Pre-Clinical Assessment of Single-Use Negative Pressure Wound Therapy During In Vivo Porcine Wound Healing.

Objective: Traditional negative pressure wound therapy (tNPWT) systems can be large and cumbersome, limiting patient mobility and adversely affecting quality of life. PICO™, a no canister single-use system, offers a lightweight, portable alternative to tNPWT, with improved clinical performance. The aim of this study was to determine the potential mechanism(s) of action of single-use NPWT (sNPWT) versus tNPWT. Approach: sNPWT and tNPWT were applied to an in vivo porcine excisional wound model, following product use guidelines. Macroscopic, histological, and biochemical analyses were performed at defined healing time points to assess multiple aspects of the healing response. Results: Wounds treated with single-use negative pressure displayed greater wound closure and increased reepithelialization versus those treated with traditional negative pressure. The resulting granulation tissue was more advanced with fewer neutrophils, reduced inflammatory markers, more mature collagen, and no wound filler-associated foreign body reactions. Of note, single-use negative pressure therapy failed to induce wound edge epithelial hyperproliferation, while traditional negative pressure therapy compromised periwound skin, which remained inflamed with high transepidermal water loss; features not observed following single-use treatment. Innovation: Single-use negative pressure was identified to improve multiple aspects of healing versus traditional negative pressure treatment. Conclusion: This study provides important new insight into the differing mode of action of single-use versus traditional negative pressure and may go some way to explaining the improved clinical outcomes observed with single-use negative pressure therapy.

Incisional Negative Pressure Wound Therapy for Prevention of Wound Healing Complications Following Reduction Mammaplasty.

BACKGROUND: It has been proposed that negative pressure wound therapy (NPWT) applied prophylactically to a closed incision may decrease the incidence of wound complications. Patients undergoing reduction mammaplasty are at risk of wound complications such as delayed healing, infection, and dehiscence, and the bilateral nature of the surgery allows for a within-patient randomized study to evaluate incisional NPWT's effect in reducing healing complications. METHODS: In this multicenter trial, 200 patients undergoing bilateral reduction mammaplasty were treated with PICO Single-Use NPWT System or standard wound-care dressings randomized to right or left breast for up to 14 days to enable within-patient comparison. Follow-up assessments were conducted to evaluate the difference in incision healing complications up to 21 days postsurgery. Healing complications (for the primary endpoint) were defined as delayed healing (incision not 100% closed by 7 days) and occurrence of dehiscence or infection within 21 days. Individual healing complications were assessed separately as secondary endpoints. RESULTS: Significantly fewer healing complications (primary endpoint) were noted in NPWT-treated breasts [113 (56.8%)] versus standard care [123 (61.8%)]. The difference of 10 (5.0%) patients with fewer healing complications using NPWT was statistically significant (P = 0.004). NPWT also resulted in a significantly lower incidence of dehiscence (secondary endpoint) compared with standard care [32 patients (16.2%) versus 52 patients (26.4%)] by day 21, a relative reduction of 38% (P < 0.001). CONCLUSIONS: This is the first major prospective, within-patient, randomized, controlled, multicenter study to provide evidence for an incisional NPWT strategy to reduce healing complications.

Simplified negative pressure wound therapy: clinical evaluation of an ultraportable, no-canister system.

The aim of this study was to evaluate a prototype negative pressure wound therapy (NPWT) system that has been developed to simplify NPWT for wounds at the lower end of the acuity scale. The new device has a single preset pressure of -80 mmHg, is single use and operates without an exudate canister. The disposable NPWT system (PICO™) was tested in a prospective, non-comparative, multicentre clinical trial to assess device functionality and clinical acceptance. Twenty patients were recruited for a maximum treatment period of 14 days. The NPWT devices were fitted with data log chips to enable longitudinal assessment of negative pressure and leak rates during therapy. Sixteen (80%) patients had closed surgical wounds, two (10%) patients had traumatic wounds and two (10%) patients received meshed split thickness skin grafts. The mean study duration was 10·7 days (range: 5-14 days) and the mean dressing wear time per individual patient was 4·6 days (range: 2-11). Fifty-five percent of wounds had closed by the end of the 14-day study or earlier, with a further 40% of wounds progressing to closure. Real-time pressure monitoring showed continuous delivery of NPWT. Three cases are discussed representing different wound locations and different patient factors that can increase the risk of post-surgical complications. Clinical studies of the disposable NPWT system confirmed the ability of the simplified single-use device to function consistently over the expected wear time. The anticipated reduced costs, ease of use and increased mobility of patients using this system may enable NPWT benefits to be available to a greater proportion of patients.

Biological effects of a disposable, canisterless negative pressure wound therapy system.

OBJECTIVE: Recent developments of negative pressure wound therapy (NPWT) systems have focused on making pumps smaller, lighter, and more portable. The recently introduced PICO system manages wound fluid through a highly breathable film within the dressing, thereby negating the need for a canister, which allows greater mobility and patient concordance. The aim of this study is to compare the biological effects of this system compared to a traditional NPWT system. METHODS: Laboratory tests were carried out to demonstrate the fluid handling properties of the PICO™ system. Porcine full thickness defect wounds and sutured incisional wounds were used to compare the biological effects. Wounds were treated with PICO dressings or traditional NPWT dressings and connected to either a PICO device or a traditional NPWT device. RESULTS: The PICO dressing manages exudate predominantly through evaporative loss (up to 85% of all fluid entering the dressing). Both traditional NPWT and the PICO system maintained therapeutic levels of negative pressure in all wounds. Both NPWT systems produced similar effects on wound edge contraction and microvascular blood flow in defect wounds. No significant changes in blood flow or wound contraction were noted in incision wounds for any NPWT combinations tested. CONCLUSIONS: The disposable, canisterless PICO NPWT system functions in the same manner as the traditional NPWT systems with regard to fluid handling, pressure transmission to the wound bed, tissue contraction, and changes in blood flow.

Color and illuminance level of lighting can modulate willingness to eat bell peppers.

BACKGROUND: Food products are often encountered under colored lighting, particularly in restaurants and retail stores. However, relatively little attention has been paid to whether the color of ambient lighting can affect consumers' motivation for consumption. This study aimed to determine whether color (Experiment 1) and illuminance level (Experiment 2) of lighting can influence consumers' liking of appearance and their willingness to eat bell peppers. RESULTS: For red, green, and yellow bell peppers, yellow and blue lighting conditions consistently increased participants' liking of appearance the most and the least, respectively. Participants' willingness to consume bell peppers increased the most under yellow lighting and the least under blue lighting. In addition, a dark condition (i.e. low level of lighting illuminance) decreased liking of appearance and willingness to eat the bell peppers compared to a bright condition (i.e. high level of lighting illuminance). CONCLUSION: Our findings demonstrate that lighting color and illuminance level can influence consumers' hedonic impression and likelihood to consume bell peppers. Furthermore, the influences of color and illuminance level of lighting appear to be dependent on the surface color of bell peppers.

Wound edge microvascular blood flow: effects of negative pressure wound therapy using gauze or polyurethane foam.

The aim of this study was to examine the effects of negative pressure wound therapy (NPWT) on wound edge microvascular blood flow, comparing different wound fillers. Wounds were created on the backs of 7 pigs. NPWT was applied, using either foam or gauze, at -50,-75, -100, -125, -150, or -175 mm Hg. Microvascular blood flow was measured in muscle tissue, subcutaneous tissue, and in the wound bed, at 0.5, 1, and 2.5 cm from the wound edge, using laser Doppler velocimetry. Similar patterns of blood flow response were observed when using foam or gauze. At 2.5 cm from the wound edge there was an increase in microvascular blood flow, while blood flow was decreased closer (0.5 cm) to the wound edge. The blood flow effects were similar at the different levels of negative pressure in muscle tissue, subcutaneous tissue, and in the wound bed. Altered microvascular blood flow to the wound edge may be one of the mechanisms by which NPWT facilitates healing.

Negative-pressure wound therapy using gauze or open-cell polyurethane foam: similar early effects on pressure transduction and tissue contraction in an experimental porcine wound model.

Negative-pressure wound therapy (NPWT), also known as topical negative-pressure therapy, is widely used to manage wounds and accelerate healing. NPWT has so far been delivered mainly via open-cell polyurethane foam, but increasing interest has been directed toward delivering NPWT via gauze. In the present study, the early effects of NPWT on pressure transduction and wound contraction were examined in wounds filled with either polyurethane foam or gauze. An experimental setup of a porcine wound model was used, in which the animals were anesthetized for 12-14 hours. Negative pressures between -50 and -175 mmHg were applied in -25 mmHg increments. Wound bed pressure was measured using a saline filled catheter sutured to the bottom of the wound. The contraction of the wound edges was also determined. The recordings were performed upon reaching steady state, which typically occurred within 1 minute. For both fillers, wound bed negative pressure increased linearly with delivered vacuum with little deviation from set pressure (correlation coefficient 0.99 in both cases). Similar tissue contraction was observed when using foam and gauze. The most prominent contraction was observed in the range of 0 to -50 mmHg with greater vacuum only producing minor further movement of the wound edge. In conclusion, the present experimental study shows that gauze and foam are equally effective at delivering negative pressure and creating mechanical deformation of the wound.

Venous leg ulcers - the search for a prognostic indicator.

Disordered cell function within chronic wounds generates many parameters that can be measured to differentiate between healing and non healing status. Theoretically, these may form the basis of a wound assessment system to define disease severity and response to treatment. In a review of tissue, wound exudate and microbiology studies of venous leg ulcers, we identify many such parameters that are associated with healing status. These include cytokines, proteases and their inhibitors, senescence markers, oxidative stress markers and microbiological status defined by culture. Some of these, such as protease level in wound exudate, have been proposed as prognostic indicators of healing status and many more could be considered potential markers to incorporate into a wound assessment system. However, no published data are available that validate known wound components to accurately reflect wound progression on a single patient basis. Rather than further characterisation of the expression of known wound biomarkers, the development of an accurate and objective test for prediction of chronic wound outcome requires identification of an appropriate combination of novel molecules that vary coordinately with healing status.