Negative-pressure wound therapy enhances local inflammatory responses in acute infected soft-tissue wound

Negative Pressure Level and Effects on Bacterial Growth Kinetics in an in vitro Wound Model

Negative Pressure Wound Therapy (NPWT) has been widely adopted in wound healing strategies due to its multimodal mechanism of action. While NPWT's positive impression on wound healing is well-established, its effect on bacterial load reduction remains equivocal. This study investigates NPWT's efficacy in reducing bioburden using an in vitro porcine skin model, focusing on the impact of Staphylococcus aureus and Staphylococcus epidermidis. Custom-made negative pressure chambers were employed to apply varying negative pressures. Porcine skin was cut into 5 × 5 cm squares and three standardized wounds of 6 mm each were created using a biopsy punch. Then, wounds were infected with S. aureus and S. epidermidis bacterial suspensions diluted 1:10,000 to obtain a final concentration of 1.5 × 104 CFU/ml and were placed in negative pressure chambers. After incubation, bacterial counts were expressed as colony-forming units (CFU) per ml. For S. aureus at 120 hours, the median CFU, mean area per colony, and total growth area were notably lower at -80 mmHg when compared to -250 mmHg and -50 mmHg, suggesting an optimal negative pressure for the pressure-dependent inhibition of the bacterial proliferation. While analyzing S. epidermidis at 120 hours, the response to the negative pressure was similar but less clear, with the minor CFU at -100 mmHg. The influence of intermittent negative pressure on the S. epidermidis growth showed notably lower median CFU with the interval therapy every hour compared to the S. aureus control group. This study contributes valuable insights into NPWT's influence on the bacterial load, emphasizing the need for further research to reformulate its role in managing contaminated wounds.

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.

Comparison of the effects of negative pressure wound therapy and negative pressure wound therapy with instillation on wound healing in a porcine model

Background

Negative pressure wound therapy with instillation (NPWTi) is a novel method based on standard negative pressure wound therapy (NPWT). This study aimed to compare the effects of standard NPWT and NPWTi on bioburden and wound healing in a Staphylococcus aureus (S.aureus) infected porcine model.

Methods

Green fluorescent protein-labeled S.aureus infected wounds were created on the back of porcine. Wounds were treated with NPWT or NPWT with instillation (saline). The tissue specimens were harvested on days 0 (12 h after bacterial inoculation), 2, 4, 6, and 8 at the center of wound beds. Viable bacterial counts, laser scanning confocal microscopy, PCR, western blot, and histological analysis were performed to assess virulence and wound healing.

Results

The bacterial count in the NPWTi group was lower than that of the NPWT group and the difference was statistically significant on day 2, day 4, day 6, and day 8 (P < 0.05). The expression levels of agrA, Eap, Spa, and Hla genes of the NPWTi group were significantly lower than that of the NPWT group on day 8 (P < 0.05). The bacterial invasion depth of the NPWTi group was significantly lower than that of the NPWT group on day 2, day 4, day 6, and day 8 (P < 0.05). Though the NPWTi group showed a significantly increased expression of bFGF and VEGF than that of the NPWT group in the early time (P < 0.05), NPWTi cannot lead to better histologic parameters than the NPWT group (P > 0.05).

Conclusion

Our results demonstrated that NPWTi induced a better decrease in bacterial burden and virulence compared with standard NPWT. These advantages did not result in better histologic parameters on the porcine wound model.

Negative Pressure Wound Therapy Promotes Wound Healing by Inhibiting Inflammation in Diabetic Foot Wounds: A Role for NOD1 Receptor

Aims: Diabetic foot results in frequent amputation and quality-of-life reduction in diabetes population. These lesions are featured by a prolonged and exaggerated inflammation with a significant impairment in local bacterial invasion. Negative pressure wound therapy (NPWT) attenuates hyperinflammation in the healing of diabetic foot wounds, but the potential mechanism of NPWT down-regulated inflammatory reaction still remains elusive. This study aims to explore the inflammatory signaling involved in the effect of NPWT on diabetic ulcer. Methods: Thirty patients with diabetic foot ulceration were divided into NPWT group (treated with NPWT, n = 10), NPWT + FK565 group (treated with NPWT combined with FK565 which is NOD1 receptor ligand, n = 10) and control group (n = 10). After two weeks treatment, samples were harvested and analyzed by histochemistry for infiltration of inflammatory cells, immunofluorescence stain for NOD1, western blotting for NOD1, RIP2 (Receptor interacting protein 2), IL-1β, TAK1 (Transforming growth factor-β-activated kinase1), p65 and real time-PCR for expression of NOD1 and RIP2. Results: NPWT could notably accelerate the diabetic wound healing through alleviating inflammatory reaction. The immunofluorescence analysis results revealed that NOD1 was mainly expressed in the cytoplasm and noticeably decreased after the NPWT treatment. And NPWT obviously decreased both the mRNA and protein level of NOD1 and RIP2. Moreover, The protein expression of IL-1β, TAK1 and p65 in the NPWT-group were significant decreased. Conclusion: NPWT effectively promotes wound healing by suppressing the wound inflammation in diabetic foot, which is mediated at least in part by suppression of NOD1 receptor.

Negative pressure wound therapy versus gauze dressings in managing open fracture wound of lower limbs: A meta-analysis of randomized controlled trials

BACKGROUND

The superiority of negative pressure wound therapy (NPWT) to standard gauze dressings for managing open fractures of the lower limbs remains controversial. This study aimed to comprehensively compare their clinical efficacy through a meta-analysis using randomized controlled trials (RCTs) alone. We hypothesized that NPWT would be more superior against infections.

METHODS

A literature search was implemented in various databases, including PubMed, Web of Science, Medline, Clinicaltrial.gov, and Cochrane Library, etc, to screen eligible RCTs. All included RCTs were evaluated for risk of bias using the Cochrane Collaboration tool. In accordance with the heterogeneity assessment, a fixed-effect or random-effect model was chosen for the data analysis.

RESULTS

Ten RCTs, including 2780 patients, were eligible for the meta-analysis. We found that patients in the NPWT group showed a lower overall infection rate (MD=0.70, 95% CI: 0.54-0.90, P = 0.005), acute wound infection rate (MD = 0.35, 95% CI: 0.16-0.77, P = 0.009), and shorter hospital stay (MD = 24.00, 95% CI: 6.82-84.46, P < 0.00001) compared with the control group. The NPWT group showed a higher proportion of patients with wound coverage than the control group. No significant difference was found between the two groups in terms of function score and other complications, including deep infection rate, amputation, and bone nonunion.

CONCLUSIONS

From the pooled results, we suggest that NPWT may be superior than traditional gauze dressings for managing open fractures of the lower limbs.

Comprehensive analysis of lncRNA and miRNA expression profiles and ceRNA network construction in negative pressure wound therapy

Background

This study aims to explore the molecular mechanism of negative pressure wound therapy (NPWT) at the transcriptome level through whole transcriptome sequencing and biometric analysis.

Methods

A rat skin defect model was constructed and randomly divided into a NPWT group and a gauze group. The tissue in the center of the wound was used for whole transcriptome sequencing, and differentially expressed messenger RNAs (DEmRNAs), long noncoding RNAs (DElncRNAs), and microRNAs (DEmiRNAs) were identified between the two groups. Quantitative real time-polymerase chain reaction (qRT-PCR) analysis was used to verify the sequencing results. Functional enrichment analysis, pathway analysis, and protein-protein interaction (PPI) network analysis of DEmRNAs were conducted. Through bioinformatics analysis, a lncRNA-associated competing endogenous RNA (ceRNA) network was identified and constructed.

Results

We detected 896 DEmRNAs, 1,471 DElncRNAs, and 20 DEmiRNAs between the two groups. qRT-PCR verified the sequencing results. Functional analysis showed that DEmRNAs were mainly enriched in immune system processes and the Notch signaling pathway. Protein tyrosine phosphatase receptor type C (PTPRC) and signal transducer and activator of transcription 1 (STAT1) were the central hub nodes in the PPI analysis. The ceRNA network contained 11 mRNAs, 15 lncRNAs, and 4 miRNAs.

Conclusions

We identified several DEmRNAs, DElncRNAs, and DEmiRNAs between the NPWT treatment group and the control group. These findings may provide new insights into the pathophysiological mechanism of NPWT and wound healing.

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.

Utilization of a Novel Negative Pressure Platform Wound Dressing on Surgical Incisions: A Case Series

Background:

Closed incision negative pressure therapy (ciNPT) has been shown to improve wound healing for patients at high risk for wound complications. Current devices consist of opaque interface dressings that do not allow ongoing visual evaluation of the surgical incision and utilize a negative pressure of −80 mm Hg to −125 mm Hg. The Negative Pressure Platform Wound Dressing (NP-PWD) was developed to address these aspects. This case series is the first evaluation of the NP-PWD in a clinical setting.

Methods:

Patients aged 18–85 undergoing an operation with an anticipated incision and primary closure were screened. Demographics, comorbidities, and operation performed were recorded. Following closure, the incision was measured and photographed before NP-PWD placement. The NP-PWD was removed at the first postoperative check (POC) between postoperative days (PODs) 3–5. Subjects were followed until PODs 9–14. POCs consisted of incision assessment, measurement, photography, and adverse event monitoring.

Results:

A total of 8 patients with 10 incisions were included in the study. Five patients were men. Median age was 56 years (IQR 53–74 years). All incisions were intact and without inflammation or infection at all POCs. Three adverse events, including small blisters and interruption of therapy, were noted.

Conclusions:

This case series reports that patients tolerated the NP-PWD on closed surgical incisions well and that all incisions were intact without evidence of inflammation or infection after 2 weeks of follow-up. Future controlled, clinical studies should further examine the safety and efficacy of the use of the NP-PWD.

Adaptive expression of biofilm regulators and adhesion factors of Staphylococcus aureus during acute wound infection under the treatment of negative pressure wound therapy in vivo

Negative pressure wound therapy (NPWT) is gaining acceptance as a physical therapy for a wide variety of infected wounds. To gain insight into the response of bacteria to NPWT in vivo, the adaptive expression of biofilm regulators and adhesion factors of Staphylococcus aureus (S. aureus), the most frequently isolated pathogen in the clinic, during acute wound infection was investigated. A 3 cm full-thickness dermal wound was created on each side of a rabbit back and inoculated with green fluorescent protein-labeled S. aureus. NPWT was initiated at 6 h post inoculation, with the wound on the contralateral side as the untreated self-control. The wounds were subjected to a 28 day observation period. Histological analysis, laser scanning confocal microscopy and scanning electron microscopy revealed a transition of S. aureus to a free-living phenotype in tissues treated with NPWT, compared with microcolonies in untreated wounds. Viable bacteria counts showed a modest reduction in the bioburden of NPWT group on day 8 (P<0.001), with ~1x10⁶ colony-forming units/g tissue. Transcript analysis of biofilm- and colonization-related genes were investigated using reverse transcription-quantitative PCR on postoperative days 1, 2, 4 and 8. The poly-beta-1,6-N-acetyl-D-glucosamine synthase locus and holin-like protein CidA/antiholin-like protein LrgA network were less active in the NPWT group compared with the untreated control group. Accordingly, the expression profile switched to an elevated expression of the adhesive factors UDP-phosphate N-acetylglucosaminyl 1-phosphate transferase (at days 0-4) and fibronectin-binding protein A and iron-regulated surface determinant protein A at >4 days during both stages of colonization. Meanwhile, low expression levels of the effector molecule (RNAIII) of the accessory gene regulator type I (agr) system was detected in NPWT group, suggesting that the bacterial density in NPWT-treated wounds was under the threshold for agr activation, thus not leading to an active and invasive infection. The wounds treated by NPWT healed completely on day 28, compared with an average of an 8.11% defect area in the control group (P<0.001). The results of the current study indicated that S. aureus responds to NPWT by regulating gene expression, manifesting a decrease in biofilm formation and an increase in bacterial colonization in vivo, which potentially benefits the wound repair and healing process.

Potential molecular mechanisms of negative pressure in promoting wound healing

Negative pressure wound therapy (NPWT) has been widely used in various lesions. This study aimed to explore the biological effects of negative pressure on the polymorphonuclear neutrophils (PMNs), macrophages, and epidermal keratinocyte cells involved in wound healing. PMNs differentiated from HL-60, macrophages were derived from THP-1 monocytes, and keratinocytes were cultured in vitro, and they were treated with 0, -0.03 mp, and -0.05 mp, respectively. Cell ultrastructure; viability; apoptosis; and protein factors such as tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), epidermal growth factor (EGF), epidermal growth factor receptor (EGFR), interleukin-17 (IL-17), and cell division cycle 42 (Cdc42) were determined by transmission electron microscopy (TEM), CCK8, flow cytometry (FCM), ELISA, and simple Western assays, respectively. After negative pressure stimulation, the cell ultrastructure of PMNs and macrophages cells was presented with a marked increase of lysosomes and a relative decrease of mitochondria. In addition, the cell viability was enhanced in PMNs and macrophages in a pressure-dependent manner and apoptosis ratios were significantly reduced in PMNs and macrophages. In addition, under -0.05 negative pressure, IFN-γ and IL-17 were significantly increased in PMNs or macrophages. Moreover, increased EGF and EGFR and Cdc42 levels in keratinocytes induced by the -0.05 mpa were detected, indicating that the migration chemotaxis of keratinocyte cells was enhanced. Negative pressure might promote cell proliferation, accelerate inflammatory responses, and promote epithelialisation during wound healing by increasing IFN-γ, IL-17, Cdc42, EGF, and EGFR in PMNs, macrophages, or keratinocytes under different negative pressures.

Are high-risk patient and revision arthroplasty effective indications for closed-incisional negative-pressure wound therapy after total hip or knee arthroplasty? A systematic review and meta-analysis

To determine the effective indications of closed-incisional negative-pressure wound therapy (ciNPWT) following total hip or knee arthroplasty, this systematic review and meta-analysis was conducted. The systematic search was performed on MEDLINE, Embase, and Cochrane Library, and 11 studies were included. The studies comparing between ciNPWT and conventional dressings were categorised into following subgroups based on patient risk and revision procedures: routine vs high-risk patient; primary vs revision arthroplasty. Pooled estimates were calculated for wound complication and surgical site infection (SSI) rates in the subgroup analyses using Review Manager. In high-risk patients, the overall rates of wound complication (odds ratio [OR] = 0.38; 95% confidence interval [CI] 0.15-0.93; P = .030) and SSI (OR = 0.24; 95% CI = 0.09-0.64; P = .005) were significantly lower in the ciNPWT; however, there were no differences in routine patients. In cases involving revision arthroplasties, the overall rates of wound complication (OR = 0.33; 95% CI = 0.18-0.62; P < .001) and SSI (OR = 0.26; 95% CI = 0.11-0.66; P = .004) were significantly lower in the ciNPWT; however, there were no differences in cases involving primary arthroplasties. In summary, ciNPWT showed a positive effect in decreasing the rates of wound complication and SSI in high-risk patients and in revision arthroplasties.

Comparison of the Efficacy Between Closed Incisional Negative-Pressure Wound Therapy and Conventional Wound Management After Total Hip and Knee Arthroplasties: A Systematic Review and Meta-Analysis

BACKGROUND

Wound-related problems after total hip arthroplasty (THA) and total knee arthroplasty (TKA) can cause periprosthetic joint infections. We sought to evaluate the effect of closed incisional negative-pressure wound therapy (ciNPWT) on wound complications, skin blisters, surgical site infections (SSIs), reoperations, and length of hospitalization (LOH).

METHODS

Studies comparing ciNPWT with conventional dressings following THA and TKA were systematically searched on MEDLINE, Embase, and the Cochrane Library. Two reviewers performed the study selection, risk of bias assessment, and data extraction. Funnel plots were employed to evaluate publication bias and forest plots to analyze pooled data.

RESULTS

Twelve studies were included herein. The odds ratios (ORs) for wound complications and SSIs indicated a lack of publication bias. ciNPWT showed significantly lower risks of wound complication (OR, 0.44; 95% confidence interval [CI], 0.22-0.9; P = .027) and SSI (OR, 0.39; 95% CI, 0.23-0.68; P < .001) than did conventional dressings. ciNPWT also yielded a significantly lower reoperation rate (OR, 0.38; 95% CI, 0.21-0.69; P = .001) and shorter LOH (mean difference, 0.41 days; 95% CI, -0.51 to -0.32; P < .001). However, the rate of skin blisters was higher in ciNPWT (OR, 4.44; 95% CI, 2.24-8.79; P < .001).

CONCLUSION

Although skin blisters were more likely to develop in ciNPWT, the risks of wound complication, SSI, reoperation, and longer LOH decreased in ciNPWT compared with those in conventional dressings. This finding could alleviate the potential concerns regarding wound-related problems after THA and TKA.

Negative pressure wound therapy vs. conventional management in open tibia fractures: Systematic review and meta-analysis

BACKGROUND

Severe open tibia fractures are disastrous injuries associated with a high incidence of complications. Negative pressure wound therapy (NPWT) is a novel treatment for open tibia fractures; however, its efficacy remains unclear. This is a systematic review and meta-analysis performed to evaluate the effect of NPWT on decreasing the infection rate, amputation rate, nonunion rate, and flap-related complications in open tibia fractures.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were systematically searched. Complications were evaluated in terms of the rates of infection, amputation, nonunion, and flap-related complications.

RESULTS

Twelve studies were included. In the meta-analysis, NPWT showed significantly lower soft-tissue infection rate (odds ratio [OR] 0.48, 95% confidence interval [CI] 0.34-0.68, P < 0.0001), nonunion rate (OR 0.61, 95% CI 0.39-0.95, P = 0.03), flap necrosis rate (OR 0.37, 95% CI 0.21-0.63, P = 0.0003), and flap revision rate (OR 0.44, 95% CI 0.22-0.89, P = 0.02) than conventional wound management. However, no significant difference was found in osteomyelitis rate (OR 0.54, 95% CI 0.09-3.28, P = 0.50) and amputation rate (OR 0.89, 95% CI 0.36-2.22, P = 0.80) between the 2 groups.

CONCLUSION

Lower rates of soft-tissue infection, nonunion, flap necrosis, and flap revision were observed in the NPWT group than in the conventional dressing group. However, additional high-quality studies are warranted to verify the efficacy of NPWT in the treatment of severe open tibia fractures. We could not make a definitive conclusion about the comparative efficacy of the 2 methods in terms of complications because of insufficient data.

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.

Negative pressure wound therapy promoted wound healing by suppressing inflammation via down-regulating MAPK-JNK signaling pathway in diabetic foot patients

AIMS

Negative pressure wound therapy displayed significant clinical benefits in the healing of diabetic foot wounds. In the present study, we investigated the mechanism of regulation of MAPK-JNK (Mitogen-activated protein kinase- c-Jun N-terminal kinase) signaling pathway by negative pressure wound therapy on these wounds.

METHODS

Twenty-six type 2 diabetes patients with foot ulceration were randomly assigned to the two groups, thirteen treated with negative pressure wound therapy and the others treated with traditional debridement therapy. Skin samples were harvested and histologically and immunohistochemical analyzed in both groups. Immunofluorescence stain, Enzyme-linked immunosorbent assay and Western blotting were performed for inducible nitric oxide synthase, inter leukin-6, tumor necrosis factor-α, P-c-Jun N-terminal kinase and c-Jun N-terminal kinase. Real time-polymerase chain reaction was performed to evaluate expression of c-Jun N-terminal kinase, extracellular signal regulated kinase1/2 and p38.

RESULTS

Negative pressure wound therapy could effectively alleviate inflammatory reaction and reduce inter leukin-6 and inducible nitric oxide synthase production after 7 days treatment. The level of tumor necrosis factor-α, inter leukin-6 and P-c-Jun N-terminal kinase were significantly decreased. However, there was no statistical difference in messenger ribonucleic acid expression of p38, extracellular signal regulated kinase1 and 2.

CONCLUSIONS

Negative pressure wound therapy possibly suppress the wound inflammation by inhibiting inter leukin-6, tumor necrosis factor-α and inducible nitric oxide synthase in diabetic foot patients. This effect is maybe mediated at least in part by suppression of Mitogen-activated protein kinase- c-Jun N-terminal kinase signaling pathway.

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.

Reducing postsurgical exudate in breast cancer patients by using San Huang decoction to ameliorate inflammatory status: a prospective clinical trial

Background

Reducing inflammatory factors in wound exudate is a promising treatment approach for healing wounds in postsurgical breast cancer patients. Traditional Chinese Medicine (tcm) treatments have been shown to be beneficial and safe for optimal regulation of oxidative stress during the postoperative period. In the present clinical trial, we evaluated the effectiveness of a promising Chinese herbal formula, San Huang decoction [shd (Radix astragali, Radix et rhizoma rhei, and Rhizoma curcuma longa, 3:1:1; supplemental Table 1)], on wound inflammatory response after mastectomy.

Methods

The study randomized 30 patients with breast cancer who fulfilled the inclusion and exclusion criteria to either a treatment (n = 15) or a control group (n = 15). Patients in the treatment group received liquid shd, taken twice daily with or without food. Treatment was given for 1 day before surgery and for 7 days postoperatively. Participants in the control group received a placebo on the same schedule as the treatment group. Outcomes measured in every subject included clinical tcm and wound inflammation symptom scores, daily and total amounts of drainage fluid, and levels of inflammatory factors in the exudate [tumour necrosis factor α (tnf-α), interleukins 6 (il-6), 8 (il-8), and 2R (il-2R), human C-reactive protein (crp)] at 2 hours and on days 1, 3, and 7 postoperatively.

Results

The total amount of drainage fluid over 7 days was significantly lower in the treatment group (572.20 ± 93.95 mL) than in the control group (700.40 ± 107.38 mL). The tcm symptom score was also lower in treatment group (day 7: 1.87 ± 0.83 vs. 4.80 ± 3.61, p = 0.049), as was the inflammatory symptom score (day 7: 0.67 ± 0.72 vs. 3.67 ± 2.50, p = 0.001). Levels of tnf-α, il-6, il-8, il-2R, and crp in drainage fluid were significantly lower with shd treatment.

Conclusions

Perioperative treatment with shd effectively lessened postoperative exudate and ameliorated inflammatory symptoms in patients who underwent surgery for breast cancer.

Effect of negative pressure wound therapy on molecular markers in diabetic foot ulcers

Diabetic foot ulcers are one of the most common complications of diabetes with high morbidity and mortality. Negative pressure wound therapy (NPWT) is one of the treatment modalities that facilitates the wound healing process; however, its molecular mechanism remains unclear. The aim of this study was to investigate the mechanism of action of NPWT in the treatment of diabetic foot ulcers via measuring the tissue expression of genes related to the wound healing process. The study included 40 patients with diabetic foot ulceration, 20 of them received NPWT and the other 20 were a control group treated with advanced moist therapy. Granulation tissue biopsies were obtained before and 10 days after treatment in both groups and subjected to real-time polymerase chain reaction to measure the mRNA expression of TGF-β1, VEGF, TNF-α, IL-1β, MMP-1, MMP-9 and TIMP-1 which are involved in the wound healing pathway. After 10 days of treatment with NPWT, the mRNA levels of IL-1β, TNF-α, MMP-1, and MMP-9 were significantly downregulated, while the levels of VEGF, TGF-β1 and TIMP-1 were significantly increased. Our study demonstrated that NPWT promotes wound healing in diabetic foot ulcers possibly by affecting growth factors, inflammatory cytokines, and matrix metalloproteinases.

Improvement of wound healing by regulated oxygen-enriched negative pressure-assisted wound therapy in a rabbit model

BACKGROUND

Development of drug therapies and other techniques for wound care have resulted in significant improvement of the cure rate and shortening of the healing time for wounds. A modified technique of regulated oxygen-enriched negative pressure-assisted wound therapy (RO-NPT) has been reported.

AIM

To evaluate the efficacy and impact of RO-NPT on wound recovery and inflammation.

METHODS

Infected wounds were established on 40 adult female white rabbits, which were then randomized to one of four groups: O₂ group, regulated negative pressure-assisted wound therapy (RNPT) group, regulated oxygen-enriched negative pressure-assisted wound therapy (RO-NPT) group and healthy control (HC) group. Each day, the O₂ group was treated with a constant oxygen supply (1 L/min) to the wound, while the RNPT group was treated with continuous regulated negative pressure (70 ± 5 mmHg) and the RNPT + O₂ group was treated with both. The HC group was treated with gauze dressing alone, which was changed every day. Leucocyte count, colony count and wound-healing rate were calculated. Levels of tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-8 were evaluated by ELISA.

RESULTS

RO-RNPT significantly decreased bacterial count and TNF-α level, and increased the wound-healing rate. IL-1β, IL-8 and leucocyte count had a tendency to increase in the early phase of inflammation and a tendency to decrease in the later phase of inflammation in the RO-RNPT group.

CONCLUSIONS

RO-NPT therapy assisted wound recovery and inflammation control compared with the RNPT and oxygen-enriched therapies. RO-NPT therapy also increased levels of IL-1β and IL-8 and attenuated expression of TNF-α in the early phase of inflammation.

Negative pressure therapy versus passive open abdominal drainage for the treatment of septic peritonitis in dogs: A randomized, prospective study

OBJECTIVE

To compare passive open abdominal drainage (POAD) and negative-pressure abdominal drainage (NPAD) using the ABThera™ system in the treatment of septic peritonitis.

STUDY DESIGN

Randomized prospective clinical trial.

ANIMALS

Dogs (n = 16) with septic peritonitis.

METHODS

Dogs with septic peritonitis were randomly assigned to one of two treatment protocols: NPAD versus POAD. Anesthesia time, operating time, duration of drainage, costs, survival, and complications were compared between techniques. Hematological and biochemical parameters in blood and abdominal fluid, and histopathological findings of omentum and abdominal wall tissue samples were compared between NPAD and POAD at time of initial surgery and at time of closure.

RESULTS

Overall survival was 81%. Treatment costs, anesthesia and operating time, drainage time, survival, and postoperative complications were similar between techniques. Loss of total plasma protein and decreased inflammation-related factors in abdominal fluid at time of closure were noted in all patients. Neutrophilic inflammation was greater in abdominal wall samples after NPAD. POAD patients showed discomfort during bandage changes and had frequent leakage of abdominal fluid outside of the bandage.

CONCLUSION

NPAD is an effective alternative to POAD for treatment of septic peritonitis, based on costs and survival. NPAD resulted in less abdominal fluid leakage, and evidence of superior healing on histological evaluation of abdominal tissues.

Negative pressure wound therapy inhibits inflammation and upregulates activating transcription factor-3 and downregulates nuclear factor-κB in diabetic patients with foot ulcerations

BACKGROUND

Negative pressure wound therapy (NPWT) is one of the most important treatments for diabetic foot, but the underlying mechanisms of its benefits still remain elusive. This study aims to evaluate the inflammatory signals involved in the effects of negative pressure therapy on diabetic foot ulcers.

METHODS

We enrolled 22 patients with diabetic foot ulceration, 11 treated with NPWT and the other 11 treated with traditional debridement. All patients were treated and observed for 1 week. Granulation tissues were harvested and analyzed in both groups, and then were histologically and immunohistochemically analyzed. Enzyme-linked immunosorbent assay, Western blot analysis, and real-time PCR were performed to evaluate the expression of interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), inducible nitric oxide synthase (iNOS), nuclear factor-κB (NF-κB) p65, I_k B-α, and activating transcription factor-3 (ATF-3).

RESULTS

After 7 days of treatment, NPWT could obviously promote diabetic wound healing because of the mild inflammation and the dense cell-deposited matrix. Meanwhile, NPWT significantly decreased the expression of TNF-α, IL-6, and iNOS (all P < .05). The result of Western blotting and real-time PCR indicated that NPWT obviously decreased the level of I_k B-α and NF-κB p65, and increased the level of ATF-3 (all P < .05).

CONCLUSION

NPWT exerts an anti-inflammatory effect, possibly through the suppression of proinflammatory enzymes and cytokines resulting from I_k B-α inhibition and ATF-3 activation, which may prevent the activation of the NF-κB pathway in human diabetic foot wounds.

The effectiveness of negative pressure therapy on infected wounds: preliminary results

Vacuum-assisted closure (VAC) therapy is a sophisticated system that maintains a closed, humid, sterile and isolated environment. Wound infection is considered a relative contraindication. The objective of this study is to extend the indications for VAC therapy to include infected wounds by demonstrating its ability to increase the antibiotic concentration in the damaged and infected tissues. Patients who presented with ulcers infected with daptomycin-sensitive bacteria were eligible to be enrolled in this prospective study. They were given antibiotic therapy with daptomycin with a specific protocol. A biopsy of the lesion was carried out to detect tissue concentration of the drug at time 0. Afterwards, the patients were subjected to VAC therapy. At the end of VAC therapy, a second lesion biopsy was performed and analysed to detect tissue concentration of the drug at time 1. A control group was enrolled in which patients followed the same protocol, but they were treated with traditional dressings. Fisher's exact test was used to compare the two groups. The results highlighted a significant increase in the concentration of antibiotics in the study group tissue; the improvement was sensibly lower in the control group. Statistical differences were not found between the two groups. The preliminary analysis of the data showed an important increase of antibiotic concentration in the tissue after VAC therapy. Despite the encouraging data, it is necessary to broaden the sample of patients and perform the same study with other antibiotics.

Early application of negative pressure wound therapy to acute wounds contaminated with Staphylococcus aureus: An effective approach to preventing biofilm formation

Negative pressure wound therapy (NPWT) has been demonstrated to be effective at preventing biofilm-associated infections; however, its role in biofilm prevention is unknown. The present study evaluated the effect of NPWT on biofilm prevention when rapidly initiated following wound contamination. Full-thickness dermal wounds (8 mm) were created in rabbit ears and inoculated with green fluorescent protein-labeled Staphylococcus aureus (S. aureus). At 6 h following inoculation, continuous NPWT at -125 mmHg was initiated, with the wounds on the contralateral ear left untreated in order to serve as self-controls. S. aureus rapidly formed mature biofilms in the wound beds post-inoculation, with a persistent bacterial burden of ~10⁵-10⁷ colony-forming units (CFUs)/wound and impaired wound healing. Compared with the untreated group, NPWT resulted in a significant reduction in biofilm matrix, which was verified by scanning electron microscopy and epifluorescence. A reduction in bacterial counts followed (P<0.05) with ~10³ CFUs/wound on postoperative day 13 and improvement in all healing parameters (P<0.05) relative to control wounds. The results of the present investigation suggest that NPWT is an effective strategy to impeding the formation of S. aureus wound biofilms when initiated rapidly following bacterial contamination. The early application of NPWT, aimed at biofilm prevention, may improve wound care.

Curbing Inflammation in Skin Wound Healing: A Review

Wound healing is a complex regulated process that results in skin scar formation in postnatal mammals. Chronic wounds are major medical problems that can confer devastating consequences. Currently, there are no treatments to prevent scarring. In the early fetus wounds heal without scarring and the healing process is characterized by relatively less inflammation compared to adults; therefore, research aimed at reducing the inflammatory process related to wound healing might speed healing and improve the final scar appearance.

The use of negative pressure wound therapy in severe open lower extremity fractures: identifying the association between length of therapy and surgical outcomes

BACKGROUND

Negative pressure wound therapy (NPWT) is a widely accepted method of temporary coverage for complex lower extremity wounds before definitive reconstruction. However, the precise role of NPWT in the perioperative management of patients with complicated lower extremity injuries remains unclear. In this study, we examine the effect of NPWT on flap complications and overall outcomes based on timing of soft-tissue reconstruction relative to initial injury and implementation of NPWT.

METHODS

We retrospectively reviewed the medical records of 32 consecutive patients presenting to a single institution receiving lower extremity reconstruction after Gustilo class IIIB or IIIC open tibial fractures over a 5-y period. Length of hospitalization, number of surgical procedures, flap failure, infection, and nonunion were parameters of interest in this study.

RESULTS

The incidence of complications in patients treated with NPWT was lower compared with patients who underwent wet-to-dry dressing changes, regardless of when surgery was performed. The highest rate of complications was observed in patients operated on >6 wk after injury and who received wet-to-dry dressing changes wound care. By comparison, those who underwent surgery within 1 wk of injury and who were bridged with NPWT had the lowest rate of complications.

CONCLUSIONS

The use of NPWT therapy in the perioperative management of patients with open lower extremity fractures reduces complication rates associated with limb salvage surgery. Our results suggest that NPWT can be used as a temporizing measure to optimize patients before flap surgery, effectively lengthening the window of opportunity for definitive reconstruction.