Wound Edge Microvascular Blood Flow during Negative-Pressure Wound Therapy: Examining the Effects of Pressures from –10 to –175 mmHg:

Securing skin grafts: A network meta-analysis

BACKGROUND

Skin grafting is one of the most common procedures in plastic surgery. However, there are no defined guidelines for optimal fixation. The aim of this network meta-analysis (NMA) was to consolidate existing evidence by comparing various graft securing methods and determining the most effective approach for clinical practice.

METHODS

An NMA was conducted using a predetermined protocol after searching several electronic databases from inception to October 2023 for studies examining skin grafting fixation outcomes in adults.

RESULTS

A total of 27 studies were included in the analysis involving 1937 patients. Negative pressure wound therapy (NPWT) was the only method to significantly improve graft take percentages in comparison with the other modalities, whereas tie-over bolster (TOB) provided the worst results in take rates when examined as events. Fibrin glue (FIB) and TOB reduced hematoma and seroma rates when data were investigated in conjunction.

CONCLUSIONS

NPWT appears to be the most effective for skin graft adherence as opposed to traditional techniques. Its cost-effectiveness remains unclear, as NPWT is a relatively costly intervention compared with other methods. FIB and TOB are methods that can serve as a method of reducing hematoma and seroma rates in patients at high risk of bleeding.

LEVEL OF EVIDENCE

I.

In vitro evaluation of a hybrid negative pressure system for wound therapy

OBJECTIVE

The objective of this study was to assess whether negative pressure could be maintained accurately and repeatably with a wall-suction-based hybrid negative pressure wound therapy (h-NPWT) system by comparing it with a commercial negative pressure wound therapy (NPWT) device.

STUDY DESIGN

In vitro experimental study.

METHODS

A commercial NPWT device (control) and three h-NPWT devices, with 0, 3, and 6 meters of additional tubing using the hospital-wall suction (groups 1, 2, and 3 respectively), were applied sequentially to a commercial NPWT dressing on a silicone skin substrate and set to run at a continuous pressure of -125 mmHg. The pressure within the wound space was monitored at 10 second intervals for 24 h. The process was repeated five times for each group.

RESULTS

The commercial NPWT device produced an average pressure variance of 3.02 mmHg, and the h-NPWT produced average variances of 4.38, 4.24 and 4.20 mmHg for groups 1, 2 and 3, respectively. All groups produced an average pressure within 0.15 mmHg of -125 mmHg over the 24-hour period, and the h-NPWT systems produced the smallest range with all values remaining within a ±5% variation from -125 mmHg.

CONCLUSION

The h-NPWT system achieved negative pressures that were comparable to those of a commercial control NPWT device. The addition of tubing between the skin substrate and the canister did not affect the pressure applied at the wound site.

CLINICAL SIGNIFICANCE

The h-NPWT device tested in this study can be considered as an alternative for negative wound therapy when a commercial device cannot be used.

A comprehensive exploration of hydrogel applications in multi-stage skin wound healing

Hydrogels, as an emerging biomaterial, have found extensive use in the healing of wounds due to their distinctive physicochemical structure and functional properties. Moreover, hydrogels can be made to match a range of therapeutic requirements for materials used in wound healing through specific functional modifications. This review provides a step-by-step explanation of the processes involved in cutaneous wound healing, including hemostasis, inflammation, proliferation, and reconstitution, along with an investigation of the factors that impact these processes. Furthermore, a thorough analysis is conducted on the various stages of the wound healing process at which functional hydrogels are implemented, including hemostasis, anti-infection measures, encouraging regeneration, scar reduction, and wound monitoring. Next, the latest progress of multifunctional hydrogels for wound healing and the methods to achieve these functions are discussed in depth and categorized for elucidation. Finally, perspectives and challenges associated with the clinical applications of multifunctional hydrogels are discussed.

Effect of negative pressure therapy on the treatment response to scar thickness and viscoelasticity

Patients with scars face a grave threat to their mental and physical health. Negative pressure has been used for scar therapy in medical care and provides a microenvironment conducive to scar healing while stimulating cell regeneration. Negative pressure may disrupt scar tissue regeneration when the pressure is too high or too low, so finding a suitable negative pressure is important. We hypothesized that different negative pressure magnitudes would affect scar tissue properties differently. This research aimed to provide practical recommendations for scar therapy. This study used three negative pressures (-105 mmHg, -125 mmHg, and -145 mmHg) to compare scar material properties. We measured scar tissue thickness and viscoelasticity with a motor-driven ultrasound indentation system. According to the results of this study, scar thickness is most effectively reduced at a negative pressure of -105 mmHg. In comparison, scar viscoelasticity continuously increases at a negative pressure of -125 mmHg. Negative pressure therapy can be recommended to scar care clinics based on the results of this study.

Negative Pressure Wound Therapy-A Vacuum-Mediated Positive Pressure Wound Therapy and a Closer Look at the Role of the Laser Doppler

Background: Negative pressure wound therapy (NPWT) is an intensely investigated topic, but its mechanism of action accounts for one of the least understood ones in the area of wound healing. Apart from a misleading nomenclature, by far the most used diagnostic tool to investigate NPWT, the laser Doppler, also has its weaknesses regarding the detection of changes in blood flow and velocity. The aim of the present study is to explain laser Doppler readings within the context of NPWT influence. Methods: The cutaneous microcirculation beneath an NPWT system of 10 healthy volunteers was assessed using two different laser Dopplers (O2C/Rad-97®). This was combined with an in vitro experiment simulating the compressing and displacing forces of NPWT on the arterial and venous system. Results: Using the O2C, a baseline value of 194 and 70 arbitrary units was measured for the flow and relative hemoglobin, respectively. There was an increase in flow to 230 arbitrary units (p = 0.09) when the NPWT device was switched on. No change was seen in the relative hemoglobin (p = 0.77). With the Rad-97®, a baseline of 92.91% and 0.17% was measured for the saturation and perfusion index, respectively. No significant change in saturation was noted during the NPWT treatment phase, but the perfusion index increased to 0.32% (p = 0.04). Applying NPWT compared to the arteriovenous-vessel model resulted in a 28 mm and 10 mm increase in the venous and arterial water column, respectively. Conclusions: We suspect the vacuum-mediated positive pressure of the NPWT results in a differential displacement of the venous and arterial blood column, with stronger displacement of the venous side. This ratio may explain the increased perfusion index of the laser Doppler. Our in vitro setup supports this finding as compressive forces on the bottom of two water columns within a manometer with different resistances results in unequal displacement.

Effects of endoluminal vacuum sponge therapy on the perfusion of gastric conduit in a porcine model for esophagectomy

BACKGROUND

After esophagectomy, the postoperative rate of anastomotic leakage is up to 30% and is the main driver of postoperative morbidity. Contemporary management includes endoluminal vacuum sponge therapy (EndoVAC) with good success rates. Vacuum therapy improves tissue perfusion in superficial wounds, but this has not been shown for gastric conduits. This study aimed to assess gastric conduit perfusion with EndoVAC in a porcine model for esophagectomy.

MATERIAL AND METHODS

A porcine model (n = 18) was used with gastric conduit formation and induction of ischemia at the cranial end of the gastric conduit with measurement of tissue perfusion over time. In three experimental groups EndoVAC therapy was then used in the gastric conduit (- 40, - 125, and - 200 mmHg). Changes in tissue perfusion and tissue edema were assessed using hyperspectral imaging. The study was approved by local authorities (Project License G-333/19, G-67/22).

RESULTS

Induction of ischemia led to significant reduction of tissue oxygenation from 65.1 ± 2.5% to 44.7 ± 5.5% (p < 0.01). After EndoVAC therapy with - 125 mmHg a significant increase in tissue oxygenation to 61.9 ± 5.5% was seen after 60 min and stayed stable after 120 min (62.9 ± 9.4%, p < 0.01 vs tissue ischemia). A similar improvement was seen with EndoVAC therapy at - 200 mmHg. A nonsignificant increase in oxygenation levels was also seen after therapy with - 40 mmHg, from 46.3 ± 3.4% to 52.5 ± 4.3% and 53.9 ± 8.1% after 60 and 120 min respectively (p > 0.05). An increase in tissue edema was observed after 60 and 120 min of EndoVAC therapy with - 200 mmHg but not with - 40 and - 125 mmHg.

CONCLUSIONS

EndoVAC therapy with a pressure of - 125 mmHg significantly increased tissue perfusion of ischemic gastric conduit. With better understanding of underlying physiology the optimal use of EndoVAC therapy can be determined including a possible preemptive use for gastric conduits with impaired arterial perfusion or venous congestion.

Polyurethane foam dressing with non-adherent membrane improves negative pressure wound therapy in pigs

OBJECTIVE

Negative pressure wound therapy (NPWT) is considered to be an effective technique to promote the healing of various wounds. The aim of this study was to evaluate different wound dressings combined with NPWT in treating wounds in Wuzhishan pigs.

METHOD

Excisions were made in the backs of the pigs and were covered with polyvinyl alcohol (PVA) dressing, polyurethane (PU) dressing or PU dressing with non-adherent membrane (PU-non-ad). NPWT was applied to the wound site. In the control group, basic occlusive dressing (gauze) without NPWT was applied. On days 0, 3, 7, 14, 21 and 28 post-surgery, the wound size was measured during dressing change, and wound healing rate (WHR) was calculated. In addition, blood perfusion within 2cm of the surrounding wound was measured by laser doppler flowmetry. Dressing specimen was collected and microbiology was analysed. Granulation tissues from the central part of the wounds were analysed for histology, vascular endothelial growth factor (VEGF) and cluster of differentiation 31 (CD31) mRNA expression.

RESULTS

The PU-non-ad-NPWT significantly (p<0.01) accelerated wound healing in the pigs. Further pathological analysis revealed that the non-adherent membrane effectively protected granulation tissue formation in PU-NPWT treated wounds. The blood perfusion analysis suggested that the non-adherent membrane improved the blood supply to the wound area. Microbiological analysis showed that non-adherent membrane decreased the bacterial load in the PU-NPWT dressing. VEGF and CD31 mRNA expression was upregulated in the wound tissue from the PU-non-ad-NPWT treated groups.

CONCLUSION

In this study, the PU dressing with non-adherent membrane was an ideal dressing in NPWT-assisted wound healing.

Negative pressure wound therapy reduces the incidence of postoperative wound dehiscence and surgical site infections after total knee arthroplasty in patients with obesity

Obesity is a risk factor for total knee arthroplasty (TKA). Wound dehiscence and surgical site infections (SSIs) are the main complications of TKA in patients with obesity. They can profoundly affect patients because they often require readmission, additional surgical interventions, lengthy intravenous antibiotic administration, and delayed rehabilitation. Negative pressure wound therapy (NPWT) exposes the wound site to negative pressure, resulting in the improvement of blood supply, removal of excess fluid, and stimulation of cellular proliferation of granulation tissue. This study aims to assess the incidence of wound dehiscence and SSIs in patients with obesity undergoing TKA after the routine use of NPWT. This sduty enrolled adult patients with obesity who underwent TKA within 8 years. A total of 360 adult patients with obesity (NPWT: 150, non-NPWT: 210) underwent TKA, and the baseline characteristics were similar between the 2 groups. Compared with the non-NPWT group, the NPWT group had a 50% lower incidence of wound dehiscence (3.33% vs 9.52%; P < .05) and a significantly lower incidence of SSIs (11.33% vs 25.24%; P < .05), including prosthetic joint infection (4.0% vs 10.0%; P < .05) and superficial wound infection (7.33% vs 15.24%; P < .05). In addition, the NPWT group had a lower need to return to the operating room for new interventions for any reason (2.67% vs 9.05%; P = .0107) than the non-NPWT group. Conventional incision NPWT can significantly reduce the incidence of wound dehiscence and SSIs in patients with obesity after TKA.

Update in combined musculoskeletal and vascular injuries of the extremities

Combined musculoskeletal and vascular injuries of the extremities are conditions in which a multidisciplinary approach is a sine qua non to ensure life initially and limb viability secondarily. Vascular injuries as part of musculoskeletal trauma are usually the result of the release of a high energy load in the wound site so that the prognosis is determined by the degree of soft-tissue damage, duration of limb ischemia, patient's medical status and presence of associated injuries. The management of these injuries is challenging and requires a specific algorithm of action, because they are usually characterized by increased morbidity, amputation rate, infection, neurological and functional deficits, and they could be life threatening. Although vascular injuries are rare and occur either isolated or in the context of major combined musculoskeletal trauma, the high index of suspicion, imaging control, and timely referral of the patient to organized trauma centers ensure the best functional outcome of the extremity in such challenging cases. Even after a successful initial treatment of a combined trauma pattern, long-term follow-up is crucial to prevent and detect early possible complications. The purpose of this manuscript is to provide an update on diagnosis and treatment of combined musculoskeletal and vascular injuries of the extremities, from an orthopedic point of view.

Superior Enhancement of Cutaneous Microcirculation Due to “Cyclic” Application of a Negative Pressure Wound Therapy Device in Humans – Local and Remote Effects

Objectives

Despite a common utilization of “Negative Pressure Wound Therapy” (NPWT) Devices in a wide range of specialties, some of the basic mechanisms of action of the techniques are still on debate. Conflicting results from prior studies demonstrate our lack of understanding how wound-bed perfusion or cutaneous microcirculation is affected by NPWT.

Methods

We conducted a prospective randomized study which included 45 healthy subjects to further investigate the acute effects of NPWT on cutaneous microcirculation underneath the applied dressing. Three modes of application, namely, continuous, intermittent, cyclic, were tested. Amongst others, measurements of elicited surface pressure and a comprehensive microcirculatory analysis were carried out by utilizing an O2C-device. For the detection of (systemic) remote effects, perfusion changes of the contra-lateral thigh were evaluated.

Results

All three tested modes of application led to a significant (p < 0.05) improvement in local tissue perfusion with an increased blood flow of max +151% and tissue oxygen saturation of +28.2% compared to baseline values. Surface pressure under the dressing significantly increased up to 29.29 mmHg due to the activation of the NPWT device. Continuous, intermittent, and cyclic application of negative pressure were accurately sensed by participants, resulting in reported pain values that mirrored the different levels of applied suction. Although the cyclic application mode showed the most pronounced effects regarding microcirculatory changes, no statistical significance between groups was observed.

Conclusion

We could demonstrate a significant improvement of cutaneous microcirculation under an applied NPWT dressing with favorable effects due to cyclic mode of application. An increased surface pressure leads to a better venous drainage of the tissue, which was shown to increase arterial inflow with a consecutive improvement of oxygen supply. Further research is warranted to evaluate our findings regarding wound bed perfusion in the clinical field with respect to formation of granulation tissue and wound healing.

Postoperative Fluid Collections in Total Joint Arthroplasty: A Narrative Review

A post-operative fluid collection (POFC) represents a common finding in both primary and revision total joint arthroplasty (TJA). Fortunately, most resolve on their own, but in instances where they become symptomatic, prompt identification and management are paramount, especially when they occur adjacent to a joint arthroplasty because of the increased the risk of developing a periprosthetic joint infection. A strong clinical suspicion with appropriate clinical exam is required along with select imaging modalities to arrive at a diagnosis. Meticulous surgical technique is crucial to prevent POFC, but new emerging treatments continue to evolve. This article presents an updated overview of incidence, pathophysiology, diagnosis, and management of POFC in the setting of TJA. We review the role of select imaging modalities as well as summarize current literature regarding new treatments such as sclerotherapy agents, acellular dermal matrices, and negative pressure wound therapy. Future studies are necessary to explore the interplay of inflammatory mediators in POFC formation and to define their role in fluid collection resolution.

Negative pressure wound therapy versus conventional wound care in cancer surgical wounds: A meta-analysis of observational studies and randomised controlled trials

The application of negative pressure wound therapy (NPWT) in cancer surgical wounds is still controversial, despite its promising usage, because of the risks of increased tumorigenesis and metastasis. This study aimed to review the risks and benefits of NPWT in surgical wounds with the underlying malignant disease compared with conventional wound care (CWC). The first outcome was wound complications, divided into surgical site infection (SSI), seroma, hematoma, and wound dehiscence. The secondary outcome was hospital readmission. We performed a separate meta‐analysis of observational studies and randomised controlled trials (RCTs) with CI 95%. Thirteen observational studies with 1923 patients and seven RCTs with 1091 patients were included. NPWT group showed significant decrease in the risk of SSI (RR = 0.45) and seroma (RR = 0.61) in observational studies with P value <0.05, as well as RCTs but were not significant (RR = 0.88 and RR = 0.68). Wound dehiscence (RR = 0.74 and RR = 1.15) and hospital readmission (RR = 0.90 and RR = 0.62) showed lower risks in NPWT group but were not significant. Hematoma (RR = 1.08 and RR = 0.87) showed no significant difference. NPWT is not contraindicated in cancer surgical wounds and can be considered a beneficial palliative treatment to promote wound healing.

Minimally Invasive Successful Reconstruction of a Severely Traumatized Upper Extremity Using Platelet-Rich Plasma and Tissue Scaffold: A Case Report

Minimally invasive reconstruction combines principles of tissue engineering and regenerative medicine for healing complex wounds. This approach was successfully demonstrated on a 64-year-old diabetic and hypertensive male patient, who was brought unconscious to our emergency after surviving an automobile collision with severe brain and right-dominant upper extremity injuries. Uncontrolled hyperglycemia, severe anemia, diffuse axonal brain injury, wrist drop, and loss of thumb extension and abduction were noted. Extensive degloving, skin necrosis, extensor and flexor forearm muscle crush injuries, and ruptured extensor tendons were observed. Serial wound debridement combined with platelet-poor plasma injection into the muscles, platelet-rich plasma injections into the tendons and subcutis, and low-negative pressure wound therapy were performed sequentially to salvage the injured soft-tissues. Improvements were noticed during the second exploration after 5 days. Surviving muscles showed adequate vascularization and revival of innervation during the third exploration after another 5 days. Thereafter, absorbable synthetic tissue scaffold was applied over a sizeable 270 cm ² wound as a flap-alternative. Tissues regenerated well within the scaffold during the next 2 months, halving the wound area to 132 cm ² . A thick split-skin graft was applied over the remaining granulating neodermis, which “took” completely. Six months postoperatively, the patient regained most hand functions and performed all activities satisfactorily, while the grafted area appeared almost identical to surroundings. Minimally invasive reconstruction thus produced satisfying results with fewer shorter simpler surgeries, minimal anesthesia, short-duration hospitalization, lower health care costs, lesser risks, and excellent patient-reported outcomes.

Modified Incisional Negative Pressure Wound Therapy Increases Seroma Evacuation: An Ex Vivo Model

Background

Incisional negative wound pressure therapy (iNPWT) is a relatively novel dressing technique with the aim of reducing postoperative wound infections and dehiscence in high-risk wounds after all kinds of surgical procedures. There is a lack of theoretical knowledge about the way those dressing would ameliorate wound healing. One aspect is the reduction of superficial tension, but significant remaining seroma might still cause deep wound infections. The aim of this study was the evaluation of technical modifications of the standard iNPWT dressing to increase seroma evacuation.

Methods

iNPWT dressings were applied on the porcine abdominal wall, and an incremental pressure ramp from 50 to 200 mmHg was performed. The resulting wound pressures were measured using (i) balloon manometry and (ii) esophageal manometry catheter. Seroma evacuation was analyzed with a seroma model. All measurements were performed with (i) standard iNPWT dressing, (ii) wound gauze diverted through the incision, and (iii) placement of suction drain tube into iNPWT.

Results

Due to the modifications of the iNPWT dressing, the vacuum applied by the iNPWT dressing could be transferred into the wound and was not only restricted to superficial layers. More importantly, placement of wound gauzes or suction drain tubes led to complete extraction of wound seroma. The placement of the suction drain tube showed the best combination of increased intrawound pressure as well as seroma evacuation.

Conclusion

Addition of a suction drain tube to the iNPWT dressing leads to an improved function of the iNPWT dressing in our ex vivo model.

Measuring In-Vivo Foot Perfusion Distal to a Near-Circumferential Negative Pressure Wound Therapy Dressing via Thermal Imaging

Background Negative pressure wound therapy (NPWT) has been shown to promote the healing of acute and chronic wounds. In our previous study, we demonstrated that a near-circumferential NPWT dressing provided "lift-off" on an in-vitro extremity model resulting in decreased pressure. We hypothesized that this decrease in pressure may increase perfusion distal to the NPWT dressing by increasing lymphatic drainage and venous flow. Methods In this study, we tested if a near-circumferential NPWT dressing caused any appreciable skin movement around the dressing. We then used a thermal imaging camera to test if there was an increase in perfusion to the foot when a near-circumferential NPWT dressing was placed around the lower leg and tested at various negative pressures. Finally, we wanted to see if an artificial "lift-off" mechanism would lead to an increase in perfusion. Results The skin was noted to stretch between the short ends of the NPWT dressing, consistent with our previously described "lift-off" mechanism. However, there was no correlation between negative pressure and perfusion to the foot in the other experiments. Conclusion This study demonstrated that a near-circumferential NPWT dressing may not have any appreciable effects on perfusion when applied on a healthy patient, however, future studies are needed to determine if similar results would be seen on a traumatized or otherwise compromised extremity.

Can Intralesional Epidermal Growth Factor Reduce Skin Graft Applications in Patients with Diabetic Foot Ulcer?

BACKGROUND

Diabetic foot ulcer (DFU) is a serious health problem. Major amputation increases the risk of mortality in patients with DFU; therefore, treatment methods other than major amputation come to the fore for these patients. Graft applications create an appropriate environment for the reproduction of epithelial cells. Similarly, epidermal growth factor (EGF) also stimulates epithelization and increases epidermis formation. In this study, we aimed to compare patients with DFU treated with EGF and those treated with a split-thickness skin graft.

METHODS

Patients who were treated for DFU in the general surgery clinic were included in the study. The patients were evaluated retrospectively according to their demographic characteristics, wound characteristics, duration of treatment, and treatment modalities.

RESULTS

There were 26 patients in the EGF group and 21 patients in the graft group. The mean duration of treatment was 7 weeks (4-8 weeks) in the EGF group and 5.3 weeks (4-8 weeks) in the graft group (P < .05). In the EGF group, wound healing could not be achieved in one patient during the study period. In the graft group, no recovery was achieved in three patients (14.2%) in the donor site. Graft loss was detected in four patients (19%), and partial graft loss was observed in three patients (14.2%). The DFU of these patients were on the soles (85.7%). These patients have multiple comorbidities.

CONCLUSIONS

EGF application may be preferred to avoid graft complications in the graft area and the donor site, especially in elderly patients with multiple comorbidities and wounds on the soles.

Closed Incision Negative Pressure Wound Therapy for Elective Hip and Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Persistent wound drainage after total joint arthroplasty (TJA) increases the risk of surgical site infections (SSIs). Closed incision negative pressure wound therapy (ciNPWT) decreases infections in traumatic wounds, but evidence for its use after elective TJA is limited. The purpose of this meta-analysis of level I studies is to determine the effect of ciNPWT on risk of SSI and wound complications following TJA.

METHODS

MEDLINE, EMBASE, CINAHL, and Cochrane Library were searched for randomized controlled trials comparing ciNPWT vs standard dressings after total hip (THA) and total knee arthroplasty (TKA). Studies exclusively involving THA for femoral neck fractures were excluded. Risk of SSI and noninfectious wound complications (blisters, seroma, hematoma, persistent drainage, dehiscence, and wound edge necrosis) following TJA were analyzed.

RESULTS

SSI risk was lower with ciNPWT compared to standard dressings (3.4% vs 7%; relative risk [RR] 0.48, P = .007), specifically in revision THA and TKA (4.1% vs 10.5%; RR 0.41, P = .03). ciNPWT increased the noninfectious complication risk after primary TKA (RR 4.71, P < .0001), especially causing wound blistering (RR 12.66, P < .0001). ciNPWT decreased hospital length of stay by 0.73 days (P = .04) and reoperation rate (RR 0.28, P = .01).

CONCLUSION

ciNPWT decreases SSI risk compared to standard dressings after revision TJA, but not primary TJA. ciNPWT is associated with >12-fold increased risk of wound blistering after primary TKA. ciNPWT plays a role in revision TJA management, but additional randomized controlled trials with uniform wound assessment methods must be performed to sufficiently power findings and draw conclusions on the use of ciNPWT after primary TJA.

Impact of Previous Irradiation on Wound Healing after Negative Pressure Wound Therapy in Head and Neck Cancer Patients-A Systematic Review

(1) Background: Negative pressure wound therapy (NPWT) has been effectively used for wound management in comparison to traditional dressings. The purpose of this study was to provide an evidence-based review of NPWT in head and neck cancer patients, as well as the impact of previous irradiation and other risk factors on wound healing. (2) Material and Methods: We conducted a comprehensive search in PubMed, Medline, Embase, Web of Science, and Cochrane Library databases for relevant literature. (3) Results: 15 studies fulfilled the inclusion criteria. The most common etiologies requiring NPWT were defects post tumor resection and flap reconstruction and oro/pharyngo-cutaneous fistulas. The neck was found to be the most common site of involvement (47.3%). The overall wound healing response rate was 87.5%. The median negative pressure recorded was 125 mm of Hg, with a median dressing change time of three days. Previous irradiation (p = 0.01; OR = 4.07) and diabetes mellitus (DM) (p = 0.001; OR = 5.62) were found to be significantly associated with delayed wound healing after NPWT. (4) Conclusion: NPWT treats complex wounds in head and neck cancer patients and should represent a significant armamentarium in head and neck cancers. Previous irradiation and DM have detrimental effects on wound healing after NPWT.

Salvaging the Unsalvageable: Negative Pressure Wound Therapy for Severe Infection of Prosthetic Breast Reconstruction

Background:

Severe infections of implant-based breast reconstruction are challenging to treat. Traditional management is removal of the implant with a further attempt at reconstruction months later once the infection has settled. This study evaluates an alternative management protocol using negative pressure wound therapy with instillation (NPWTi).

Methods:

Consecutive patients with severe peri-prosthetic infection following breast reconstruction were managed using the Implant Salvage Protocol: removal of the prosthesis with application of a NPWTi dressing, changed every 3 days until a negative culture was obtained. A new prosthesis was then placed in the pocket. Data were collected on patient demographics, microbiological, hospital/operative information, and overall success of salvage. Descriptive statistics were used for analysis.

Results:

In total, 30 breast prostheses in 28 patients were treated for severe peri-prosthetic infection. Twenty-five (83%) implants were salvaged. Mean time from initial reconstruction surgery to presentation was 49.5 days (median 23, range 7–420). Mean hospital stay was 11.5 days (median 12.0, range 6–22), mean number of returns to the operating theater was 3.7 (median 3.0, range 2–7), and mean number of days to negative culture was 5.2 (median 4.0, range 1–14). The most common organisms were methicillin-sensitive Staphylococcus aureus (n = 9) and Serratia marcescens (n = 4). Most had a tissue expander (n = 24, 80%) or implant (n = 5, 16.7%) placed at the completion of therapy. There was no record of capsular contracture nor recurrent infection during follow-up (mean 39.4 months, range 6–74 months).

Conclusion:

An estimated 83% of prosthetic breast reconstructions with severe infection were successfully salvaged using NPWTi.

Application of negative tissue interstitial pressure improves functional capillary density after hemorrhagic shock in the absence of volume resuscitation

Microvascular fluid exchange is primarily dependent on Starling forces and both the active and passive myogenic response of arterioles and post-capillary venules. Arterioles are classically considered resistance vessels, while venules are considered capacitance vessels with high distensibility and low tonic sympathetic stimulation at rest. However, few studies have investigated the effects of modulating interstitial hydrostatic pressure, particularly in the context of hemorrhagic shock. The objective of this study was to investigate the mechanics of arterioles and functional capillary density (FCD) during application of negative tissue interstitial pressure after 40% total blood volume hemorrhagic shock. In this study, we characterized systemic and microcirculatory hemodynamic parameters, including FCD, in hamsters instrumented with a dorsal window chamber and a custom-designed negative pressure application device via intravital microscopy. In large arterioles, application of negative pressure after hemorrhagic shock resulted in a 13 ± 11% decrease in flow compared with only a 7 ± 9% decrease in flow after hemorrhagic shock alone after 90 minutes. In post-capillary venules, however, application of negative pressure after hemorrhagic shock resulted in a 31 ± 4% decrease in flow compared with only an 8 ± 5% decrease in flow after hemorrhagic shock alone after 90 minutes. Normalized FCD was observed to significantly improve after application of negative pressure after hemorrhagic shock (0.66 ± 0.02) compared to hemorrhagic shock without application of negative pressure (0.50 ± 0.04). Our study demonstrates that application of negative pressure acutely improves FCD during hemorrhagic shock, though it does not normalize FCD. These results suggest that by increasing the hydrostatic pressure gradient between the microvasculature and interstitium, microvascular perfusion can be transiently restored in the absence of volume resuscitation. This study has significant clinical implications, particularly in negative pressure wound therapy, and offers an alternative mechanism to improve microvascular perfusion during hypovolemic shock.

[RETRACTED] Negative pressure wound therapy versus conventional dressing for open fractures in lower extremity trauma

AIMS

It has been generally accepted that open fractures require early skeletal stabilization and soft-tissue reconstruction. Traditionally, a standard gauze dressing was applied to open wounds. There has been a recent shift in this paradigm towards negative pressure wound therapy (NPWT). The aim of this study was to compare the clinical outcomes in patients with open tibial fractures receiving standard dressing versus NPWT.

METHODS

This multicentre randomized controlled trial was approved by the ethical review board of a public sector tertiary care institute. Wounds were graded using Gustilo-Anderson (GA) classification, and patients with GA-II to III-C were included in the study. To be eligible, the patient had to present within 72 hours of the injury. The primary outcome of the study was patient-reported Disability Rating Index (DRI) at 12 months. Secondary outcomes included quality of life assessment using 12-Item Short-Form Health Survey questionnaire (SF-12), wound infection rates at six weeks and nonunion rates at 12 months. Logistic regression analysis and independent-samples t-test were applied for secondary outcomes. Analyses of primary and secondary outcomes were performed using SPSS v. 22.0.1 and p-values of < 0.05 were considered significant.

RESULTS

A total of 486 patients were randomized between January 2016 and December 2018. Overall 206 (49.04%) patients underwent NPWT, while 214 (50.95%) patients were allocated to the standard dressing group. There was no statistically significant difference in DRI at 12 months between NPWT and standard dressing groups (mean difference 0.5; 95% confidence interval (CI) -0.08 to 1.1; p = 0.581). Regarding SF-12 scores at 12 months follow-up, there was no significant difference at any point from injury until 12 months (mean difference 1.4; 95% CI 0.7 to 1.9; p = 0.781). The 30-day deep infection rate was slightly higher in the standard gauze dressing group. The non-union odds were also comparable (odds ratio (OR) 0.90, 95% CI 0.56 to 1.45; p = 0.685).

CONCLUSION

Our study concludes that NPWT therapy does not confer benefit over standard dressing technique for open fractures. The DRI, SF-12 scores, wound infection, and nonunion rates were analogous in both study groups. We suggest surgeons continue to use cheaper and more readily available standard dressings. Cite this article: Bone Joint J 2020;102-B(7):912-917.

False vocal cord perforation with abscess treated by negative pressure wound therapy

Perforation of the larynx is very rare but may result in severe airway complications that include pneumothorax, pneumonia, mediastinitis, and retropharyngeal abscess. If conservative treatment fails, aggressive treatments including reconstructive surgery with pedicle flap are considered. Negative pressure wound therapy has been used for large skin defects, necrotizing fasciitis, pharyngocutaneous fistula, stoma dehiscence, osteoradionecrosis of the mandible, chyle fistula, flap failure, and lymphangioma in the field of head and neck surgery. We report a case of false vocal cord perforation with abscess successfully treated by negative pressure wound therapy after abscess treatment. The result suggests that negative pressure wound therapy can be an alternative or adjunctive approach for larynx perforation when the perforation is difficult to close after conservative therapy.

Topical negative-pressure wound therapy: emerging devices and techniques

Introduction: The treatment of chronic wounds constitutes a massive financial burden to society and our health-care system. Therefore, efficient wound care is of great importance to all kinds of medical fields. The implementation and modification of negative-pressure wound therapy can be seen as a major improvement in wound healing. Many different NPWT applications evolved trying to address various wound etiologies.Areas covered: This review aims to give an overview of various NPWT applications, show its effects on wound healing, and discuss future modifications.Expert opinion: NPWT as a delivery device for cold plasma, growth factors, or targeted stem cells to the wound bed and the ability to monitor the inflammatory activity, bacterial load and wound healing factors can be seen as possible future steps to individualized wound care. In addition, it requires high-quality experimental studies to develop the ideal foam in terms of microstructure, pore size, and material properties.

Use of abdominal negative pressure wound therapy in different indications: a case series

Negative pressure wound therapy (NPWT) is a widely used wound management system. Several articles have been published on the advantages and complications of this system. Abdominal dressing negative pressure system (abdominal NPWT) is a newer technology, developed and used in open abdomen cases. The adherence of the sponge to the intra-abdominal organs is prevented by a polyurethane foam. This study presents a number of case series where an abdominal NPWT (ABThera, KCI, US) has been used to treat other vital organs, helping to prevent complications such as organ rupture and fatal bleeding.

Technological Advances in Wound Treatment of Exotic Pets

Although most research about the use of technological advances for wound healing was performed in laboratory animals but oriented to human medicine, recent technological advances allowed its application not only to small animals but also to exotic pets. This article reviews the literature available about some of these techniques (negative wound pressure therapy, photobiomodulation [laser therapy], electrical stimulation therapy, therapeutic ultrasonography, hyperbaric oxygen therapy), and other advances in wound management (skin expanders, xenografts, and bioengineered autologous skin substitutes) in exotic pet species.

EWMA Document: Negative Pressure Wound Therapy

1. Introduction Since its introduction in clinical practice in the early 1990's negative pressure wounds therapy (NPWT) has become widely used in the management of complex wounds in both inpatient and outpatient care.¹ NPWT has been described as a effective treatment for wounds of many different aetiologies^2,3 and suggested as a gold standard for treatment of wounds such as open abdominal wounds,^4-6 dehisced sternal wounds following cardiac surgery^7,8 and as a valuable agent in complex non-healing wounds.^9,10 Increasingly, NPWT is being applied in the primary and home-care setting, where it is described as having the potential to improve the efficacy of wound management and help reduce the reliance on hospital-based care.¹¹ While the potential of NPWT is promising and the clinical use of the treatment is widespread, highlevel evidence of its effectiveness and economic benefits remain sparse.^12-14 The ongoing controversy regarding high-level evidence in wound care in general is well known. There is a consensus that clinical practice should be evidence-based, which can be difficult to achieve due to confusion about the value of the various approaches to wound management; however, we have to rely on the best available evidence. The need to review wound strategies and treatments in order to reduce the burden of care in an efficient way is urgent. If patients at risk of delayed wound healing are identified earlier and aggressive interventions are taken before the wound deteriorates and complications occur, both patient morbidity and health-care costs can be significantly reduced. There is further a fundamental confusion over the best way to evaluate the effectiveness of interventions in this complex patient population. This is illustrated by reviews of the value of various treatment strategies for non-healing wounds, which have highlighted methodological inconsistencies in primary research. This situation is confounded by differences in the advice given by regulatory and reimbursement bodies in various countries regarding both study design and the ways in which results are interpreted. In response to this confusion, the European Wound Management Association (EWMA) has been publishing a number of interdisciplinary documents^15-19 with the intention of highlighting: The nature and extent of the problem for wound management: from the clinical perspective as well as that of care givers and the patients Evidence-based practice as an integration of clinical expertise with the best available clinical evidence from systematic research The nature and extent of the problem for wound management: from the policy maker and healthcare system perspectives The controversy regarding the value of various approaches to wound management and care is illustrated by the case of NPWT, synonymous with topical negative pressure or vacuum therapy and cited as branded VAC (vacuum-assisted closure) therapy. This is a mode of therapy used to encourage wound healing. It is used as a primary treatment of chronic wounds, in complex acute wounds and as an adjunct for temporary closure and wound bed preparation preceding surgical procedures such as skin grafts and flap surgery. Aim An increasing number of papers on the effect of NPWT are being published. However, due to the low evidence level the treatment remains controversial from the policy maker and health-care system's points of view-particularly with regard to evidence-based medicine. In response EWMA has established an interdisciplinary working group to describe the present knowledge with regard to NPWT and provide overview of its implications for organisation of care, documentation, communication, patient safety, and health economic aspects. These goals will be achieved by the following: Present the rational and scientific support for each delivered statement Uncover controversies and issues related to the use of NPWT in wound management Implications of implementing NPWT as a treatment strategy in the health-care system Provide information and offer perspectives of NPWT from the viewpoints of health-care staff, policy makers, politicians, industry, patients and hospital administrators who are indirectly or directly involved in wound management.

Management of Surgical Incisions Using Incisional Negative-Pressure Therapy

Use of negative-pressure therapy (NPT) is a well-established therapy for chronic, open, contaminated wounds, promoting formation of granulation tissue and healing. The application of NPT after primary closure (ie, incisional NPT) has also been shown to reduce surgical site infection and surgical site occurrence in high-risk procedures across multiple disciplines. Incisional NPT is believed to decrease edema and shear stress, promote angiogenesis and lymphatic drainage, and increase vascular flow and scar formation. Incisional NPT may be considered when there is a high risk of surgical site occurrence or surgical site infection, particularly in procedures with nonautologous implants, such as hernia mesh or other permanent prosthetics. Here we discuss the proposed physiologic mechanism as demonstrated in animal models and review clinical outcomes across multiple specialties.

[Application of modified keystone flap in repairing of skin and soft tissue defect around joint]

OBJECTIVE

To explore the effectiveness of keystone flap in repairing skin and soft tissue defects around joint.

METHODS

Between March 2013 and December 2017, 10 patients of skin and soft tissue defects around the joint were repaired with keystone flaps. There were 6 males and 4 females. The age ranged from 17 to 72 years, with an average age of 57.5 years. The skin and soft tissue defects located around the joints, including 2 cases of hip joints, 4 cases of knee joints, 3 cases of elbow joints, and 1 case of wrist joint. The cause of skin and soft tissue defects included scar contracture in 3 cases, basal cell carcinoma in 3 cases, squamous-cell carcinoma in 3 cases, and dermatofibrosarcoma protuberant in 1 case. The area of defects ranged from 4 cm×3 cm to 11 cm×11 cm. The keystone flap was designed beside the wound, and the V-shaped flap was designed at the longer side of the fan-shaped flap. The area of flap ranged from 7 cm×3 cm to 35 cm×10 cm. The flap was constantly compressed by vacuum assisted closure after operation for 3-6 days.

RESULTS

Primary wound healing was achieved and the flaps survived. All patients were followed up 6-24 months (mean, 15 months). The texture and color of flap was similar to the adjacent area. The appearance and function of joint were satisfactory.

CONCLUSION

The keystone flap is a feasible and efficient way to repair the wound around joint. Furthermore, the skin color and texture is similar to the surrounding tissue after healing.

The efficacy of negative pressure wound therapy for diabetic foot ulcers: A systematised review

AIM

This review investigated the current state of knowledge on negative pressure wound therapy (NPWT) used to treat diabetic foot ulceration (DFU), its clinical effectiveness and any current issues in the research. NICE have recommended research into the clinical effectiveness of different dressing types for DFUs since 2015.

METHODS

A systematic search of the British Nursing Index, CINAHL, Cochrane Central and PubMed was undertaken. Only primary studies were included and studies investigating a combination of NPWT and other therapies were excluded. All the included studies were published in English between 2008 and 2018 and were peer reviewed.

RESULTS

The search yielded seven studies for inclusion in the qualitative analysis. The studies included a variety of methodologies specifically; 3 randomized controlled trials, 2 case series', 1 non-controlled trial and 1 randomized case-control study. Three main themes were identified and formed the focus of the qualitative synthesis.

DISCUSSION

All the included studies reported that NPWT led to better clinical outcomes when compared to standard treatment. However, the studies had numerous methodological flaws such as the absence of validated tools for the measurement of outcomes such as wound area and depth; a lack of statistical power calculations to determine adequate sample sizes or the significance of outcome measures. Additionally, there was little consistency in the pressures used for the NPWT devices. Finally, many of the controlled trials did not conform to the standard of reporting trials stipulated by the CONSORT statement.

Study of negative pressure wound therapy as an adjunct treatment for acute burns in children (SONATA in C): protocol for a randomised controlled trial

BACKGROUND

Although negative pressure wound therapy (NPWT) is widely used in the management of several wound types, its efficacy as a primary therapy for acute burns has not yet been adequately investigated, with research in the paediatric population particularly lacking. There is limited evidence, however, that NPWT might benefit children with burns, amongst whom scar formation, wound progression and pain continue to present major management challenges. The purpose of this trial is to determine whether NPWT in conjunction with standard therapy accelerates healing, reduces wound progression and decreases pain more effectively than standard treatment alone.

METHODS/DESIGN

A total of 104 children will be recruited for this trial. To be eligible, candidates must be under 17 years of age and present to the participating children's hospital within 7 days of their injury with a thermal burn covering <5% of their total body surface area. Facial and trivial burns will be excluded. Following a randomised controlled parallel design, participants will be allocated to either an active control or intervention group. The former will receive standard therapy consisting of Acticoat™ and Mepitel™. The intervention arm will be treated with silver-impregnated dressings in addition to NPWT via the RENASYS TOUCH™ vacuum pump. Participants' dressings will be changed every 3 to 5 days until their wounds are fully re-epithelialised. Time to re-epithelialisation will be studied as the primary outcome. Secondary outcomes will include pain, pruritus, wound progression, health-care-resource use (and costs), ease of management, treatment satisfaction and adverse events. Wound fluid collected during NPWT will also be analysed to generate a proteomic profile of the burn microenvironment.

DISCUSSION

The study will be the first randomised controlled trial to explore the clinical effects of NPWT on paediatric burns, with the aim of determining whether the therapy warrants implementation as an adjunct to standard burns management.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ACTRN12618000256279 . Registered on 16 February 2018.

Continuous Negative Pressure Drain is Associated with Better Outcome: A Randomized Prospective Trial in Plastic Surgery Patients

BACKGROUND

A randomized prospective trial to compare the effects on minimizing complications using continuous negative pressure drain and intermittent suction mode in plastic surgeries.

METHODS

There were 174 cases of stage II post-auricular flap expansion and ear reconstruction, 76 cases of skin expansion flap repair, 56 cases of breast augmentation surgery, 58 cases of abdominoplasty, and 76 cases with free skin grafts. Patients were randomized to intermittent suction mode group (control group) and continuous negative pressure external drain group (intervention group) stratified by surgery types. In the intervention group, different pressure levels were applied according to the surgery types. The drainage volume, the length of time of external drainage, incidence of seroma, flap necrosis, the first intending healing rate and drain-associated bleeding were recorded and compared.

RESULTS

Generally, fewer complications and better healing were observed in the intervention group. In patients with stage II post-auricular flap expansion and ear reconstruction, lower incidence of flap necrosis and seroma, higher first intention healing rate, greater drain volume but shorter time of drainage were observed in the intervention group (p < 0.05 for all). Similar results were shown in patients with skin expansion flap repair, breast augmentation, abdominoplasty, and free skin grafts. In patients who underwent free skin grafts, a higher graft success rate and lower graft infection rate were also observed (p < 0.01 for both). No drain-associated bleeding was observed.

CONCLUSIONS

A continuous negative pressure drain was associated with better outcomes in patients underwent various plastic surgeries and is a powerful technique in the postoperative management of plastic surgery.

LEVEL OF EVIDENCE II

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Chinese Trauma Surgeon Association for management guidelines of vacuum sealing drainage application in abdominal surgeries-Update and systematic review

Vacuum sealing drainage (VSD) is frequently used in abdominal surgeries. However, relevant guidelines are rare. Chinese Trauma Surgeon Association organized a committee composed of 28 experts across China in July 2017, aiming to provide an evidence-based recommendation for the application of VSD in abdominal surgeries. Eleven questions regarding the use of VSD in abdominal surgeries were addressed: (1) which type of materials should be respectively chosen for the intraperitoneal cavity, retroperitoneal cavity and superficial incisions? (2) Can VSD be preventively used for a high-risk abdominal incision with primary suture? (3) Can VSD be used in severely contaminated/infected abdominal surgical sites? (4) Can VSD be used for temporary abdominal cavity closure under some special conditions such as severe abdominal trauma, infection, liver transplantation and intra-abdominal volume increment in abdominal compartment syndrome? (5) Can VSD be used in abdominal organ inflammation, injury, or postoperative drainage? (6) Can VSD be used in the treatment of intestinal fistula and pancreatic fistula? (7) Can VSD be used in the treatment of intra-abdominal and extra-peritoneal abscess? (8) Can VSD be used in the treatment of abdominal wall wounds, wound cavity, and defects? (9) Does VSD increase the risk of bleeding? (10) Does VSD increase the risk of intestinal wall injury? (11) Does VSD increase the risk of peritoneal adhesion? Focusing on these questions, evidence-based recommendations were given accordingly. VSD was strongly recommended regarding the questions 2-4. Weak recommendations were made regarding questions 1 and 5-11. Proper use of VSD in abdominal surgeries can lower the risk of infection in abdominal incisions with primary suture, treat severely contaminated/infected surgical sites and facilitate temporary abdominal cavity closure.

Influence of negative pressure wound therapy on peri-prosthetic tissue vascularization and inflammation around porous titanium percutaneous devices

Negative Pressure Wound Therapy (NPWT) has been shown to limit downgrowth around percutaneous devices in a guinea pig model. However, the influence of NPWT on peri-prosthetic tissue characteristics leading to limited downgrowth is still unclear. In order to investigate this, 12 CD hairless rats were assigned into two groups, NPWT and Untreated (n = 6/group). Each animal was implanted with a porous coated titanium percutaneous device and was dressed with a gauze and semi-occlusive base dressing. Post-surgery, animals in the NPWT Group received a regimen of NPWT treatment (-70 to -90 mmHg). After 4 weeks, tissue was collected over the device and stained with CD31 and CD68 to quantify blood vessel density and inflammation, respectively. The device with the surrounding tissue was also collected to quantify downgrowth. NPWT treatment led to a 1.6-fold increase in blood vessel densities compared to untreated tissues (p < 0.05). NPWT treatment also resulted in half the downgrowth as the Untreated Group, although not statistically significant (p = 0.19). Additionally, the results showed a trend toward increased CD68 cell densities in the NPWT Group compared to the Untreated Group (p = 0.09). These findings suggest that NPWT may influence wound healing responses in percutaneous devices by increasing blood vessel densities, limiting downgrowth and potentially increasing inflammation. Overall, NPWT may enhance tissue vascularity around percutaneous devices, especially in patients with impaired wound healing. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2091-2101, 2019.

A Role for Postoperative Negative Pressure Wound Therapy in Multitissue Hand Injuries

In this study, we compared outcomes in patients with acute hand injury, who were managed with or without negative pressure wound therapy (NPWT) after reconstructive surgery. All of the patients who sustained acute and multitissue injuries of the hand were identified. After reconstructive surgery, a conventional dressing was applied in Group 1 and NPWT was applied in Group 2. The dressing and NPWT were changed every 3 days. The mean age and Hand Injury Severity Scoring System score of both groups were not significantly different. Disabilities of the Arm, Shoulder, and Hand (DASH) scores were evaluated 1 month after all the sutures were removed and 1 year postoperatively, which were both significantly lower in Group 2. Applying NPWT to the hand promoted wound healing by reducing edema, stabilizing the wound, and providing immobilization in a functional position. Early wound healing and decreased complications enabled early rehabilitation, which led to successful functional recovery, both objectively and subjectively.

Mechanical Forces in Cutaneous Wound Healing: Emerging Therapies to Minimize Scar Formation

Significance: Excessive scarring is major clinical and financial burden in the United States. Improved therapies are necessary to reduce scarring, especially in patients affected by hypertrophic and keloid scars. Recent Advances: Advances in our understanding of mechanical forces in the wound environment enable us to target mechanical forces to minimize scar formation. Fetal wounds experience much lower resting stress when compared with adult wounds, and they heal without scars. Therapies that modulate mechanical forces in the wound environment are able to reduce scar size. Critical Issues: Increased mechanical stresses in the wound environment induce hypertrophic scarring via activation of mechanotransduction pathways. Mechanical stimulation modulates integrin, Wingless-type, protein kinase B, and focal adhesion kinase, resulting in cell proliferation and, ultimately, fibrosis. Therefore, the development of therapies that reduce mechanical forces in the wound environment would decrease the risk of developing excessive scars. Future Directions: The development of novel mechanotherapies is necessary to minimize scar formation and advance adult wound healing toward the scarless ideal. Mechanotransduction pathways are potential targets to reduce excessive scar formation, and thus, continued studies on therapies that utilize mechanical offloading and mechanomodulation are needed.

Mechanical effects of negative pressure wound therapy on abdominal wounds - effects of different pressures and wound fillers

The mechanical deformation of the wound edge resulting from negative pressure wound therapy (NPWT) at the standard setting of around -120 mmHg has positive effects in promoting wound healing. However, it may cause pain to the patient during treatment. It is therefore important to study the mechanical effects of the wound edges using lower pressure and different wound fillers. Abdominal wounds were created on eight pigs. The wounds were sealed for NPWT using foam or gauze. Negative pressures between -20 and -160 mmHg were applied, and the decrease in wound diameter and the force with which the edges of the wound were drawn together (wound edge force) were measured. Increasing levels of negative pressure resulted in a gradual decrease in wound diameter and increase in wound edge force and reached a maximum at -120 mmHg, which is the pressure commonly used in clinical practice. Both the decrease in wound diameter and the increase in wound edge force was greater with foam than with gauze. A pressure of -80 mmHg has only 15% less effect than -120 mmHg, while a lower pressure (-40 mmHg) diminished the effects on diameter and force markedly. The NPWT-induced decrease in wound diameter and increase in wound edge force are greater at higher levels of negative pressure and when using foam than when using gauze as a wound filler. It may be possible to tailor the type of wound filler and level of negative pressure to obtain the best balance between wound healing and patient comfort.

Effectiveness of Acellular Dermal Matrix on Autologous Split-Thickness Skin Graft in Treatment of Deep Tissue Defect: Esthetic Subjective and Objective Evaluation

BACKGROUND

A split-thickness skin graft (STSG) is performed to cover a large full-thickness skin defect. Esthetic and functional deficits can result, and many studies have sought to overcome them. This study compared the effectiveness of the acellular dermal matrix (ADM) graft and STSG concerning esthetic and functional effectiveness of ADM on scar quality.

METHODS

Of the patients who underwent anterolateral thigh free flap from 2011 to 2015, patients who received skin graft only (n = 10) or skin graft with ADM (n = 20) for coverage of the donor site were enrolled. In all cases, autologous STSG was performed with 1:1.5 meshed 0.008-0.010-inch-thick skin. In the skin graft with ADM group, 0.008-0.013-inch-thick meshed ADM (CGderm^®; CGBio, Inc., Seungnam, Korea) was co-grafted. Negative-pressure wound therapy (CuraVAC^®; CGBio, Inc., Seungnam, Korea) was applied to both groups in continuous mode at -120 mmHg. We investigate early outcomes (skin loss rate, duration of negative-pressure wound therapy, days to removal of stitches, days to achieve complete healing, and complications) and late outcomes in terms of scar quality (vascularity, pigmentation, pliability and height) and graft-related symptoms (itching sensation and pain). Assessments used the Vancouver Scar Scale and the Patient and Observer Scar Assessment Scale. Skin fold was measured to evaluate the elasticity of scar tissue.

RESULTS

In the Vancouver Scar Scale, vascularity subscore (p = 0.003) and total score (p = 0.016) were significantly lower in the skin graft with ADM group. In Patient and Observer Scar Assessment Scale, the pain (p = 0.037) and stiffness subscores (p = 0.002), and total score (p = 0.017) were significantly lower in the skin graft with ADM group.

CONCLUSIONS

Skin graft with ADM results in better scar quality in objective and subjective aspects.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The acute effects of lower limb intermittent negative pressure on foot macro- and microcirculation in patients with peripheral arterial disease

Background

Intermittent negative pressure (INP) applied to the lower leg and foot increases foot perfusion in healthy volunteers. The aim of the present study was to describe the effects of INP to the lower leg and foot on foot macro- and microcirculation in patients with lower extremity peripheral arterial disease (PAD).

Methods

In this experimental study, we analyzed foot circulation during INP in 20 patients [median (range): 75 (63-84yrs)] with PAD. One leg was placed inside an air-tight vacuum chamber connected to an INP-generator. During application of INP (alternating 10s of -40mmHg/7s of atmospheric pressure), we continuously recorded blood flow velocity in a distal foot artery (ultrasound Doppler), skin blood flow on the pulp of the first toes (laser Doppler), heart rate (ECG), and systemic blood pressure (Finometer). After a 5-min baseline sequence (no pressure), a 10-min INP sequence was applied, followed by 5-min post-INP (no pressure). To compare and quantify blood flow fluctuations between sequences, we calculated cumulative up-and-down fluctuations in arterial blood flow velocity per minute.

Results

Onset of INP induced an increase in arterial flow velocity and skin blood flow. Peak blood flow velocity was reached 3s after the onset of negative pressure, and increased 46% [(95% CI 36–57), P<0.001] above baseline. Peak skin blood flow was reached 2s after the onset of negative pressure, and increased 89% (95% CI 48–130), P<0.001) above baseline. Cumulative fluctuations per minute were significantly higher during INP-sequences compared to baseline [21 (95% CI 12–30)cm/s/min to 41 (95% CI 32–51)cm/s/min, P<0.001]. Mean INP blood flow velocity increased significantly ~12% above mean baseline blood flow velocity [(6.7 (95% CI 5.2–8.3)cm/s to 7.5 (95% CI 5.9–9.1)cm/s, P = 0.03)].

Conclusion

INP increases foot macro- and microcirculatory flow pulsatility in patients with PAD. Additionally, application of INP resulted in increased mean arterial blood flow velocity.