Effects of negative pressure wound therapy on cellular energetics in fibroblasts grown in a provisional wound (fibrin) matrix

Negative pressure wound therapy (NPWT) using reticulated open cell foam dressing (ROCF) is effective for treatment of recalcitrant wounds; however, the effects of this therapy on cellular metabolism remain to be elucidated. The effect of two different subatmospheric pressure applications on the cell energetics of human fibroblasts grown in a 3D fibrin matrix was studied using two different pressure-manifolding materials, an ROCF or gauze under suction (GUS). It was found that levels of cytochrome c oxidase, energy charge, and adenosine triphosphate/adenosine diphosphate were significantly increased following the application of NPWT using ROCF vs. GUS ( p <0.05). Increases in these parameters likely reflect an improved energetic status. In addition, levels of transforming growth factor-β and platelet-derived growth factor (α and β isoforms) were significantly increased (80 and 53%, respectively; p <0.05) over static control cultures following treatment with NPWT using ROCF but not following GUS. These growth factors are known to be important during wound healing. Clearly, both the material used as the dressing to manifold the subatmospheric pressure and the pressure used have a dramatic effect on cellular response.     

Novel negative pressure wound therapy device without foam or gauze is effective at −50 mmHg

Negative pressure wound therapy (NPWT) promotes healing in acute or chronic wounds. Conventional NPWT devices consist of a filler (such as foam or gauze) that covers the wound and of a permeable membrane and tubing that connects the space under the membrane to a suction pump. The permeable membrane increases airflow and thus increases the required pump capacity that can cause patient discomfort or even ischemia in wounds with compromised vascularity. In addition, foam or gauze may fragment and become colonized with bacteria over time. To mitigate these, negative aspects, we have developed a new impermeable single layer component membrane dressing to deliver NPWT that does not need a foam or gauze to function. Therefore, the purpose of this study was to introduce this novel NPWT system (platform wound device, PWD) and evaluate its usability and effectiveness in the treatment of porcine full‐thickness burns. A total of 48 burn wounds were created across four Yorkshire pigs on the dorsum. Wounds were created on day 0 and continuous NPWT with ?50 mmHg and ? 80 mmHg was initiated immediately. Subsequently, the burns were debrided on day 3 and animals were euthanized on day 7. The efficacy of the PWD on wound healing and reduction of bacterial burden was measured and compared to wounds that did not receive NPWT. The results showed that PWD promoted wound healing by outperforming the wounds that did not receive NPWT and that PWD was efficient at reducing bacteria from the burn eschar and from the wound bed. In conclusion, this study demonstrated that PWD promoted wound healing with a negative pressure as low as ?50 mmHg, which likely benefits healing and avoids potential safety issues.     

Comparison of bacteria and fungus‐binding mesh,foam and gauze as fillers in negative pressure wound therapy – pressure transduction,wound edge contraction,microvascular blood flow and fluid retention

Bacteria‐ and fungus‐binding mesh binds with and inactivates bacteria and fungus, which makes it an interesting alternative, wound filler for negative pressure wound therapy (NPWT). This study was conducted to compare the performance of pathogen‐binding mesh, foam and gauze as wound fillers in NPWT with regard to pressure transduction, fluid retention, wound contraction and microvascular blood flow. Wounds on the backs of 16 pigs were filled with pathogen‐binding mesh, foam or gauze and treated with NPWT. The immediate effects of 0, ?40, ?60, ?80 and ?120 mmHg, on pressure transduction and blood flow were examined in eight pigs using laser Doppler velocimetry. Wound contraction and fluid retention were studied during 72 hours of NPWT at ?80 and ?120 mmHg in the other eight pigs. Pathogen‐binding mesh, gauze and foam provide similar pressure transduction to the wound bed during NPWT. Blood flow was found to decrease 0·5 cm laterally from the wound edge and increase 2·5 cm from the wound edge, but was unaltered 5·0 cm from the wound edge. The increase in blood flow was similar with all wound fillers. The decrease in blood flow was more pronounced with foam than with gauze and pathogen‐binding mesh. Similarly, wound contraction was more pronounced with foam, than with gauze and pathogen‐binding mesh. Wound fluid retention was the same in foam and pathogen‐binding mesh, while more fluid was retained in the wound when using gauze. The blood flow 0·5–5 cm from the wound edge and the contraction of the wound during NPWT were similar when using pathogen‐binding mesh and gauze. Wound fluid was efficiently removed when using pathogen‐binding mesh, which may explain previous findings that granulation tissue formation is more rapid under pathogen‐binding mesh than under gauze. This, in combination with its pathogen‐binding properties, makes this mesh an interesting wound filler for use in NPWT.     

Impact of negative‐pressure wound therapy on bacterial behaviour and bioburden in a contaminated full‐thickness wound

The use of negative‐pressure wound therapy (NPWT) has displayed significant clinical benefits in the healing of infected wounds. However, the effects of NPWT on bacterial colonisation and infection of traumatic wounds has been controversial. The aim of this study is to evaluate the impact of NPWT treatment in rabbits with a contaminated full‐thickness wound on bacterial behaviour, including colony morphology, spatial distribution, fissional proliferation, and bacterial bioburden. Full‐thickness wounds were created on the back of rabbits, and were inoculated with bioluminescent Staphylococcus aureus. The wounds were treated with sterile gauze dressings and NPWT with continuous negative pressure (−125 mm Hg). Wound samples were harvested on days 0 (6 hours after bacterial inoculation), 2, 4, 6, and 8 at the centre of wound beds before irrigation. Scanning electron microscopy and transmission electron microscopy (TEM) analyses were performed to determine the characteristic bacteriology. Laser scanning confocal microscopy was performed to obtain bioluminescent images, which were used to observe spatial distribution of the GFP‐labelled S. aureus within the tissue and quantify the bacterial bioburden. NPWT resulted in sparse amounts of scattered bacteria on the wound surface or as sparsely spaced single colonies within the tissue. Wound bioburden on day 8 in the NPWT and gauze groups was 34.6 ± 5.5% and 141.9 ± 15.4% of the baseline values (N = 6), respectively (P < .0001). TEM showed a lack of S. aureus active fission within NPWT‐treated tissue. NPWT can impact S. aureus colony morphology and spatial distribution both on the surface and within wound tissue, and reduce S. aureus as early as 48 hours after therapy initiation. Additionally, NPWT inhibits bacterial fissional proliferation in microcolonies.     

负压技术治疗复杂性和难愈性创面疗效观察

目的 了解负压创面治疗技术(NPWT)治疗复杂性和难愈性创面的效果.方法 选择2005年9月-2008年11月因复杂性和难愈性创面入住笔者单位治疗的67例患者,按随机化方法分为负压治疗组35例和常规治疗组32例.负压治疗组患者创面给予压力-16.63 kPa行24 h间断吸引,或以-10.64 kPa压力行24 h持续吸引.常规治疗组患者创面覆以凡士林纱布并加盖等渗盐水湿纱布及干纱布.比较2组患者治疗时间、手术次数、治疗费用及治愈方式. 结果负压治疗组患者在治疗时间、手术次数、治疗费用上均明显低于常规治疗组(P<0.05).负压治疗组治愈方式以自行愈合(40.0%)及游离皮片移植后愈合(40.0%)为主,常规治疗组则以带蒂组织瓣移植(66.7%)和游离皮片移植(23.3%)后愈合为主. 结论与常规治疗相比,NPWT治疗复杂性和难愈性创面后可缩短患者住院时间,降低手术难度,减少手术次数及治疗费用等,值得推广.     

Definition of efficiency in vacuum therapy – a randomised controlled trial comparing Redon drains with V.A.C.® Therapy™

Redon drains are still used to suction wounds for vacuum sealing. Vacuum‐assisted closure (V.A.C.^®; Kinetic Concepts Inc, San Antonio, TX) is a computer‐controlled therapy system for delivering topical negative pressure therapy. The efficiency of V.A.C. in the treatment of pressure ulcers was prospectively studied in a randomised controlled trial in which patients with pressure ulcers were randomly assigned to negative pressure wound therapy (NPWT) using either V.A.C. or Redon bottles. The target parameters were absolute and relative proportion of wound area consists of granulation tissue, fibrin and necrosis. Other outcome measures were the number of dressing changes and time invested using each system. The study was terminated after a post hoc analysis after inclusion of ten patients because of the significantly better results when using V.A.C., and the substantially larger care effort needed in the Redon group compared with the V.A.C. group. An increase in surface granulation tissue of 54% was observed in the V.A.C. group, and a reduction in the Redon group (P = 0·001). The Redon group showed an increase in fibrin tissue at the wound base of 21·8%, whereas in the V.A.C group, a 27% reduction was observed (P = 0·035). Necrosis was reduced in the V.A.C. group, but this difference did not reach significance. Redon bottles are not a good alternative for V.A.C. therapy for delivering NPWT.     

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

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

The comparison of two negative‐pressure wound therapy systems in a porcine model of wound healing

The purpose of this study was to compare two negative‐pressure wound healing systems (NPWT), ?75 mmHg with a silicone‐coated (SC) dressing and ?125 mmHg with polyurethane foam dressing (standard of care). In addition, this study compared the effects of two different dressing interfaces, SC dressing and gauze, with ?75 mmHg pressure. For both comparisons, two groups of five pigs were evaluated over a 21‐day time course. Two excisional wounds were made on each animal and NPWT dressings were applied. A canvas saddle was constructed to hold the NPWT device so the animal had free range of the pen. Dressings were changed twice a week and wound measurements were taken. Specimens for histology and gene expression analyses were taken on day 7 and 21. These data show that there is increased expression in a few genes associated with remodeling and inflammatory processes in the NPWT‐125 with polyurethane foam as compared with the NPWT‐75 with SC dressing. These two systems, however, are equivalent with respect to wound healing, histology, and gene expression over 21 days of healing. Further, we demonstrate that there is no difference in measure of healing between the SC dressing and a basic gauze dressing.     

两种负压创面治疗技术临床疗效比较

Objective To compare the differences of the clinical effects, side effects and treatment-related cost between two kinds of negative-pressure wound therapy (NPWT). Methods Forty-four inpa-tients with acute, subacute, and chronic wounds were divided into simplified NPWT group ( A group) and conventional NPWT group ( B group) according to the random number table. Wounds of patients in A group were treated with gauze + continuous suction with hospital central negative pressure ( -10.64 kPa) for 24 hs; wounds of patients in B group were treated with sponge + interrupted suction with a purpose-designed suction appliance ( -16.63 kPa) for 24 hs. Gross wound condition, treatment time, survival rates of skin graft and flap, changes of bacterial species on wound, treatment cost, and ratio of side effects between two groups were compared. Results There was no significant difference between A and B groups in respect of gross wound condition, treatment time [ A group (29 ± 12) d, B group (26 ± 13) d, P > 0. 05 ], changes of bacterial species, survival rates of skin graft [ A group (98 ± 4 ) % , B group ( 98 ± 4 ) % , P > 0. 05 ] and flap (A group 98% , B group 100% , P >0.05). Treatment cost of A group $ (374 ± 134) was obviously lower than that of B group $ (9825 ± 4956) ( P <0. 01 ), while more side effects were observed in A group (33.3%) than that in B group (5.0%) ( P < 0.05 ). Conclusions Both simplified NPWT and NPWT with purpose-designed appliance ean effectively improve wound healing. The simplified method may cause many side effects and has a potential risk of inciting nosocomial infection, but it can be conveniently employed with a low cost. In contrast, the cost of using purpose-designed appliance should be cut down to meet the aim of generalization.     

Initial clinical experiences with a new,portable, single‐use negative pressure wound therapy device

Since the introduction of negative pressure wound therapy in combination with reticulated open cell foam (NPWT/ROCF) in 1997, the clinical and economic benefits of this therapy have been showed in several randomised‐controlled studies. This article describes the clinical application of a new portable NPWT unit. The V.A.C.Via? Therapy System (KCI USA, Inc., San Antonio, TX) offers continuous negative pressure and dynamic pressure control for wound treatment of low exudating (<80 ml/day), small‐to‐medium size wounds, grafts and flaps in all care settings, including homecare. We describe four cases in which this new device was successfully used.     

Retrospective clinical evaluation of gauze-based negative pressure wound therapy

Negative pressure wound therapy (NPWT) is an established modality in the treatment of challenging wounds. However, most existing clinical evidence is derived from the use of open-cell polyurethane foam at -125 mmHg. Alternative negative pressure systems are becoming available, which use gauze at a pressure of -80 mmHg. This study describes clinical results from a retrospective non comparative analysis of 30 patients treated with Chariker-Jeter gauze-based negative pressure systems (V1STA, Versatile-1 and EZ-Care; Smith & Nephew, Inc.) in a long-term care setting. The mean age of the patients was 72 years. The wounds consisted of chronic (n = 11), surgical dehiscence (n = 11) and surgical incision (n = 8). Wound volume and area were recorded at commencement and at the cessation of therapy. Discontinuation of therapy was instigated upon closure through secondary intention or when size and exudate were sufficiently reduced that the wounds could be managed by conventional wound dressing (median 41 days). An overall median reduction in wound volume of 88.0% (P < 0.001) and a 68.0% reduction in area (P < 0.001) compared with baseline were observed over the course of NPWT. The overall rate of volume reduction (15.1% per week) compares favourably with published data from foam-based systems.     

Simultaneous irrigation and negative pressure wound therapy enhances wound healing and reduces wound bioburden in a porcine model

Infected foot wounds are one of the most common reasons for hospitalization and amputation among persons with diabetes. The objective of the study was to investigate a new wound therapy system that employs negative pressure wound therapy (NPWT) with simultaneous irrigation therapy. For this study, we used a porcine model with full‐thickness excisional wounds, inoculated with Pseudomonas aeruginosa. Wounds were treated for 21 days of therapy with either NPWT, NPWT with simultaneous irrigation therapy using normal saline or polyhexanide biguanide (PHMB) at low or high flow rates, or control. Data show that NPWT with either irrigation condition improved wound healing rates over control‐treated wounds, yet did not differ from NPWT alone. NPWT improved bioburden over control‐treated wounds. NPWT with simultaneous irrigation further reduced bioburden over control and NPWT‐treated wounds; however, flow rate did not affect these outcomes. Together, these data show that NPWT with simultaneous irrigation therapy with either normal saline or PHMB has a positive effect on bioburden in a porcine model, which may translate clinically to improved wound healing outcomes.     

Clinical evaluation of improvised gauze‐based negative pressure wound therapy in military wounds

The use of negative pressure wound therapy (NPWT) in civilian and military wounds is found effective in promoting granulation tissue, decreasing exudate and improving patient comfort. The Use of gauze‐based NPWT is increasing in civilian trauma cases with availability of proprietary systems using gauze as filler material rather than the traditionally used reticulated open‐cell foam. Military trauma wounds differ from civilian trauma wounds in energy of impact, degree and nature of contamination as well as the hostile environments. The Use of gauze as filler material for NPWT in military trauma wounds is less well studied. This study is a retrospective analysis of use of improvised gauze‐based NPWT in military trauma wounds. The whole assembly was constructed from commonly available operation theatre supplies and no proprietary system was used. Results were very encouraging and the use of this improvised method can be useful and cheap alternative to costly proprietary systems.     

Clinical evaluation of gauze‐based negative pressure wound therapy in challenging wounds

The aim of this randomised clinical study was to evaluate the effectiveness and safety of gauze‐based negative pressure wound therapy (NPWT) in patients with challenging wounds. A total of 50 consecutive patients who had wound drainage for more than 5 days, required open wound management and had existence of culture positive infection were included the study. In this study, gauze‐based NPWT was compared with conventional dressing therapy in the treatment of patients with difficult‐to‐heal wounds. The patients were randomly divided into two groups. Group I (n = 25) was followed by conventional antiseptic (polyhexanide solution) dressings, and group II (n = 25) was treated with saline‐soaked antibacterial gauze‐based NPWT. The wounds' sizes, number of debridement, bacteriology and recurrence were compared between group I and group II. The mean age of the patients was 59·50 years (range 23–97). In group I, average wound sizes of pre‐ and post‐treatment periods were 50·60 ± 55·35 and 42·50 ± 47·92 cm², respectively (P < 0·001). Average duration of treatment was 25·52 ± 16·99 days, and average wound size reduction following the treatment was 19·99% in this group. In group II, the wounds displayed considerable shrinkage, accelerated granulation tissue formation, decreased and cleared away exudate. The average wound sizes in the pre‐ and post‐treatment periods were 98·44 ± 100·88 and 72·08 ± 75·78 cm², respectively (P < 0·001). Average duration of treatment was 11·96 ± 2·48 days, and average wound size reduction following the treatment was 32·34%. The patients treated with antibacterial gauze‐based NPWT had a significantly reduced recurrence (2 wounds versus 14 wounds, P = 0·001), and increased number of the culture‐negative cases (22 wounds versus 16 wounds, P < 0·047) in a follow‐up period of 12 months. There was a statistically significant difference between two groups in all measurements. As a result, we can say that the gauze‐based NPWT is a safe and effective method in the treatment of challenging infective wounds when compared with conventional wound management.     

The influence of different sizes and types of wound fillers on wound contraction and tissue pressure during negative pressure wound therapy

Negative pressure wound therapy (NPWT) contracts the wound and alters the pressure in the tissue of the wound edge, which accelerates wound healing. The aim of this study was to examine the effect of the type (foam or gauze) and size (small or large) of wound filler for NPWT on wound contraction and tissue pressure. Negative pressures between --20 and --160 mmHg were applied to a peripheral porcine wound (n = 8). The pressure in the wound edge tissue was measured at distances of 0·1, 0·5, 1·0 and 2·0 cm from the wound edge and the wound diameter was determined. At 0·1 cm from the wound edge, the tissue pressure decreased when NPWT was applied, whereas at 0·5 cm it increased. Tissue pressure was not affected at 1·0 or 2·0 cm from the wound edge. The tissue pressure, at 0·5 cm from the wound edge, was greater when using a small foam than when using than a large foam. Wound contraction was greater when using a small foam than when using a large foam during NPWT. Gauze resulted in an intermediate wound contraction that was not affected by the size of the gauze filler. The use of a small foam to fill the wound causes considerable wound contraction and may thus be used when maximal mechanical stress and granulation tissue formation are desirable. Gauze or large amounts of foam result in less wound contraction which may be beneficial, for example when NPWT causes pain to the patient.     

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

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

Negative pressure wound therapy in spinal fusion patients

Post‐operative wound complications are some of the most common acute complications following spine surgery. These surgical site infections (SSI) contribute to increased healthcare related costs. Negative pressure wound therapy (NPWT) has long been used for treatment of soft tissue injury or defects. NPWT may reduce the incident of SSI following spinal fusion procedures; however, its potential applications need further clarification. Thus, we conducted a retrospective analysis of two cohorts to compare NPWT to traditional sterile dressings following spinal fusions in regards to post‐operative outcomes. Following institutional review board approval, 42 patients who had a NPWT were matched by type of surgery to 42 patients who had traditional dressings. A retrospective chart‐review was completed. Outcome measures, particularly SSI and need for reoperation, were analyzed using one‐way ANOVA for both univariate and multivariate analysis. When controlled for sex and body‐mass index, the use of a NPWT was independently correlated with decreased SSI (P = .035). Superficial dehiscence, seroma, need for additional outpatient care, and need for operative revision were all found to occur at higher rates in the traditional dressing cohort. Closed incisional negative pressure wound therapy provides a cost‐effective method of decreasing surgical site infection for posterior elective spine surgeries.     

Integrated negative pressure wound therapy system with volumetric automated fluid instillation in wounds at risk for compromised healing

Nearly all wounds are at risk for compromised healing due to excessive exudation, oedema, contaminants and presence of inflammatory mediators. Compromised wounds have the potential to develop complications, such as infection, which may lead to delayed wound healing, prolonged hospitalisation and more frequent readmissions. It is generally believed that the wound advances from contamination to colonisation when the bacteria on the wound's surface begin to replicate and increase their metabolic activity. Heavy bacterial bioburden increases the metabolic requirements, stimulates a proinflammatory environment and encourages the in-migration of monocytes, macrophages and leukocytes - all of which can negatively impact wound healing. Bacteria also secrete harmful cytokines which can lead to vasoconstriction and decreased blood flow. Thus, controlling or preventing infections is essential for normal wound healing process to occur. While the mainstay of treating wound infection has historically included intravenous, oral and/or topical antimicrobials in addition to frequent gauze dressing changes, a shift towards wound management with advanced modalities, such as negative pressure wound therapy (NPWT), has occurred during the past decade. This review will provide expert opinion and scientific support for the use of NPWT with instillation (NPWTi; V.A.C. Instill? Wound Therapy and V.A.C. VeraFlo? Therapy, KCI USA, Inc., San Antonio, TX) for the treatment of at-risk and complicated wounds.     

Measurement of vancomycin hydrochloride concentration in the exudate from wounds receiving negative pressure wound therapy: a pilot study

It has been reported that negative pressure wound therapy (NPWT) is effective in the treatment of contaminated wounds. We hypothesised that systemically administered antibiotics migrate to wound site effectively by NPWT, which provides the antibacterial effect. We measured and compared the concentrations of vancomycin in the exudate and blood serum. Eight patients with skin ulcers or skin defect wounds who were treated with NPWT and were administered an intravenous drip of vancomycin were enrolled in this study. The wound surfaces were muscle, muscle fascia or adipose tissue. We administered vancomycin intravenously to NPWT patients (1–3 g/day). The exudate was obtained using 500 ml V.A.C. ATS^® canisters without gel. Three days later, the concentrations of vancomycin were measured. The mean concentration of vancomycin in the exudate from NPWT was 67% of the serum vancomycin concentration. We found that concentrations of vancomycin in NPWT exudates are higher than the previously reported concentrations in soft tissue without NPWT. The proactive use of NPWT might be considered in cases of suspected wound contamination when a systemic antibiotic is administered.