Cardiogenic shock and acute respiratory distress syndrome are a life-threatening medical emergency that often requires extracorporeal membrane oxygenation (ECMO). After the crisis has passed, several complications may occur at ECMO removal sites, including skin necrosis, lymphorrhea, major vessel exposure, and wound infection. These complications may result in a longer hospital stay despite improvement in general patient condition.
Lymphorrhea of the groin is a potential complication of ECMO resulting from damage to lymphatic ducts during surgical approaches to femoral vessels. Clinically, it appears as lymphocele or lymph fistula in 1% to 4% of cases.1,2 Continued lymph accumulation in fresh wounds may cause wound disruption and increase the risk of wound infection, with a reported incidence of up to 18%.1–3 These complications represent significant potential morbidity and mortality for patients.3
Negative-pressure wound therapy (NPWT) promotes wound healing through the creation of a moist wound-healing environment, drainage of superfluous fluid, reduction of tissue edema, and accelerating the formation of vascularized granulation tissue.4,5 The purpose of this study was to evaluate the effectiveness of NPWT for management of complicated wounds at ECMO sites.
This was a single-center retrospective study of nine consecutive patients who underwent NPWT for wound complications at ECMO removal sites at a university hospital (Samsung Medical Center, Seoul, Korea) from August 2015 to December 2016. The ECMO line insertion and removal were performed by thoracic surgeons, and patients were included in this study after referral to the plastic surgery department because of complicated wounds at ECMO removal sites.
Complicated wounds were defined as skin flap necrosis with lymphorrhea and/or femoral vessel exposure at the ECMO removal site that lasted more than 2 weeks after ECMO was removed. Patients who underwent ECMO cannulation at sites other than the femoral vessels and those who were lost to follow-up were excluded from this study.
The following demographic and medical history data were recorded for all patients: age, sex, presence of comorbidities (obesity, hypertension, diabetes mellitus), previous lymphatic complications (eg, previous surgery, previous catheter insertion), reason for ECMO insertion, presence of wound infection, species of microorganism found in the wound, duration of NPWT, post-NPWT procedures, and posttreatment complications.
This study was granted full approval by the facility’s institutional review board. Written patient consent was not obtained because of the nature of the retrospective chart review, and identifiable personal data were not used. Verbal patient consent was obtained for patient images.
Applications of NPWT
The NPWT was applied when a complicated wound of appropriate duration at the ECMO removal site was confirmed. The NPWT sponge (Curavac; Daewoong Pharmaceutical, Seoul, Korea) was cut to the size of the wound and placed within it. Researchers applied a bacteria-binding mesh, Cutimed Sorbact (Abigo Medical AB, Gothenburg, Sweden), to exposed femoral vessels before application of NPWT. The Sorbact has the advantage of mechanical removal of bacteria, and it prevents adhesion of the sponge to femoral vessels. Single-layer Sorbact also was applied over the remaining wound bed such that it would not interfere with NPWT (Figure 1).
Continuous negative pressure at 125 mm Hg was applied, and the dressing was changed every 2 to 3 days. The mesh was removed with the sponge, and new mesh was applied during changes of NPWT. Bacterial cultures were performed via wound bed swab before the start of NPWT treatment and after the last application of NPWT. All patients received empirical antibiotic therapy, followed by definitive antibiotic treatment according the results of bacterial cultures.
The decision to stop the NPWT was based on the formation of fresh granulation tissue and decreased lymphorrhea. When lymphorrhea decreased, and fresh granulation tissue was present, surgical closure of the wound was performed. The wound was usually closed in two layers. When the femoral vessels were not completely covered by the granulation tissue, the granulation tissue was used as a turnover flap to cover femoral vessels after undermining skin flap (Figure 1). The skin was closed by primary closure, or a skin graft was placed over the granulation tissue.
A total of 11 patients were referred to the plastic surgery department with wound complications at their ECMO removal site. Two patients were excluded because they were transferred to other hospitals and were lost to follow-up. Therefore, nine patients were treated with this NPWT method. All patients had ECMO inserted to address a cardiogenic cause. No patients had a history of vascular surgery or insertion of a catheter in inguinal regions.
The mean age of the nine patients (five males and four females) was 49.2 years (range, 14–66 years). Of these patients, four had diabetes mellitus, three had hypertension, and none had morbid obesity. Demographic and general characteristics of the patients are presented in the Table 1. No patients reported previous inguinal lymphatic complications before ECMO insertion. Seven had wound site bacterial contamination (see the Table 1 for a breakdown of species).
The mean number of NPWT changes was 7.4 (range, 4–10), and the mean duration of NPWT was 21.2 days (range, 12–30 days). After NPWT, when the wound bed had healthy granulation tissue, primary closure was attempted in seven patients, secondary healing in one patient, and split-thickness skin graft in one patient. Wound healing was achieved in all patients within 2 weeks, and no recurrence was observed before discharge. There were no cases of femoral vessel injury or aneurysm during NPWT application. Results of bacterial swab culture on the wound bed showed conversion to negative culture after completion of NPWT treatment in all seven patients with positive bacterial wound cultures, and no patients experienced aggravated wound infections during application of NPWT.
Two sample cases are provided to illustrate the study results.
A 48-year-old woman required ECMO after cardiogenic shock. The ECMO was sustained for 3 days, and the inguinal wound was closed after removal of ECMO. Skin necrosis with lymphorrhea and femoral vessel exposure developed 2 weeks after closure. Enterococcus faecium bacteria were detected in the wound, so vancomycin 0.9 g/d and meropenem 1,000 mg/d were administrated intravenously for 13 days. The thoracic surgery team consulted with the plastic surgery team. Bacteria-binding mesh was applied on the exposed vessels, and NPWT was applied for 15 days. After undermining the skin flap, granulation tissue was turned over to cover femoral vessels, and the skin was closed primarily. No recurrence of wound complications was observed up to patient discharge from the institution (Figure 1).
A 54-year-old man underwent ECMO treatment because of acute myocardial infarction. After removal from ECMO, a complicated wound involving a wide skin defect, lymphorrhea, and femoral vessel exposure developed. Acinetobacter baumannii was cultured from wound bed swabs, so meropenem 1,000 mg/d and colistimethate 150 mg/d were administrated intravenously for 12 and 17 days, respectively. The NPWT in combination with bacteria-binding mesh was applied. Granulation tissue formation started after two cycles (6 days) of NPWT. After 10 cycles (30 days) of NPWT, lymphorrhea disappeared, fresh granulation tissue completely covered the wound bed, and significant wound contraction was achieved. Split-thickness skin graft was performed, and there was no recurrence of wound complications (Figure 2).
Extracorporeal membrane oxygenation systems are a lifesaving treatment option for patients with cardiogenic shock and acute respiratory distress syndrome. However, groin incisions for the ECMO system are prone to complications including wound dehiscence, lymphatic leaks, and hematomas.6 Lymphatic complications after groin incision and dissection are attributed to tissue destruction during vascular surgery dissection without attention to detailed ligation of small lymphatics.7 In a life-threatening medical emergency, it is difficult to preserve small lymphatics during ECMO. The resulting lymphorrhea disturbs the wound healing process and makes the wound prone to secondary infection through bacterial contamination, which will inhibit wound healing and may lead to wound complications.8 Further, femoral vessels are often exposed in complicated ECMO site wounds. In this study, researchers showed that NPWT use in a controlled environment (ie, a hospital) is safe and efficient for the treatment of complicated wounds at ECMO sites, including around a large exposed femoral arterial vessel.
Uncontrolled lymphatic drainage can be a source of significant morbidity for the patient, and wound infection may occur in up to 57% of cases.8 In this study, all patients with complicated groin wounds experienced accompanying lymphorrhea, suggesting that lymphatic complications can be expected in close association with wound complications. In the present study, lymphorrhea was controlled after 4 to 10 cycles of NPWT in all patients. Upon completing NPWT, the open wound was closed via primary closure, skin graft, and/or secondary healing. After closure, there were no recurrent complications.
These results are in accordance with previous studies.3,7,9,10 Recently, Aydin et al9 reported that patients who underwent NPWT as the primary therapy in the treatment of lymphatic complications following peripheral vascular interventions demonstrated more rapid wound healing, early drainage control, and shorter hospital stays. The NPWT enhances vascularized granulation tissue formation, decreases interstitial fluids, and accelerates the wound healing process by decreasing inflammatory mediators in the wound.5 Such physiologic changes may help stop lymphatic leakage within a few weeks after application of NPWT.9 Although lymph nodes never regenerate after surgical dissection, lymphatic vessels can.11 During the wound healing process, lymphatic vessels surrounding intact tissues progress toward the center of the wound.12 Therefore, enhanced wound healing via NPWT may contribute to the regeneration of lymphatic vessels and resolution of lymphorrhea. However, the exact mechanisms of NPWT for the treatment of lymphorrhea need to be clarified in future studies. In the treatment of lymphatic complications, NPWT also reduces the burden on medical staff by reducing the need for frequent changes of conventional dressings.
Since the first introduction of NPWT by Fleischmann et al13 in 1993, it has become one of the most effective methods in the management of various kinds of wounds.5,14,15 However, there are concerns regarding the use of NPWT for infected wounds.16 While placing an NPWT dressing on the bed of an infection for several days may promote bacterial growth, there has been no definite research on changes in bacterial load and type of bacteria during NPWT.17 In previous studies, NPWT has been effectively applied to various infected wounds including deep sternal wounds, vascular grafts, those related to musculoskeletal tumor surgery, and pediatric necrotizing fasciitis.18–21 Infected sternotomy wounds are a clinical indication for NPWT.22
In this study, most of the wounds at ECMO removal sites had bacterial contamination with various species on swab culture (seven of nine patients). Complicated groin wounds at ECMO removal sites can be easily contaminated because the wounds are close to the genitals, and such cases are always accompanied by lymphorrhea. However, the results of bacterial culture showed conversion to negative culture after a mean of 7.4 changes of NPWT in all patients, and no patients developed a secondary wound infection during application of the NPWT. Similar to these results, Pinocy et al23 reported that NPWT rapidly cleared groin wounds of infection, resulting in total elimination of bacteria with 14 days of NPWT. Recently, Lo et al24 demonstrated an important increase in antibiotic concentration in the tissue after NPWT, which suggested a positive effect of NPWT for the treatment of infected wounds. Also, Li et al25 demonstrated that NPWT could inhibit the growth, virulence, and biofilm formation of Staphylococcus aureus in an animal wound model. The authors believe that the combination of NPWT, systemic antibiotic treatment, and the use of bacteria-binding mesh all contributed to the conversion to negative bacterial culture for the patients in this study.
Bacteria-binding mesh (Cutimed Sorbact) has proven efficacy for treating colonized and infected wounds. The mesh is a dialkylcarbamoyl chloride–coated dressing that irreversibly binds bacteria at the wound surface, resulting in removal when the dressing is changed.26 Ciliberti et al27 reported that bacteria-binding mesh as a wound contact layer during NPWT significantly reduced the bacterial burden in wounds with moderate or high levels of colonization. Moreover, this bacteria-binding mesh has a nonadhesive property allowing it to be used as a wound contact layer for easy removal of NPWT sponges.
Exposure of major vessels was thought to be a major contraindication to NPWT because of the possible occurrence of aneurysm and vessel injury.16 However, a recent study of 161 patients demonstrated that NPWT could be applied to exposed femoral vessels for perivascular surgical site infection in the groin after vascular surgery.28 Although 66% of patients underwent vascular grafts in the groin region, bleeding during NPWT occurred in only 7.1% of 161 patients with surgical site infections. Similarly, NPWT has been applied safely to vital structures such as the orbital region and facial nerves.29,30 Adhesion of sponges to the major vessels can be a cause of aneurysm or vessel injury during dressing changes. This study found that the use of bacteria-binding mesh as a wound contact layer during NPWT prevented adhesion of the sponge to the femoral vessels. No cases of aneurysm or injury to femoral vessels were noted during application of NPWT. Coverage of major vessels using any kind of nonadhesive, mesh-type dressing, such as silicone-based dressings, may prevent vessel injuries during NPWT changes.
These results demonstrate that granulation tissue formation with wound contraction was effective for covering the femoral vessels in the groin region when NPWT was applied. The exposed femoral vessels could be completely covered by newly formed granulation tissue (Figure 2). In cases where the femoral vessels were not completely covered by granulation tissue, fresh granulation tissue around the femoral vessels could be approximated to cover the vessels (Figure 3). When approximation was impossible, the granulation tissue could be used as a turnover flap to cover the vessels after subcutaneous undermining of the skin flap (Figure 1). Subcutaneous dissection in these cases facilitated approximation of the granulation tissue for coverage of the femoral vessel with the dead space effectively obliterated. Also, the skin flap could easily be closed with decreased tension after subcutaneous dissection.
Because of the small number of patients and the retrospective nature of the study, the authors cannot exclude the possibility that other factors may have effects on the wound site. Although neither vessel injuries nor major bleeding developed, the safety of using NPWT on exposed major vessels needs to be confirmed in future prospective controlled studies with larger patient numbers. Also, the severity of lymphorrhea was not objectively evaluated in this study. Although lymphatic complications were managed successfully by NPWT, surgical exploration and ligation of leaking lymphatics may be necessary in cases with severe lymphoceles.1
Despite these limitations, to the best of the authors’ knowledge, this study is the first to address the use of NPWT for complicated wounds after ECMO removal. Further prospective, large-scale studies are warranted to clarify the indications, detailed techniques (intermittent or continuous mode, degree of pressure), outcomes, and complications related to the use of NPWT for complicated wounds following ECMO removal.
The current study suggests that NPWT may be a safe and effective treatment option in the management of complicated wounds at ECMO removal sites. Nonadhesive, mesh-like dressing materials such as bacteria-binding mesh can be effectively used as a wound contact layer to prevent femoral vessel injuries. This preliminary study will inform future studies on the use of NPWT for the management of complicated wounds in cases with exposed major vessels.
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Keywords:Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
bacteria-binding mesh; extracorporeal membrane oxygen; lymphorrhea; negative-pressure wound therapy; skin necrosis; wound complications; wound healing; vessel exposure