The Utility of Negative Pressure Wound Therapy in the Management of Complex Deep Cardiothoracic Surgical Site Infections

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NPWT is a well-known therapeutic modality that has been effectively used for a vast range of surgical wounds and infections. It has been used in acute and chronic wounds that are difficult to manage, in both cardiothoracic and non-cardiothoracic settings.^1,2 NPWT was first used in the management of empyema in 2006 and was found to be an effective tool for intrapleural collections.³ NPWT has also been widely used in the management of infections in the postoperative period following lung resection, necrotizing pleuropulmonary infections, and mediastinitis after esophageal surgery.⁴ More recently, it has been used in the management of deep sternal and thoracic wound infections.⁵

In a prospective cohort study, Perez et al⁶ demonstrated the use of NPWT in patients with severe abdominal sepsis or abdominal compartment syndrome, with no complications at 3-month follow-up. A population-based study compared the use of NPWT with conventional wound therapy in patients with osteomyelitis and found that patients who received NPWT had a significantly reduced rate of recurrence and increased bacterial clearance.⁷ Other successful trials of NPWT in non-cardiothoracic practice describe its safety and effectiveness with satisfactory cosmetic and functional results. These include Chen et al,⁸ in which NPWT was applied in the setting of resected extremities affected by soft tissue sarcoma, and Karaaslan et al,⁹ in which it was applied on deeply infected, complicated wounds after spinal stenosis surgery. Further evidence of the usefulness of NPWT can be observed in the positive outcome of its application on split-thickness skin grafts.¹⁰

NPWT has been trending in the field of cardiothoracic surgery, mostly as a result of several publications that report its successful use. A study of NPWT in the management of severe intrathoracic infections in 27 patients concluded that it is safe to use in the thoracic cavity and may even be a good alternative to OWT in some patients.¹¹ Another study detailed the successful use of NPWT in the management of persistent and infected pleural spaces.¹² Some studies have promoted NPWT as the definitive, first-line treatment modality for superficial sternal wound infections.¹³ However, there is a lack of research focused only on deep sternal infections. A recent meta-analysis that included 22 studies on deep sternal infections (1980 patients) reported that NPWT significantly reduced overall mortality, ICU stay, and length of hospital stay.¹⁴ Few studies have been published on the use of intrapleural NPWT for empyema.^15,16

The current study aims to demonstrate the efficacy of NPWT in enhancing wound healing, reducing morbidity and mortality, shortening hospital stays, and thus providing a better outcome in cardiothoracic surgery patients. In addition, it aims to demonstrate the safety of NPWT within the thoracic cavity and assess its use in complex deep cardiothoracic surgical site infection; these complex cases are limited and involve varied underlying disease processes.

Any cardiothoracic surgery patient who was treated with NPWT and survived the in-hospital stay was included. NPWT was used to treat 18 patients, most with complex deep cardiothoracic surgical site infections. These patients were admitted to the cardiothoracic surgery units at King Fahad University Hospital, Khobar, Saudi Arabia, between July 2014 and February 2020. Ethical approval was obtained from the Institutional Review Board (IRB-2018-01-325).

Patient data collected included primary surgical intervention, local complications, wound cultures, age, sex, and comorbidities, in addition to ICU admissions and hospital stays (Tables 1-3). Local complications were related to CABG surgery in 7 patients, decortication of empyema in 4 patients, diaphragmatic or hiatal hernia repair in 2 patients, chest wall tumor resection in 2 patients, and pectus excavatum correction, sternoclavicular osteomyelitis, and esophago-cutaneous fistula repair in 1 patient each. All patients were admitted secondary to complex deep cardiothoracic surgical site infection, and the diagnosis was confirmed through cultures and chest radiographs that were obtained during the patient's stay and follow-up visits.

The current study focused solely on the use of NPWT in cardiothoracic patients with deep complex surgical site infections. The exclusion criteria were as follows: patients who had been treated only using conventional methods, patients who had received NPWT elsewhere in the body (other than in cardiothoracic wounds), and patients with superficial wounds involving the dermal layers only.

The method of NPWT application started with ensuring sterility of the wound and surrounding skin by thoroughly washing out the wound and applying antiseptic agents. This was followed by application of a silicone contact layer. A black foam sponge was prepared in a sterile environment and carefully shaped to fit the cavity securely, ensuring that it was not overpacked, to prevent excessive pressure on the surrounding tissues (which may have caused tissue ischemia due to pressure necrosis). The first layer of adhesive transparent film then was applied, ensuring good coverage of the complete wound and a few centimeters beyond it. After that, the drainage tube was applied at a small opening in the transparent film. Another layer of the adhesive transparent film was applied over the sides of the drainage tube and the wound to ensure a tight seal with no pressure leak points. The machine was turned to the desired pressure (ie, continuous at −125 mm Hg), and the operator observed the sponge being suctioned; any leak site was reinforced with the adhesive film.

Drainage of the content and the appropriate function of the machine were assessed daily for inpatients. After 3 days, the NPWT dressing was removed to reassess the wound and debride any necrotic tissues, after which a new NPWT dressing was applied. This was done at regular intervals to track the changes within the wound and manage them accordingly. For patients who were discharged on a portable NPWT machine, clear instructions were given on how the machine worked, and they were followed up at the wound care facility twice weekly, where the wound team changed the dressing and evaluated the wound.

A total of 18 patients were included in the study. One patient died as a result of septic shock due to multi-organ failure unrelated to the use of NPWT; this patient did not fit the inclusion criteria of the study. The demographics of the study subjects are shown in Table 1. The male-to-female ratio was 5:4, with a mean age of 49 years (median, 52). The majority (77.8%) of patients had either diabetes mellitus or hypertension, or both. Identified risk factors in the study population included percutaneous coronary intervention, pneumonia, and tuberculous pleural effusion.

Seventy-eight percent of patients either required antibiotics or had positive wound cultures. Among these patients, polymicrobial infection was detected in 55.6%. Isolated pathogens are listed in Table 2. All patients had complex deep surgical site infections post-cardiothoracic surgeries and received NPWT dressing.

The average (SD) duration of NPWT application was 26.4 (29.1) days, with pressure of −125 mm Hg. The length of hospital stay ranged from 7 to 256 days (mean, 62.8 days). NPWT dressing was applied traditionally in most patients, with the exception of the 4 patients with stage III empyema. In those 4 patients (patients 1, 2, 7, and 18), vacuum was created by inserting a chest tube within the pleural space. An airtight seal was created by closing the wound and the pleura with an adhesive dressing. This method helped treat the empyema in those patients by controlling the exudate and maintaining the negative pressure within the pleural cavity. In the 4 patients with empyema, NPWT duration ranged from 4 to 37 days, with a mean total hospital stay of 33.8 days. No complications were reported with the application of vacuum therapy. Only 3 patients required readmission. One patient required readmission due to sinus reoccurrence, 1 for skin infection, and 1 for Pseudomonas aeruginosa infection.

The 4 patients who developed empyema were treated with intrathoracic NPWT. This technique has been mentioned in the literature in comparison with more traditional methods of wound care, describing the benefits of NPWT over conventional dressings.² However, the question of whether it is superior to traditional methods has not been adequately evaluated through randomized prospective studies. In the current study, all 4 patients with stage III empyema who developed deep infections were treated with the NPWT dressing technique and demonstrated a good outcome.

Patient 1 was a 26-year-old female with a significant past surgical history, including bariatric surgery, mammoplasty, and liposuction (Table 3). She was admitted with left-sided stage III empyema, which was evacuated surgically through thoracotomy and decortication. Later, she developed a surgical site infection and wound dehiscence. She was taken to the operating room for wound exploration and debridement. Unhealthy tissue was removed, and the wound was copiously irrigated with a 0.9% sodium chloride solution. A ring wound retractor was applied to keep the wound open. An NPWT sponge was refashioned and advanced into the cavity until the pleural space was reached. The dressing was carefully placed, taking care to ensure it covered the entire wound and avoiding sealing it forcefully tight, to allow adequate tissue perfusion. A transparent layer was then draped over the sponge and the wound to completely seal it. A small opening was made over the layer and the suctioning tube was inserted, after which another layer of the transparent drape was applied to secure it in place. The device was connected, and a suctioning pressure of −125 mm Hg was selected. After stabilizing the pressure of the device and ensuring its adequacy, it was monitored daily while the patient was in the surgical ward, and the dressing was changed on a regular basis to evaluate the wound. The wound showed complete elimination of unhealthy tissue and demonstrated healthy granulation tissue growth after 21 days of therapy. The patient was given an appointment with plastic surgery after 6 months for possible scar revision.

Patient 7 was a 46-year-old female with a history of pneumonia complicated by parapneumonic effusion; she was managed initially with computed tomography-guided aspiration and antibiotics (Table 3). Eventually, she presented with right-sided stage III empyema. She was admitted for open thoracotomy with decortication. For postoperative wound care, the same dressing method as in patient 1 was applied and used for 13 days.

Patient 2 was a 49-year-old male with parapneumonic effusions secondary to pneumonia who eventually presented with empyema of the right hemithorax (Table 3). He underwent video-assisted thoracoscopic surgery and decortication for evacuation of the empyema; however, wound infection and dehiscence occurred postoperatively. The patient was returned to the operating room for wound debridement and NPWT application. NPWT was applied for 4 days, and the wound was approximated using a delayed primary closure technique.

Patient 18 was a 46-year-old male involved in a motor vehicle accident who was managed at another facility (Table 3). He sustained multiple rib fractures and thoracic aortic dissection, the latter of which was managed by interventional radiology specialists using a stent. He was then referred to the facility of the authors of the current manuscript; at the time of that presentation, he had developed empyema and was deteriorating. He was promptly transferred and taken to the operating room after undergoing a full preoperative assessment. During the operation, posterolateral thoracotomy, decortication, and 3-rib fixation were performed. NPWT was applied intrapleurally and set to a constant pressure of −125 mm Hg.

Patient 8 was a 44-year-old male who presented with recurrent chest wall chondrosarcoma. He underwent radiotherapy and 3 surgeries. The tumor was resected, and cyanoacrylate was used in chest wall reconstruction. Cyanoacrylate is used to avoid traditional suturing techniques, improve cosmetic results, and hasten wound closure. However, it should be used cautiously because of the risk of toxicity in the form of dermatologic and respiratory conditions.¹⁷ Cyanoacrylate has also been used in conjunction with NPWT to prevent air leaks and provide a durable seal, especially in anatomically challenging locations.¹⁸ Patient 8 then developed a surgical site infection that was managed with NPWT. He was discharged home and followed up for dressing changes and NPWT maintenance every 2 to 3 days for 2 weeks.

Patient 10 was a 23-year-old male with a history of tuberculosis and right-sided pleural effusion that was managed with chest tube drainage. Later, granuloma developed at the site of the chest tube insertion. The mass was surgically excised, and NPWT dressing was applied for 5 days.

NPWT was first described in the literature in the early 1990s by Fleischmann et al, who successfully used this therapeutic method in 15 patients with open fractures.¹⁹ Since then, NPWT has been adopted to manage a wide range of wounds and infections.⁴ In NPWT, also known as vacuum-assisted closure, subatmospheric pressure is applied to tissue to promote angiogenesis and blood flow, thereby enhancing granulation tissue formation. It also keeps the wound surface dry of exudate, thus decreasing the rate of bacterial overgrowth. Healing is facilitated by bringing the wound edges together. NPWT has been shown to reduce edema and bacterial colonization, and to eliminate excess exudate.^20,21 Minor complications associated with the use of NPWT have been reported, including bleeding at the dressing site, pain associated with sponge changes, mild allergic reactions, and odor changes.²¹

The use of NPWT requires training as well as a general understanding of how the machine works, associated indications and contraindications, maintenance, and follow-up care. The whole team—nursing staff, wound care therapists, residents, specialists, and consultants in the field—should be equipped with the skills required to treat patients with this modality of care.

In the current retrospective analysis, aided by patients' data, a systematic comparison was created to evaluate the applicability of NPWT in deep intrapleural wounds and the acceleration of wound healing in deep and debilitating cardiothoracic wounds. As noted previously, the 18 patients included were of varying ages, with a male-to-female ratio of 5:4, and 1 patient was not included due to mortality from septic shock with multiorgan failure. Patients were categorized according to complications of varying etiologies as follows: 7 post-CABG, 3 with congenital anomalies, 2 due to malignancies, and 6 with an infectious origin (4 patients with empyema, 1 patient with sternoclavicular osteomyelitis, and 1 with an esophago-cutaneous fistula). A heterogeneous group of patients is presented, displaying diversity in the use of NPWT.

In the current study, complicated empyema was managed with OWT, and NPWT applied after the evacuation of purulent collection. All patients had favorable outcomes. Palmen et al²² previously described similar results in their study comparing patients who underwent conventional treatment vs NPWT after OWT. They reported reduced morbidity and mortality in the NPWT group, which supports the findings of the current study.

In this study, NPWT dressing was used in a patient with osteomyelitis. The 62-year-old male sustained trauma to the right sternoclavicular joint resulting from falling down the stairs, which led to the development of osteomyelitis. He underwent multiple sessions of debridement and evacuation of purulent collections After the infection was cleared, NPWT dressing was applied for 15 days to bridge the wound for final closure.

Three patients presented with a congenital anomaly: pectus excavatum, hiatal hernia, and diaphragmatic hernia. The first case in the group of congenital anomalies was an 18-year-old male with a history of pectus excavatum repair with retrosternal bar insertion for 9 years. He was admitted for removal of the bar, and the postoperative stay went smoothly. A few days after discharge, however, he presented to the outpatient department for follow-up, at which time a wound infection was noted. The patient was readmitted and underwent wound debridement followed by application of NPWT dressing. Over a 12-day period the dressing was changed frequently, and evaluation of the wound showed good growth of granulation tissue and a faster approximation of the wound edges. The second patient was a 56-year-old female who presented with recurrent hiatal hernia. Her symptoms were worsening, and she was a candidate for surgical repair by means of the thoracoabdominal approach. The postoperative course was complicated by an esophageal leak. After this complication was addressed through the thoracic incision, NPWT dressing was applied to the wound. Good and healthy granulation tissue was achieved in 30 days. The last patient with diaphragmatic hernia was a 31-year-old male who presented to the emergency department with severe progressive dyspnea. After a full work-up and investigations, it appeared that he had a left diaphragmatic hernia involving the spleen, stomach, and colon. A multidisciplinary approach led to the decision to perform surgical intervention consisting of left posterolateral thoracotomy and laparotomy. The hernia repair was achieved using mesh; however, abdominal closure was not feasible without the risk of causing abdominal compartment syndrome. NPWT dressing was used for 5 days as a bridge to aid the closure process (Figure 1).

Patients with recent CABG were grouped in the current study because they had somewhat similar complications of the surgical wound. The 7 patients in this group had variable levels of wound complications ranging from mediastinitis to wound abscess. Three patients in this group developed mediastinitis, 2 of whom exhibited symptoms of mediastinitis 1 month postoperatively (Table 3). Patient 3 was a 78-year-old female, and patient 5 was a 57-year-old male. After the diagnosis of mediastinitis was established, each patient immediately underwent debridement followed by application of NPWT in the operating room. Time of NPWT until final closure was 4 days for patient 3 (Figure 2) and 7 days for patient 5. Patient 12 was a 47-year-old male who was brought to the emergency department with a massive hemothorax 2 months after CABG. Emergency thoracotomy was performed in the operating room, and the bleeding was controlled. Postoperatively, the patient developed mediastinitis and empyema. Infection source control was done, and wound care was established by using NPWT with frequent reassessment and reapplication for a total of 40 days.

In the current study, NPWT was also used to treat a patient with an esophago-cutaneous fistula. The 35-year-old female had a recent history of a motor vehicle accident. She sustained a cervical fracture at the level of the C5 body, which mandated neurosurgical intervention, including plate fixation. This management was complicated by perforation at the cervical esophagus, resulting in a deep surgical site infection. The patient underwent thorough debridement of the deep surgical site infection, and a combined surgical approach involving a neurosurgeon and a thoracic surgeon to remove the plate and repair the esophageal perforation. Approximately 2 weeks after discharge, the patient presented with an esophago-cutaneous fistula. After the failure of conservative management, the patient was admitted for definitive management. The fistula was excised, the esophagus was repaired, and NPWT was applied. After 12 days of NPWT, the wound showed good healing, and final closure was achieved.

In the current study, the longest duration of NPWT dressing application in any patient was 120 days, in a 74-year-old female with multiple comorbidities. She developed mediastinitis post-CABG. She had also developed hospital-acquired pneumonia in the days following the operation, resulting in a severe cough that led to sternal wound dehiscence. The wound was managed with traditional dressing for the first few days, after which NPWT was applied for 2 weeks. The patient then underwent secondary wound closure performed by a plastic surgeon in the operating room. This management failed; sepsis occurred, with cultures showing infection with resilient multidrug-resistant Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, and P aeruginosa. After stabilizing the patient and eradicating the infection, a grueling period of wound debridement and NPWT application ensued. After a total of 104 days and 5 months of hospitalization, the wound reached a stage at which final closure was feasible. General surgery and plastic surgery teams collaborated to achieve wound reconstruction. Reconstruction began by transposing an omental flap to the mediastinum, after which a pectoral flap was repositioned by the plastic surgeons to amend the wound defect. The patient had a long hospital stay of 8 months' duration that began with wound dehiscence, was complicated by infection and sepsis, and finally ended following the great effort of all teams involved, with the patient achieving full recovery and being discharged in good condition.

Pathogens isolated from wound cultures play a key role in wound healing and targeted antimicrobial therapy. For patients in the current study who showed signs of wound infection, wound cultures were obtained from the first surgical intervention and broad-spectrum antibiotics were started immediately, after which antimicrobial therapy was tailored based on culture sensitivity.

The concept of maintaining intrapleural negative pressure is a concern of many cardiothoracic surgeons, especially when using NPWT in the setting of deep infections. The current study aimed to demonstrate the safety of using NPWT in a variety of cases, including a case of diaphragmatic hernia with difficulty reducing the abdominal organs into the peritoneal cavity due to chronicity of the case, and another case of empyema thoracis by connecting the tube directly into the pleural space.

NPWT is an evolving therapeutic modality with expanding indications. It has been used in the management of superficial and deep wounds, ranging from ulcers to deep sternal wound infections.^23,24 The use of antimicrobials with debridement and NPWT has shown better outcomes when compared with normal saline dressing.⁴ The findings of the current study demonstrate the benefits of NPWT in 18 patients who had undergone cardiothoracic surgery.

The current study has some limitations. It is a retrospective cohort study with a small sample size. The study lacks a control group for comparison of hospital stay, morbidity and mortality. Randomized controlled trials are needed to further analyze the efficacy of NPWT after cardiothoracic surgery and provide more comprehensive evidence on the technique.

The findings of the current study show that, compared with alternative treatment modalities, NPWT can shorten hospital stays and duration of treatment in patients with complex deep surgical site infections. The use of NPWT in the thoracic and cardiac setting is an emerging practice that could potentially enhance wound healing immensely, as well as shorten the hospital stay and decrease morbidity and mortality secondary to deep complex wound infection in cardiothoracic patients. Future research should focus on expanding the evidence base for NPWT in cardiothoracic settings, with the inclusion of a broad range of patients.

Authors: Yasser Aljehani, MD; Farouk Alrashaid, MD; Hatem El-bawab, MD; Naif Alkhaldi, MBBS; Hmood Alsadery, MBBS; Norah Alayyaf, MBBS; Jana AlSaikhan, MBBS; and Sumiyah AlShamekh, MBBS

Affiliation: Department of General Surgery, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia

ORCID: Aljehani, 0000-0002-5885-9999; Alreshaid, 0000-0001-6668-7173; Alkhaldi, 0000-0001-5145-2662; Alsadery, 0000-0003-1133-114X; AlShamekh, 0000-0003-1027-7030; El-bawab, 0000-0003-0515-8221

Disclosure: The authors disclose no financial or other conflicts of interest.

Correspondence: Yasser Aljehani, MD; Imam Abdulrahman Bin Faisal University, King Fahd Hospital of the University, General Surgery, Alkhobar, Dammam, Eastern 00000 Saudi Arabia; yjehani@iau.edu.sa

Manuscript Accepted: March 20, 2024