CHAPTER
57

The chest and abdomen are unique anatomical units with very specific surgical complications and adverse events. The chest wall functions as a protective cage around the vital organs of the body, and significant disruption of its structure can have dire respiratory and circulatory consequences.1 The complex interplay of twelve paired ribs with the internal and external muscles that compose the chest wall has both a structural and a functional role. The chest wall protects the heart, lungs, and liver; provides a flexible skeletal framework to stabilize the actions of the shoulder and arm; and promotes respiratory movement, all while reliably delivering more than 20,000 breaths a day. Chest wall complications are associated with significant morbidity and rapid life-threatening consequences. The management and reconstruction of complex chest wall defects has significantly improved over the past half century, with long-term success rates changing from 50% to the current 90 to 99% and hospital stays reduced from an average of 84 days to less than 13 days.² The past several decades have seen a marked improvement in the management and reconstruction of complex chest wall defects.³ Widespread acceptance of muscle and myocutaneous flaps such as the latissimus dorsi, pectoralis major, serratus anterior, and rectus abdominis has led to a sharp decrease in infections and mor tality.⁴ Successful reconstructions are critically dependent upon a detailed knowledge of the functional anatomy and blood supply of the chest and the underlying pathophysiology of a particular disease process.

Abdominal wall reconstruction patients have varied presentations, and postoperative complications have numerous causes. The goals of abdominal wall reconstruction are to reestablish the integrity of the myofascial layer and provide external cutaneous coverage. In the United States, there are an estimated 4 million laparotomies performed annually, associated with a 2 to 30% incidence of incisional hernia, which produces roughly 150,000 to 250,000 ventral hernias.5 This equates to a cost of approximately $2 billion at a time when health care is transitioning toward value-based reimbursement and pay for performance concepts, and when efficiency and cost containment are prioritized with little tolerance for complications.⁶ Surgical complications can result any time but are particularly common after tumor resection, necrotizing soft tissue infections, or traumatic injury. These clinical scenarios represent the most complicated abdominal wall reconstructions, sometimes requiring multiple staged procedures.

Physiology, Basic Science, and the Disease Process

The inspiratory and expiratory muscles of the rib cage work in a precisely coordinated movement to execute a functional breath. In the pleural cavity, the lung remains in an inflated state by mechanical coupling of the chest wall and the lung. The work of breathing is minimized by mesothelial cells with microvilli that are enmeshed in hyaluronic acid–rich lubricants. Elevated movement of the ribs leads to forced inspiration by increasing the dimensions of the chest through a “bucket-handle” motion and by elevation of the sternum through a “pump-handle” motion. The muscles of inspiration work actively to create a reduced intrapleural pressure to induce inhalation. Because of its distinctive curved geometry and specialized metabolic demands, the diaphragm is the most important respiratory muscle. With assistance from the external intercostal muscles, the diaphragm contracts during inspiration to enlarge the thoracic cavity. Paired sternocleidomastoids and scalene muscles act as secondary accessory muscles to aid in raising the sternum and elevating the upper ribs. Upon relaxation of the diaphragm, the elastic recoil of the lung in addition to contraction of the abdominal muscles leads to passive expiration. Pulmonary function tests measure forced expiratory volume in 1 second (FEV₁), tidal volume, and the ratio of FEV₁ to forced vital capacity ratio to quantify this process. The pathophysiology of lung disease may be broadly classified into either obstructive or restrictive disease. Obstructive processes involve the impediment of expiration by obstruction of the bronchioles and bronchi.

Indications for abdominal wall reconstruction are multifactorial and include tumor ablation, congenital anoma lies, and trauma. Each indication has an underlying distinct pathophysiology, which must be specifically addressed for successful surgical correction and to avoid iatrogenic complications. Hernias of the abdominal wall can result from genetically impaired collagen formation, deposition, organization, or degradation; from wound-healing deficiencies; and from injury, failed laparotomy closures, or failed hernia repairs.⁷ Decades ago, it was suggested that both primary and recurrent hernias resulted from abnormal collagen metabolism.⁸ Original proposed risk factors for the development of hernias included tobacco use and a strong family history of hernia, which suggests a genetic predisposition. Subsequently, ratios of type I and type III collagen and tissue metalloprotease expression in patients with inguinal and incisional hernias were studied to try to isolate a cause.⁹ Further studies have suggested that mechanical strain on load-bearing tissues can induce secondary changes in tissue fibroblast function that in turn can result in failure of abdominal wall repairs.¹⁰

Preoperative Planning and Patient Selection

A physical examination should be performed to assess the patient’s general condition, the abdominal wall integrity, the extent and location of any abdominal wall abnormalities, and the presence of scars that could become an obstacle to raising reliable tissue flaps. Routine laboratory tests and a nutritional workup are advised. Preoperative computed tomography to examine the defect characteristics and abdominal wall anatomy and vascularity is helpful for surgical planning. Correct diagnosis of chest and abdominal wall defects is critical to proper management. After an appropriate clinical evaluation, imaging studies are a helpful adjunct for detection and diagnosis of chest and abdominal defects and defining the relevant wall anatomy. Different imaging modalities are available to evaluate defects.¹¹ Computed tomography (CT) allows for visualization of the thoracic cage, intra-abdominal organs, and the abdominal wall; three-dimensional data sets; and multiplanar reformation capabilities. CT may assist in detecting lung collapse, fluid collections, bowel obstruction, incarceration, strangulation, and traumatic wall hernias. Magnetic resonance imaging (MRI) also permits the detection of soft tissue defects and abdominal wall hernias, although this modality does not usually offer further sensitivity and therefore may be cost prohibitive.

In the repair of chest and abdominal wall defects, the surgeon must consider a multitude of factors to identify the appropriate surgical technique to accomplish the reconstructive goals. An individualized approach is required and must take into account the patient’s age, comorbidities, physiological status, defect size, available local tissue, and presence of contamination. In addition, the patient’s pulmonary function should be evaluated preoperatively (e.g., with spirometry) because most patients undergoing major chest wall procedures will have some degree of postoperative respiratory dysfunction. Failed extubation and prolonged ventilator dependence could follow major chest wall surgery in patients with poor preoperative respiratory function. The plastic surgeon should communicate with the thoracic surgeon to develop a clear reconstructive plan. For intrathoracic reconstruction, the plastic surgeon should be familiar with bronchopleural fistula and empyema.

Although more studies are needed, it is evident that some primary hernias are the result of a genetic predisposition, whereas the rest may be related to acquired structural collagen abnormalities from mechanical strain, with or without associated predisposing risk factors, such as tobacco use, diabetes, advanced age, male sex, sleep apnea, prostatism, and obesity.12 Factors associated with destruction of the collagen in the lung in chronic obstructive pulmonary disease (COPD) and emphysema likely result in poor wound healing and increased hernia formation in patients with these diseases.

Intraoperative and Perioperative Considerations That Influence Complications

Although advancements in chest wall reconstruction have resulted in fewer postoperative complications, rates still remain high, reported between 25 and 46%.^13,14 These patients commonly present with multiple medical comorbidities, which can complicate their management. Although most complications are generally minor, larger chest wall resections with significant loss of skeletal support often develop paradoxical chest wall motion, leading to prolonged ventilator dependence and major respiratory impairment, complications that can cascade into respiratory failure, multisystem organ failure, and even death.^15,16 Minor wound-healing complications of the soft tissue overlying the skeletal reconstruction can progress to major complications such as mesh explantation, deep space infections, and bronchocutaneous fistulae, particularly in the setting of concomitant adjuvant radiation therapy and chemotherapy. Anatomic location of the chest wall resection was more predictive of outcomes than was defect size. Patients with superior rib resections often require more days of mechanical ventilation than do patients with inferior resections.¹⁷ Overlapping superior or middle rib region resections are significantly associated with greater morbidity. This can be attributed to alterations in chest wall motion, secondary to the loss of the “pump-handle” mechanism of inspiration, which requires a chest wall fulcrum dependent on the superior ribs and their attachment to the sternum. Patients who have a sternectomy experienced a significantly longer period of ventilator dependence (10.2 versus 2.6 days), demonstrating the importance of the superior chest wall in proper pulmonary functioning.¹⁸

The goals of abdominal wall reconstruction, regardless of the cause of the defect, are to reestablish the integrity of the myofascial layer and provide durable cutaneous coverage while minimizing the risk of hernia recurrence. Although it is impossible to restore the abdominal wall to its native state after surgical wounding or to cure patients with hernia of their intrinsic collagenopathies, strategies can be used to maximize the possibility of a successful outcome in abdominal wall reconstruction. Restoring the layered nature of the abdominal myofascia, the native location of key muscle groups, and the tone and contour of the abdominal wall is often achievable with contemporary surgical maneuvers. The importance of a meticulous dual-layered repair; centralizing the rectus abdominis muscle complexes; and reinforcing the repair with mesh, especially for hernias larger than 4 cm in greatest dimension, cannot be overemphasized.¹⁹

The incidence of ventral hernia formation after various types of abdominal incisions is 10.5% for midline, 7.5% for transverse, and 2.5% for paramedian incisions.⁷ Given the likely similar rates of incisional hernia formation after transverse and midline incisions, surgeons should plan incisions based solely on the operative exposure desired to safely complete procedures. A factor known to be linked to incisional hernia formation is the manner in which the initial midline myofascial incision is closed. Specifically, animal and human trials have shown that a 4:1 suture–to–wound length ratio is optimal to reduce wound-related morbidity and incisional hernia formation. This suture strategy is often misunderstood; for clarification, it typically involves 5- to 7-mm fascia bites and 3 to 4 mm of travel. This “small-stitch” approach results in improved healing and reduced rates of wound infections.

In general, patients have prolonged healing periods after abdominal wall reconstruction because of the dynamic function and mobility of the abdominal musculature. Based on specific unique indications, each patient’s postoperative care regimen should be individually tailored to allow for sufficient healing of the surgical site. Perioperative management of high-risk patients should include appropriate deep venous thrombosis (DVT) chemoprophylaxis according to the Caprini risk score.²⁰ Sequential compression devices and early ambulation should be used with low-molecular-weight fractionated heparins administered postoperatively. Perioperative antibiotics are indicated, and cases with violation of the gastrointestinal tract should be offered broader coverage for anaerobic and gram-negative bacteria. For ventral hernia, closed suction drains are used liberally and are kept in place on average 1 to 2 weeks until less than 30 mL of drainage is collected per day. Abdominal wall reconstruction Patients should refrain from strenuous activities and exercises that isolate the abdominal core for at least 6 to 12 weeks after abdominal wall reconstruction. Patients may gain comfort from the use of an abdominal binder for 3 months, and then with any expected heavy physical activity thereafter. Routine follow-up includes a physical examination in an outpatient clinic, often performed weekly for 1 month after discharge, then every 3 months for 1 year, and then annually thereafter.

Surgical site infections are common after both chest and abdominal wall reconstruction. The exact incidence is difficult to determine, because most series poorly define this outcome variable. The U.S. Centers for Disease Control and Prevention (CDC) recommends that surgical site infections be specified as superficial, deep, or organ space infections.21 Additionally, categorization of the intraoperative level of wound contamination based on CDC criteria into clean, clean-contaminated, contaminated, and dirty wounds is important to appropriately stratify patients by risk of surgical site infection. In patients with clean-contaminated and contaminated wounds, a prospective multi-institutional study evaluating the role of a porcine acellular dermal matrix (ADM) to repair abdominal wall defects reported a 34% rate of superficial surgical site infections. In contrast, studies of clean wounds have reported infection rates of 0 to 12%.²² Mesh infections are one of the most serious complications that can occur after both chest and abdominal wall reconstruction. The exact incidence of this problem is difficult to discern from the literature because of the use of poorly defined terms and inconsistent reporting practices. Mesh infections are reported to occur in 0 to 3.6% of laparoscopic ventral hernia repairs and 6 to 10% of open repairs using mesh.²³ The most common organism infecting mesh is Staphylococcus aureus, seen in up to 81% of cases; this suggests skin flora contamination during mesh implantation. However, gram-negative organisms, such as Klebsiella and Proteus spp., have been implicated in up to 17% of mesh infections. Management of mesh infections is complex and requires patient individualization as well as a knowledge of bacterial susceptibility for a particular hospital. In general, control of local sepsis is important, as is preserving native tissue for eventual reconstruction.

Seroma

Seroma formation can occur after both chest and abdominal wall reconstruction, particularly in cases involving large undermined flaps, which create significant dead space. If symptomatic, seromas can be aspirated percutaneously or under ultrasound guidance. In most cases, small seromas will be reabsorbed over time. Resection of a previous hernia sac is important to prevent seroma formation. In open ventral hernia repair, drains are often placed in an attempt to obliterate the dead space caused by the hernia and tissue dissection. These drains can cause retrograde bacterial contamination, and seromas can form after drain removal. Long subcutaneous tunnels, meticulous securing of drain exit sites with drain sutures that prevent intussusception of the drain, and meticulous drain exit site wound management using antibiotic-impregnated dressings should be used to reduce the risk of retrograde bacterial infection. Seroma formation is common after abdominal component separation and with muscle flaps of the trunk because of the extensive tissue dissection, and drains may be necessary for up to 4 to 6 weeks. Intraoperative techniques, such as quilting sutures, fibrin sealant, and postoperative abdominal binders, may help to prevent or reduce seroma formation.²⁴

Mediastinitis

Infection may manifest as mediastinitis or empyema. Sternal wound infection after cardiac surgery occurs in approximately 0.5 to 9% of cases. Pairolero and Arnold classified sternal wounds based on timing of presentation of infection.²⁵ Type I wounds occur in the first few days postoperatively. These wounds may contain incisional dehiscence with serosanguineous discharge and/or sternal instability. Type II wounds occur in the first several weeks and may present with cellulitis, mediastinal purulence, and positive cultures. Type III wounds occur months to years postoperatively and are distinguished by draining sinus tracts and chronic osteomyelitis. Major risk factors for sternal dehiscence and subsequent infection are obesity, diabetes, COPD, and bilateral harvest of internal mammary arteries. The treatment for sternal infection and dehiscence is radical débridement of all infected tissue, culture-directed antibiotic therapy, and obliteration of dead space. In addition, chest reconstruction with vascularized tissue, most commonly pectoralis myocutaneous advancement, and rectus abdominis myocutaneous and other flap procedures, such as latissimus dorsi or omentum, have proved to be effective treatments and have lowered mortality rates²⁶ (Table 57.1).

Flail Chest (Paradoxical Motion)

Trauma and the ablation of large oncological defects may require the resection of multiple ribs, leading to disruption of chest wall integrity and paradoxical chest movement, a condition known as flail chest. When a flail segment, usually 5 cm or greater in diameter, loses continuity with the surrounding chest wall, ventilation becomes progressively inefficient. Variations include posterior flail segments, anterior flail segments, and sternal flail with fracture of bilateral anterior ribs. The segment requires adequate fixation to restore normal respiratory physiology. Defects, depending on their size, may be amendable to either a soft tissue or bony reconstruction. Soft tissue reconstruction is appropriate for two-rib and some three-rib (< 5 cm in diameter) segmental loss without functional consequences. Surgical stabilization has been shown to decrease mechanical ventilator days, improve long-term outcome, and lower the cost of hospitalization in select patients. Note that restoration of chest wall integrity after reconstruction may not restore lung function if underlying pathology such as significant lung contusion is not addressed.

Autologous tissues such as rib grafts and fascial grafts have been falling out of favor for restoration of chest wall stability since the introduction of synthetic mesh. Semi-rigid chest wall reconstruction can be achieved by suturing synthetic or bioprosthetic mesh under tension to span the skeletal defect that follows large chest wall resections. Some authors also suggest the use of more rigid fixation with polymethylmethacrylate or polypropylene mesh for such defects. Polymethylmethacrylate reconstruction is commonly advocated to repair large anterior and anterolateral chest wall contour defects, whereas large defects in flat surfaces on the anterior and posterior aspect of the chest may be repaired with prosthetic mesh. The ideal prosthetic material features, as described by le Roux and Shama,27 include rigidity that reduces paradoxical movement, inertness that allows tissue ingrowth, malleability, and radiolucency that does not obstruct radiographic evidence of tumor relapse.

Table 57.1 Thigh-based and torso-based pedicled flaps used in chest and abdominal wall reconstruction

Synthetic mesh in general may increase complication rates when it is placed directly over viscera or when the operative site has been irradiated or contaminated with bacteria. Synthetic mesh is contraindicated in contaminated wounds unless prolonged dependence on a ventilator will result from not using it.27 In the latter situation, bioprosthetic mesh is an alternative. Many bioprosthetic meshes are available; these include xenogeneic ADM, preferentially used for chest wall reconstruction. Bioprosthetic meshes have been shown in animal models to allow tissue ingrowth, become incorporated and revascularized, and be valuable for wounds with a high risk of infection or complications. The main limitations are their high cost, unproven long-term stability in the chest wall, and theoretic risk of stretching or laxity with ongoing remodeling. Bioprosthetic mesh may be a good option for defects that have bacterial contamination or an increased risk of skin dehiscence with mesh exposure; the material tolerates cutaneous exposure without the need for explantation.

Once the synthetic or bioprosthetic material is placed and secured to the edges of the defect, well-vascularized soft tissue coverage should be provided to minimize the chance of exposure and infection. The use of prosthetic mesh sutured under tension to re-create semirigid chest wall stability after repair of large defects has been shown to reduce ventilator dependence and hospital stay. However, the absolute need for rigid or semirigid skeletal stability reconstruction of the chest wall after resection has been challenged, particularly for smaller defects. Arnold and Pairolero25 reported that pulmonary function is not ultimately compromised after major chest wall resection, such as removal of the entire sternum, if reconstruction is performed without mesh. Furthermore, the resulting pulmonary insufficiency after chest wall resection is often less significant than that after trauma.¹⁵

Bronchopleural Fistula and Empyema

Bronchopleural fistula and chronic empyema are two of the most common conditions necessitating reconstruction of the pleural space and often occur together. The incidence of postpneumonectomy stump fistula is 0 to 12%, although postpneumonectomy empyema has a reported incidence of 2.2 to 16%.²⁸ The presence of untreated dead space and bronchopleural fistula after lobectomy or pneumonectomy will usually result in infection. The postoperative mortality rate of pneumonectomy increases to 25% if the course is complicated by empyema and to approximately 50% if bronchopleural fistula is present. Soft tissue flaps are often used to reinforce the repair after closure of a fistula or to fill the intrathoracic dead space after drainage of a fluid collection. Flaps used in bronchopleural fistula closure include intercostal muscle, pericardial fat, diaphragm, extrathoracic muscle, omental, and free flaps.

Pedicled flaps commonly used to fill intrathoracic dead space are described in Table 57.1 and illustrated in Fig. 57.1.²⁶ These flaps can be introduced into the thoracic cavity through the original wound or through a new, separate thoracotomy. For single-stage treatment of empyema without a bronchopleural fistula, the empyema is drained and the dead space is irrigated, filled with a muscle flap, and closed. If the patient is too ill to undergo an extended single-stage procedure or if the infection is long-standing and resistant, treatment may begin with a drainage procedure, such as the Eloesser procedure²⁹ (Fig. 57.2). When bronchopleural fistula is also present, it must be addressed as well.

Hernia

The most common abdominal wall defects faced by reconstructive surgeons are incisional hernias. The incidence of incisional hernia is approximately 11% after a midline laparotomy⁵ (Fig. 57.3). One in three incisional hernias will cause symptoms, and approximately 4 percent of patients undergoing laparotomy will undergo an additional operation to repair an incisional hernia.³⁰ Patients with hernias are at risk of developing bowel-related complications such as enterocutaneous fistulas, obstruction, incarceration, and strangulation. Functional problems in hernia patients include poor respiratory effort, loss of abdominal domain, and weak abdominal musculature. Cosmetic problems are also common concerns of patients with abdominal hernias. Incisional hernias are notorious for their high recurrence rate after repair and for their high rate of surgical complications. One study found that the 5-year reoperation rate was 23.% after the first hernia repair operation, 35.3% after the second, and 38.7% after the third.³¹ The infection rate after ventral hernia repair is 4 to 16%, and the risk significantly increases if the patient had a previous infection (41% versus 12% in one study). Bowel-related complications such as adhesions, obstruction, erosion, and fistulization are other known complications of hernia repair, especially with the use of synthetic mesh.

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