Abdo Reconstruction

Considerations in Abdominal WallReconstructionJustin M. Sacks, M.D. 1 Justin M. Broyles, M.D. 1 Donald P. Baumann, M.D., F.A.C.S. 2

1Department of Plastic and Reconstructive Surgery, The JohnsHopkins Hospital, Baltimore, Maryland

2Department of Plastic Surgery, The University of Texas M.D.Anderson Cancer Center, Houston, Texas

Semin Plast Surg 2012;26:57.

Address for correspondence and reprint requests Justin M. Sacks,M.D., Johns Hopkins Outpatient Center, 601 N. Calvert St., Suite8140D, Baltimore, MD 21287 (e-mail: [email protected]).

Reconstruction of complex defects of the abdominal wall isboth challenging and technically demanding for plastic sur-geons. Therefore, it is imperative that the operating surgeon isknowledgeable of the etiologies, pertinent anatomy, andproper postoperative care of these patients. Although thesedefects can be attributed to a myriad of etiologic factors, theobjectives in abdominal wall reconstruction are consistentand include the restoration of abdominal wall integrity,protection of intraabdominal viscera, and the prevention ofhernia or bulge formation while maintaining an aestheticallyfavorable result.1

Abdominal Wall Defects

Etiologies for complex abdominal wall defects include trau-ma, oncologic processes, radiation necrosis, infection, post-operative incisional hernias, and congenital anomalies. Eachof these etiologic factors provides for unique challenges indetermining reconstructive timing and course. The decision

to pursue immediate versus delayed abdominal reconstruc-tion is based upon patient comorbidities, etiology of thedefect, wound contamination, and overall clinical condition.In most situations, immediate reconstruction is preferredsecondary to physiologic advantages of closing the abdomen.However, immediate reconstruction is deferred in amyriad ofsituations including signicant inammation and infection,wound contamination, and concomitant medical or surgicalcomorbidities that prohibit surgery.

If abdominal reconstruction is delayed, temporary ab-dominal coverage can be achieved in several ways. Skingrafts can provide adequate, temporary closure for thesepatients while minimizing donor-site morbidity. In addi-tion, vacuum-assisted closure may provide superior, tem-porary coverage for a wound bed while increasingvascularization and potentially decreasing bacterial coloni-zation.2 Finally, temporary abdominal closure can beachieved using bioprosthetic or synthetic mesh; eithertype of mesh provides support and protects the

Keywords

abdominal wall complex defects abdominal wall

reconstruction anatomic zones

Abstract Reconstruction of complex defects of the central abdomen is both challenging andtechnically demanding for plastic surgeons. Advancements in the use of pedicle and freetissue transfer along with the use of bioprosthetic and synthetic meshes have providedfor novel approaches to these complex defects. Accordingly, detailed knowledge ofabdominal wall and lower extremity anatomy in combination with insight into thedesign, implementation, and limitations of various aps is essential to solve thesecomplex clinical problems. Although these defects can be attributed to a myriad ofetiologic factors, the objectives in abdominal wall reconstruction are consistent andinclude the restoration of abdominal wall integrity, protection of intraabdominalviscera, and the prevention of herniation. In this article, it is our goal to review pertinentanatomy, pre- and postoperative care regimens, and the various local, regional, anddistant aps that can be utilized in the reconstruction of these complex clinical cases ofthe central abdomen.

Issue Theme Abdominal WallReconstruction; Guest Editor,Lior Heller, M.D.

Copyright 2012 by Thieme MedicalPublishers, Inc., 333 Seventh Avenue,New York, NY 10001, USA.Tel: +1(212) 584-4662.

DOI http://dx.doi.org/10.1055/s-0032-1302458.ISSN 1535-2188.

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intraabdominal contents while minimizing signicant uidlosses and wound inammation.

Anatomy

Skin and Subcutaneous TissuesA thorough understanding of the anatomy of the abdominalwall is paramount when planning abdominalwall reconstruc-tion. The integrity and quantity of skin and subcutaneoustissue is related tomany factors such as age, body habitus, andprevious surgery. Underlying supercial tissues can be gross-ly divided into skin, subcutaneous fat, Camper fascia, and thedeeper Scarpa fascia. These supercial layers have importantconsiderations when considering closure and wound careoptions.

Musculofascial LayersAn understanding of the musculofascial layers is critical toabdominal wall reconstruction. The rectus abdominis muscleand pyramidalis muscles are located anteriorly. Each rectusabdominis fuses at the midline to form the linea alba. Thepyramidalis muscles are considered by many to be function-ally insignicant triangular muscles and are present in ap-proximately 80% of the population. The external oblique,internal oblique, and transversus abdominis muscles arelocated anterolaterally and fuse with the lateral aspect ofthe rectus abdominis bilaterally.

The arcuate line of the abdomen is a horizontal line thatrepresents an important anatomic landmark with respect tothe rectus sheath. Cranial to the arcuate line, the anteriorrectus sheath is composed of the aponeuroses of the externaloblique and anterior leaf of the aponeuroses of the internaloblique muscle. Similarly, the posterior rectus sheath iscomposed of the posterior leaf of the aponeurosis of theinternal oblique muscle, the transverses abdominis muscles,and the transversalis fascia. Caudal to the arcuate line, theanterior rectus sheath is composed of the aponeurosis of theexternal and internal obliques and the transverses abdominis.At this point, the posterior rectus sheath is composed of thetransversalis fascia only.

Blood SupplyThe vascular supply to the abdomen can be subdivided intothree zones based upon regional anatomy. A regional vascu-lar map initially described by Huger provides a simplistic, yetreliable model for illustration.3 Zone I is located in theanterior midline portion of the abdomen in the vicinity ofthe rectus abdominis and is supplied by the deep epigastricarteries. Specically, the superior and the deep inferiorepigastric arteries supply the rectus muscle and the overly-ing skin and subcutaneous tissues. Zone II encompasses thecaudal aspect of the anterior abdominal wall and derives itsvascular supply from four main arterial systems. The super-cial external pudendal and supercial epigastric arteriesare both derived from the femoral artery and supply thesupercial fascia and skin in this area. The inferior epigastricand deep circumex arteries supply the musculature in thisarea. Zone III is described as the most lateral aspect of the

abdominalwall cranial and it derives its vascular supply fromthe intercostal and lumbar arteries, which arise from theaorta.

Patient Evaluation

History and Physical ExaminationIn addition to anatomic knowledge, it is essential to under-stand patient characteristics that could lead to potentialcomplications in abdominal wall reconstruction. Accordingly,laboratory assessment as well as consultation from otherservices including general surgery, internal medicine, andnutrition plays a vital role in the successful outcome of theoperation. In addition, aspects of a patient's past medicalhistory such as peripheral vascular disease, diabetes mellitus,autoimmune disorders, and hematologic disorders can beassociated with impairedwound healing and should alert theteam to aggressively prevent these complications.

When acquiring a patient's history, it is important to focuson prior surgical history and prior abdominal wall radiationexposure. Prior abdominal surgery can compromise theability to mobilize aspects of the abdominal wall. The pres-ence of colostomies, ileostomies, and urostomies should alertthe surgeon to the potential for wound healing difculties asthesehave the potential to spread enteric bacteria throughoutthe defect. Furthermore, prior abdominal surgery can alterperfusion to the underlying fascia and potentially createvisceral adhesions, which can complicate reconstructionefforts.4 Finally, prior radiation exposure can decreasewound-healing capacity and alter local tissue perfusion,two aspects that can further complicate abdominal wallreconstruction.

A careful assessment focusing on the patient's socialhistory can provide guidance pertaining to pre- and postop-erative care. Accordingly, social habits such as tobacco use andalcohol dependency can lead to impaired wound healingthrough vasoconstriction and immunosuppression, respec-tively. Attention should be paid to the patient's employmentas heavy lifting can be contraindicated in these patients forprolonged periods and may impair the livelihood of patientsengaged in manual labor. Finally, given the relatively longrecovery time for many of these patients, a strong socialsupport system should be in play to assist the patient in theirrecovery.

Preoperative physical examination should focus on factorssuch as body mass index and evaluation of potential donorsites for ap coverage. Weight reduction for obese patients isrecommended to decrease complication rates, although thisis not always feasible in the setting of traumatic abdominalwall repair. Furthermore, physical examination should focuson the potential suitability for ap harvest both cranial andcaudal to the defect.

Wound bed evaluation should focus on establishing a cleanand well-vascularized wound base. If the abdominal defect isan acute, uncontaminated wound, simple surgical debride-ment can prepare the surrounding tissues for adequatecoverage. Chronic abdominal wounds require further evalua-tion prior to temporary or denitive coverage. The patient's

Seminars in Plastic Surgery Vol. 26 No. 1/2012

Considerations in Abdominal Wall Reconstruction Sacks et al.6

medical abnormalities such as coagulation abnormalities,glucose levels, and vascular deciencies should rst be ad-dressed. Further aggressive debridement of devitalized tissueand eradication of microorganisms should be performedsequentially until the chronic wound is converted into anacute wound. At this point, the patient should have sufcientgranulation tissue to pursue further reconstruction.

Imaging StudiesAbdominal computed tomography (CT) or magnetic reso-nance imaging (MRI) evaluation can identify the extent of theabdominal wall defect and the integrity of adjacent muscu-lofascial structures to aid in preoperative planning. Whenusing pedicled aps from the abdomen, such as the verticalrectus abdominis myocutaneous (VRAM) or anterolateralthigh (ALT) ap, CT scans performed with contrast can delin-eate the vascular anatomy to the theseaps. The deep inferiorepigastric vessels can be seen clearly going to the rectusmuscle and coursing through this structure. This preoperativending allows the surgeon tomake operative decisions aheadof time, especially if the patient has had previous surgerypotentially damaging these vessels.5 CT angiography is in-valuable in accurately identifying the abdominal wall vascu-lature when planning a free tissue transfer. This is ofparticular importance in the reconstruction of the radiatedabdominal wall where vascular anatomy can be altered

signicantly and perforating vessels can be difcult to local-ize. Recipient vessels for free tissue transfer along withpedicle vessels can be localized with routine CT angiographyof the abdominal wall.

In conclusion, a careful assessment and a comprehensiveworkup may be required in some of the complex abdominalwall reconstruction patients. This approach will allow cus-tomizing the management for each individual patient andwill help decrease postoperative complications.

References1 Butler CE. The role of bioprosthetics in abdominal wall reconstruc-tion. Clin Plast Surg 2006;33(2):199211, vvi

2 Weed T, Ratliff C, Drake DB. Quantifying bacterial bioburdenduring negative pressure wound therapy: does the wound VACenhance bacterial clearance? Ann Plast Surg 2004;52(3):276279,discussion 279280

3 Huger WE Jr. The anatomic rationale for abdominal lipectomy. AmSurg 1979;45(9):612617

4 Lin SJ, Butler CE. Subtotal thigh ap and bioprosthetic meshreconstruction for large, composite abdominal wall defects. PlastReconstr Surg 2010;125(4):11461156

5 RozenWM, Ashton MW, Grinsell D, Stella DL, Phillips TJ, Taylor GI.Establishing the case for CT angiography in the preoperativeimaging of abdominal wall perforators. Microsurgery 2008;28(5):306313


Considerations in Abdominal Wall Reconstruction Sacks et al. 7

Intraabdominal Challenges Affecting AbdominalWall ReconstructionJennifer Movassaghi Moffett, M.D. 1 Uri Gedalia, M.D. 2 Amy Shengnan Xue, M.S. 3 Lior Heller, M.D. 3

1Division of Surgical Oncology, Michael E.DeBakey Department ofSurgery, Baylor College of Medicine; and General Surgery, Houston,Texas

2Private Practice, Houston, Texas3Division of Plastic Surgery, Baylor College of Medicine, Houston,Texas


Address for correspondence and reprint requests Lior Heller, M.D.,Baylor College of Medicine, Medical Building, 1977 Butler Blvd., SuiteE6.100, Houston, TX 77030 (e-mail: [email protected]).

Annually, more than 200,000 reconstructions of large ab-dominal wall defects are performed in the United States.These defects present a unique challenge for surgeons.Most cases require a multidisciplinary approach to restoreproper function and integrity of the abdominal wall. Such ateam approach should include general surgeons, plastic andreconstructive surgeons, anesthesiologists, nutritionists, aswell as pre- and postoperative rehabilitation experts. Manycontributing factors have been linked to the formation ofabdominal wall defects, specically previous abdominal sur-geries, traumatic injuries leading to one or more intraabdo-minal pathologies, infection and abscess formation, radiationchanges, stula formation, and gross anatomic defects as aresult of tumor resection.

Optimal reconstructive results require a successful repairat the rst attempt because the risk for incisional herniaincreases with each additional repair. Timing of reconstruc-tion depends on the resolution of any acute or subacuteinammation caused by the underlying pathology. The sur-gical team must address the complexity of the underlyingpathology as well as the patient's general condition during

preoperative evaluation to avoid and reduce incidence ofpostoperative complications, including prosthetic mesh in-fection, mesh disintegration due to urine or fecal leaks, andneed for reoperation.

Infection and Intraabdominal Abscesses

An infected surgical eld, due to skin and/or intraabdominalinfection(s), can be detrimental to an attempted repair of theabdominal wall defect. These two distinct entities requiredifferent approaches in treatment. Identifying and control-ling the source of the infection is the mainstay ofmanagement.

Wound and Skin InfectionsInfection of the skin structures can affect abdominal wallreconstruction adversely by injecting the underlying meshand/or repair with bacteria. This may cause breakdown of therepair and hinder possible reattempts at reconstruction.Because wounds have a 40% chance of recolonization despitecomplete healing, the use of antibiotics should depend on the

Keywords

abdominal wallreconstruction

stula enterocutaneous

stula vesicocutaneous

stula

Abstract Abdominal wall defects may arise from trauma, infection, and prior abdominalsurgeries, such as tumor resections. Although ideally reconstruction should be accom-plished as soon as possible to restore the integrity and function of the abdominal wall, itis not always a viable option. A successful reconstruction must take into considerationthe local environment of the defect, as well as the global condition of the patient.Therefore, it is imperative that a multidisciplinary team be involved to optimize thepatient's care, particularly when a defect is complicated by a wound infection, anabscess, a stula, or a neoplasm. Our goal in this article is to explore the challengesevoked by each of these special situations, and review the necessary steps for successfulmanagement.

Issue Theme Abdominal WallReconstruction; Editor,Lior Heller, M.D.



8

clinical status of the wound and the patient, instead of solelyon culture results.1After identifying the source of infection, itmaybehelpful to assess for possible deeper penetration of theinfection using computed tomography (CT). Depending onthe size, depth, and etiology of the infected area, varioustechniques (such as surgical debridement, negative pressuredressings, or the more conventional wet-to-dry dressings)may be implemented to control the spread of infection andbring the area to a point where reconstruction is possible.Broad-spectrum intravenous antibiotic therapy should beinitiated until culture specicities and sensitivities areavailable.

Intraabdominal Infections (Diffuse Infections,Abscesses, and Organ-Specic Abscesses)Most cases of intraabdominal infection are caused by perfo-ration or leakage after a gastrointestinal anastomosis, orsevere inammation and infection of an intraabdominalorgan, including appendicitis, hepatic abscesses, secondarypancreatic infections and diverticulitis, all of which maynecessitate surgical exploration and drainage. The vast ma-jority of such abscesses can be effectively diagnosed viaabdominal CT imaging and drained percutaneously. Surgicalintervention is necessary in patients with multiple abscessesor abscesses in proximity to vital structures. In particular,closure of the abdominal wall in patients with secondarypancreatic infections is a signicant challenge, as 10 to 15% ofthese patients develop severe necrotizing pancreatitis, re-quiring repeated debridements.1 In this case, abdominal wallreconstruction is delayed until the infection is contained.

Fistulas

Enterocutaneous FistulasPostoperative stulas are a common, but dreaded complica-tion of intraabdominal interventions, and account for 75 to85% of the enterocutaneous (EC) stulas. They are most oftenassociatedwith operations performed for inammatory bow-el disease, malignancy, and adhesiolysis and can result fromunintentional enterotomy, erosion caused by synthetic mesh,or leakage from an anastomotic site. The remaining 15 to 25%of the EC stulas are spontaneous stulas caused by malig-nancy, radiation injury, inammatory bowel disease, diver-ticulitis, appendicitis, perforated ulcer disease, or ischemicbowel.2 Studies have shown that a concomitant abdominalwall defect is the strongest negative prognostic factor forspontaneous stula closure.4

Fistulas are often linked with infection, tissue ischemia,close contact with biomaterials, recurrent malignancy, radia-tion damage, as well as local factors such as scarring, brosis,and dense adhesions,which can increase the riskof iatrogenicenterotomies during repeat operations. Recurrent stulas areassociated with a higher level of morbidity and mortality asfurther surgical exploration and violation of abdominal wallincrease the risk for additional complications (Fig. 1).3

Once an EC stula has been identied, radiographic inves-tigation is crucial to dene the precise location of the stula,its anatomic tract, abscess cavities, and any associated dis-

ruption of the bowel wall. This is typically accomplished withuoroscopic stulography. The initial step for treating ECstulas includes treatment of any coexisting infections withappropriate antibiotic therapy, percutaneous or open drain-age of all uid collections, wound care, control of stuladrainage, and optimization of the patient's nutritional sta-tus.1 Of note, patients with an EC stula without evidence ofsepsis or a localized infection do not require prophylacticantibiotics as doing so can promote the selection of highlyresistant bacteria.2

Most sources recommend delaying surgery for at least 4 to6 months in patients with EC stulas to decrease morbidityand mortality.2,4 Management should involve a stepwiseapproach with the primary focus on treatment of sepsis,drainage of uid or purulent collections, correction of elec-trolyte imbalance and malnutrition, optimizing the patient'spreoperative status, as well as allowing the patient's abdomi-nal wall to heal with minimal inammation. The SOWATS[sepsis, optimization of nutritional state, wound care, anato-my (of the stula), timing of surgery, and surgical strategy]guideline provides detailed protocol in each of the abovecriterion for treatment of enterocutaneous stulas.5 Onlyafter these associated comorbidities have been addressedshould repair of the stula be addressed, and the reconstruc-tive surgeon proceed with denitive abdominal wall repair.

Special precautions should be taken to preserve skinintegrity of areas surrounding a high-output stula to de-crease local irritation and infection, as an intact abdominalwall is necessary for subsequent abdominal closure. Skinprotection can be accomplished with a variety of barriers,adhesives, andwound drainage bagswith the ultimate goal ofdrainage containment while facilitating patient mobility andcomfort.

Timing is a primary concern in abdominal wall closure inpatients with EC stulas. It is important to remember thatrepair of the stula takes precedence and the plastic surgeonmust be cautious in attempting abdominal repair that mayhinder a future, more denitive reconstruction. Candidatesfor denitive abdominal repair at time of stula excisioninclude patients with small defects and no underlying riskfactors for incisional hernias such as marked obesity, malnu-trition, and history of prior incisional hernias. In the eventthat closure of the abdomen with direct approximation orother reconstructive technique is feasible, the abdominal wallmay be left open intentionally. In this case, temporary cover-age such as a wet to dry dressings, with a split thickness skingraft followed by a staged reconstruction is indicated.3

Vesicocutaneous FistulaVesicocutaneous (VC) stulas usually occur as a result ofprocedures such as hysterectomies, bladder resections, andsuprapubic catheterizations. Postoperative irradiation forbladder and prostate carcinomas, as well as trauma andvesical calculi may also play a role in the formation of VCstulas. In cases of complete bladder resection with neo-bladder reconstruction (involving small bowel resection andformation of an ileal conduit and anastomosis of both uretersto the conduit) the presence of multiple anastomoses


Intraabdominal Challenges Affecting Abdominal Wall Reconstruction Moffett et al. 9

predispose for stula formation. The constant leakage ofurine results in maceration, and eventual destruction ofskin with ensuing infection, discomfort, and malodor.

An intravenous urogram (IVU), voiding cystourethrogram(VCU), and cystoscopy are useful in making the diagnosis.Other cross-sectional imaging modalities, such as CT scansand magnetic resonance imaging (MRI) are needed if the

stulous tract is complicated andmalignancy cannot be ruledout with routine imaging modalities.

The primary management of VC stulas has been opensurgery; however, if detected earlier in its course, they can bemanaged with an indwelling Foley catheter instead. If the VCstula is large, infectious or neoplastic in origin, open surgicalmanagement with excision of the stulous tract interposed

Figure 1 (A) A 34-year-old man with a history of pancreatitis, currently with jejunal cutaneous stulas and recurrent ventral hernia after rst repairwith Gortex mesh. (B) Fascia defect after removal of the mesh and the hernia sac. (C) The mesh and the hernia sac were removed during surgery, whichcaused injury to the small bowel in three areas. (D) Fascia is located after minimally invasive component separation, and the porcine acellular dermalmatrix (PADM) was applied in an underlay fashion. The tunnels, through which the minimally component separation was achieved, can be seen in thisimage. (E) Patient 2 months after surgical repair.


Intraabdominal Challenges Affecting Abdominal Wall Reconstruction Moffett et al.10

with amyocutaneous ap is ideal for treatment. VC stulas ofinfectious origin may be treated at the time of the denitiveabdominal wall repair. An open abdominal wound with asuspected VC stula should be repaired with temporarycoverage until stula is ruled out with appropriate imagingstudies. As a rule, all stulas must be repaired prior to adenitive abdominal wall reconstruction, especially in casesof complex defects requiring bioprosthetic meshes. Urineexposure can cause weakness and disintegration of thebiological mesh (Fig. 2).

Neoplasm

In evaluating reconstruction in patients with neoplasticprocesses, timing has minimal effect on the considerationsas resection and reconstruction can typically be performed ina single stage. However, due to the complexity of reconstruc-tion resulting from massive resection defects, this scenariodeserves further discussion. Amultidisciplinary team, involv-ing surgical oncology and plastic surgery, is crucial formanagement of these patients.

There are additional factors requiring consideration in thesurgical reconstruction in patients with a history of neo-

plasm. First, recent chemotherapymay inhibit wound healingthus making the timing of treatment a special factor inreconstruction. Second, prior radiation treatment can causetissue injury, increased tissue friability, aswell as formation ofabdominal wall defects.6 Acute radiation to a wound causessmall vessel stasis and occlusion, leading to local ischemia anddecreased tensile strength in the tissue. Ionizing radiation hasbeen found to directly impede broblast proliferation andcause irreversible damage to exposed skin and tissue.7 As aresult, surgical planning for a previously irradiated patientshould include mobilization of distant aps to allow use ofnonirradiated tissue.8

Conclusion

Acquired abdominal wall defects can arise from tumor resec-tion, trauma, infection, and radiation damage. Ideally, imme-diate reconstruction is the best approach. Unfortunately, itmay not be possible in all cases, thus temporary coverage orstaged abdominal wall reconstruction may be necessary. Acooperative approach between the plastic surgeon and thegeneral surgeon is crucial in managing patients with abdom-inal wall defects and their associated complications. Implicitto this process is resolution of all intraabdominal pathologiesprior to proceeding with abdominal wall reconstruction.Preoperative stabilization of wound infection and optimiza-tion of nutritional status are essential to the success ofabdominal wall reconstruction. Optimal surgical outcomedepends on the seamless collaboration of a multidisciplinaryteam and reconstructive techniques individualized to eachpatient based upon tissue requirements and comorbidities.

References1 Bradley EL III, Allen K. A prospective longitudinal study of obser-vation versus surgical intervention in the management of necro-tizing pancreatitis. Am J Surg 1991;161(1):1924, discussion2425

2 Rohrich RJ, Lowe JB, Hackney FL, Bowman JL, Hobar PC. Analgorithm for abdominal wall reconstruction. Plast ReconstrSurg 2000;105(1):202216, quiz 217

3 Szczerba SR, Dumanian GA. Denitive surgical treatment of in-fected or exposed ventral hernia mesh. Ann Surg 2003;237(3):437441

4 Lowe JB III. Updated algorithm for abdominal wall reconstruction.Clin Plast Surg 2006;33(2):225240, vi

5 Visschers RGJ, Olde Damink SW, Winkens B, Soeters PB, vanGemert WG. Treatment strategies in 135 consecutive patientswith enterocutaneous stulas. World J Surg 2008;32(3):445453

6 Graves G, Cunningham P, Raaf JH. Effect of chemotherapy on thehealing of surgical wounds. Clin Bull 1980;10(4):144149

7 Miller SH, Rudolph R. Healing in the irradiated wound. Clin PlastSurg 1990;17(3):503508

8 CohenM, GreviousM. The use of muscle aps for themanagementof recalcitrant gastrointestinal stulas. Clin Plast Surg 2006;33(2):295302

Figure 2 A 78-year-old patient, with a history of abdominal wounddehiscence after cystectomy and neobladder reconstruction, under-went fascia closure with biologic mesh. A urine leakage developedafter application of the biologic mesh and caused mesh disintegration.


Intraabdominal Challenges Affecting Abdominal Wall Reconstruction Moffett et al. 11

Anesthetic Considerations for Abdominal WallReconstructive SurgeryRachel Slabach, M.D. 1 Johan P. Suyderhoud, M.D. 1

1Department of Anesthesia, Georgetown University Hospital,Washington, DC


Address for correspondence and reprint requests Johan P.Suyderhoud, M.D., Associate Professor of Anesthesia, Physiology andBiophysics, Department of Anesthesia, Georgetown UniversityHospital, 3800 Reservoir Rd., NW, Washington, DC 20007(e-mail: [email protected]).

Anesthesia for Abdominal WallReconstructionAnesthetic considerations for abdominal wall reconstruction(AWR) are numerous and depend upon the medical status ofthe patient. No national registry for abdominal wall recon-struction exists; however, according to the American Societyfor Aesthetic Plastic Surgery's Cosmetic Surgery National DataBank, there were 144,929 abdominoplasties performed in2010,making it the fourthmost common cosmetic procedure.1

Historically these patients have fallen into several categories:cosmetic, status postabdominal trauma, postbariatric surgeryor extreme weight loss, ventral hernia, and status postinfec-tion/abdominal wall dehiscence. Although there are no exactnumbers of patients in each of these categories, many of theanesthetic considerations are consistent across this spectrum.In particular, the higher incidence of obesity and its comorbidconsequences in patients undergoing abdominoplasty entailsadditional anesthetic considerations.

Preoperative EvaluationObese patients are at a higher risk for other health compli-cations, specically hypertension, coronary artery disease,hyperlipidemia, diabetes, degenerative disk disease, and ob-

structive sleep apnea. Morbid obesity increases the risk ofmajor perioperative pulmonary embolisms from DVT aswell.2 Patients with additional comorbidities, such as obesityand sleep apnea, have a higher risk of anesthetic complica-tions.3 Estimates for assessing a patient's obesity include bodymass index (BMI kg/m2) and hipwaist ratio, both of whichare helpful predictors. Patients with a waist circumferencegreater than 102 cm for men and greater than 89 cm forwomen are at increased risk for obesity-related diseases.2

Preoperatively these patients need to be evaluated and opti-mized medically for surgery. Hypertension is a commonailment in this patient population and should be controlledpreoperatively. Pulmonary hypertension is frequent andsymptoms may include exertional dyspnea, fatigue, andsyncope. If the patient is either morbidly obese, or exhibitssigns and symptoms of heart failure or coronary arterydisease, they should have a preoperative functional cardiacevaluation, such as dobutamine stress echocardiography, toassess the extent of myocardial dysfunction and the risk ofright or left ventricular failure. Additionally, patients whohave undergone bariatric surgery prior to their abdomino-plasty should be evaluated for vitamin and nutritionaldeciencies.

Keywords

abdominal wallreconstruction

regional anesthesia intraoperative

monitoring postoperative

management

Abstract Anesthesia considerations for abdominal wall reconstruction (AWR) are numerous anddepend upon the medical status of the patient and the projected procedure. Obesity,sleep apnea, hypertension, and cardiovascular disease are not uncommon in patientswith abdominal wall defects; pulmonary functions and cardiac output can be affectedby the surgical procedure. Patients with chronic obstructive pulmonary disease are alsoat a higher risk of coughing during the postoperative awakening process, which cancompromise the reconstruction of the fascia. Given the increased complexity of thepatients presenting for AWR, and the importance of the anesthesia for these specicprocedures, it is important that surgeons are aware of the challenges that anesthesi-ologists face when treating these patients. Some of these challenges and theirresolution are reviewed here.

Issue Theme Abdominal WallReconstruction; Guest Editor,Lior Heller, M.D.



12

Obstructive Sleep ApneaObesity can have deleterious effects to the upper airway.Increasing upper airway fat can promote upper airway nar-rowing and collapse, predisposing to obstructive sleep apnea(OSA). OSA is a sleep disorder dened as the cessation ofairow for more than 10 seconds despite respiratory effort,which occurs ve or more times per hour of sleep and isassociated with a decrease in arterial saturation of greaterthan 4%.4 There is a fourfold increase in OSA with eachincrease in standard deviation of BMI.5 OSA signicantlyimpacts the anesthetic management of these patients. Pa-tients with severe disease, classied on the apnea-hypopneaindex (AHI) of greater than 30 events per hour of sleep, have agreater likelihood of severe desaturation with induction ofanesthesia. Patients with OSA frequently use continuouspositive airway pressure (CPAP) treatment at home to allevi-ate their symptoms. Patients requiring CPAP greater than10 cm H2O have a greater likelihood of difcult mask ventila-tion.3 Additionally, these patients are more sensitive to avariety of anesthetic drugs, particularly sedative/hypnoticsand narcotics.

Airway ManagementObese patients present several challenges to the anesthesiol-ogist related to airway management. Excessive amounts ofairway adipose tissue can lead to difculties with maskventilation and intubation attempts on obese patients. Aneck circumference greater than 40 cm is an independentpredictor of difcult intubation.6 Although BMI alone is not apredictor of difcult laryngoscopy or failure to intubate,Brodsky et al demonstrated that patients with a BMI greater

than 35 have a sixfold higher risk for difcult laryngoscopy.7

Likewise, Lundstrom et al demonstrated in the Danish Na-tional Registry database that a BMI greater than 35 signi-cantly increased the difculty of intubation, and was a betterpredictor of airway difculty than body weight alone.8 Withthis in mind, additional steps need to be taken to secure theairway in obese patients. Preoxygenation is critical in thispatient population. In the standard patient, four deep breathsof 100% oxygen at total lung capacity provide an extra marginof safety. However, in the obese population, the expiratoryreserve volume (ERV) and functional residual capacity (FRC)are markedly reduced leading to a loss in lung capacity andrapid desaturation. Therefore, preoxygenation becomes evenmore critical in the obese population. Several studies havedemonstrated that both preoxygenating and performingintubation with the patient in the ramp position (Fig. 1)increases the time before desaturation and the success ofintubation.9,10 This tendency for rapid desaturation as well asdifcult laryngoscopy requires succinct intubation techni-ques with high likelihoods for success. In the past, awakeberoptic-assisted bronchoscopy was considered the tech-nique of choice for obese patients with an anticipated difcultintubation. Although considered a very safeway to secure theairway, it is quite dependent on operator experience; notinfrequently, it can be uncomfortable for the patient, mainlyas a result of inadequate local anesthetic topicalization of theairway due to redundant airway tissue. New developments inairway devices nowallow the anesthesia provider to intubatethe patient while asleep, with equally and/or greater successand safety. One option is the laryngeal mask airway (LMA-Fastrach; LMA North America, San Diego, CA). This allows

Figure 1 Comparison of conventional sniff versus ramped position prior to attempted laryngoscopy and intubation in morbidly obesepatients (photo courtesy of Maurizio Cerida and Richard Levitan HUP).


Anesthetic Considerations for Abdominal Wall Reconstructive Surgery Slabach, Suyderhoud 13

the anesthesiologist to place the LMA for ventilation and thenintubate with a specially designed endotracheal tube (ETT)through the LMA with or without direct visualization of thevocal cords. Another airway device is the AirTraq laryngo-scope (PRODOL Meditec, Viscaya, Spain), a disposable intu-bating device that allows direct visualization of vocal cordswhile providing correct alignment for ETT placement. TheAirTraq increases both the speed and success of intubationin the morbidly obese as compared with standard laryngos-copy blades.11 More recently, the GlideScope (Verathon,Bothell, WA) videolaryngoscopy (GVL) has become the deviceof choice for securing the difcult airway. It is comprised of aplastic video blade connected to an external video monitor.The position of the camera at the tip of the blade requires verylittle extension of the head and neck to view the vocal cords,making it ideal for those patients with limited range ofmotion of the head or neck, while facilitating a direct viewof the vocal cords allowing the operator to insert a stylettedETT.

Anesthetic ConsiderationsPatients with increased BMI undergoing anesthesia for ab-dominal wall surgery present several anesthetic challenges.Body habitus and patient positioning, as well as the plannedscope of surgery, all factor into what anesthetic may beappropriate. In general, anesthesia falls into two categories:general anesthesia or regional anesthesia. General anesthesiarequires the patient be fully anesthetized, with airway pro-tection because of concomitant airway reex obtundation. Asdiscussed, securing the airway in an obese patient may beparticularly difcult. The patient is asleep for the duration ofthe procedure and allowed to emerge from anesthesia oncethe procedure has nished. Regional anesthesia encompassesmore options. A patient may have strictly regional anesthesiawith no additional anesthetics, regional with mild to moder-ate sedation, or a patient may have general anesthesia for theprocedure and then have regional anesthesia placed forpostoperative pain relief.

Abdominal wall reconstruction requires that the patientbe anesthetized fromT4 to L1. This region can be anesthetizedwith neuraxial anesthesia, either by epidural or spinal anes-thesia. Both provide adequate anesthesia and analgesia to theoperative eld and can be used alone for surgery or inconjunctionwith sedation or general anesthesia. The benetsof spinal anesthesia are a rapid, predictable onset of surgicalanesthesia, usually within 5 to 15minutes, and a denser blockbecause of its placement directly in conuence with thecerebrospinal uid (CSF). Spinal anesthesia can be accom-plished as a single-shot technique or with an intrathecalcatheter that can be left in place for further use duringprolonged surgery.

However, if a catheter is to be used neuraxially, the moreroutinemethodwould be an epidural catheter conventionallyplaced in the epidural space outside of the dura. Medicationinfused through the catheter diffuses through the durawhereit has effect on the nerve roots. The density of the epiduralblock and eld of distribution can be manipulated by theconcentration and volume of local anesthetic (LA) infused in

the catheter. This is ideal for providing intraoperative as wellas postoperative anesthesia to the surgical area. Additionalmedication can be added during the procedure, thus allowingappropriate anesthesia and analgesia no matter the length ofthe operation. The epidural catheter can be left in placepostoperatively to provide continuous postoperative pa-tient-controlled analgesia.

There are, however, limitations to performing spinal orepidural anesthesia in patients undergoing AWR. Althoughthey are effective means for providing intraoperative anes-thesia, caudal spreadwill lead to sensory andmotor blockadeof the lower extremities, preventing ambulation (whichadmittedly is not usually a major postoperative concern afterAWR) as well as increase the risk of urinary retention.Likewise, local anesthetic spread rostrally can lead to lossof accessory muscles of respiration up to and includingparalysis of the diaphragm, resulting in mild to profoundrespiratory compromise in AWR patients, who may alreadyexhibit cardiopulmonary dysfunction from a combination ofanatomic and physiologic factors such as body habitus,anatomic defects, and nutritional/metabolic deciencies.Rostral spread of LA can also block spinal cardiac acceleratorbers, resulting in hypotension and decreases in cardiacoutput. Additionally, an AWR patient frequently is bedriddenor immobile, placing them at risk for thromboembolic diseaseand necessitating the use of preventative or prophylacticanticoagulant therapy. Concomitant multiorgan dysfunctionin complex AWR patients can also lead to disorders ofcoagulation as well. Both features would be contraindicationsto either epidural or spinal anesthesia because of the risk ofepidural hematoma, potentially leading to compression of thespinal cord with disastrous effects. Epidural hematomas arealso a consideration in these patients who are at risk for deepvenous thrombosis (DVT) and pulmonary embolism (PE) andmay be placed on anticoagulation immediately postopera-tively. Furthermore, the tendency for these patients to beobese, as well as the anatomic nature of the abdominal walldefect itself may make patient positioning for placement ofthe epidural or spinal technically difcult or impossible.Therefore, spinal or epidural anesthesia may not be an optionfor every patient undergoing abdominal wall reconstruction.

A transversus abdominal plane (TAP) block is a compart-ment block that can be used as regional anesthesia inconjunctionwith sedation or general anesthesia. In this block,the anterior abdominal wall is anesthetized by placing a largevolume of local anesthetic into the plane between the inter-nal oblique and the transversus abdominis muscle at thetriangle of Petit with ultrasound-assisted needle placement.This reliably gives anesthesia to the area under the umbilicus.With the addition of an oblique subcostal TAP block thesupraumbilical region is also anesthetized, thus providinganesthesia to the entire abdominal wall.12 This block isusually placed after the patient has been anesthetized andused for postoperative analgesia. Advantages of this type ofregional anesthesia aremany. Specically, there is a reductionin postoperative narcotic requirement, which is crucial in apopulation at high risk for OSA. Additionally,with a TAP block,the entire abdominal wall is anesthetized, including the


Anesthetic Considerations for Abdominal Wall Reconstructive Surgery Slabach, Suyderhoud14

musculature, reducing the need for muscle relaxants and sodecreasing the risk of residual muscle paralysis postopera-tively. In a series of patients undergoing major abdominalsurgery, those that received the TAP block required 75% lessnarcotics for the rst 24 hours and had average visual analogpain scores immediately after emergence from anesthesia of 1versus 6.6 without the TAP block.13

There are no studies that compare different anesthetictechniques in AWR surgery; a balanced general anestheticmay prove to be the most reasonable approach. Generalanesthesia will provide a secured airway conduit to deliveranesthetic agents and oxygen. Ventilator modes to promoteadequate oxygenation and ventilation while minimizing car-diopulmonary compromise can be achieved, such as (1)selective positive end expiratory pressure (PEEP); (2) recruit-mentmaneuvers tominimize atelectasis, increases in hypoxicpulmonary vasoconstriction, and right ventricular strain; (3)considerations for lung protective ventilator strategies suchas reduced tidal volume ventilation; and (4) minimizing peakinspiratory pressure (< 2530 cm H2O) to limit increases inabdominal compartment pressures. Narcotic administrationwill reduce the inhalational agent requirement while provid-ing adequate perioperative pain relief. Finally, the control ofmuscle relaxation can be titrated to help the surgeon achieveideal operating conditions and thus optimize the surgicalresult.

Intraoperative ConsiderationsIf the goal of every anesthetic is to promote cardiovascularstability, then that goal is evenmore so in the AWR patient. Toprovide a sufcient level of anesthesia, the anesthesiologistmust rely on monitoring that corroborates preservation ofcardiopulmonary function. As such, modalities such as intra-arterial pressure monitoring, including the use of newernoninvasive cardiac output derived from arterial waveformdata, central venous and pulmonary artery catheters (both formonitoring as well as vascular access in patients with poten-tially limited intravenous access), and transesophageal echo-cardiography may be used. These monitors assist indetermining hemodynamic function while also guiding theanesthesiologist in the very important role of proper intra-operative uid management. Abdominal compartment syn-drome is a frequent comorbid condition in AWR patients andcan result in signicant multiorgan dysfunction, such ascardiac compromise, visceral ischemia, renal insufciency,systemic inammatory syndrome and/or sepsis, and respira-tory impairment. The goal of the anesthesiologist must be toprovide sufcient uid replacement to prevent end organunderperfusion, while at the same time not giving too muchuid that would lead to end organ impairment resulting fromincreased intraabdominal pressure and the aforementionedsequelae. This degree of ne-tuning may be difcult toachieve without advanced monitoring modalities, especiallyin lengthy surgical procedures in patients with signicantcomorbidities. Recent laboratory studies support the notionthat judicious uid restriction, as advocated in other types ofabdominal surgery procedures,14 in conjunction with vaso-pressor use (norepinephrine) may support this goal while

having no adverse effect on splanchnic and renal organfunction.15 More recent studies, however, point to the dif-culty of correctly judging the degree of uid restriction by aset protocol; these authors and others show that excessiveuid restriction in abdominal surgery can be deleterious.16

From the anesthesiologist's perspective, these studies togeth-er validate the necessity of enhanced cardiovascular moni-toring to individualize uid management in each patient, notto base it on protocol alone.

The positioning of obese patients intraoperatively presentsits own unique challenges. Many facilities do not have oper-ating tables that are large enough to bear theweight or size ofthese patients. Additionally, padding that would be consid-ered adequate for a standard patient is not sufcient for thispopulation and complications can occur. Although AWRsurgery is usually performed in the supine surgical position,even this can present complications for obese patients. A casereport of a patient with rhabdomyolysis of gluteal muscleleading to renal failure postoperatively17 demonstrates howextra precautions need to be taken for the obese patient,particularly when the case is lengthy.

Anesthetic Effects on the Anesthetized PatientAll forms of general anesthesia have signicant effects onpulmonary physiology. Induction of anesthesia decreasesfunctional residual capacity (FRC) by 15 to 25%; when theFRC falls below the closing capacity of the lung, this leads toincreases in intrapulmonary shunting and may exacerbatehypoxemia.18 This reduction in FRC may not return to base-line for up to 72 or more hours, andmay render a patient whohas marginal pulmonary reserve to begin as ventilator-de-pendent postoperatively. Obese patients have decreasedchest wall and lung compliance as well, further reducingFRC. In the nonobese patient, normal tidal volume respirationoccurs at lung volumes above FRC. In obese patients, however,normal tidal volume ventilation impinges on FRC, and isfurther exacerbated whenmoving from the upright to supineposition and with the induction of anesthesia.19 Thus, hyp-oxemia and desaturation occurs far more rapidly in thesepatients. FRC reduction occurs within minutes of inductionand regardless of the type of anesthesia or the use of musclerelaxants. The net effect is a signicant increase in venousadmixing, or shunt, with hypoxemia, alongwith reductions inFRC, both because of anesthetic agents and positioning-related changes (cephalad displacement of the diaphragmby abdominal contents, muscle relaxants, chest wall compli-ance, etc.). Addition of PEEP is a provenmethod to recruit FRCduring mechanical ventilation while reducing atelectasis.PEEP of 10 cm H2O will improve oxygenation, compliance,and recruitment in morbidly obese patients undergoingsurgery with general anesthesia.20 Additional factors to con-sider in assuming the anesthetized/supine position includeincreases in atelectasis either byabsorption (via FiO2 of 1.0) orcompression, impaired mucociliary clearance, increases inpulmonary vascular resistance, and increased airway resis-tance. Additionally, volatile agents used during anesthesiaprofoundly blunt the patient's hypoxic drive to respiration,while narcotics used intraoperatively for pain blunt the



hypercarbic drive. Combined, these effects may inhibit theAWR surgery patient's drive to respire adequately in theimmediate postoperative period. In patients undergoingAWR, these anesthesia-related effects are understandablyexacerbated because of underlying factors such as obesity,increases in abdominal compartment pressures, increasedsensitivities to narcotics from OSA, and preexisting pulmo-nary dysfunction. All of these factors provide challenges to theanesthesiologist in maintaining pulmonary function homeo-stasis during surgery, and, equally important, allowing thepatient to resume adequate spontaneous respiratory functionpostoperatively.

Postoperative ManagementAt the conclusion of AWR surgery, the anesthesiologist musttake several factors into consideration before attemptingextubation. Clearly, a patient can be extubated when he orshe meets accepted extubation criteria, which include anappropriate level of consciousness, sustained hand grip andhead lift for more than 5 seconds (indicating appropriatereversal of muscle relaxation), negative inspiratory force ofgreater than 25 cmH2O, and a respiratory rate to tidal volumeratio of less than 105, among others. In addition, the patientshould be stable from a cardiac and pulmonary standpoint,and have acceptable parameters for EtCO2 and oxygen satu-ration as well. However, factors such as the length of theprocedure, the degree of difculty in securing the airway inthe rst place, the need to provide abdominal laxity aftersurgical repair, and the degree of intraabdominal pressurepostrepair maymodify the decision to extubate immediately.Obese patients are more likely to be difcult intubations, andtherefore difcult extubations.6 Obese patients also retainlipophilic anesthetic medications, which can delay emer-gence from anesthesia and lead to increased somnolence inrecovery.

If the decision is to extubate immediately after surgery inthe AWR patient who was a difcult intubation, the anes-thesiologist will have two competing priorities. Surgicalrepair may necessitate minimizing and eliminating cough-ing and bucking at the point of extubation to prevent wounddisruption and dehiscence. The difcult airway may requirea very awake and alert intubated patient before ETT remov-al, with its attendant possibility of coughing and bucking,and surgical repair integrity. The method of deep extuba-tion is used frequently when the anesthesiologist wants tominimize coughing and increases in abdominal pressuresduring emergence from anesthesia. Patients are reversedfrom muscle relaxants and then allowed to breathe sponta-neously while deeply anesthetized, before removing theETT and assisting with ventilation while the volatile agentsare discontinued thereafter. The AWR patient, however,may have airway, body habitus, and surgical repair consid-erations that would preclude this approach. Therefore,other methods to blunt airway reexes must be used.Judicious titration of narcotics in the moments prior toextubation can provide sufcient antitussive action so asto facilitate a smooth extubation, provided enhanced nar-cotic sensitivity in obese/OSA patients is taken into account.

Injection of 50 to 100mg of lidocaine endotracheally willalso obtund the cough reex and allow the patient to bettertolerate an ETT. To ensure airway integrity, however, theanesthesiologist may elect to place an ETT exchange cathe-ter prior to extubation to allow for enhanced success shouldreintubation be required. These catheters provide a meansof delivering oxygen as well, but are not effective forventilation. As an alternative, the awakening patient mayhave the ETT removed and an LMA placed immediatelyafterward, and then allowed to awaken with this airwaydevice in place rather than the ETT. LMAs are well toleratedin the awakening patient and provide a somewhat moresecure airway than mask ventilation, with or without anoral airway.

During and immediately after extubation, measuresshould be undertaken to prevent and/or reduce postoperativeatelectasis and clinically signicant hypoxemia. As withintubation, the obese patient may benet from extubatingin the upright position rather than supine. Signicant atelec-tasis occurs in obese patients compared with the nonobesepatient in the immediate postoperative period, and position-ing patients upright may mitigate this to some degree byreducing abdominal content intrusion on diaphragmaticexcursion and lung volumes.21 Additionally, immediate ap-plication of noninvasive ventilation after extubation in selectAWRpatientsmay hasten the return of baseline lung functionand limit postoperative atelectasis, hypoxemia, and desatu-ration, as has been demonstrated in morbidly obese patientsafter bariatric surgery.22,23

Pain control postoperatively is a signicant consider-ation. Narcotics blunt the hypoxic response and may leadto hypoventilation and inadequate oxygenation. The pro-pensity of the obese population to have OSA also compli-cates the postoperative picture. Therefore, it is desirable tolimit the use of narcotics. The use of nonnarcotic analgesia,such as Ketoralac or acetaminophen is recommended tominimize respiratory depression. Regional anesthesia, usedas a sole anesthetic or as an adjunct, will also reduce theneed for postoperative narcotics and help to prevent respi-ratory depression. If narcotics are given postoperativelyascurrent American Society of Anesthesiology guidelines rec-ommendthe patient should have continuous pulse oxim-etry monitoring while in bed or until that time whenoxygen saturation remains above 90% during sleep onroom air.24

References1 ASAPS Press Center Cosmetic Procedures in 2010. AmericanSociety for Aesthetic Plastic Surgery. Available at: http://www.surgery.org/media/statistics. Accessed February 12, 2012

2 Ogunnaike BO,Whitten CW. Anesthesia and obesity. In Barash PG,Cullen BF, Stoelting RK, Cahalan Meds. Clinical Anesthesia. 6th ed.Philadelphia: Lippincott Williams &Wilkins; 2009;12301246

3 Passannante AN, Tielborg M. Anesthetic management of patientswith obesity with and without sleep apnea. Clin Chest Med2009;30(3):569579, x

4 Nabili S, Verneuil A. Sleep Apnea. 2011. Available at: http://www.medicinenet.com/sleep_apnea/article.htm


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5 Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. Theoccurrence of sleep-disordered breathing among middle-agedadults. N Engl J Med 1993;328(17):12301235

6 Sinha AC. Some anesthetic aspects of morbid obesity. Curr OpinAnaesthesiol 2009;22(3):442446

7 Brodsky JB, Lemmens HJ, Brock-Utne JG, Vierra M, Saidman LJ.Morbid obesity and tracheal intubation. Anesth Analg 2002;94(3):732736

8 Lundstrm LH, Mller AM, Rosenstock C, Astrup G, Wetterslev J.High body mass index is a weak predictor for difcult and failedtracheal intubation: a cohort study of 91,332 consecutive patientsscheduled for direct laryngoscopy registered in the Danish Anes-thesia Database. Anesthesiology 2009;110(2):266274

9 Dixon BJ, Dixon JB, Carden JR, et al. Preoxygenation is moreeffective in the 25 degrees head-up position than in the supineposition in severely obese patients: a randomized controlledstudy. Anesthesiology 2005;102(6):11101115, discussion 5A

10 Collins JS, Lemmens HJ, Brodsky JB, Brock-Utne JG, Levitan RM.Laryngoscopy andmorbid obesity: a comparison of the sniff andramped positions. Obes Surg 2004;14(9):11711175

11 Ndoko SK, Amathieu R, Tual L, et al. Tracheal intubation ofmorbidly obese patients: a randomized trial comparing perfor-mance of Macintosh and Airtraq laryngoscopes. Br J Anaesth2008;100(2):263268

12 Hebbard P. Subcostal transversus abdominis plane block underultrasound guidance. Anesth Analg 2008;106(2):674675, authorreply 675

13 McDonnell JG, ODonnell B, Curley G, et al. The analgesic efcacy oftransversus abdominis plane block after abdominal surgery: aprospective randomized controlled trial. Anesth Anal 2007;104;193197

14 Brandstrup B, Tnnesen H, Beier-Holgersen R, et al; Danish StudyGroup on Perioperative Fluid Therapy. Effects of intravenous uidrestriction on postoperative complications: comparison of twoperioperative uid regimens: a randomized assessor-blindedmulticenter trial. Ann Surg 2003;238(5):641648

15 Hiltebrand LB, Koepi E, Kimberger O, Sigurdsson GH, Brandt S.Hypotension during uid-restricted abdominal surgery: effects of

norepinephrine treatment on regional and microcirculatoryblood ow in the intestinal tract. Anesthesiology 2011;114(3):557564

16 Futier E, Constantin JM, Petit A, et al. Conservative vs restrictiveindividualized goal-directed uid replacement strategy in majorabdominal surgery: a prospective randomized trial. Arch Surg2010;145(12):11931200

17 Bostanjian D, Anthone GJ, Hamoui N, Crookes PF. Rhabdomyolysisof gluteal muscles leading to renal failure: a potentially fatalcomplication of surgery in the morbidly obese. Obes Surg2003;13(2):302305

18 DonH. Themechanical properties of the respiratory systemduringanesthesia. Int Anesthesiol Clin 1977;15(2):113136

19 Adams JP,Murphy PG. Obesity in anaesthesia and intensive care. BrJ Anaesth 2000;85(1):91108

20 Pelosi P, Ravagnan I, Giurati G, et al. Positive end-expiratorypressure improves respiratory function in obese but not in normalsubjects during anesthesia and paralysis. Anesthesiology 1999;91(5):12211231

21 Eichenberger A, Proietti S, Wicky S, et al. Morbid obesity andpostoperative pulmonary atelectasis: an underestimated problem.Anesth Analg 2002;95(6):17881792

22 Joris JL, Sottiaux TM, Chiche JD, Desaive CJ, Lamy ML. Effect of bi-level positive airway pressure (BiPAP) nasal ventilation on thepostoperative pulmonary restrictive syndrome in obese patientsundergoing gastroplasty. Chest 1997;111(3):665670

23 Neligan PJ, Malhotra G, Fraser MW, et al. Continuous positiveairway pressure via the Boussignac system immediately afterextubation improves lung function in morbidly obese patientswith obstructive sleep apnea undergoing laparoscopic bariatricsurgery. Anesthesiology 2009;110(4):878884

24 Gross JB, Bachenberg KL, Benumof JL, et al; American Society ofAnesthesiologists Task Force on Perioperative Management. Prac-tice guidelines for the perioperative management of patients withobstructive sleep apnea: a report by the American Society ofAnesthesiologists Task Force on Perioperative Management ofpatients with obstructive sleep apnea. Anesthesiology 2006;104(5):10811093, quiz 11171118



Bioprosthetic Mesh in Abdominal WallReconstructionDonald P. Baumann, M.D., F.A.C.S. 1 Charles E. Butler, M.D., F.A.C.S. 1

1Department of Plastic Surgery, The University of Texas MD AndersonCancer Center, Houston, Texas


Address for correspondence and reprint requests Charles E. Butler,M.D., Department of Plastic Surgery, Unit 1488, The University ofTexas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX

Over the past 20 years, implantable surgical mesh productsused for abdominal wall reconstruction have evolved in anattempt to improve mesh-related repairs. Mesh productshave evolved from unilaminar synthetic materials to bilami-nar synthetic meshes to bioprosthetic mesh products derivedfrom human and animal sources. The continued renementand development of new mesh materials arises from theclinical need to provide a mesh material that can replicatethe host tissue that it is replacing. There has been a long-standing general acceptance of the use of mesh to reinforce astable ventral hernia repair. However, the addition of a meshmaterial has improved, but not resolved, the problem of highhernia recurrence following ventral hernia repair. Ventralhernia repair is associated with a 10-year cumulative recur-rence rate of 32% with the use of synthetic mesh materials insmall (

prospective, controlled trial suggests that 32% of ventralhernias repaired with synthetic mesh recur within 3 years;the rate approaches 63% for primary repair alone.1 In addi-tion, the risk of hernia recurrence increases with each addi-tional operation. Flum and coworkers reported that 12% ofpatients undergoing incisional hernia repair required at leastone subsequent reoperationwithin 5 years; the length of timebetween reoperations was progressively shorter after eachadditional repair. The 5-year rates of reoperation were 24%after the rst reoperation, 35% after the second, and 39% afterthe third.2 These data underscore the importance of mini-mizing the risk for subsequent reoperations by employing thebest evidence-based approach at the time of the initial herniarepair.

This situation has prompted a search for optimal techni-ques and mesh materials for use in abdominal wall recon-struction. A mesh material with more favorable propertiesthan traditional mesh could have a major effect on surgicalpractice and patient outcomes. The ideal mesh materialwould be nontoxic, avoid chronic inammation and immunerejection, and resist infection after implantation. It wouldbecome completely remodeled into host tissue with mechan-ical and biologic properties similar to those of the replacedtissue. The mesh would serve as a biologic tissue scaffold andbecome rapidly revascularized and inltrated with host cells,to avoid encapsulation and seroma formation. It also needs tomaintain its strength and original surface area during remod-eling to prevent bulge and/ormesh failure. Themeshmust notinduce adverse systemic or local reaction or pose a risk ofdisease transmission. In addition, an optimal mesh materialmust resist visceral adhesions to limit the risk of bowelobstruction and enterocutaneous stulization and to facili-tate subsequent reoperative laparotomy if needed in thefuture. The optimal mesh could be implanted into contami-nated wounds and tolerate cutaneous exposure without theobligatory requirement of surgical explantation. Unfortu-nately, this ideal mesh material is not yet available.

Synthetic and Bioprosthetic Mesh Materials

Awide variety of synthetic mesh products is available for usein abdominal wall reconstruction, including both absorbableand permanent synthetic meshes. However, synthetic meshhas limitations that preclude it from being widely used inabdominal wall reconstruction. For example, absorbablemesh such as polyglactin 910 (Vicryl, Ethicon Inc., Somer-ville, NJ) can be a useful adjunct in the management of theopen abdomen by temporarily containing the viscera, but itbecomes degraded and resorbed over time and is associatedwith an extremely high hernia recurrence rate.6

Synthetic meshes are categorized as macroporous, micro-porous, or composite.7,8Macroporous meshes include mono-lament and multiple-lament polypropylene. Thesematerials have large pore sizes that allow for in-growth ofscar tissue. When placed in contact with abdominal viscera,macroporous meshes are associated with the formation ofbowel adhesions, obstructions, and enterocutaneous stu-lae.9,10 Therefore, these materials should be avoided or used

in combination with omental coverage or antiadhesive bar-riers when placed in contact with bowel. Microporousmeshes, such as expanded polytetrauoroethylene (ePTFE),have a smaller pore size that does not allow clinically relevanttissue in-growth and may lead to encapsulation, peripros-thetic uid collection, and bacterial overgrowth. Althoughmicroporous mesh has a lower afnity for visceral adhesions,it is more susceptible to infection, and when clinical infectionoccurs surgical explantation is usually required rather than aconservative salvage of the repair. Awide variety of compositematerials are now available that combine macroporous mesh(usually polypropylene or polyester) on one side to promotetissue in-growth and an antiadhesive layer on the other(peritoneal) side to reduce risk for adhesions to the meshrepair. Clinical evidence suggests reduced risk of adhesions tocomposite and coated synthetic meshes compared withtraditional synthetic meshes.1115 The relative benets ofthese different synthetic meshes with regard to adhesionformation, risk for infection, and outcomes have variedwidelyin different animal and human clinical studies.9,13,1619 Fur-thermore, prospective data are lacking regarding the clinicalbenets of these prostheses for ventral hernia repair, and nohigh-level evidence or comparative clinical data are currentlyavailable. Finally, lightweight polypropylene mesh with thin-ner-diameter polypropylene bers and larger interstices iscurrently being used in both open and laparoscopic herniarepairs. There are data to suggest good functional outcomesequal or better than those achieved with traditional heavy-weight polypropylene synthetic mesh, although denitivelong-term comparative studies are lacking.20 Despite numer-ous advances in synthetic mesh technology, the paramountproblem still exists: the placement of a persistent foreignbody that does not remodel into biologic tissues, the risk ofinfection, and the management of infected or exposed syn-thetic mesh.

Bioprosthetic meshes are an equally diverse and expand-ing class of mesh materials. These are materials derived fromhuman or animal tissue, decellularized and processed toallow implantation into humans. Certain specic character-istics are thought to contribute to the successful use ofparticular biologic repair materials in the setting of woundcontamination or low-grade infection. Thesemesh propertiesinclude an intact, native extracellularmatrix and the ability tosupport tissue regeneration through revascularization andcell repopulation. It has been hypothesized that resistance toinfection for biologic repair materials is related to the in-growth of cells and vasculature structures.21 The neovascula-rization demonstrated in studies of some biologic repairmaterials may allow these materials to better resist infectionwhen placed in a potentially contaminated eld.21 The abilityof some biologic repair materials to support regeneration isbased on animal studies that demonstrated early biologicactivity, including cellular inltration and revasculariza-tion.2225 Numerous animal studies have shown that alteringthe extracellular matrix through suboptimal processing and/or cross-linking may have a negative effect on host responseto the repair material.2628 Resorption and encapsulationhave been demonstrated with several biologic repair


Bioprosthetic Mesh in Abdominal Wall Reconstruction Baumann, Butler 19

materials in an animal model of abdominal wall repair.26

These latter investigators suggested that the lack of integra-tion and tissue regeneration with these materials may ac-count for poor initial wound healing. In one study ofabdominal repair following harvest of transverse rectusabdominis musculocutaneous aps for breast reconstruction,biopsies of the biologic repair material showed cell density,vasculature, and collagen orientation similar to those ofnormal abdominal fascial tissue.29 Another study foundthat biologic repairmaterial from an irradiated, contaminatedabdominal wall repair site that was explanted 14 monthsafter implantation demonstrated remodeling of the biologicrepair material, including revascularization and cellular re-population.30 To date, no comparative trials have been com-pleted evaluating different biologic repair materials inincisional hernia repair, and differentiation between prod-ucts is based on early ndings with a limited number ofavailable bioprosthetic mesh materials. Similar animal andclinical studies are awaited for the majority of bioprostheticmesh materials.

Evolution of the Use of Bioprosthetic Mesh

The use of autologous deepithelialized and nondeepithelial-ized skin for inguinal and ventral hernia repair has beendescribed in the literature as an auto-dermoplasty forabdominal wall reconstruction.31 Therefore, the concept ofusing biologic tissue for structural repair of abdominal walldefects is not necessarily a newconcept.32Bioprostheticmeshmaterials are dened as biologic tissue derived from amammalian source, either allograft or xenograft. The bio-prosthetic mesh undergoes processing that completely re-moves all cellular components while preserving the nativeextracellular matrix architecture. If the material is processedcorrectly to be tissue conductive and to maintain the nativeextracellular matrix microarchitecture, the bioprostheticmesh material undergoes brovascular in-growth with host

cell repopulation after implantation and then continues tobecome remodeled by the host into tissue.

A historical perspective on currently used bioprostheticmeshmaterials includes porcine small bowel submucosa (SIS)for bladder reconstruction, human acellular dermal matrix(HADM) for skin and mucosal grafting, and porcine acellulardermalmatrix (PADM) for bladder sling suspension and otherurogynecologic procedures.33,34 Porcine small intestine sub-mucosa was studied in a canine ventral hernia model thatshowed the SIS extracellular matrix scaffold was replaced bywell-organized host tissues including differentiated skeletalmuscle.35 Human acellular dermal matrix and xenogenicmaterials such as PADM, bovine acellular dermal matrix(BADM), and bovine pericardium were initially designed forindications other than abdominal wall reconstruction.3638

They were subsequently adopted by surgeons due to theoverwhelming need for better mesh properties for abdominalwall reconstruction.Table 1 lists some of the commercial bioprosthetic mesh

materials available at the time of this article's preparation.Thesematerials are classied by tissue source, animal species,crosslinked versus noncrosslinked, sterilization process, proc-essing details, and storage media.39 We do not make anyrecommendations regarding the choice of specic prostheticrepair materials; however, certain features of synthetic andbiologic repair materials should be considered during theselection process. Specic characteristics such as adequatestrength, ease of handling during implantation, ability toresist adhesions when placed in contact with the bowel,reduced risk of infection through support for tissue incorpo-ration and revascularization, and early and late mechanicalproperties are important factors to consider when selecting abioprosthetic mesh. Differences in mesh processing includethe cell extraction and sterilization techniques and whetherthe mesh is stored in a hydrated state or nonhydrated statewithin the package. Bioprosthetic mesh materials are alsocategorized by tissue properties (thickness of the material

Table 1 Bioprosthetic Mesh Materials

Product Animal Source TissueSource

ChemicallyCrosslinked

Sterilization Manufacturer

AlloDerm Adult human Dermis None None LifeCell(Branchburg, NJ)

Allomax None Gammairradiation Bard Davol Inc. (Warwick, RI)

Flex HD None None Ethicon (Somerville, NJ)

Xenmatrix Adult porcine Dermis None Unknown Bard Davol Inc. (Warwick, RI)

Strattice None External beamradiation LifeCell(Branchburg, NJ)

Permacol HMDI Gammairradiation Covidien(Dublin, Ireland)

Surgisis Small intestinesubmucosa

None Ethyleneoxide Cook Medical(Bloomington, IN)

Veritas Adult bovine Pericardium None External beamradiation Synovis (St.Paul, MN)

Surgimend Fetal bovine Dermis None Ethyleneoxide TEIBiosciences(South Boston, MA)

HMDI, hexamethylene diisocyanate; EDC, 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide.


Bioprosthetic Mesh in Abdominal Wall Reconstruction Baumann, Butler20

and size available). Depending on the source tissue (human,bovine, porcine), tissue properties such as thickness, rm-ness, and size availability will vary.

There is an evolving understanding of the behavior andeffect of bioprosthetic mesh in abdominal wall reconstruc-tion, with limited high-level data on the mechanism of actionand long-term outcomes, particularly comparative outcomesbetween products, techniques, and patient selection. There-fore, we as surgeons must make decisions based on what wecurrently know and what is not as clearly understood. It isclear that bioprosthetic mesh implanted in direct contactwith bowel results in fewer adhesions than prosthetic meshmaterials. Studies in animal models suggest that certainbiologic repair materials can be placed in contact with thebowel.2224,28 Many studies have demonstrated that certainacellular dermalmatrices placed directly over thebowel resistvisceral adhesions to the repair site in ventral hernia repairsand are markedly less than the adhesions associated withpolypropylene repairs.2224,28 Clinical studies have reportedgood outcomeswith somebioprostheticmeshes for incisionalhernia repair in high-risk patient groups. In these reports,patients complications could bemanaged nonsurgically evenwhen their wounds became infected.4042 Some biopros-thetic meshes have been used successfully to repair largecontaminated and/or irradiated abdominal wall defects inpatients with cancer when the meshes are placed directlyover the bowel.30,43 Bioprosthetic mesh materials tolerateplacement into contaminated wound environments and areable to undergo vascularization and incorporation, as has beendescribed clinically in the setting of ostomy creation, un-planned bowel surgery, and trauma.43,44 This is a criticaladvantage of bioprosthetic mesh over prosthetic meshes inthat thebioprostheticmeshdoes not need tobe removed in theface of wound contamination or clinically active infection. Inaddition, bioprosthetic mesh tolerates cutaneous exposurewithout requiring explantation, and such exposures can usu-ally be managed conservatively with dressing changes. Somebiologic repair materials have also demonstrated antimicrobialactivity in vitro and in animalmodels, and the ability of certainbiologic prostheses to support revascularization may contrib-ute to clearance of bacteria.45,46 A recent study in a rabbitmodel, for example, found that a human acellular dermalmatrix repair material was signicantly superior to PTFE interms of the ability to allow for clearance of Staphylococcusaureus inoculate at the level expected for contamination.47

With regard to theprocessingof thebioprostheticmesh, thecurrent understanding is that if the native extracellular matrixof the material is preserved, then the mesh is tissue conduc-tive and recognized by the host, such that the host remodelsthe tissue with cellular inltration, revascularization, andcollagen deposition rather than scar tissue and encapsulation.Animal studies found that the early strength of the incorpo-ration into the musculofascial defect edge was similar forbioprosthetic mesh and polypropylene mesh.24 Supraphysio-logic chemical crosslinking of the collagenwithin the biopros-thetic mesh signicantly reduced cellular and vascularinltration, reducing the degree of remodeling in animalstudies.28,48 This results in nearly crosslinked bioprosthetic

meshmaterials undergoingmore of an encapsulation responsewith surrounding scar tissue rather than actual cellular andvascular inltration into the mesh, thus limiting the ability toremodel and incorporate.

There is a large gap in the understanding of comparativeclinical outcomes between various classes of allograft andxenograft bioprosthetic mesh, as well as for specic commer-cially available products within each bioprosthetic mesh class.Denitive studies of evidence-based indications and contra-indications based on high-level data such as long-term clinicalprospective randomized trials are yet to be completed. Inaddition, studies of long-term comparative outcomes of bio-prosthetic mesh compared with other synthetic mesh optionshave yet to be performed. This is important for specicindications where both mesh types (bioprosthetic or synthet-ic) can be used. One of the potential shortcomings of bio-prosthetic mesh is the potential for bulge and laxity; this hasbeen demonstrated with the use of human acellular dermalmatrix with varied but clinically important high rates of bulgeand laxity.30,49 It is unclear how the xenograft bioprostheticmeshes will perform over the long term when evaluated forrecurrent hernia or bulge formation. An additional factor thatmerits discussion is the cost-effectiveness of bioprostheticmesh compared with synthetic mesh alternatives. Studiesare needed on the economic impact of using bioprostheticmesh for various indications, ranging from the most compli-cated cases (where itmay verywell be the onlyoption) tomoreroutine cases (where other mesh types may be options). Thiswill require large multicenter trials of various patient popu-lations, defect types, and abdominal wall repair techniques.More data need to be generated to establish functional out-comes, patient selection, and economic value.

Current Indications for Utilization ofBioprosthetic Mesh

The following indications are based largely on existing animaldata, short-term, low-level evidence from clinical studies,case reports, and surgeons experiences with extensive use ofbioprosthetic and synthetic mesh. These indications aregeneral and are based on our opinions and the existinglow-level evidence.50

1. Contaminated wound (existing wound infection, adjacentostomy, planned or inadvertent disruption of the gastro-intestinal continuity, enterocutaneous stula)

2. Complex repair in a patient at high risk for development ofwound-healing problems such as subcutaneous infection,persistent seroma, skin dehiscence, and/or need forreoperation

3. Planned exposed mesh or high likelihood of a cutaneousexposure (open abdominal wound closure with a bridgingrepair or unreliable skin coverage with risk of skindehiscence)

4. Unavoidable direct placement of implantable mesh overbowel and/or other abdominal viscera

5. Planned or high likelihood of the patient requiring a futurelaparotomy through the repair site


Bioprosthetic Mesh in Abdominal Wall Reconstruction Baumann, Butler 21

Technical Considerations To OptimizeOutcomes With Bioprosthetic MeshReconstruction of the Abdominal Wall

The overall principles of abdominal wall reconstruction in-clude optimization of the patient, preparation of the wound,centralization and reapproximation of the rectus musclesalong the midline when possible, and the use of appropriateprosthetic or bioprosthetic material to reinforce the closure.One key element of the inset of bioprosthetic mesh is to placethe mesh in an inlay (intraperitoneal), preperitoneal, orretrorectus position under appropriate physiologic tension.Onlay bioprosthetic mesh placement has been used success-fully and is an option when the musculofascia can be primar-ily closed at the midline. Onlay mesh may be preferred insome situations, such as a hostile abdomen inwhich adequatelysis of adhesions is unsafe or impossible to expose theundersurface of themusculofascial edges. Physiologic tensionrepresents the resting tension of the abdominal wall whenthe patient is awake. This is in contradistinction to a tension-free repair, popularized with autologous inguinal herniarepairs in the past. Mesh inset under physiologic tensionfacilitates and stimulates appropriate collagen remodeling tofacilitate mechanical strength and potentially reduce the riskof material bulge and laxity. The edges of the bioprostheticmesh should overlap the undersurface of the musculofascialedge by at least 3 to 5 cm to allow for remodeling brovascu-lar incorporation. This method of bioprosthetic mesh inlaytakes advantage of the mesh's remodeling mechanism, incontrast to simple scarring and encapsulation with nontis-sue-conductive meshes.23,28,51 This will maximize theultimate tensile strength of the junction between the bio-prosthetic mesh and the musculofascia.

The anatomic plane of the inlay bioprosthetic mesh insethas direct implications on the degree of incorporation at themesh-musculofascial interface. When possible, it is prefer-able to avoid insetting the bioprosthetic mesh in directcontact with the peritoneum or preperitoneal fat. To avoidthis, the senior author (CEB) prefers to dissect the preper-itoneal fat pad away from the posterior rectus sheath so thatthe mesh is placed in direct continuity with the posteriorsheath fascia. This improves the mechanical strength at themeshmusculofascial interface rather than suturing themesh to the preperitoneal fat and peritoneal surface. Inaddition, the preperitoneal ap can be positioned dorsallyto the bioprosthetic mesh suture line to further limit adhe-sion in the suture inset areas. Alternatively, the retrorectusplane presents another good option when the bioprostheticmesh is sutured to the semilunar line from between therectus muscle and the posterior rectus sheath. Onlay meshplacement is technically easier but has several signicantdrawbacks; we do not recommend it as a primary option.The limitations of the onlay repair include the fact that if areinforced repair is going to be performed, one generallymust be able to close the fascia rst; this is not possible inmany of the cases where there are large defects and theinset of the material as an inlay actually helps offset thetension to close the fascial defect. Thus, an inlay mesh

placement facilitates primary fascial closure, whereas onlaymesh placement is performed after primary fascial closureis achieved. In addition, the seroma rate is at least theoreti-cally higher when the bioprosthetic mesh is placed in thesubcutaneous plane. Although there may be some bio-mechanical advantages to an inlay repair compared withan onlay repair, there may be some situations in which anonlay repair may be the only safe option, as is the case whenit is impractical to reenter a hostile abdomen.

The bioprosthetic mesh inlay repair is reinforced in asecond layer of primary fascial closure over bioprostheticmesh whenever technically feasible. This dual layer repair ispreferred to a bridging interposition repair. Centralizationof the rectus abdominis muscle complexes reduces thefascial defect and facilitates primary fascial closure. Primaryfascial coverage also allows for complete apposition ofbioprosthetic mesh to the surrounding musculofascial de-fect edge, eliminates bioprosthetic mesh exposure to thesubcutaneous fat, and may limit seroma formation. Incircumstances in which primary fascial closure is notattainable, a bridging repair is performed. This is performedas a dual circumferential inlay technique43 that allows twoconcentric suture lines to afx the bioprosthetic meshdirectly to the musculofascia. Creating direct oppositionof the bioprosthetic mesh to the undersurface of the fascialdefect itself prevents any uid collections from occurringbetween the two layers, which can result in lack of or delayin brovascular incorporation and remodeling. In addition,closed suction drains are placed between the musculofasciaand the bioprosthetic mesh to prevent any potential uidcollections from developing at the meshmusculofascialinterface.

An adjunct surgical technique to improve outcomes inabdominal wall reconstruction is to combine bioprostheticmesh inlay repair with component separation. Componentseparation has the ability to medialize the rectus complexesand reduce the defect size, with the ultimate goal of allowinga primary fascial closure over the inlay bioprosthetic meshand therefore reinforce a repair. Component separation alsowill reduce the subsequent tension on the midline, reducingthe fascial incision closure and/or musculofascia to implantincision tension. This is accomplished by separating theexternal oblique aponeurosis and delaminating the externaloblique muscle from the internal oblique muscle interface.This results in an ofoading of the bilateral superolateralvector distraction of the external oblique muscle on thecentral wound closure.

At times, unfavorable wound-healing scenarios will beencountered, with wound infection, dehiscence, or break-down of overlying skin aps leading to exposure of thebioprosthetic mesh. The bioprosthetic mesh's tolerances ofbacterial contamination and exposure allowan acute openingdue to wound separation to be reclosed over drains afterclearing any infection and ensuring there is adequate skinlaxity for closure. Small defects can be left open to heal bysecondary intension with standard saline-soaked dressingchanges or negative pressurewound therapy (NPWT) devices.NPWT is a useful adjunct in the management of exposed


Bioprosthetic Mesh in Abdominal Wall Reconstruction Baumann, Butler22

bioprostheticmesh. The goal ofNPWT is to prevent desiccationand dehydration of the bioprosthetic material. NPWT can beused to develop a revascularized mesh granulation bed suit-able for skin graft coverage or serve as a temporizing measureto facilitate a delayed primary closure or ap coverage as theclinical circumstances dictate. The use of nonadherent barrierdressing materials between the NPWT foam and bioprostheticmesh prevents trauma to the bioprosthetic mesh and preventsfoam retention on the bioprosthetic mesh. Various materialscan be used, such as wide-mesh petroleum-impregnatedgauze or perforated silicone dressings; alternatively, the useof microporous foam (such as polyvinyl alcohol foam) directlyover the bioprosthetic mesh is an option. A skin graft can beapplied onto granulated bioprosthetic mesh. It is unknownexactly what clinical indicators are reliable for determiningwhen a skin graft will survive over the bioprosthetic mesh. Inour experience, this typically does not require completegranulation tissue over thematerial but rather the appearanceof buds of granulation tissue to the surface of the materialthrough the existing adnexal structures (hair follicle and sweatgland channels). If the defect is large with exposed biopros-thetic mesh at the base, the best choice is generally autologousskin ap tissue, either locally advanced from the abdomen,rotation advancement ap, pedicled regional ap, or freeap.

Conclusion

Bioprosthetic mesh products have several potential advan-tages over other synthetic permanent materials in selectclinical situations. Indications for implantation of biopros-thetic mesh in abdominal wall reconstruction includecontaminated wounds, complex repairs at high risk fordeveloping wound-healing problems, high likelihood ofa cutaneous exposure, and unavoidable direct placementof mesh over bowel. Further studies will be importantfor comparing long-term outcome and cost factors tobetter dene the role, in

Abdo Reconstruction

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