Efficacy of Negative Pressure Wound Therapy With Instillation and Dwell Time for the Treatment of a Complex Chronic Venous Leg Ulcer

Both the complexity and features of a wound affect local healing and determine the possible success of wound closure. Older age, cardiovascular/pulmonary disease, obesity or poor nutritional status, renal failure, diabetes, local colonization/infection, large-sized wounds, slough, and high levels of exudate are some of the main risk factors in the management of chronic wounds. Undoubtedly, systemic treatment is fundamental. However, good wound bed preparation, using either advanced dressings or surgical treatment, is necessary to stimulate the initiation of wound healing.¹

The purpose of this case study was to verify if negative pressure wound therapy (NPWT) could gently remove exudate and edema and promote granulation as a result of subatmospheric pressure, which acts both macroscopically and on cellular activity.² Particularly, the authors wanted to determine if a newer NPWT device with instillation and dwell time (NPWTi-d) could stop viscous slough disposal and reduce bacterial load and contaminant/infection, maintaining the acute phase and moving the chronic wound towards healing.

The authors report a paradigmatic case of a patient with a complex chronic venous leg ulcer (VLU). The patient was a 57-year-old male with metabolic syndrome, obesity, diabetes, and heart disease who presented with extremely painful circumferential VLUs of the right leg (Figure 1) for 2 years’ duration and locally colonized by Enterobacter species for more than 1 year’s duration. The ulcer had previously been treated by a general practitioner with a hydrofiber combined with silver dressing. The ulcer measured 12 cm x 25 cm. The patient was also under medical treatment for the aforementioned comorbidities, resulting in a generally stable condition but with impairment of wound healing. Patient consent for this multiphase treatment was acquired in accordance with scientific literature and surgical procedure guidelines.

At the authors’ Institute of Plastic Surgery at the University Hospital of Padova in Padova, Italy, the treatment of a complex wound requires fixed steps, such as surgical debridement, NPWTi-d (V.A.C. VERAFLO Therapy; 3M + KCI) solution per microbiologic swab, and, once good granulation tissue has formed, attempted final closure would follow the application of a skin graft (as in the present case). Typically, the authors’ prefer the use of NPWTi-d over traditional NPWT when treating chronic and infected wounds.

In 2014, the patient underwent surgical debridement and local application of NPWTi-d (settings: -100 mm Hg, 32 mL of instilled volume, 10-minute dwell time, and 2-hour cycle length); initially, 0.05% of sodium hypochlorite was instilled (Figure 2) for the presence of Enterobacter species. However, at the first dressing change 3 days into NPWTi-d treatment (Figure 3, Figure 4), microbiological swabs showed negative, so the authors changed the solution to normal saline. Intravenous cefazolin was administered for 1 week postoperatively as a precaution since the patient had diabetes and the wound had colonized. After 16 days of NPWTi-d treatment, a skin graft was applied (Figure 5, Figure 6A), and the wound was treated with a polyvinyl alcohol foam connected to a traditional NPWT device (settings: -75 mm Hg, continuous pressure) as a dressing for 1 week (Figure 6B). The wound showed improved healing following 1 week of NPWT use (Figure 7). The wound achieved complete healing at 25 days and remained closed and stable at 3-month follow-up (Figure 8). No adverse events were observed.

At the treating institution, NPWTi-d represents a necessary step in the treatment of infected, complex, chronic ulcers. Both preclinical literature and clinical outcomes support the efficacy of NPWTi-d for this wound type; additionally, NPWTi-d not only removes exudate, but also cleanses the wound from slough and debris and reduces bacterial load (it does not completely eliminate bacterial load in the wound bed).^3-7 The efficacy of NPWTi-d to promote granulation tissue formation has been reported in a non-infected porcine model study.⁸ In the study by Lessing et al,⁸ the NPWTi-d-treated wounds had statistically significantly thicker granulation tissue than the traditional NPWT-treated wounds; however, further studies are required to verify this outcome.

According to the literature, the authors strongly believe that NPWTi-d behaves as a continuous cleaning that enforces the first surgical step and reduces the need for more operative procedures, which should be avoided in patient population due to the risks associated with anesthesia. Kim et al⁹ reported similar beliefs that such treatment must be reserved for select patients with complex wounds who have multiple comorbidities—as in the present case—or who are affected by severe infection (as in a diabetic ulcer), or a complicated posttraumatic wound (eg, due to osteomyelitis).

Finally, it is important to recognize that, to the authors’ knowledge, there were no documented guidelines for the appropriate use of NPWTi-d and its settings at the time in which this case occurred (ie, 2014), whereas today guidelines on appropriate NPWTi-d settings exist,^5,10 although none focuses on the specific wound type, nor on which solution is most appropriate for instillation.

Although this treatment can only be performed in a hospital setting, the authors believe that NPWTi-d should be recommended for the treatment of complex wounds due to its ability to reduce bacterial load, minimize hospital length of stay, decrease the number of surgical debridements, and facilitate quicker wound closure.^3,9

In this paper, the authors presented only 1 case focused on the treatment of a VLU; as such, this report is limited by the single case study of only a chronic wound of venous origins.

In the authors’ experience, the NPWTi-d setting must be customized to the patient per pain and local condition that may change over time. The choice of solution should be decided according to the microbiologic swab. It is important to remember that, in order to prevent bacterial resistance,  local antibiotics are not recommended.¹¹

In patients with complex wounds, the authors’ preferred choice is to start with NPWTi-d before moving to a traditional NPWT device for the final reconstruction with skin grafts or flaps.

Further studies are required to both clarify the appropriate association between wound type and solution type and verify if this device can be used in all ulcers (eg, diabetic, pressure).

Authors: Carlotta Scarpa, MD, PhD; Eleonora de Antoni, MD; Vincenzo Vindigni, MD, PhD; and Franco Bassetto, MD

Affiliation: Institute of Plastic Surgery, University Hospital of Padova, Padova, Italy

Correspondence: Carlotta Scarpa, MD, PhD, Researcher, Institute of Plastic Surgery, Neurosciences, Via Giustinani 2, Padova, Padova 35100 Italy; carlotta.scarpa@unipd.it

Disclosure: Professor Bassetto has been part of the Advisory Board of Acelity (previous owners of KCI, the manufacturer of the NPWTi-d device). Dr. Scarpa received finances and an invitation from KCI to attend a congress sponsored by the company.