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Chest wall infection

OVERVIEW

What is chest wall infection?

Chest wall infection falls under the scope of thoracic surgery. With the rise of chest wall surgery in recent years, it has gained increasing attention from thoracic surgeons. Chest wall infections can be classified as superficial or deep. Superficial infections refer to skin and subcutaneous infections, which are relatively easier to treat. In contrast, deep infections involve muscles, bones, and intrathoracic organs, making treatment more challenging and associated with a high mortality rate. Deep chest wall infections commonly occur as complications after open-heart surgery in cardiothoracic surgery.

What is the development overview of chest wall infection?

Since Julian et al.[1] first reported the use of a median sternotomy for cardiac surgery in 1957, this surgical approach has become the standard for open-heart surgery. While this approach has benefited countless cardiovascular patients, postoperative sternal wound infections often cause unbearable suffering for patients.

It is well known that the incidence of deep sternal wound infection (DSWI) is approximately 1%–5%[2]. Given the large number of cardiac surgeries performed, the absolute number of patients experiencing DSWI amounts to thousands. Despite advancements in cardiac surgical diagnosis, treatment, and monitoring, there has been no improvement in the incidence of DSWI[3].

For patients, even if the surgery itself is successful, postoperative DSWI can be catastrophic, with a mortality rate as high as 10%–47%[4]. Patients with DSWI often require reoperation, longer hospital stays, higher costs[4, 5], and significantly reduced long-term survival[5, 6]. It is reasonable to consider DSWI a dreaded complication.

What are the classification and characteristics of chest wall infection?

1. Classification by etiology, location, and depth of infection

  1. By etiology:
  1. By location:
  1. By depth of infection:

2. Classification of chest wall osteomyelitis

  1. By cause:
  1. By location:
  1. By disease course:

3. Characteristics of chest wall infection

  1. Tissue defects
  2. Requires repair and reconstruction
  3. Close relationship with intrathoracic structures
  4. Can affect systemic organs

SYMPTOMS

What are the symptoms of chest wall infection?

Although symptoms may vary depending on the infected area, chest wall infections primarily manifest with typical signs of "infection," including localized redness, swelling, warmth, and pain, and may even involve fever, chills, or pus discharge. If the infection extends deeper into bones or organs, corresponding symptoms such as bone pain, chest pain, or severe organ infection may occur.

Clinically, surgical site infections are common, particularly after median sternotomy in cardiac surgery. These infections can be categorized as superficial or deep. Below, we describe the main symptoms using post-sternotomy infection as an example.

Post-sternotomy infection falls under the category of surgical site infection (SSI). SSI refers to infections occurring within 30 days post-surgery in the incision or deep tissues, or within one year if an implant is involved. These infections are classified by location as superficial incisional, deep incisional, or organ/space infections[7].

CAUSES

What Causes Chest Wall Infections (Deep Sternal Wound Infections)?

The etiology of chest wall infections has been extensively studied, particularly for deep sternal wound infections (DSWI). Numerous early studies have explored the risk factors for DSWI[3, 5, 6, 8].

Although research findings vary, the following risk factors are widely recognized by experts[3]:

DIAGNOSIS

How to diagnose chest wall infection (deep sternal wound infection)?

The Centers for Disease Control and Prevention (CDC) defines deep sternal wound infection (DSWI) as[6,9,10]:

The presence of any one of the following three manifestations:

  1. Isolation of pathogenic microorganisms from mediastinal tissue or pleural fluid cultures;
  2. Direct visualization of mediastinitis during surgery;
  3. Presence of chest pain, chest instability, fever (exceeding 38°C), purulent discharge from the mediastinum, plus any one of the following two:

DSWI diagnosis is primarily based on clinical manifestations[6]. Chest CT has high sensitivity in diagnosing DSWI and can assess the extent of dehiscence. MRI has some value in the early diagnosis of DSWI[6].

What tests are needed for chest wall infection?

Diagnosis can be made based on medical history, clinical manifestations, and local puncture cultures. The main tests include local puncture and pathogen culture of secretions.

TREATMENT

Which department should be consulted for chest wall infection?

Chest wall infection falls under the scope of thoracic surgery, so the initial consultation should be with the thoracic surgery department.

How is chest wall infection (deep sternal wound infection) treated?

  1. Anti-infection treatment

Before obtaining evidence of the corresponding pathogenic microorganisms, empirical antibiotic therapy is a key part of medical treatment. Once DSWI is diagnosed, the combined use of broad-spectrum antibiotics is most critical, covering methicillin-resistant Gram-positive bacteria, Gram-negative bacteria, and anaerobic bacteria. It is recommended to seek microbiological evidence from multiple sources. Once microbiological results are available, treatment should be guided by culture. The classic systemic antibiotic treatment cycle is 6 weeks[6]. When the clinical efficacy of antibiotics is not evident, antifungal treatment is often required[6].

  1. Surgical treatment

For DSWI, there are multiple surgical treatment options available. Due to differences in case selection among teams and variations in application methods across regions, there is currently no unified standard for treatment processes and protocols, nor randomized controlled trials. Therefore, it remains unclear which approach is more effective for patient treatment.

What are the updates in surgical techniques for deep sternal wound infection?

In 1963, with the invention of closed suction and irrigation devices, this treatment method gradually replaced traditional surgical dressing changes. This was a revolutionary advancement in DSWI treatment methodology, as it eliminated chest instability and facilitated secondary healing. Subsequently, the invention of the Redon drainage catheter achieved more satisfactory outcomes. However, for delayed or long-standing infections, this treatment offers limited benefits[6].

In 1997, a more effective treatment method—topical negative pressure (TNP) therapy—was introduced[6]. Today, TNP is recommended by many experts as a superior transitional treatment compared to traditional methods[7]. Unfortunately, the terminology for this technology remains inconsistent.

Some literature refers to it as negative pressure wound therapy (NPWT), while other studies call it vacuum-assisted closure (VAC). In fact, all three terms describe the same treatment concept. Domestic clinical applications of NPWT-VAC for DSWI have been reported. Some scholars argue that prolonging this transitional approach may be harmful, potentially leading to secondary infections or fatal bleeding. Therefore, foreign scholars recommend limiting its use to no more than 3 weeks[6].

What are the current surgical treatment methods for deep sternal wound infection in China?

Our treatment experience shows that thoracic reconstruction plays a decisive and dominant role in DSWI treatment. For patients dissatisfied with conventional treatment, thoracic reconstruction is ultimately unavoidable. Thoracic reconstruction includes several different procedures: pectoralis major muscle flap transplantation, rectus abdominis muscle flap transplantation, omental transposition, and latissimus dorsi muscle flap transplantation. In cases of severe skin damage, skin flap transplantation may be required alongside muscle flap transplantation, or a combination of two different muscle flap transplantations may be used.

Depending on the location and size of the lesion and the surgeon's experience, different researchers report varying surgical approaches. Domestically, Wang Wenzhang et al.[11] reported the efficacy of thoracic reconstruction—pectoralis major muscle flap transplantation—in a group of 118 DSWI patients. Except for one case that combined rectus abdominis muscle flap transplantation, all other cases of simple pectoralis major muscle flap transplantation—thoracic reconstruction—were successful, with an average operation time of (100 ± 55) minutes, blood loss of (120 ± 70) mL, and an average hospital stay of (14 ± 9) days. Follow-up at 40 months showed no recurrence.

Although no consensus has been reached, pectoralis major muscle flap transplantation is the most commonly used procedure for DSWI. Depending on the condition or if the first pectoralis major muscle flap transplantation fails, rectus abdominis muscle flap transplantation or omental transposition are typical alternatives. Further research is needed to determine which treatment method is better and which results in higher post-treatment quality of life for patients.

DIET & LIFESTYLE

What should chest wall infection patients pay attention to in their diet?

If it is only a superficial infection of the skin and subcutaneous tissue, active cooperation with treatment is sufficient, and it generally does not affect diet and daily life.

However, deep infections involving muscles, bones, and intrathoracic organs are more challenging to treat and often require hospitalization, so dietary choices should follow the advice of the attending physician.

PREVENTION

How to Prevent Chest Wall Infections (Deep Sternal Wound Infections)?

Primarily physician-led preventive strategies:

As mentioned earlier, risk factors for DSWI such as advanced age, obesity, and a history of COPD cannot be corrected through preoperative adjustments. However, for modifiable risk factors, preventive measures span the entire perioperative period—before, during, and after the first cardiac surgery. For example, hemodynamic stability, blood glucose control, strict aseptic techniques, antibiotic prophylaxis, and meticulous surgical planning by the surgical team are theoretically beneficial for DSWI prevention.

Preoperative Prevention: The nasal cavity is a reservoir for Staphylococcus aureus colonization, while the skin harbors Staphylococcus epidermidis. Assuming DSWI is associated with both, nasal and skin decolonization could theoretically reduce DSWI incidence[3].

Some researchers applied mupirocin ointment to the nasal cavity preoperatively, believing it could reduce DSWI rates, though this has not been confirmed by others[3]. Others combined nasal mupirocin with chlorhexidine solution showers to reduce skin and mucosal staphylococcal colonization, which appeared effective in lowering DSWI incidence. However, the benefits of these strategies require further study[3].

Intraoperative Prevention: Kramer et al.[12] suggested that multidisciplinary intensive blood glucose control helps reduce DSWI incidence post-cardiac surgery.

Their study involved perioperative cardiac surgery patients using continuous insulin infusion to maintain blood glucose tightly between 80–120 mg/dL. Over 18 months, DSWI incidence decreased from 2.6% to 1%, showing statistical significance and demonstrating a preventive effect against DSWI.

Postoperative Prevention: Research on postoperative prevention is limited. Most patients are transferred to the ICU post-surgery. Undoubtedly, rational antibiotic prophylaxis, intensive glucose control, surgical site stabilization, negative pressure drainage, adequate analgesia, prevention of surgical site bleeding, mechanical ventilation to rest respiratory muscles, timely extubation, appropriate nutritional support, and prevention of catheter-related infections and ventilator-associated pneumonia all contribute to reducing postoperative DSWI incidence.