Systematic review of molecular mechanism of action of negative-pressure wound therapy

Effectiveness of Closed Incision Negative Pressure Wound Therapy for Infrainguinal Bypass in the Vascular Quality Initiative

BACKGROUND

To analyze surgical site infections (SSIs) after infrainguinal bypass for standard dressings versus closed incision negative pressure wound therapy (ciNPWT) in the Society for Vascular Surgery's Vascular Quality Initiative (VQI).

METHODS

We retrospectively analyzed SSI after infrainguinal bypass procedures in the VQI from December 2019 to December 2021 comparing ciNPWT and standard dressings. The primary outcome of any superficial or deep wound infection at 30 days was analyzed in a subset of procedures with 30-day follow-up data (cohort A, n = 1,575). Secondary outcomes including in-hospital SSI, return to the operating room (OR) for infection, and length of stay (LOS) were analyzed for all procedures (cohort B, n = 9,288). Outcomes were analyzed in propensity-matched cohorts.

RESULTS

Patients who received ciNPWT (n = 1,389) were more likely to be female (34% vs. 32%, P = 0.04) with a higher rate of smoking history (90% vs. 86%, P = 0.003), diabetes (54% vs. 50%, P = 0.007), obesity (34% vs. 26%, P < 0.001), prior peripheral vascular intervention (57% vs. 51%, P < 0.001), and to prosthetic conduit (55% vs. 48%, P < 0.001) compared to patients with standard dressings (n = 7,899). After propensity matching of cohort A (n = 1,256), the 30-day SSI rate was 4% (12/341) in the ciNPWT and 6% (54/896) in the standard dressing group (P = 0.07, 95% CI 0.03-1.06). In the propensity-matched in-hospital cohort B (n = 5,435), SSI was 3% (35/1,371) in the ciNPWT group and 2% (95/4,064) in the standard dressing group (P = 0.66). There was no difference in the rate of return to the OR for infection, 1% (36/4,064) vs. 1% (19/1,371) (P = 0.13) or LOS, 9.0 vs. 9.0 days (P = 0.86) for the standard versus ciNPWT groups.

CONCLUSIONS

In this analysis of the VQI registry, the use of ciNPWT after infrainguinal bypass did not result in a statistically significant decrease in 30-day SSI. We recommend that surgeons consider the use of ciNPWT as part of a bundled process of care for high risk rather than all patients, as it may reduce SSI after infrainguinal bypass.

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.

Application of a meshed artificial dermal scaffold and negative-pressure wound therapy in the treatment of full-thickness skin defects: a prospective in vivo study

Artificial dermal scaffolds (ADSs) have great value in repairing deep skin defects. However, problems such as unsatisfactory angiogenesis and local dropsy or empyema often occur, resulting in delayed or even failed wound healing. Negative pressure wound therapy (NPWT) is an effective therapy to promote wound healing or shorten wound bed preparation time. Studies on whether it can improve the effects of ADSs have never been interrupted, and no consensus has been reached. In this study, an improved ADS was prepared by mesh technology, physicochemical experiments were conducted, cell adhesion and proliferation were assessed with the meshed ADS, and in vivo experiments were conducted to investigate the effects of meshed ADS or ADS combined with NPWT in repairing full-thickness skin defects. The results showed that the meshed ADS showed through-layer channels arranged in parallel longitudinal and transverse intersections. The cell experiments confirmed the good cytocompatibility. The in vivo experiments showed that there were no differences in the take rate or contraction of grafted skin among all experiment groups. The meshed ADS exhibited good histocompatibility, and there were no differences in tissue inflammation, dermal angiogenesis, or degradation among all groups. In addition, necrosis, dropsy, or empyema of the dermal scaffold were found in all experiment groups except for the meshed ADS + NPWT group, which showed better wound repair results, including fewer scaffold-related complications and satisfactory skin graft survival and wound contraction. In conclusion, this novel meshed ADS, which has a regular through-layer mesh structure and possesses stable physicochemical properties and good biocompatibility, combined with NPWT can ensure adequate subdermal drainage and reduce the risk of scaffold-related complications, thereby improving the quality and efficiency of wound repair, promoting a broader application of biomaterials, and helping physicians and readers implement more effective wound management.

Exploring an Innovative Approach: Integrating Negative-Pressure Wound Therapy with Silver Nanoparticle Dressings in Skin Graft Procedures

BACKGROUND

Skin grafting is a helpful instrument in a plastic surgeon's arsenal. Several types of dressings were designed to facilitate the process of graft integration. Negative-pressure wound therapy is a proven dressing method, enhancing graft survival through several mechanisms: aspiration of secretions, stimulation of neoangiogenesis, and promotion of an anti-inflammatory environment. Silver nanoparticle dressings also bring multiple benefits by bearing an antimicrobial effect and providing a humid medium, which are favorable for epithelialization. The combination of NPWT (negative-pressure wound therapy) with AgNPs (silver nanoparticles) has not been widely studied.

MATERIALS AND METHODS

This study aimed to compare the outcomes of silver nanoparticle sheets with the combination of negative-pressure wound therapy and silver nanoparticle dressings. We conducted a comparative prospective study on 80 patients admitted to the Plastic Surgery Department of "Prof. Dr. Agrippa Ionescu" Emergency Clinical Hospital between 1st of January 2020 and 31st of December 2022. The study population was randomized to receive either silver nanoparticle dressings or negative-pressure wound therapy (NPWT) combined with silver nanoparticle dressings. Various parameters were monitored, including patient comorbidities and graft-related data such as defect etiology, graft integration, and graft size. Dressings were changed, and graft status was evaluated at 7, 10, and 14 days postoperatively. Additionally, baseline C-reactive protein (CRP) levels were measured before surgery and 7, 10, and 14 days postoperatively.

RESULTS

The study demonstrated an enhanced integration of skin grafts at all evaluation stages when employing NPWT combined with AgNPs, particularly evident 10 days post operation. Significant variations in graft integration were also observed based on factors such as diabetes, cardiovascular disease, graft size, or the origin of the grafted defect. Moreover, dynamic C-reactive protein monitoring showed a statistically significant decrease in CRP levels 10 days post operation among patients treated with NPWT in conjunction with silver dressing, consistent with the nearly complete integration of skin grafts at this evaluation threshold.

CONCLUSION

Several factors influence the postoperative evolution of split-skin grafts. Postoperative dressings target local factors to enhance graft integration further. Our research demonstrated that the innovative combination of NPWT-assisted dressings, complemented by a silver nanoparticle sheet, resulted in improved benefits for graft integration and the alleviation of systemic inflammation.

Effectiveness of negative-pressure wound therapy to standard therapy in the prevention of complications after vascular surgery

Wound complications are common after vascular surgery and many may be preventable. Negative pressure wound therapy (NPWT) dressings may be able to reduce wound complications relating to closed incisions following vascular surgery and several devices are currently available along with a large body of literature. This review article will describe the use of NPWT dressings in vascular surgery. We will summarize the currently available systems, the likely mechanism of action of NWPT, the published studies to date and we will give our recommendations regarding the priorities for future research on this topic.

Effect of Negative Pressure Wound Therapy on Surgical Site Infections following Stoma Reversal in Colorectal Surgery: A Meta-Analysis

BACKGROUND

Surgical site infections (SSI) are common complications after surgery, which cause other complications and increase medical costs. However, the effect of negative-pressure wound therapy (NPWT) for the prevention of SSI at stoma reversal remains inconclusive, with controversial results. This meta-analysis aimed to evaluate the safety and efficacy of NPWT following stoma reversal in colorectal surgery to prevent SSI and other wound complications.

METHODS

We conducted a systematic search of the PubMed, EMBASE, and Cochrane Library databases for articles published up to July 2022 and identified relevant studies reporting the NPWT administration following stoma reversal in colorectal surgery compared with non-pressure dressing. The primary outcome was the incidence of SSI, and the secondary outcomes were hematoma, seroma, and length of hospital stay (LOS).

RESULTS

Nine studies were included in the meta-analysis, with 825 patients with (n = 310) or without (n = 515) NPWT. Pooled SSI rate was lower in the NPWT group than in the non-pressure dressing group (OR = 0.50; 95% CI: 0.29, 0.84; P = 0.01). There was no significant effect on hematoma (OR = 0.21; 95% CI: 0.03, 1.27; P = 0.09), seroma (OR = 0.26; 95% CI: 0.05, 1.28; P = 0.1) and LOS (MD = -0.16, 95% CI: -0.83, 0.51; P = 0.64).

CONCLUSION

The use of NPWT following stoma reversal in colorectal surgery reduced the incidence of SSI. However, this conclusion needs to be interpreted with caution, and further studies should be conducted to confirm in higher-quality RCTs.

Negative pressure wound therapy for flap closed-incisions after 3D-printed prosthesis implantation in patients with chronic osteomyelitis with soft tissue defects

BACKGROUND

The flap closed-incisions healing after 3D-printed prosthesis implantation in Chronic Osteomyelitis with Soft Tissue Defects (COSTD) is critical. This study aimed to explore the safety and effectiveness of Negative Pressure Wound Therapy (NPWT) in promoting flap closed-incisions healing.

METHODS

Retrospective analysis of clinical data was performed, including baseline, surgical and hospitalization information. The efficacy of NPWT was assessed by comparing the ASEPSIS scores, Visual Analogue Scale (VAS), Activity of Daily Living Scale (ADLS), and Lower Extremity Functional Scale (LEFS), as well as the major postoperative complications.

RESULTS

The study included 20 patients, 13 received conventional dressing (Control group) and 7 received NPWT treatment (NPWT group). These two groups exhibited a notable disparity in the distribution of ASEPSIS scores, and the median scores were 24 in Control group and 9 in NPWT group (p = 0.001). Eight patients in the Control group experienced major incisional complications, including 7 cases of exudation, 3 cases of infection, 2 cases of non-healing, and 1 case of dehiscence, while none were observed in the NPWT group (p = 0.015). The VAS, ADLS, and LEFS scores were significantly improved in the NPWT group compared to the Control group (p = 0.003, 0.017, and 0.043, respectively).

CONCLUSIONS

The study findings suggest that NPWT applied to the healing process of flap closed-incisions after 3D prosthesis implantation in patients with COSTD can reduce the occurrence of postoperative major complications and promote the recovery of lower limb function and daily activities, which should be recommended for clinical practice.

Molecular mechanisms of action of negative pressure wound therapy: a systematic review

Negative pressure wound therapy (NPWT) has significantly advanced wound care and continues to find new applications. Its effects at a molecular level however, remain a subject of debate. The aim of this systematic review is to summarize the current evidence regarding the molecular mechanisms of action of NPWT. Medline, Embase, EBSCO databases and clinical trial registries were searched from inception to January 2023. Clinical studies, animal models or in-vitro studies that quantitatively or semi-quantitatively evaluated the influence of NPWT on growth factors, cytokine or gene-expression in the circulation or wound-bed were included. Risk of Bias assessment was performed using the RoBANS tool for non-randomized studies, the COCHRANE's Risk of Bias 2(ROB-2) tool for randomized clinical studies, OHAT tool for in-vitro studies or the SYRCLE tool for animal model studies. A descriptive summary was collated and the aggregated data is presented as a narrative synthesis. This review included 19 clinical studies, 11 animal studies and 3 in-vitro studies. The effects of NPWT on 43 biomarkers and 17 gene expressions were studied across included studies. NPWT stimulates modulation of numerous local and circulating cytokines and growth factor expressions to promote an anti-inflammatory profile. This is most likely achieved by downregulation of TNFα, upregulation of VEGF, TGF-β and fibronectin.

Roles of negative pressure wound therapy for scar revision

The purpose of this study is to review the research progress of negative pressure wound therapy (NPWT) for scar revision and discuss the prospects of its further study and application. The domestic and foreign literatures on NPWT for scar revision were reviewed. The mechanism and application were summarized. NPWT improves microcirculation and lymphatic flow and stimulates the growth of granulation tissues in addition to draining secretions and necrotic tissue. As a significant clinical therapy in scar revision, NPWT reduces tension, fixes graft, and improves wound bed. In the field of scar revision, NPWT has been increasingly used as an innovative and constantly improving technology.

Efficacy of Strategies Intended to Prevent Surgical Site Infection After Lower Limb Revascularization Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The objective of this study is to evaluate the efficacy of strategies intended to prevent surgical site infection (SSI) after lower limb revascularization surgery.

BACKGROUND

SSIs are common, costly complications of lower limb revascularization surgery associated with significant morbidity and mortality.

METHODS

We searched MEDLINE, EMBASE, CENTRAL, and Evidence-Based Medicine Reviews (inception to April 28, 2022). Two investigators independently screened abstracts and full-text articles, extracted data, and assessed the risk of bias. We included randomized controlled trials (RCTs) that evaluated strategies intended to prevent SSI after lower limb revascularization surgery for peripheral artery disease. We used random-effects models to pool data and GRADE to assess certainty.

RESULTS

Among 6258 identified citations, we included 26 RCTs (n=4752 patients) that evaluated 12 strategies to prevent SSI. Preincision antibiotics [risk ratio (RR)=0.25; 95% CI, 0.11-0.57; n=4 studies; I2 statistic=7.1%; high certainty] and incisional negative-pressure wound therapy (iNPWT) (RR=0.54; 95% CI, 0.38-0.78; n=5 studies; I2 statistic=7.2%; high certainty) reduced pooled risk of early (≤30 days) SSI. iNPWT also reduced the risk of longer-term (>30 days) SSI (pooled-RR=0.44; 95% CI, 0.26-0.73; n=2 studies; I2 =0%; low certainty). Strategies with uncertain effects on risk of SSI included preincision ultrasound vein mapping (RR=0.58; 95% CI, 0.33-1.01; n=1 study); transverse groin incisions (RR=0.33; 95% CI, 0.097-1.15; n=1 study), antibiotic-bonded prosthetic bypass grafts (RR=0.74; 95% CI, 0.44-1.25; n=1 study; n=257 patients), and postoperative oxygen administration (RR=0.66; 95% CI, 0.42-1.03; n=1 study) (low certainty for all).

CONCLUSIONS

Preincision antibiotics and iNPWT reduce the risk of early SSI after lower limb revascularization surgery. Confirmatory trials are required to determine whether other promising strategies also reduce SSI risk.

The effectiveness of negative-pressure wound therapy for wound healing after stoma reversal: a randomized control study

Purpose

The purse-string closure (PSC) method is used for skin closure after stoma reversal to reduce surgical site infections (SSIs). However, PSC requires a longer healing period than primary closure. The application of negative-pressure wound therapy (NPWT) may reduce the healing period of many wound types. This study aimed to investigate whether the application of NPWT promotes wound healing after the PSC method for stoma reversal.

Methods

This study was a randomized controlled study. Patients who had undergone stoma reversal surgery were randomized to receive NPWT or simple dressing after surgery. The primary outcome was a complete wound-healing period. We also investigated SSI, hospital stay, total cost, and the patient and observer scar assessment scale (POSAS) as secondary outcomes.

Results

A total of 36 patients were randomized into 2 groups. The median wound healing period was shorter in the NPWT group than in the control group (17.5 days [range, 11-24 days] vs. 21.5 days [range, 14-41 days], P = 0.006). SSI rate and hospital stay did not differ between the groups. However, the number of dressings was lower in the NPWT group than in the control group (5 [range, 3-7] vs. 17 [range, 10-30], P < 0.001). The total cost for dressing was comparable between the groups. The POSAS was not different between the groups.

Conclusion

This study revealed that NPWT application after PSC for stoma reversal site is effective in reducing the wound healing period compared to simple dressing, without increasing SSI and total cost.

Negative-Pressure Wound Therapy (NPWT) in Horses: A Scoping Review

Obtaining a healthy wound environment that is conductive to healing in horses can be challenging. Negative-pressure wound therapy (NPWT) has been employed in humans to enhance wound healing for decades. The existing evidence for the effectiveness of NPWT remains uncertain in equine medicine. The aim of this review is to investigate NPWT applications and benefits in horses. A scoping review was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines for scoping reviews on three databases (PubMed, Web of Science-Thompson Reuters, and Wiley Online Library). Twenty-four manuscripts were considered. After removing duplicates, 17 papers underwent abstract screening. Of these, 16 + 1 (cited by others) were evaluated for eligibility according to PICOs, including no case reports/retrospective studies, four original articles, and three reviews. Fifteen manuscripts met the inclusion criteria. The focus of the articles was wound management; they included three reports of wounds communicating with synovial structures. Traumatic wounds and surgical-site infections are indications for NPWT. NPWT presents several advantages and few complications making it an attractive alternative to conventional wound management. However, randomized controlled trials should be performed to quantify the benefits and establish precise protocols in horses.

The three-tube method via precise interventional placement for esophagojejunal anastomotic fistula after gastrectomy: a single-center experience

BACKGROUND

Esophagojejunal anastomotic leakage is a serious complication after total gastrectomy. This study evaluated the safety and efficacy of transnasal placement of drainage catheter, jejunal decompression tube, and jejunal nutrition tube under fluoroscopy for treatment of esophagojejunal anastomotic fistula after gastrectomy in gastric cancer patients.

METHODS

This is retrospective review of patients with esophagojejunal anastomotic fistula treated with transnasal placement of abscess drainage catheter, decompression tube, and jejunal nutrition tube under fluoroscopy. Fistula healing time, patient survival, and Eastern Cooperative Oncology Group (ECOG) performance status before and after treatment were evaluated.

RESULTS

Sixty-four patients were included in the study. Insertion of the transnasal abscess drainage catheter, decompression tube, and jejunal nutrition tube was successful on the first attempt in all patients, while 35 patients received transnasal abscess drainage, 13 received percutaneous abscess drainage, and 16 received transnasal drainage plus percutaneous abscess drainage. Immediately after placement of the tube, the mean volume of drainage was 180 mL (range, 10-850 mL); the amount steadily decreased from then on. The clinical success rate was 84.3% (54/64). Median time to fistula healing was 58 days (range, 7-357 days).

CONCLUSIONS

Transnasal insertion of transnasal abscess drainage catheter, jejunal decompression tube, and jejunal nutrition tube under fluoroscopy appears to be a simple, minimally invasive, effective, and safe method for treating esophagojejunal anastomotic fistula after gastrectomy.

Applications of endoscopic vacuum therapy in the upper gastrointestinal tract

Endoscopic vacuum therapy (EVT) is an increasingly popular treatment option for wall defects in the upper gastrointestinal tract. After its initial description for the treatment of anastomotic leaks after esophageal and gastric surgery, it was also implemented for a wide range of defects, including acute perforations, duodenal lesions, and postbariatric complications. Apart from the initially proposed handmade sponge inserted using the “piggyback” technique, further devices were used, such as the commercially available EsoSponge and VAC-Stent as well as open-pore film drainage. The reported pressure settings and intervals between the subsequent endoscopic procedures vary greatly, but all available evidence highlights the efficacy of EVT, with high success rates and low morbidity and mortality, so that in many centers it is considered to be a first-line treatment, especially for anastomotic leaks.

Sprayable Berberine-Silk Fibroin Microspheres with Extracellular Matrix Anchoring Function Accelerate Infected Wound Healing through Antibacterial and Anti-inflammatory Effects

The conventional method of applying local medications for treating wound infections is often ineffective because of the dilution of drugs by the excess wound exudate. In addition, there have been insufficient studies investigating the adhesion between drug-loaded nanomaterials and cells or tissue. To address this intractable problem, berberine-silk fibroin microspheres (Ber@MPs) with an extracellular matrix-anchoring function were developed in this study. The microspheres were prepared from silk fibroin using the polyethylene glycol emulsion precipitation method. Subsequently, berberine was loaded onto the microspheres. Our results revealed that Ber@MPs firmly anchored to cells, continuously releasing berberine in the microenvironment. Moreover, both Ber@MPs and Ber@MPs-cell complexes exerted a strong and long-lasting antibacterial effect against Staphylococcus aureus and Staphylococcus epidermidis in the microenvironment, despite the large amount of wound exudate. In addition, Ber@MPs effectively resisted the inflammatory response induced by lipopolysaccharides and accelerated the migration of fibroblasts and neovascularization of endothelial cells cultured in inflammation-induced media. Finally, the in vivo experiments confirmed that the Ber@MP spray accelerated the healing of infected wounds via its antibacterial and anti-inflammatory effects. Therefore, this study provides a novel strategy for treating infected wounds in the presence of excess exudate.

Liver insulin-like growth factor-1 mediates effects of low-intensity vibration on wound healing in diabetic mice

Chronic wounds in diabetic patients are associated with significant morbidity and mortality; however, few therapies are available to improve healing of diabetic wounds. Our group previously reported that low-intensity vibration (LIV) could improve angiogenesis and wound healing in diabetic mice. The purpose of this study was to begin to elucidate the mechanisms underlying LIV-enhanced healing. We first demonstrate that LIV-enhanced wound healing in db/db mice is associated with increased IGF1 protein levels in liver, blood, and wounds. The increase in insulin-like growth factor (IGF) 1 protein in wounds is associated with increased Igf1 mRNA expression both in liver and wounds, but the increase in protein levels preceded the increase in mRNA expression in wounds. Since our previous study demonstrated that liver was a primary source of IGF1 in skin wounds, we used inducible ablation of IGF1 in the liver of high-fat diet (HFD)-fed mice to determine whether liver IGF1 mediated the effects of LIV on wound healing. We demonstrate that knockdown of IGF1 in liver blunts LIV-induced improvements in wound healing in HFD-fed mice, particularly increased angiogenesis and granulation tissue formation, and inhibits the resolution of inflammation. This and our previous studies indicate that LIV may promote skin wound healing at least in part via crosstalk between the liver and wound. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Influence of advanced wound matrices on observed vacuum pressure during simulated negative pressure wound therapy

Biomaterials and negative pressure wound therapy (NPWT) are treatment modalities regularly used together to accelerate soft-tissue regeneration. This study evaluated the impact of the design and composition of commercially available collagen-based matrices on the observed vacuum pressure delivered under NPWT using a custom test apparatus. Specifically, testing compared the effect of the commercial products; ovine forestomach matrix (OFM), collagen/oxidized regenerated cellulose (collagen/ORC) and a collagen-based dressing (CWD) on the observed vacuum pressure. OFM resulted in an ∼50% reduction in the observed target vacuum pressure at 75 mmHg and 125 mmHg, however, this effect was mitigated to a ∼0% reduction when fenestrations were introduced into the matrix. Both collagen/ORC and CWD reduced the observed vacuum pressure at 125 mmHg (∼15% and ∼50%, respectively), and this was more dramatic when a lower vacuum pressure of 75 mmHg was delivered (∼20% and ∼75%, respectively). The reduced performance of the reconstituted collagen products is thought to result from the gelling properties of these products that may cause occlusion of the delivered vacuum to the wound bed. These findings highlight the importance of in vitro testing to establish the impact of adjunctive therapies on NPWT, where effective delivery of vacuum pressure is paramount to the efficacy of this therapy.

Negative-Pressure Wound Therapy: What We Know and What We Need to Know

Negative-pressure wound therapy (NPWT) promotes wound healing by applying negative pressure to the wound surface. A quarter of a century after its introduction, NPWT has been used in various clinical conditions, although molecular biological evidence is insufficient due to delay in basic research. Here, we have summarized the history of NPWT, its mechanism of action, what is currently known about it, and what is expected to be known in the future. Particularly, attention has shifted from the four main mechanisms of NPWT to the accompanying secondary effects, such as effects on various cells, bacteria, and surgical wounds. This chapter will help the reader to understand the current status and shortcomings of NPWT-related research, which could aid in the development of basic research and, eventually, clinical use with stronger scientific evidence.

Combined computational analysis and cytology show limited depth osteogenic effect on bone defects in negative pressure wound therapy

Background: The treatment of bone defects remains a clinical challenge. The effect of negative pressure wound therapy (NPWT) on osteogenesis in bone defects has been recognized; however, bone marrow fluid dynamics under negative pressure (NP) remain unknown. In this study, we aimed to examine the marrow fluid mechanics within trabeculae by computational fluid dynamics (CFD), and to verify osteogenic gene expression, osteogenic differentiation to investigate the osteogenic depth under NP. Methods: The human femoral head is scanned using micro-CT to segment the volume of interest (VOI) trabeculae. The VOI trabeculae CFD model simulating the bone marrow cavity is developed by combining the Hypermesh and ANSYS software. The effect of trabecular anisotropy is investigated, and bone regeneration effects are simulated under NP scales of -80, -120, -160, and -200 mmHg. The working distance (WD) is proposed to describe the suction depth of the NP. Finally, gene sequence analysis, cytological experiments including bone mesenchymal stem cells (BMSCs) proliferation and osteogenic differentiation are conducted after the BMSCs are cultured under the same NP scale. Results: The pressure, shear stress on trabeculae, and marrow fluid velocity decrease exponentially with an increase in WD. The hydromechanics of fluid at any WD inside the marrow cavity can be theoretically quantified. The NP scale significantly affects the fluid properties, especially those fluid close to the NP source; however, the effect of the NP scale become marginal as WD deepens. Anisotropy of trabecular structure coupled with the anisotropic hydrodynamic behavior of bone marrow; An NP of -120 mmHg demonstrates the majority of bone formation-related genes, as well as the most effective proliferation and osteogenic differentiation of BMSCs compared to the other NP scales. Conclusion: An NP of -120 mmHg may have the optimal activated ability to promote osteogenesis, but the effective WD may be limited to a certain depth. These findings help improve the understanding of fluid mechanisms behind NPWT in treating bone defects.

Negative Pressure Wound Therapy: Supra-Physiological or Just Physical Effects of Positive Pressure?

This communication provides a new insight into the unexplained physiology of beneficial effects of negative pressure wound therapy (NPWT). Possible mechanisms of beneficial effects of NPWT in failing replantation and free tissue transfer are discussed. Positive pressure generated by NPWT as well as its draining action creates exudate-free tight tissue-to-tissue interface, which may enhance neovascularization.

Evolution of Negative Pressure Wound Therapy in Orthopaedic Trauma

Negative Pressure Wound Therapy (NPWT) has evolved from open wound management to now include closed incision management. It has been a major advance in the management of open wounds and closed incisional wounds especially in orthopaedic trauma surgery. Because of the success of NPWT in the late 1990s and early 2000s, surgeons began using NPWT with adjuncts on closed incisions as a way to help prevent surgical wound dehiscence especially in at-risk patients for wound problems. It has been well established that obesity, diabetes, and smoking in addition to other comorbidities increase the risk of wound dehiscence and surgical site infections in orthopaedic patients. It is widely used for open wound management, often associated with open fractures, and in the mitigation of risk of surgical site infections over closed incisions (incisional negative pressure wound therapy). Newer systems allow the use of various topical wound solutions to be instilled in conjunction with NPWT, termed NPWTi-d. This has shown promising results in difficult wounds that may be resistant to standard NPWT. This article reviews the evolution and use of NPWT in orthopaedic trauma.

The Association between Neoadjuvant Radio-Chemotherapy and Prolonged Healing of Anastomotic Leakage after Esophageal Resection Treated with EndoVAC Therapy

(1) Background: Endoscopic vacuum therapy (EVT) has become the mainstay in the treatment of early anastomotic leakage (AL) after esophageal resection. The effect of nRCT on the efficacy of EVT is currently unknown. (2) Methods: Data of 427 consecutive patients undergoing minimally invasive esophagectomy between 2013 and 2022 were analyzed. A total of 26 patients received EVT for AL after esophagectomy between 2010 and 2021. We compared a cohort of 13 patients after treatment with EVT for anastomotic leakage after neoadjuvant radiochemotherapy (nRCT) with a control group of 13 patients after neoadjuvant chemotherapy (nCT) using inverse propensity score weighting to adjust for baseline characteristics between the groups. EVT therapy was assessed regarding patient survival, treatment failure as defined by a change in treatment to stent/operation, duration of treatment, and secondary complications. Statistical analysis was performed using linear regression analysis. (3) Results: Time to EVT after initial tumor resection did not vary between the groups. The duration of EVT was longer in patients after nRCT (14.69 days vs. 20.85 days, p = 0.002) with significantly more interventions (4.38 vs. 6.85, p = 0.001). The success rate of EVT did not differ between the two groups (nCT n = 8 (61.54%) vs. nCT n = 5 (38.46%), p = 0.628). The rate of operative revision did not vary between the groups. Importantly, no mortality was reported within 30 days and 90 days in both groups. (4) Conclusions: EVT is a valuable tool for the management of AL after esophageal resection in patients after nRCT. While the success rates were comparable, EVT was associated with a significantly longer treatment duration. Anastomotic leakages after nRCT often require prolonged and multimodal treatment strategies while innovative strategies such as prophylactic endoVAC placement or use of a VAC-Stent may be considered.

Effectiveness of prophylactic application of negative pressure wound therapy in stopping surgical site wound problems for closed incisions in breast cancer surgery: A meta-analysis

We performed a meta-analysis to evaluate the effect of prophylactic application of negative pressure wound therapy in stopping surgical site wound problems for closed incisions in breast cancer surgery. A systematic literature search up to April 2022 was performed and 2223 women with closed incisions in breast cancer surgery at the baseline of the studies; 964 of them were using the prophylactic application of negative pressure wound therapy, and 1259 were using standard dressings. Odds ratio (OR) with 95% confidence intervals (CIs) were calculated to assess the effect of prophylactic application of negative pressure wound therapy in stopping surgical site wound problems for closed incisions in breast cancer surgery using the dichotomous method with a random or fixed-effect model. The prophylactic application of negative pressure wound therapy women had a significantly lower total wound problems (OR, 0.62; 95% CI, 0.43-0.90, P = .01), lower surgical site wound infection (OR, 0.59; 95% CI, 0.36-0.96, P = .03), lower wound dehiscence (OR, 0.54; 95% CI, 0.39-0.75, P < .001) and lower wound necrosis (OR, 0.44; 95% CI, 0.27-0.71, P < .001), in women with closed incisions in breast cancer surgery compared with standard dressings. However, prophylactic application of negative pressure wound therapy did not show any significant difference in wound seroma (OR, 0.73; 95% CI, 0.32-1.65, P = .45), and hematoma (OR, 0.73; 95% CI, 0.33-1.59, P = .001) compared with standard dressings in women with closed incisions in breast cancer surgery. The prophylactic application of negative pressure wound therapy women had a significantly lower total wound problems, surgical site wound infection, wound dehiscence, and wound necrosis and no significant difference in wound seroma, and hematoma compared with standard dressings in women with closed incisions in breast cancer surgery. The analysis of outcomes should be with caution because of the low sample size of 5 out of 12 studies in the meta-analysis and a low number of studies in certain comparisons.

Negative pressure wound therapy for surgical wounds healing by primary closure

BACKGROUND

Indications for the use of negative pressure wound therapy (NPWT) are broad and include prophylaxis for surgical site infections (SSIs). Existing evidence for the effectiveness of NPWT on postoperative wounds healing by primary closure remains uncertain.

OBJECTIVES

To assess the effects of NPWT for preventing SSI in wounds healing through primary closure, and to assess the cost-effectiveness of NPWT in wounds healing through primary closure.

SEARCH METHODS

In January 2021, we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries and references of included studies, systematic reviews and health technology reports. There were no restrictions on language, publication date or study setting.

SELECTION CRITERIA

We included trials if they allocated participants to treatment randomly and compared NPWT with any other type of wound dressing, or compared one type of NPWT with another.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed trials using predetermined inclusion criteria. We carried out data extraction, assessment using the Cochrane risk of bias tool, and quality assessment according to Grading of Recommendations, Assessment, Development and Evaluations methodology. Our primary outcomes were SSI, mortality, and wound dehiscence.

MAIN RESULTS

In this fourth update, we added 18 new randomised controlled trials (RCTs) and one new economic study, resulting in a total of 62 RCTs (13,340 included participants) and six economic studies. Studies evaluated NPWT in a wide range of surgeries, including orthopaedic, obstetric, vascular and general procedures. All studies compared NPWT with standard dressings. Most studies had unclear or high risk of bias for at least one key domain. Primary outcomes Eleven studies (6384 participants) which reported mortality were pooled. There is low-certainty evidence showing there may be a reduced risk of death after surgery for people treated with NPWT (0.84%) compared with standard dressings (1.17%) but there is uncertainty around this as confidence intervals include risk of benefits and harm; risk ratio (RR) 0.78 (95% CI 0.47 to 1.30; I² = 0%). Fifty-four studies reported SSI; 44 studies (11,403 participants) were pooled. There is moderate-certainty evidence that NPWT probably results in fewer SSIs (8.7% of participants) than treatment with standard dressings (11.75%) after surgery; RR 0.73 (95% CI 0.63 to 0.85; I² = 29%). Thirty studies reported wound dehiscence; 23 studies (8724 participants) were pooled. There is moderate-certainty evidence that there is probably little or no difference in dehiscence between people treated with NPWT (6.62%) and those treated with standard dressing (6.97%), although there is imprecision around the estimate that includes risk of benefit and harms; RR 0.97 (95% CI 0.82 to 1.16; I² = 4%). Evidence was downgraded for imprecision, risk of bias, or a combination of these. Secondary outcomes There is low-certainty evidence for the outcomes of reoperation and seroma; in each case, confidence intervals included both benefit and harm. There may be a reduced risk of reoperation favouring the standard dressing arm, but this was imprecise: RR 1.13 (95% CI 0.91 to 1.41; I² = 2%; 18 trials; 6272 participants). There may be a reduced risk of seroma for people treated with NPWT but this is imprecise: the RR was 0.82 (95% CI 0.65 to 1.05; I² = 0%; 15 trials; 5436 participants). For skin blisters, there is low-certainty evidence that people treated with NPWT may be more likely to develop skin blisters compared with those treated with standard dressing (RR 3.55; 95% CI 1.43 to 8.77; I² = 74%; 11 trials; 5015 participants). The effect of NPWT on haematoma is uncertain (RR 0.79; 95 % CI 0.48 to 1.30; I² = 0%; 17 trials; 5909 participants; very low-certainty evidence). There is low-certainty evidence of little to no difference in reported pain between groups. Pain was measured in different ways and most studies could not be pooled; this GRADE assessment is based on all fourteen trials reporting pain; the pooled RR for the proportion of participants who experienced pain was 1.52 (95% CI 0.20, 11.31; I² = 34%; two studies; 632 participants). Cost-effectiveness Six economic studies, based wholly or partially on trials in our review, assessed the cost-effectiveness of NPWT compared with standard care. They considered NPWT in five indications: caesarean sections in obese women; surgery for lower limb fracture; knee/hip arthroplasty; coronary artery bypass grafts; and vascular surgery with inguinal incisions. They calculated quality-adjusted life-years or an equivalent, and produced estimates of the treatments' relative cost-effectiveness. The reporting quality was good but the evidence certainty varied from moderate to very low. There is moderate-certainty evidence that NPWT in surgery for lower limb fracture was not cost-effective at any threshold of willingness-to-pay and that NPWT is probably cost-effective in obese women undergoing caesarean section. Other studies found low or very low-certainty evidence indicating that NPWT may be cost-effective for the indications assessed.

AUTHORS' CONCLUSIONS

People with primary closure of their surgical wound and treated prophylactically with NPWT following surgery probably experience fewer SSIs  than people treated with standard dressings but there is probably no difference in wound dehiscence (moderate-certainty evidence). There may be a reduced risk of death after surgery for people treated with NPWT compared with standard dressings but there is uncertainty around this as confidence intervals include risk of benefit and harm (low-certainty evidence). People treated with NPWT may experience more instances of skin blistering compared with standard dressing treatment (low-certainty evidence). There are no clear differences in other secondary outcomes where most evidence is low or very low-certainty. Assessments of cost-effectiveness of NPWT produced differing results in different indications. There is a large number of ongoing studies, the results of which may change the findings of this review. Decisions about use of NPWT should take into account surgical indication and setting and consider evidence for all outcomes.

A new hybrid stent using endoscopic vacuum therapy in treating esophageal leaks: a prospective single-center experience of its safety and feasibility with mid-term follow-up

Self-expandable metal stents (SEMS) and endoscopic vacuum therapy (EVT) are endoscopic options for treating leaks of the esophagus. VACStent® is a variant of SEMS that aims to combine the advantages of SEMS and EVT in one device. Due to this unique construction, VACStent® can build a barrier to the leak and facilitate wound healing with EVT, all while maintaining intestinal passage. We present the first prospective feasibility study of VACStent® for treating leaks of the upper gastrointestinal tract. Between September 2019 and November 2020, we performed a prospective, investigator-initiated, single-center study and included all patients who underwent endoscopic stenting with VACStent® for various kinds of esophageal leaks, such as spontaneous, iatrogenic or anastomotic leaks. We included 20 patients, who underwent a total of 24 endoscopic VACStent® implantations. Technical success of the application of the VACStent® was achieved in all interventions (n = 24, 100%). Overall, clinical success in closing the leaks with VACStent® treatment was achieved in 60% of patients (12/20). No severe VACStent® treatment-related adverse events occurred. Oral feeding with supplement high-energy drinks failed in all patients due to clogging of the suction tube. VACStent® is a safe and feasible endoscopic treatment option for leaks of the upper gastrointestinal tract. However, our data could not show the expected advantage of orally feeding the patients during the treatment with the VACStent® in its current form. Efficacy of VACStent® compared to EVT or SEMS needs to be investigated in a further study. ClinicalTrials.gov Identifier: NCT03962179.

The effects of negative pressure wound therapy on wounds with cerebrospinal fluid leakages

Objective:

Negative pressure wound therapy (NPWT) has been widely used for a variety of wounds with good outcomes. However, it is contraindicated in the management of wounds with cerebrospinal fluid (CSF) leakages. The reason is the fear of a sudden shift of CSF fluid as a result of suction leading to brain herniation or coning. There is a paucity of data to either support or negate such claims. We aimed to determine the effect of NPWT in the management of patients with wounds with CSF leakages.

Method:

This was a longitudinal prospective study of patients having wounds with CSF leakages managed with NPWT in our institute. Outcome measures evaluated were changes in the level of consciousness, Glasgow Coma Scale (GCS) score, length of hospital stay, mean effluent collected, time taken for the wounds to heal/close and complications related to NPWT.

Results:

A total of 12 patients with wounds that had CSF leakage were managed with NPWT over two years. Of the patients, nine had wounds in communication with the brain, with three patients having spinal cord wounds. The average effluent collected on the first day of applying NPWT was 510ml, and by the third day this had fallen to approximately 200ml. The mean time taken for wounds to close was 12.3 days. There was no evidence of herniation nor any other morbidities or mortalities reported in any of our patients.

Conclusion:

NPWT, as indicated in this series, had a beneficial effect in the management of wounds with CSF leakage. NPWT, once applied to the wound, caused a tamponade effect that resulted in stoppage of the leakage of the CSF and did not lead to suction of the fluid, as previously thought. The dressings ensured an airtight system, preventing communication between the wound and the external environment, thus reducing sepsis while awaiting definitive wound closure.

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.

Characterization of Macrophage and Cytokine Interactions with Biomaterials Used in Negative-Pressure Wound Therapy

Macrophages are innate immune cells that help wounds heal. Here, we study the potential immunomodulatory effects of negative-pressure wound therapy (NPWT) materials on the macrophage inflammatory response. We compared the effects of two materials, Granufoam™ (GF) and Veraflo Cleanse™ (VC), on macrophage function in vitro. We find that both materials cause reduced expression of inflammatory genes, such as TNF and IL1B, in human macrophages stimulated with bacterial lipopolysaccharide (LPS) and interferon-gamma (IFNγ). Relative to adherent glass control surfaces, VC discourages macrophage adhesion and spreading, and may potentially sequester LPS/IFNγ and cytokines that the cells produce. GF, on the other hand, was less suppressive of inflammation, supported macrophage adhesion and spreading better than VC, and sequestered lesser quantities of LPS/IFNγ in comparison to VC. The control dressing material cotton gauze (CT) was also immunosuppressive, capable of TNF-α retention and LPS/IFNγ sequestration. Our findings suggest that NPWT material interactions with cells, as well as soluble factors including cytokines and LPS, can modulate the immune response, independent of vacuum application. We have also established methodological strategies for studying NPWT materials and reveal the potential utility of cell-based in vitro studies for elucidating biological effects of NPWT materials.

Circular RNA Expression Profiles Following Negative Pressure Wound Therapy in Burn Wounds with Experimental Pseudomonas aeruginosa Infection

Infections of burn wounds, especially those caused by Pseudomonas aeruginosa, could trigger sepsis or septic shock, which is the main cause of death after burn injury. Compared with traditional saline-wet-to-dry dressings, negative pressure wound therapy (NPWT) is more effective for the prevention and treatment of wound infections. However, the mechanism by which NPWT controls infection and accelerates wound healing remains unclear. Accordingly, in this study, the molecular mechanisms underlying the effects of NPWT were explored using a murine model of P. aeruginosa-infected burn wounds. NPWT significantly reduced P. aeruginosa levels in wounds, enhanced blood flow, and promoted wound healing. Additionally, NPWT markedly alleviated wound inflammation and increased the expression of wound healing–related molecules. Recent evidence points to a role of circular RNAs (circRNAs) in wound healing; hence, whole-transcriptome sequencing of wound tissues from NPWT and control groups was performed to evaluate circRNA expression profiles. In total, 12 up-regulated and 25 down-regulated circRNAs were identified between groups. Among these, five significant differentially expressed circRNAs acting as microRNA sponges were identified, and their predicted targets were verified by reverse transcription-quantitative polymerase chain reaction. These results further support the roles of circRNAs in wound healing by NPWT and the prevention of P. aeruginosa infection, providing key molecular targets for further functional analyses.

Roles of Oxidative Stress and Raftlin in Wound Healing Under Negative-Pressure Wound Therapy

Background

Negative-pressure wound therapy (NPWT) is an effective way to promote wound healing. However, its mechanisms have not been investigated thoroughly. Growing evidence suggests that oxidative stress and Raftlin levels play important roles in wound healing. However, whether NPWT promotes wound healing through this mechanism remains unclear.

Purpose

Our study focuses on the different levels of oxidative stress and antioxidant response between wounds treated by NPWT and routine dressing change. The objective of this study was to measure the differences in Raftlin levels between the two groups, which is a new biomarker related to wound healing.

Methods

We divided 48 male Sprague-Dawley rats with identical full-thickness skin defects into two groups. At specific times (0, 3, 5, 7, 9, 11, and 13 days after surgery), wound tissue samples were obtained for immunohistochemistry and biochemical analysis. The expression of Raftlin and levels of oxidative stress, including malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) levels were measured by biochemical analysis. Wound-healing times were also compared.

Results

In the NPWT group, MDA levels were significantly decreased on days 3, 5, and 7. Furthermore, the expressions of SOD and CAT were significantly reduced on days 3 and 5. Our data also revealed that Raftlin was significantly upregulated across the whole period of wound healing. Moreover, wound healing in the NPWT group was significantly more rapid (16 days on average) than in the control group (24 days on average). On day 13 post surgery, the wound-healing percentage in the NPWT group was 91%, while that in the control group was 48%.

Conclusion

NPWT may promote wound healing by upregulating Raftlin and inhibiting oxidative stress levels.

A Novel Hybrid Stent with Endoscopic Vacuum Therapy for Treating Leaks of the Upper Gastrointestinal Tract

Introduction

Self-expanding metal stents (SEMS) are an established option for treating leaks in the upper gastrointestinal tract, and endoscopic vacuum therapy (EVT) has become a promising alternative. A novel approach is the use of an esophageal hybrid SEMS (VACStent®), which can maintain esophageal passage during EVT. We present the first study demonstrating successful use of the VACStent® for treating leaks of the upper gastrointestinal tract.

Method

We performed a retrospective, single-center study of all patients who underwent endoscopic stenting with the VACStent® of leaks in the upper gastrointestinal tract.

Results

Indications for treatment with the VACStent® were: iatrogenic esophageal perforation (n = 1), spontaneous perforation (n = 2), esophageal fistula (n = 2), and anastomotic leak after upper gastrointestinal surgery (n = 5). Successful application of the VACStent® was achieved in all patients (n = 10; 100%) with a total of 15 interventions. VACStent® therapy was used as a first-line treatment in 5 patient (success rate 80%; 4 out 5 patients) and as a second-line treatment after failed previous endoscopic therapy in 5 patients (success rate 60%; 3 out of 5 patients). Overall, VACStent® treatment was successful in 70% of the patients (7 out of 10). No severe VACStent® treatment-related adverse events occurred.

Conclusion

The initial experience has been that the technical application of the VACStent® is safe and technically feasible. However, due to the small number of patients this study could not show the clear advantages of this novel hybrid stent. More studies are necessary to show significant advantages.

Use of Negative Pressure Wound Therapy in the Treatment of Limb Wounds: A Case Series of 42 Horses

Traumatic limb injuries are common in horses. Negative pressure wound therapy (NPWT) has been proven to promote wound healing in human medicine. It has also been described for the treatment of wounds in horses. In this retrospective study, clinical records of 42 (n = 42) animals were assessed. Categories of wounds, duration of NPWT application, frequency of resetting the NPWT device, technical complications, and tolerance to the procedure were recorded. 42 wounds were classified as bony (n = 15; 36 %), articular (n = 14; 33 %), tenosynovial (n = 9; 21%), muscular (n = 2; 5%) and cutaneous (n = 2; 5 %). NPWT was used to help (1) first intention healing by preoperative (n = 3; 7 %) or postoperative (n = 7; 17%) application, (2) second intention healing (n = 31; 74%), and (3) delayed primary closure (n = 1; 2%). Duration of NPWT application ranged from 2 to 36 days (mean 11.5), with the system staying in place for periods ranging from 1 to 7 days (mean 4.5). In 69% (n = 29) of the cases, healing was considered satisfactory at discharge. 26 % (n = 11) of horses were discharged whilst ideally NPWT should have been continued. 2 animals (n = 2; 5%) were euthanized after surgery due to unrelenting pain. The procedure was well tolerated except in 1 horse who showed signs of discomfort at the first application. This study demonstrated that NPWT with long periods of application can be used successfully to manage various types of limb wounds.

Filling the vacuum: Role of negative pressure wound therapy in open wound management in cats

Practical relevance:

Open wounds and their treatment present a common challenge in veterinary practice. Approaching 15 years ago negative pressure wound therapy (NPWT) started to be incorporated into clinical veterinary medicine, and its availability is becoming more widespread in Europe and the USA. Use of this therapy has the potential to significantly increase the healing rate of open wounds as well as free skin grafts in small animals, and it has been occasionally described for the management of feline wounds.

Aim:

This review describes the mechanisms of action of, and indications for, NPWT, and offers recommendations for NPWT specific to feline patients.

Evidence base:

The information presented is based on the current evidence and the author’s clinical experience of the technique gained over the past 12 years. Comparative studies of different treatment options are lacking and, since wound healing in cats and dogs differs, cat-specific studies are especially needed. Well-designed wound healing studies comparing different advanced techniques will improve open wound healing in cats in the future, and potentially allow better understanding of the role of NPWT in this setting.

Adipose-Derived Stem Cell Conditioned Medium and Wound Healing: A Systematic Review

Adipose-derived stem cells (ASCs) have been growing in popularity for their potential in wound healing and tissue engineering. Stem cell therapies are limited in application, with the need to maintain cell viability and function as well as safety concerns. It has been increasingly reported that the effects of ASCs are predominantly attributable to the paracrine effects of the secreted factors, which can be collected in conditioned medium (CM). The goal of this systematic review is to investigate the effects on wound healing of CM collected from ASC culture. Original articles relevant to ASC-CM and wound healing (in vitro: dermal fibroblast, epidermal keratinocytes and their equivalent cell lines; in vivo: full-thickness wound models) were included. The agreement level of selections between two investigators were calculated by the kappa scores. And the information concerning to the publications, CM preparation and its application and effects were extracted and reported in a systematic way and summarized in tables. In total, 121 publications were initially identified through a search of the PubMed/MEDLINE database with a specific search algorithm, and 36 articles were ultimately included after two screenings. Nineteen were in vitro studies that met the search criteria and 17 were in vivo studies with or without in vitro data. In summary, based on the included articles, treatment with ASC conditioned medium (ASC-CM), to a large extent, resulted in positive effects on wound healing in vitro and in vivo. Modulation of the culture conditions of ASCs producing the CM, including hypoxic conditions, alternative substrates, medium supplementation, as well as genetic modification of cells, favorably promoted the effects of ASC-CM. Finally, a discussion of the future perspectives and therapeutic potential of ASC-CM, which also addresses the limitations of the field, is presented. A limitation of the evidence is the inconsistency in CM preparation methods among included articles. In conclusion, ASC-CM is a promising novel cell-free therapy for wound healing in regenerative medicine and warrants further exploration.

Surgical multidisciplinary approach in the management of odontogenic or non-odontogenic neck infections

In recent years, in our university hospital, the number of odontogenic and non-odontogenic abscesses has been rapidly increasing. We included 70 patients from January 4^th 2018 to February 19^th 2020 affected by the odontogenic ones. Deep neck infection can spread to the chest and is associated with high morbidity and mortality. The purpose of this mini-review is to demonstrate that, in case of complications, a multidisciplinary approach is needed to treat these infections, so that all practitioners should work together to achieve the patient’s rapid recovery.

Cost-effectiveness of adjunctive negative pressure wound therapy in paediatric burn care: evidence from the SONATA in C randomised controlled trial

Negative pressure wound therapy (NPWT) has been shown to improve clinical outcomes for children with burns by accelerating wound re-epithelialisation. Its effects on healthcare costs, however, remain poorly understood. The aim of this study was to evaluate the cost-effectiveness of NPWT from a healthcare provider perspective using evidence from the SONATA in C randomised controlled trial, in which 101 children with small-area burns were allocated to either standard care (silver-impregnated dressings) or standard care in combination with adjunctive NPWT. The primary outcome, time to re-epithelialisation, was assessed through a blinded photographic review. Resource usage and costs were prospectively recorded for each participant for up to 6 months. Incremental cost-effectiveness ratios and dominance probabilities were estimated and uncertainty quantified using bootstrap resampling. Mean costs per participant—including dressings, labour, medication, scar management, and theatre operations—were lower in the NPWT group (AUD $903.69) relative to the control group (AUD $1669.01). There was an 89% probability that NPWT was dominant, yielding both faster re-epithelialisation and lower overall costs. Findings remained robust to sensitivity analyses employing alternative theatre costs and time-to-re-epithelialisation estimates for grafted patients. In conclusion, adjunctive NPWT is likely to be a cost-effective and dominant treatment for small-area paediatric burns (ANZCTR.org.au:ACTRN12618000256279).

The Horse as a Model for the Study of Cutaneous Wound Healing

Significance: Cutaneous wounds are a major problem in both human and equine medicine. The economic cost of treating skin wounds and related complications in humans and horses is high, and in both species, particular types of chronic wounds do not respond well to current therapies, leading to suffering and morbidity. Recent Advances: Conventional methods for the treatment of cutaneous wounds are generic and have not changed significantly in decades. However, as more is learned about the mechanisms involved in normal skin wound healing, and how failure of these processes leads to chronic nonhealing wounds, novel therapies targeting the specific pathologies of hard-to-heal wounds are being developed and evaluated. Critical Issues: Physiologically relevant animal models are needed to (1) study the mechanisms involved in normal and impaired skin wound healing and (2) test newly developed therapies. Future Directions: Similarities in normal wound healing in humans and horses, and the natural development of distinct types of hard-to-heal chronic wounds in both species, make the horse a physiologically relevant model for the study of mechanisms involved in wound repair. Horses are also well-suited models to test novel therapies. In addition, studies in horses have the potential to benefit veterinary, as well as human medicine.

Large abdominal hernia repair with closed incision negative pressure therapy: a case series

OBJECTIVE

A major challenge of large abdominal incisional hernia repair is the high rates of wound complications. Closed incision negative pressure therapy (CINPT) can offer many treatment advantages in the management of these wounds and has been shown to reduce complications for other postoperative incisions. This study assesses the wound outcomes for hernia repair patients receiving CINPT.

METHOD

A six-year retrospective case series of patients who had undergone large abdominal incisional hernia repair wounds treated with CINPT was conducted. Outcomes for patients treated with CINPT were compared with patients who had not received CINPT acting as a control.

RESULTS

A total of 23 patients were treated with CINPT after hernia repair and compared with 12 patients in the control group. A statistically significant decreased rate of return to theatre (odds ratio: 0.12) was found in this study. Non-significant reductions in wound infection, seroma and wound dehiscence were also seen. No adverse events with CINPT therapy were reported.

CONCLUSIONS

CINPT, when used after large abdominal incisional hernia repair, may help in the prevention of wound complications.

Negative-pressure wound therapy for donor-site closure in radial forearm free flap: A systematic review and meta-analysis

Negative‐pressure wound therapy (NPWT) is often used for skin graft site dressing, and several studies have reported that its use improves skin graft failure in the forearm flap donor site. The present systematic review aimed to evaluate the efficacy of NPWT with skin graft for donor‐site closure in radial forearm free flap (RFFF) reconstruction. A systematic search in PubMed, Web of Science, and Cochrane Library databases was conducted. The search terms used for PubMed were ([radial forearm]) AND ([donor]) AND ([negative pressure or vacuum]). This review was registered in the International Prospective Register of Systematic Reviews and performed in accordance with the preferred reporting items for systematic reviews and meta‐analyses statement. Three prospective randomised controlled trials and three retrospective comparative studies were included. Compared with conventional bolster dressing, the use of NPWT dressing did not lead to significant improvements in partial skin graft loss, tendon exposure, and other complications. NPWT improved hand functionality earlier; nonetheless, the cost of the device and dressings was a disadvantage. The use of NPWT for skin graft fixation in the RFFF donor site is not generally recommended.

Should Negative Pressure Therapy Replace Any Other Temporary Abdominal Closure Device in Open-Abdomen Management of Secondary Peritonitis?

AIM

To clarify the advantages of negative pressure therapy (NPT) compared to other methods of temporary abdominal closure (TAC) in the management of secondary peritonitis.

METHODS

We retraced the history of known methods of TAC, and analyzed their advantages and disadvantages. We evaluated as the NPT mechanisms, both from the macroscopic that bio-molecular point of view, well suits to manage this difficult condition.

RESULTS

The ideal TAC technique should be quick to apply, easy to change, protect and contain the abdominal viscera, decrease bowel edema, prevent loss of domain and abdominal compartment syndrome, limit contamination, allow egress of peritoneal fluid (and its estimation) and not result in adhesions. It should also be cost-effective, minimize the number of dressing changes and the number of surgical revisions, and ensure a high rate of early closure with a low rate of complications (especially entero-atmospheric fistula). For NPT, the reported fistula rate is 7%, primary fascial closure ranges from 33 to 100% (average 60%) and the mortality rate is about 20%. With the use of NPT as TAC, it may be possible to extend the window of time to achieve primary fascial closure (for up to 20-40 days).

CONCLUSION

NPT has several potential advantages in open-abdomen (OA) management of secondary peritonitis and may make it possible to achieve all the goals suggested above for an ideal TAC system. Only trained staff should use NPT, following the manufacturer's instructions when commercial products are used. Even if there was a significant evolution in OA management, we believe that further research into the role of NPT for secondary peritonitis is necessary.

Closed incision negative pressure wound therapy versus standard dressings in obese women undergoing caesarean section: multicentre parallel group randomised controlled trial

OBJECTIVE

To determine the effectiveness of closed incision negative pressure wound therapy (NPWT) compared with standard dressings in preventing surgical site infection (SSI) in obese women undergoing caesarean section.

DESIGN

Multicentre, pragmatic, randomised, controlled, parallel group, superiority trial.

SETTING

Four Australian tertiary hospitals between October 2015 and November 2019.

PARTICIPANTS

Eligible women had a pre-pregnancy body mass index of 30 or greater and gave birth by elective or semi-urgent caesarean section.

INTERVENTION

2035 consenting women were randomised before the caesarean procedure to closed incision NPWT (n=1017) or standard dressing (n=1018). Allocation was concealed until skin closure.

MAIN OUTCOME MEASURES

The primary outcome was cumulative incidence of SSI. Secondary outcomes included depth of SSI (superficial, deep, or organ/body space), rates of wound complications (dehiscence, haematoma, seroma, bleeding, bruising), length of stay in hospital, and rates of dressing related adverse events. Women and clinicians were not masked, but the outcome assessors and statistician were blinded to treatment allocation. The pre-specified primary intention to treat analysis was based on a conservative assumption of no SSI for a minority of women (n=28) with missing outcome data. Post hoc sensitivity analyses included best case analysis and complete case analysis.

RESULTS

In the primary intention to treat analysis, SSI occurred in 75 (7.4%) women treated with closed incision NPWT and in 99 (9.7%) women with a standard dressing (risk ratio 0.76, 95% confidence interval 0.57 to 1.01; P=0.06). Post hoc sensitivity analyses to explore the effect of missing data found the same direction of effect (closed incision NPWT reducing SSI), with statistical significance. Blistering occurred in 40/996 (4.0%) women who received closed incision NPWT and in 23/983 (2.3%) who received the standard dressing (risk ratio 1.72, 1.04 to 2.85; P=0.03).

CONCLUSION

Prophylactic closed incision NPWT for obese women after caesarean section resulted in a 24% reduction in the risk of SSI (3% reduction in absolute risk) compared with standard dressings. This difference was close to statistical significance, but it likely underestimates the effectiveness of closed incision NPWT in this population. The results of the conservative primary analysis, multivariable adjusted model, and post hoc sensitivity analysis need to be considered alongside the growing body of evidence of the benefit of closed incision NPWT and given the number of obese women undergoing caesarean section globally. The decision to use closed incision NPWT must also be weighed against the increases in skin blistering and economic considerations and should be based on shared decision making with patients.

TRIAL REGISTRATION

ANZCTR identifier 12615000286549.

Study Comparing Platform Wound Dressing, a Negative-Pressure Device without a Filler, with Three Conventional Negative-Pressure Wound Therapy Systems in the Treatment of Excisional and Incisional Wounds

BACKGROUND

All common negative-pressure wound therapy systems include a material, usually foam or gauze, at the wound/device interface. In this preclinical study, the authors have compared the effects on different wound healing parameters in the three most common negative-pressure wound therapy systems (i.e., V.A.C.VIA, PREVENA, and PICO) with a new device without foam or gauze (i.e., Platform Wound Dressing). A strong effort was made to avoid bias. The study was conducted under good laboratory practice conditions, with the presence of an independent observer.

METHODS

In pigs, three types of wounds were studied: full-thickness excisions, open incisions, and sutured closed incisions. Several macroscopic and microscopic parameters were studied. The pigs were euthanized on day 9 and all wounds were processed for histology and excisions for immunohistochemistry.

RESULTS

In general, the devices produced similar results, with only a few significant differences. In the excisions, the Platform Wound Dressing reduced wound area more than the V.A.C.VIA and the PICO. In the excisional wounds, reepithelialization was the same. In open incisions, PREVENA was better than the Platform Wound Dressing. Histologic examination showed that, in open incisions, there was less inflammation in the PREVENA-treated in comparison with the Platform Wound Dressing- and the PICO-treated wounds. Immunohistochemical analyses showed that the Platform Wound Dressing-treated excisions had significantly more blood vessels (von Willebrand factor) than the V.A.C.VIA-treated ones and that the PICO caused less T-cell activation (CD3) than the other two.

CONCLUSION

The devices-with foam, with gauze, or without either and just an embossed membrane-performed equally in general.

Treatment of Breast Cancer-Related Lymphedema Using Negative Pressure Massage: A Pilot Randomized Controlled Trial

OBJECTIVE

To evaluate the efficacy of negative pressure massage treatment (NPMT) compared with manual lymphatic drainage (MLD) in women with chronic breast cancer-related lymphedema (LE). We hypothesized that NPMT would result in greater improvements in LE and upper limb function.

DESIGN

Pilot single-blinded randomized controlled trial.

SETTING

Health sciences university.

PARTICIPANTS

Of 64 women screened, 28 met eligibility requirements (ie, >18y of age; completed active treatment for breast cancer; had unilateral arm LE for ≥1y; were not receiving LE care; had stable LE) and were randomized to the NPMT (n=15) and control groups (n=13).

INTERVENTIONS

The intervention group received NPMT and the control group received MLD; both received twelve 60-minute sessions over 4-6 weeks.

MAIN OUTCOME MEASURES

Bioimpedance (lymphedema index [L-Dex] units]), limb volume (mL) calculated from limb circumference, and Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH) score.

RESULTS

Outcomes were analyzed for 28 women. Compared to the MLD group, the NPMT group demonstrated greater improvement with a large effect size in L-Dex scores (P=.001; standardized mean difference [SMD]=-1.15; 95% confidence interval, -1.96 to -0.35) and interlimb volume differences (P=.038; SMD=-0.83; 95% confidence interval, -1.60 to -0.05). Differences in DASH scores were not statistically significant (P=.067).

CONCLUSIONS

Compared to MLD, treatment with NPMT resulted in greater improvement in L-Dex scores and interlimb volume differences in women with a duration of unilateral upper limb LE of >1 year. Our findings need to be confirmed in a larger randomized controlled trial.

Biofilm-Innate Immune Interface: Contribution to Chronic Wound Formation

Delayed wound healing can cause significant issues for immobile and ageing individuals as well as those living with co-morbid conditions such as diabetes, cardiovascular disease, and cancer. These delays increase a patient’s risk for infection and, in severe cases, can result in the formation of chronic, non-healing ulcers (e.g., diabetic foot ulcers, surgical site infections, pressure ulcers and venous leg ulcers). Chronic wounds are very difficult and expensive to treat and there is an urgent need to develop more effective therapeutics that restore healing processes. Sustained innate immune activation and inflammation are common features observed across most chronic wound types. However, the factors driving this activation remain incompletely understood. Emerging evidence suggests that the composition and structure of the wound microbiome may play a central role in driving this dysregulated activation but the cellular and molecular mechanisms underlying these processes require further investigation. In this review, we will discuss the current literature on: 1) how bacterial populations and biofilms contribute to chronic wound formation, 2) the role of bacteria and biofilms in driving dysfunctional innate immune responses in chronic wounds, and 3) therapeutics currently available (or underdevelopment) that target bacteria-innate immune interactions to improve healing. We will also discuss potential issues in studying the complexity of immune-biofilm interactions in chronic wounds and explore future areas of investigation for the field.

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.

Negative pressure wound therapy does not diminish efficacy of topical antibiotic powder in a preclinical contaminated wound model

AIMS

High-energy injuries can result in multiple complications, the most prevalent being infection. Vancomycin powder has been used with increasing frequency in orthopaedic trauma given its success in reducing infection following spine surgery. Additionally, large, traumatic injuries require wound coverage and management by dressings such as negative pressure wound therapy (NPWT). NPWT has been shown to decrease the ability of antibiotic cement beads to reduce infection, but its effect on antibiotic powder is not known. The goal of this study was to determine if NPWT reduces the efficacy of topically applied antibiotic powder.

METHODS

Complex musculoskeletal wounds were created in goats and inoculated with a strain of Staphylococcus aureus modified to emit light. Six hours after contaminating the wounds, imaging, irrigation, and debridement and treatment application were performed. Animals received either vancomycin powder with a wound pouch dressing or vancomycin powder with NPWT.

RESULTS

There were no differences in eradication of bacteria when vancomycin powder was used in combination with NPWT (4.5% of baseline) compared to vancomycin powder with a wound pouch dressing (1.7% of baseline) (p = 0.986), even though approximately 50% of the vancomycin was recovered in the NPWT exudate canister.

CONCLUSION

The antimicrobial efficacy of the vancomycin powder was not diminished by the application of NPWT. These topical and locally applied therapies are potentially effective tools that can provide quick, simple treatments to prevent infection while providing coverage. By reducing the occurrence of infection, the recovery is shortened, leading to an overall improvement in quality of life. Cite this article: Bone Joint Res 2021;10(2):149-155.

Negative pressure wound therapy for skin necrosis prevention after snakebite in the emergency department: A retrospective cohort study

This retrospective cohort study aimed to compare the effectiveness of conventional treatment and ultra-early application of negative pressure wound therapy (NPWT) in patients with snakebites.Patients who visited the emergency department within 24 hours after a snakebite were assigned to the non- NPWT or NPWT group. Swelling resolution time and rates of necrosis, infection, and operations were compared between the 2 groups. The Stony Brook Scar Evaluation Scale was used to measure short- and long-term wound healing results.Among the included 61 patients, the swelling resolution time was significantly shorter in the NPWT group than in non- NPWT group (P = .010). The NPWT group showed lower necrosis (4.3% versus 36.8%; P = .003) and infection (13.2% and 4.3%; P = .258) rates than the non- NPWT group. The median Stony Brook Scar Evaluation Scale scores were higher in the NPWT group than in the non- NPWT group (P< .001).These findings suggest that ultra-early application of NPWT reduces edema, promotes wound healing, and prevents necrosis in patients with snakebites.

The modulation of the burn wound environment by negative pressure wound therapy: Insights from the proteome

Negative pressure wound therapy has been used to promote wound healing in a variety of settings, including as an adjunct to silver-impregnated dressings in the acute management of paediatric burns. Fluid aspirated by the negative pressure wound therapy system represents a potentially insightful research matrix for understanding the burn wound microenvironment and the intervention's biochemical mechanisms of action. The aim of this study was to characterize the proteome of wound fluid collected using negative pressure wound therapy from children with small-area thermal burns. Samples were obtained as part of a randomized controlled trial investigating the clinical efficacy of adjunctive negative pressure wound therapy. They were compared with blister fluid specimens from paediatric burn patients matched according to demographic and injury characteristics. Protein identification and quantification were performed via liquid chromatography tandem mass spectrometry and sequential window acquisition of all theoretical mass spectra data-independent acquisition. Proteins and biological pathways that were unique to or enriched in negative pressure wound therapy fluid samples were evaluated using principal components, partial least squares-discriminant, and gene ontology enrichment analyses. Eight viable samples of negative pressure wound therapy fluid were collected and analyzed with eight matched blister fluid samples. A total of 502 proteins were quantitatively profiled in the negative pressure wound therapy fluid, of which 444 (88.4%) were shared with blister fluid. Several proteins exhibited significant abundance differences between fluid types, with negative pressure wound therapy fluid showing a higher abundance of matrix metalloproteinase-9, arginase-1, low affinity immunoglobulin gamma Fc region receptor III-A, filamin-A, alpha-2-macroglobulin, and hemoglobin subunit alpha. The results lend support to the hypothesis that negative pressure wound therapy augments wound healing through the modulation of factors involved in the inflammatory response, granulation tissue synthesis, and extracellular matrix maintenance. Data are available via ProteomeXchange with identifier PXD023168.