Negative Pressure Wound Therapy with Instillation in Lower Extremity Wounds May Contribute to Cost-Savings: 4 Case Reports

Delayed wound healing is sometimes complicated by the accumulation of wound debris, which can include microorganisms, fibrinous or proteinaceous extracellular materials, immune cells, and dead tissue.¹ These can induce a state of persistent inflammation, triggering the overproduction of growth factors and cytokines and preventing transition to controlled cell differentiation and repair of extracellular architecture. Therefore, wound cleansing is an integral part of the management of acute and chronic wounds, and debris should be removed while inflicting minimal injury to tissues.² Methods for accomplishing this include mechanical or autolytic debridement, larval therapy, hydrosurgery, and other techniques, sometimes used in combination with one another.

Negative pressure wound therapy (NPWT) has been widely documented for its ability to manage both acute and chronic wounds; however, the presence of thick exudate or slough can impair the direct contact between the NPWT dressings and the wound bed, necessitating an intermediary step to prepare the wound for healing.³ NPWT with instillation and dwell (NPWTi-d) of topical solutions is one option for solubilizing and removing these contaminants while simultaneously applying the benefits of NPWT.⁴ NPWTi-d cycles through periods of fluid instillation with a soak time, followed by fluid removal and application of negative pressure. This is delivered via reticulated open cell foam dressings, which may be standard (ROCF-V) or have 1 cm through holes to support the removal of thicker exudate (ROCF-CC).^5,6 As NPWTi-d cycles act upon these dressings, their collapse and expansion across the surface of the wound bed has been proposed to provide additional mechanical support for cleansing debris.³

In our practice, devitalized tissue is a common impediment to wound healing, and in such cases frequent cleansing is needed to support granulation and control exposure to infectious materials. This case series describes the use of NPWTi-d to cleanse lower extremity wounds and support early discharge from the hospital and eventual closure.

Prior to data collection, patients provided written informed consent for the use of deidentified case information and photos. Institutional Review Board approvals or waivers were obtained according to the policy of the medical center where care took place. Upon presentation, the initial wounds were assessed. The wounds included in this study exhibited high levels of debris that would impair the benefits of conventional NPWT and required extensive cleansing or repeated debridements. Surgical debridement was performed, and in the case of infection, antibiotics were provided. NPWTi-d (3M Veraflo Therapy; 3M) consisted of instillation of 0.9% normal saline with a dwell time of 8 to 10 minutes. This was followed by 3- to 3.5 hour cycles of negative pressure at -125 mm Hg. Dressings were ROCF-V (3M V.A.C. Veraflo Dressing; 3M) or ROCF-CC (3M V.A.C. Veraflo Cleanse Choice Dressing; 3M) dressings, depending on slough thickness. Dressing changes were performed every 2 to 3 days. After conclusion of NPWTi-d, patients were discharged from the hospital and transitioned to conventional NPWT. Dressing changes continued to be undertaken every 2 to 3 days. When applicable, wound closure was enhanced using autologous epidermal micrografts (3M Cellutome Epidermal Harvesting System; 3M). The wounds were then managed with standard dressings or advanced wound dressings (eg, antibacterial or silver-impregnated dressings).

Case 1 (Figure 1) was a 24-year-old male without notable medical history who presented with a potassium hydroxide chemical burn on his right foot. The burn occurred while the patient was wearing work boots and the injury was not readily apparent until several hours later. The patient previously presented to an urgent care facility, which treated and released him with a basic wound care plan. This plan was followed until the patient presented to our medical center for advanced wound care. Moderate swelling and dorsal fluctuance was observed. Chairside incision and drainage were performed, and the patient was scheduled for immediate formal surgical debridement, hospital admission, and initiation of NPWTi-d. Due to the presence of significant nonviable tissue around the wound edge, ROCF-CC dressings were selected to clear the wound bed of thick debris. NPWTi-d with ROCF-CC dressings was initiated, with instillation cycles of 30 mL normal saline onto the wound bed, a dwell time of 8 minutes, and 3.5 hours of negative pressure. NPWTi-d was applied for 6 days, after which the wound was clean with defined wound edges, optimal for transition to conventional NPWT. After 3 weeks of NPWT, autologous skin grafting with epidermal micrografts was performed. Wound care after graft placement consisted of multilayer compression bandaging and advanced wound dressings. On follow-up 3 months post-surgery, the wound was completely healed.

Case 2 (Figure 2) was a nonambulatory 51-year-old male with a history of multiple sclerosis, limb girdle weakness, and profound lower extremity lymphedema. The patient sustained a deep-tissue laceration of the right medial calf, which was self-treated at home for a few days prior to presenting to the clinic. The patient was admitted to the hospital for medical management, surgery, and NPWTi-d. Surgical debridement was performed, and the wound was partially closed. With management, lymphedema was significantly reduced. NPWTi-d was initiated using ROCF-V dressings, with instillation of 8 mL of normal saline, a dwell time of 10 minutes, and 3.5 hours of negative pressure. NPWTi-d was applied for 7 days, after which the patient was discharged to a skilled nursing facility with conventional NPWT for 3 weeks, followed by multilayer compression bandaging. On follow-up 6 months post-surgery, the wound was fully healed.

Case 3 (Figure 3) was an 83-year-old male with a contusion to the right lower leg with probable compartment syndrome, resulting in a large, gelatinous hematoma and extensive soft tissue necrosis involving 80% of the right medial calf. Upon admission to the hospital, examination revealed intact peripheral pulses, adequate range of motion, and no fractures. Surgical debridement and pulsed lavage were performed, and the wound was partially closed. In the operating room, NPWTi-d was applied with ROCF-CC dressings, with cycles consisting of instillation of 10 mL normal saline, a dwell time of 8 minutes, and 3 hours of negative pressure. After 6 days, the wound bed exhibited healthy granulation and was ready for transition to NPWT. The patient was transferred to a skilled nursing facility with conventional NPWT. After 3 weeks of NPWT, the wound was highly granulated, and the wound depth had been greatly reduced. With the wound bed prepared, autologous skin grafting with epidermal micrografts was performed. Upon follow-up 5 months post-surgery, the wound was fully healed.

Case 4 (Figure 4) was a 73-year-old male with a diabetic foot infection involving his lateral left foot. Upon admission, he was diagnosed with cellulitis and osteomyelitis of the left metatarsal. He was admitted for a partial ray resection and surgical debridement. In the operating room, NPWTi-d with ROCF-V dressings was applied, instilling 8 mL of normal saline with a dwell time of 8 minutes, followed by 3 hours of negative pressure. Parenteral antibiotics were administered. After 6 days, the patient was discharged with conventional NPWT and oral antibiotics, and healing progressed uneventfully for 1 month. However, the patient subsequently developed further breakdown with more exposed, non-viable bone and infectious changes, which necessitated surgery for osteomyelitis. This additional bone resection was followed by 3 weeks of NPWT. Full closure was achieved 1 month after NPWT was discontinued.

To assess the potential for cost-savings in this limited case series, we reviewed the literature to estimate the typical inpatient stay for managing similar wound types. Compared to the 6- to 7-day hospital stay for NPWTi-d, the mean length of stay for chemical burn, traumatic lower limb laceration, nonfracture compartment syndrome, and diabetic foot osteomyelitis was 7 to 22.6 days (Table 1).^7-11

In this case series, we managed a variety of different wound types that exhibited significant amounts of debris on the wound bed upon initial presentation. Following an initial debridement, NPWTi-d was used to cyclically cleanse the wound and support the growth of healthy granulation tissue. After NPWTi-d, all the wounds showed signs of improvement, exhibiting healthy granulation and clearly defined wound edges. This wound bed preparation enabled transition to outpatient care, achieving the desired goals of therapy without complication. In 1 case (case 4), the patient did later return to the hospital for osteomyelitis approximately 1 month after discharge; however, this result is not necessarily related to NPWTi-d, which is unable to treat the underlying factors that predispose the patient to recurring infection. Despite this setback, the infection was successfully treated, and full closure was achieved 1 month after surgery.

The positive outcomes we observed with NPWTi-d replicate those documented by previously published studies. Multiple case studies utilizing NPWTi-d with ROCF-V or ROCF-CC dressings to manage various wound types covered with thick slough or nonviable tissue have reported that NPWTi-d significantly improved wound condition.^4,12-14 The resulting wounds exhibited less debris, allowing transition to NPWT or another bridge to closure. In these studies, NPWTi-d was frequently paired with an initial or recurring sharp debridement when possible, and antibiotics were administered when infection was present. The duration of NPWTi-d depends on the goals of therapy, which include removal of slough and growth of granulation tissue. In a retrospective analysis of patient with infected wounds managed with NPWT or NPWTi-d, Kim et al reported that the NPWTi-d group had fewer operations, shorter time to final surgical procedure, a higher percentage of closed wounds, a higher percentage of wounds that remained closed at 1 month, and a shorter length of hospital stay.³ In a meta-analysis comparing NPWTi-d to conventional NPWT, Gabriel et al reported that NPWTi-d was associated with fewer surgical debridements, shorter time to readiness for final closure, and shorter length of therapy.¹⁵ Interestingly, they did not detect a significant difference in the length of hospital stay, demonstrating how this measure can depend on additional factors indirectly related to wound care.

Although NPWTi-d is safe and effective to use for contaminated wounds, NPWTi-d does not treat infection and should be used alongside antibiotics if an infection is present. Antiseptic topical solutions--including hypochlorite-based solutions, silver nitrate, sulfur-based solutions, and biguanides--can be instilled with NPWTi-d to suppress microbial growth. The use of NPWTi-d with a polyhexanide biguanide solution after initial debridement (with antibiotic administration following standard protocol) has been associated with a significant reduction in wound bacterial counts compared to traditional NPWT.¹⁶ However, in a prospective, randomized study comparing NPWTi-d using normal saline or 0.1% polyhexanide plus 0.1% betaine, there were no significant differences in closure rate or length of stay.¹⁷ This suggests that the use of antiseptic solutions is not necessary to achieve the benefits of NPWTi-d. In all 4 of the patients in the current study, 0.9% normal saline was instilled onto the wound surface and was deemed sufficient to reach the goals of therapy.

The NPWTi-d settings were influenced by the international consensus guidelines on NPWTi-d and were modified to meet the needs of each case.¹⁸ In the guidelines update, the expert panel recommended a dwell time of 10 minutes, and negative pressure cycles of 2 to 3 hours for ROCF-V and 2 to 2.5 hours for ROCF-CC, at -125 mm Hg.¹⁸ The panel reasoned that ROCF-CC dressings were primarily used over wounds with highly fibrinous surfaces, which might benefit the most from more frequent instillation cycles. However, the time settings of NPWTi-d have varied greatly in the existing literature, while still retaining wound cleansing efficacy. Willmore et al described the use of “short-term” NPWTi-d, which employed 5-minute dwell times and 15-minute negative pressure cycles, to rapidly reduce devitalized tissue in patients awaiting surgical debridement.¹⁹ In our practice, the dwell and cycle times are modified to suit the wound depth and amount of debris present on the wound surface. Longer cycle duration, which increases the impact of NPWT while decreasing the total number of instillations per day, has proved to be effective when used over lower extremity wounds.

The cost of materials when applying NPWTi-d is typically higher than that for standard of care (including standard wound dressings, advanced wound dressings, and traditional NPWT devices), indicating a need for cost-benefit analyses to determine when NPWTi-d is most cost-effective. In a hypothetical economic model based on mixed etiology wounds managed with NPWTi-d or conventional NPWT, there was an estimated $1418 per-patient cost savings with NPWTi-d, owing to a significant reduction in the number of debridements, a shorter hospital stay, a shorter length of therapy, and shorter time to wound closure observed in the NPWTi-d group.²⁰ Likewise, in a retrospective review of 10 venous leg ulcers managed with NPWTi-d for 7 days, the 6 month cost of care was estimated to be $1000 less per patient than standard compression therapy.²¹ For this case series, patients were discharged after 6 to 7 days, which is shorter than the typical duration of hospital stay for the various wound types (Table 1). Hospital expenses for our geographical location can range from $2277 to $3000 per day,²² suggesting a significant opportunity for cost savings with NPWTi-d, which is estimated to cost $194.80 daily.²⁰ Furthermore, once the wound is clear of debris, NPWTi-d can be discontinued and conventional NPWT can be used as a less-expensive adjunctive therapy, extending the continuum of care at home or in a tertiary setting while reducing costs.²³ This was the approach employed in all 4 of our cases.

As with all case series, this study is inherently limited by its small sample size and subjective inclusion criteria. The cases were selected to demonstrate a variety of wound types that were encountered in the podiatry clinic, but do not represent the full range of NPWTi-d outcomes that may be observed in other healthcare environments. These cases were primarily acute wounds, and outcomes will likely be affected by wound chronicity or the presence of significant comorbidities. Although the shorter-than-average hospital stay reported here is representative of our experience using NPWTi-d for wounds with high exudate or debris, the cost comparison is not the result of a systematic analysis or a controlled study, and further cost-analysis is required. In order to extrapolate accurate and generalizable comparisons between the use of NPWTi-d and standard care practices, studies with larger cohorts are also needed.

At our medical center, NPWTi-d was effective in cleansing wounds with high levels of debris within 6 to 7 days, supporting the growth of healthy granulation tissue conducive to healing. Use of NPWTi-d allowed patients to be quickly discharged with conventional NPWT and other supportive therapies, eventually achieving closure in all 4 cases. Despite having higher initial costs compared to standard dressings, NPWTi-d could be a crucial early step as part of a wound management strategy designed to mitigate expenses incurred by delaying healing.

OrthoNeuro, Columbus, OH; 
Heritage College of Osteopathic Medicine, Ohio University, Dublin, OH

Ralph J. Napolitano, Jr, 191 W Union St., Athens, OH 45701, drralph@newalbanydpm.com