linked
XenMatrix Bard/Davol Non–cross-linked
Surgisis Cook
Veritas Synovis Pericardium
Tutopatch Tutogen Pericardium Little data
SurgiMend TEI Biosciences Fetal dermis
Aseptic without irradiation
Non–cross linked
Aseptic
Proprietary Tutoplast process
to remove cells and preserve
matrix
PORCINE DERMIS
Chemically cross-linked Large sizes; No refrigeration
Terminally sterilized
Electron beam sterilized
PORCINE INTESTINE
Modified intestinal submucosal
matrix; Non–cross-linked
BOVINE
Non–cross-linked
POTENTIAL
ADVANTAGES
Preserved matrix
Large reported clinical
experience
No refrigeration or
rehydration
Low-dose gamma irradiation
to sterilize
or rehydration; Large
reported clinical experience
Large sheets
No rehydration
No rehydration; Large sheets Few clinical data
Long clinical experience; No
refrigeration
Favorable fetal collagen
content;
Long shelf life
POTENTIAL
DISADVANTAGES
Freeze dried;
Needs refrigeration;
Small sizes
Small reported clinical
experience
Small reported clinical
experience;
Requires hydration
Concern for increased foreign
body reaction due to heavy
cross-linking; Chemical odor
and concern for inflammation
Few clinical data
Reports of enzymatic degradation; Requires rehydration
Small clinical experience in
ventral hernia
Requires rehydration;
Very little data
2. Tissue Sources for Biologic Mesh Materials (Table 18-1)
s
The application of biologic materials to abdominal wall repair began with autologous source
material. Tensor fascia lata (TFL) has the widest experience. De-epithelialized autologous
dermis also has been used. Muscle flaps and now even composite tissue transfers, both
pedicle based and free flaps, have been described. Autologous small bowel and omentum
also are reported as tissue sources for abdominal wall repair. Donor site morbidity is the
obvious limitation of autologous biologic tissue sources. There are no large studies of TFL
or autologous dermis in abdominal wall repair, and the long-term durability, especially
when used as bridging repair, is not known.
s
The need for more readily available biologic reconstructive matrices and the limitation
of autologous tissue donor site morbidity led to the development of off-the-shelf human
allograft sources for abdominal wall reconstruction. To date, this has been dominated by
human dermal allografts. Although early results have been good, there is an inherent limitation in the need for human tissue banking and the risk of transmission of infectious
disease. Before processing, potential donors undergo screening that includes a medical and
social history review, physical examination and serologic testing to minimize the risk of
disease transmission. Donor tissue that passes rigorous screening then undergoes physical
and chemical processing to further reduce the risk of disease transmission before implantation. Occasionally, social and cultural restrictions may preclude the application of human
tissue sources to specific patient groups.
318 Section VI • Mesh Choices
s
The unique regulatory limitations of human tissue banking and the need for better process-
ing quality control drove the introduction of xenografts as biologic materials for abdominal
wall reconstruction. This also reduces the cost of xenografts that on the average are 50% less
expensive than allografts. This trend has been dominated by porcine intestinal submucosa,
porcine dermis, bovine fetal dermis, and bovine adult pericardium. One fundamental limitation of xenografts is the presence in humans of preformed anti-xenograft antibodies. The
anti-galactose-alpha-1,3-galactose antibodies are the best described. There is also evidence
for the induction of nonspecific inflammatory pathways as part of a generalized foreign
body reaction. With xenografts as with allografts, social and cultural restrictions may apply.
3. Biologic Mesh Modification and Processing
s
The use of biologic allografts and xenografts for soft tissue repair required the development
of processing techniques that allowed for the removal of immunogenic cells, while preserving a functional biologic matrix. This remnant biologic matrix is constructed primarily of
collagen, and depending on the degree of preservation of the native structure, maintains
measurable biologic function even in the acellularized state.
s
Porcine intestinal submucosa is a readily available source of biologic matrix. In its var-
ied forms it maintains adequate mechanical qualities and has a recognized safety profile
when applied for abdominal wall repair or reconstruction. The proprietary process for
stripping and harvesting the intestinal submucosa results in modification of the original
biologic structure. Intestinal submucosa also has been laminated to improve mechanical
performance.
s
The importance of preserving the native dermal matrix structure and to what degree is
still debated. Cross-linking of dermal matrix xenografts was introduced as a method to
increase mechanical strength and to protect the collagen-based implant against enzymatic
degradation by collagenases. Cross-linking also is believed to reduce the immunogenic
potential of the acellularized matrix, due mainly to expression of galactose-alpha-1,3galactose molecular epitopes. In its simplest form, cross-linking causes molecular bonds
to form between native collagen molecules. Several steps during biologic mesh processing can cause matrix cross-linking, as with the use of detergents, enzymes, or high-energy
beams for sterilization. These steps, in addition to intentional chemical modification of
the matrix or terminal sterilization, all induce varying degrees of matrix cross-linking. The
level of matrix cross-linking can be quantified by measuring the mesh collagen melting
point. Higher degrees of cross-linking result in higher matrix melting points. Examination
by electron microscopy also can be used to look for the preservation of biologic matrix
structure. If the goal of biologic mesh–based soft tissue reconstruction is to support the
repopulation of the donor matrix with host cells, like endothelial cells and fibroblasts, it
appears that high levels of cross-linking impair that recellularization process. The host may
even recognize a highly cross-linked material as foreign and induce a foreign body capsule
response. A balance must therefore be struck between biologic mesh durability and regenerative potential. The end result is observed to be varying degrees of incorporation, resorption, or encapsulation. It appears that the outcome depends on material source, material
processing, host response, surgical technique, and the level of wound contamination or
inflammation. Further experimental studies and well-designed clinical trials are needed to
characterize the optimum materials and methods.
s
Allografts and xenografts vary in the degree of terminal sterilization. Some methods limit
terminal sterilization, using instead aseptic techniques. It is believed that this ensures
preservation of extracellular matrix structure with improved biologic function following
implantation. Other biologic mesh materials undergo true terminal sterilization, as with
low-dose gamma irradiation. It is believed that this step may be important to minimizing
infectious complications.
Chapter 18 • Biologic Mesh Choices for Surgical Repair 319
Table 18-2. Summary of Biologic Mesh Mechanisms of Action
TISSUE PROCESSING IMMUNOLOGIC RESPONSE BIOLOGIC RESPONSE HOST RESPONSE/OUTCOME
Matrix preserved
Block alpha-gal epitope
Matrix structure significantly
modified
Exposure of foreign antigens
Matrix heavily cross-linked
Relatively inert Fibroblast ingrowth
Immunologically active or
inflammatory
Angiogenesis
Remodeling
Increased proteases
Inflammation
Scar formation
Some cellular ingrowth
Limited cellular ingrowth
Inflammation
Giant cell formation
Matrix tissue regeneration
Matrix resorption and potential scar
plate
Host foreign body encapsulation
Contraction
4. Mechanism of Action of Biologic Meshes (Table 18-2)
s
s
The primary function of soft tissue prostheses, whether synthetic or biologic meshes, is
to provide immediate and long-term mechanical stability to the abdominal wall reconstruction. Level one evidence derived from a randomized, controlled trial found that the
use of a reinforcing mesh prosthesis reduces the incisional hernia recurrence rate by 50%.
The major risk of synthetic mesh implants is the permanent foreign body reaction, infection, encapsulation, extrusion, and erosion. There is now experimental and clinical evidence that biologic meshes may be repopulated with endothelial cells, revascularized and
then incorporated into an abdominal wall reconstruction. It is the early establishment of
a blood supply that is believed to establish improved resistance to infection. Further, as a
blood supply is restored, other cells involved in tissue repair like inflammatory cells and
fibroblasts may be recruited to promote more normal wound healing, and ideally, tissue
regeneration.
Biologic meshes provide the potential for extracellular matrix directed repair signaling.
Preserved vascular channels, for example, may allow endothelial cells or their precursors
to enter the matrix, supporting angiogenesis by the process of inosculation. Other matrix
molecules like fibronectin and glycosaminoglycans, when preserved, may act as signals for
fibroblast integration and host collagen synthesis. The amount of other matrix molecules
also varies widely depending on the biologic mesh tissue source. Human dermis, for example, contains relatively more elastin than porcine dermis, rendering it more compliant.
5. Reported Clinical Results with Biologic Meshes
s
The choice of biologic mesh material may be based on a variety of considerations, includ-
ing characteristics of the patient and abdominal wall defect, surgeon familiarity with the
material, and cost. The risk for surgical wound complication and subsequent infection may
determine the selection of a synthetic versus a biologic repair material. On the balance,
the biologic mesh material should provide sustained mechanical function resulting in an
acceptable recurrence rate with resistance to wound infection, especially when compared
to the synthetic counter parts.
320 Section VI • Mesh Choices
s
s
s
s
s
The majority of reports of surgeons’ experience with biologic mesh repairs come from
single center, retrospective reviews. A randomized controlled trial of biologic mesh-based
repairs versus synthetic mesh–based repairs for ventral hernia has never been reported.
Multi-institutional, single-arm studies suggesting a proof-in-principle for the safety and
efficacy of biologic mesh–based repairs are now appearing. It is broadly concluded that biologic mesh–based abdominal wall reconstructions can be safe and effective. Like most new
techniques and technologies, it also appears surgical technique and material choice in the
application of biologic meshes together affect outcomes. Without high level evidence, the
decision tree remains primarily driven by surgeon experience and expert opinion.
The most frequent early application of biologic mesh for abdominal wall reconstruction
was to manage complex ventral hernia repairs. This usually meant the need to perform
an abdominal wall reconstruction in the setting of moderate or even significant contamination. Many surgeons reported the reliability of biologic mesh–based repairs, and the
opportunity to avoid the technique of intentional, incisional ventral hernia. Numerous
series now report the ability to safely salvage an abdominal wall repair when at increased
risk for wound complication, with wound infection and recurrence rates that are acceptable when compared to more standard synthetic mesh–based repairs in lower risk settings.
It was recognized that planned incisional hernia leads almost uniformly to progressive loss
of domain; an increased risk of intestinal fistulization; and by definition, the requirement
for further reconstructive procedures. Included was the frequent need for a skin graft with
donor site morbidity.
The increased use of decompressive laparotomies and damage control laparotomies
resulted in an increased number of surgical patients with complex abdominal wall injuries. The ability to manage the open abdomen over a prolonged period of time supported
this clinical approach. Often, at the time of abdominal wall repair, a reinforcing material was needed by the surgeon because of contamination and the risk of wound healing
delay, hypotensive hypoperfusion of the abdominal wall, or other common comorbidities
like obesity or immunosuppression. Biologic mesh reinforced abdominal wall repairs are
reported as safe and reliable in this setting as well.
Accumulating reports of the risk for the intraperitoneal placement of synthetic onlay meshes
(IPOM) also drove the application of biologic meshes to abdominal wall reconstruction.
The U.S. NSQuIP database and Dutch Hernia Registry found that reoperation in the presence of a prior synthetic mesh in the intraperitoneal position significantly increased the
risk of unplanned bowel injury and resection from 3% to 23 % .
Some surgeons and centers have reported recurrence rates for incisional hernia as high as
100% when using biologic meshes. A consensus is emerging that this is not the universal
experience and that some of this is due to surgical technique and some of it is due to material properties. It appears that the use of biologic meshes to bridge a gap in the abdominal
wall leads to a high incidence of “bulging” or recurrence. Regardless of the definition of
recurrent incisional hernia, a bulging defect is visible, it may impair abdominal wall function as during a sit-up, and usually the patient is displeased with the result. Some of this
may be an inherent biologic limitation of the biologic meshes, in that in order for revascularization and general recellularization to occur, the biologic implant must be in contact
with well-perfused host tissue. It now appears that biologic meshes perform better when
used as reinforcing materials to an already reconstructed abdominal wall, as after component separation. The human allograft dermis also contains more elastin that may result
in more stretching, leading to a clinical bulge. It is not clear whether porcine dermis or
intestinal submucosa does this less or should be held to the same limitations.
Chapter 18 • Biologic Mesh Choices for Surgical Repair 321
s
s
Selected References
Breuing K, Butler CE, Ferzoco S, et al: Incisional ventral hernias: Review of the literature and recommendations regarding the grading
and technique of repair, Surgery 148(3):544–558, 2010.
Diaz JJ Jr, Conquest AM, Ferzoco SJ, Vargo D, Miller P, Wu YC, et al: Multi-institutional experience using human acellular dermal matrix
for ventral hernia repair in a compromised surgical field, Arch Surg 144(3):209–215, 2009 Mar.
Espinosa-de-Los-Monteros A, de la Torre JI, Marrero I, Andrades P, Davis MR, Vasconez LO: Utilization of human cadaveric acellular
dermis for abdominal hernia reconstruction, Ann Plast Surg 58(3):264–267, 2007 Mar.
Franz MG: The biology of hernia formation, Surg Clin North Am 88(1):1–15, 2008 Feb:vii.
Gray SH, Vick CC, Graham LA, Finan KR, Neumayer LA, Hawn MT: Risk of complications from enterotomy or unplanned bowel resec-
tion during elective hernia repair, Arch Surg 143(6):582–586, 2008 Jun.
Halm JA, de Wall LL, Steyerberg EW, Jeekel J, Lange JF: Intraperitoneal polypropylene mesh hernia repair complicates subsequent
abdominal surgery, World J Surg 31(2):423–429, 2007 Feb.
Luijendijk RW, Hop WCJ, van den Tol P, de Lange DCD, Braaksma MMJ, Ijzermans JNM, et al: A comparison of suture repair with mesh
repair for incisional hernia, New England Journal of Medicine 343(6):392–398, 2000 Aug 10.
Currently, biologic meshes are very compliant, especially when compared to most syn-
thetic meshes. This can make handling more difficult and most surgeons experience a
learning curve for understanding the unique material properties. This has resulted in limited adaptation to laparoscopic applications, for example. The concern for bulging following a bridging technique also has limited the development of laparoscopic ventral hernia
repair using biologic meshes.
No head-to-head comparative trials have been performed to date evaluating different bio-
logic repair materials in incisional hernia repair, and differentiation between products is
based on early reported findings with only a limited number of the available prostheses.
Detailed human and animal data describing the qualities of biologic repair materials are
only available for some of these prostheses.