Vessel transformation in chronic wounds under topical negative pressure therapy: an immunohistochemical analysis

Topical negative pressure wound therapy to prevent wound complications following caesarean delivery in high-risk obstetric patients: A randomised controlled trial

BACKGROUND AND AIMS

We investigated whether the use of a prophylactic negative pressure wound therapy (NPWT) system in women undergoing caesarean would decrease wound complications in a high-risk population.

MATERIALS AND METHODS

A randomised controlled trial was performed. Women with risk factors for wound complications undergoing caesarean delivery were randomised to a standard dressing or NPWT placed over their caesarean wound. We standardised the closure of the subcutaneous fat and skin layers, both with Vicryl. Patients were followed for wound complications for up to 6 weeks after their caesareans. The incidence of wound complications was the primary outcome. The single-use NPWT system, PICO, was provided by Smith and Nephew for use in this trial. The trial was registered on clinicaltrials.gov, # NCT03082664.

RESULTS

We report here on 154 women randomised to either a standard dressing or to the NPWT. Wound complication rates were equivalent between groups, with 19.4 and 19.7% (P = 0.43) of women with follow-up information available experiencing wound complications.

CONCLUSION

We found no difference in wound complications in women with risk factors treated with a prophylactic NPWT system or standard wound dressing at the time of caesarean birth.

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.

An improved bone transport surgical method for treating chronic ischemic ulcers (thromboangiitis obliterans)

Introduction

The chronic ischemic injury of the upper/lower limbs caused by thromboangiitis obliterans (TAO, Buerger's disease) is difficult to heal, leading to high morbidity and amputation risk, seriously lowering the quality of life of patients. So far, the pathogenesis of this disease is still not clear, and there are still no effective therapeutic approaches. Here, we first use an improved bone transport technique to treat TAO-related foot ulcers and achieve good therapeutic effects.

Materials and Methods

In this report, 22 patients met the inclusion criteria, and we provide an improved bone transport technique to repair TAO-related chronic lower limb wounds, which have a minimally surgical incision and a satisfying surgical field.

Results

The improved bone transport technique resulted in TAO-related chronic lower extremity wound healing in most patients (18, M:F 16:2) within the first treatment cycle. All wounds healed completely after two treatment cycles. After these cycles, the cold sensation in the patients' feet was significantly relieved, and the rest pain in the lower extremities was significantly relieved (Visual Analog Scale, P < 0.0001). Furthermore, the Laser Doppler flowmeter showed that the blood perfusion and percutaneous oxygen pressure of the affected foot were higher than in preoperation (P < 0.0001). To conclude, bone transport technology is available for the refractory wounds of the extremity, which may promote healing by increasing blood circulation and tissue oxygen supply.

Conclusions

In summary, the improved surgical method of the bone transport technique is worth considering in the treatment of thromboangiitis obliterans-related foot ulcers.

Novel imaging methods reveal positive impact of topical negative pressure application on tissue perfusion in an in vivo skin model

The influence of topical negative pressure application (TNPA) on tissue perfusion still remains controversial. TNPA was applied for 30 minutes on intact skin of 21 healthy participants. Measurements of tissue oxygen saturation and tissue temperature as signs of tissue perfusion were performed before application of the TNPA, directly after removal of the TNPA and 5, 10, 15, 20, and 30 minutes after removal of the dressing using the near infrared imaging (NIRI) and a thermal imaging camera. Tissue oxygen saturation showed an increase from 67.7% before applying the TNPA to 76.1% directly after removal of TNPA, followed by a decrease of oxygen saturation 30 minutes after removal of TNPA. The measured temperature of the treated skin area increased from 32.1°C to 36.1°C after removal of TNPA with a consecutive decrease of the temperature 30 minutes after removal. TNPA resulted in both a higher tissue oxygen saturation and a higher skin temperature after 30 minutes compared to the beginning. TNPA increases both tissue oxygen saturation and skin temperature as sign of an increase of tissue perfusion. NIRI and thermal imaging proved to be useful for measuring changes in tissue perfusion.

Role of Endoscopic Vacuum Therapy as a Treatment for Anastomosis Leak after Esophageal Cancer Surgery

Esophageal anastomotic leak is the most common and serious complication following esophagectomy. However, the standard treatment for anastomotic leaks remains unclear. Recently, endoscopic vacuum therapy has become an important non-surgical alternative treatment method for patients with esophageal anastomotic leak. This treatment involves the endoscopic placement of a sponge connected to a nasogastric tube into the defect cavity or lumen. Subsequently, continuous negative pressure is delivered to the cavity through the tube. Several studies have reported a treatment success rate of 80% to 100%. In this study, we review the mechanism of action, the method of performing the procedure, its safety and efficacy, and prognostic factors for failure of endoscopic vacuum therapy in the management of patients with anastomotic leak, and on this basis attempted to confirm the possibility of establishing a standardized treatment protocol using endoscopic vacuum therapy.

Practical Things You Should Know about Wound Healing and Vacuum-Assisted Closure Management

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Understand the basics of negative-pressure wound therapy and practical uses of various vacuum-assisted closure dressings. 2. Understand the mechanisms of action of negative-pressure therapies and other important adjuncts, such as perfusion imaging. 3. Discuss the evidence for hyperbaric oxygen therapy in wound care.

SUMMARY

Wound healing requires creating an environment that supports the healing process while decreasing inflammation and infection. Negative-pressure wound therapy has changed the way physicians manage acute and chronic wounds for more than 20 years. It contracts wound edges, removes exudate, including inflammatory and infectious material, and promotes angiogenesis and granulation tissue formation. These effects have been consistently demonstrated in multiple animal and human randomized controlled trials. Recent innovations that include instillation therapy and closed incision have further increased our arsenal against difficult-to-treat wounds and incisions at high risk of complications. Instillation of topical wound solutions allows physicians to cleanse the wound without return to the operating room, resulting in fewer debridements, shorter hospital stays, and faster time to wound closure. Other concepts have yielded negative-pressure therapy on top of closed surgical incisions, which holds incision edges together, reduces edema, promotes angiogenesis, and creates a barrier to protect incisions during the critical healing period, thereby reducing surgical-site complications, especially infection. Other practical adjuncts to the modern-day treatment of acute and chronic wounds include indocyanine green angiography, which allows real-time assessment of perfusion, and hyperbaric oxygen treatment, which has been suggested to augment healing in acute, chronic, specifically diabetic foot ulcers and radiation-related wounds.

Role of endoscopic vacuum therapy in the management of gastrointestinal transmural defects

A gastrointestinal (GI) transmural defect is defined as total rupture of the GI wall, and these defects can be divided into three categories: perforations, leaks, and fistulas. Surgical management of these defects is usually challenging and may be associated with high morbidity and mortality rates. Recently, several novel endoscopic techniques have been developed, and endoscopy has become a first-line approach for therapy of these conditions. The use of endoscopic vacuum therapy (EVT) is increasing with favorable results. This technique involves endoscopic placement of a sponge connected to a nasogastric tube into the defect cavity or lumen. This promotes healing via five mechanisms, including macrodeformation, microdeformation, changes in perfusion, exudate control, and bacterial clearance, which is similar to the mechanisms in which skin wounds are treated with commonly employed wound vacuums. EVT can be used in the upper GI tract, small bowel, biliopancreatic regions, and lower GI tract, with variable success rates and a satisfactory safety profile. In this article, we review and discuss the mechanism of action, materials, techniques, efficacy, and safety of EVT in the management of patients with GI transmural defects.

Negative pressure wound therapy use in diabetic foot syndrome-from mechanisms of action to clinical practice

BACKGROUND

Diabetes and its complications constitute a rising medical challenge. Special attention should be given to diabetic foot syndrome (DFS) due to its high rate of associated amputation and mortality. Negative pressure wound therapy (NPWT) is a frequently used supportive modality in a diabetic foot with ulcerations (DFUs).

DESIGN

Here, we reviewed the current knowledge concerning the tissue and molecular mechanisms of NPWT action with an emphasis on diabetes research followed by a summary of clinical DFU studies and practice guidelines.

RESULTS

Negative pressure wound therapy action results in two types of tissue deformations-macrodeformation, such as wound contraction, and microdeformation occurring at microscopic level. Both of them stimulate a wound healing cascade including tissue granulation promotion, vessel proliferation, neoangiogenesis, epithelialization and excess extracellular fluid removal. On the molecular level, NPWT results in an alteration towards more pro-angiogenic and anti-inflammatory conditions. It increases expression of several key growth factors, including vascular endothelial growth factor and fibroblast growth factor 2, while expression of inflammatory cytokinesis reduced. The NPWT application also alters the presence and function of matrix metalloproteinases. Clinical studies in DFU patients showed a superiority of NPWT over standard therapy in terms of efficacy outcomes, primarily wound healing and amputation rate, without a rise in adverse events. International guidelines point to NPWT as an important adjuvant therapy in DFU whose use is expected to increase.

CONCLUSIONS

This current knowledge improves our understanding of NPWT action and its tailoring for application in diabetic patients. It may inform the development of new treatments for DFU.

Vascular architecture in free flaps: Analysis of vessel morphology and morphometry in murine free flaps

The aim of this study was to analyze the development of vascular architecture as well as vascular morphometry and morphology of anastomosed microvascular free flaps. Free pectoral skin flaps were raised in 25 rats and anastomosed to the femoral vessels in the groin region. CD31 immunohistology was performed after 3, 7 and 12 d (each 5 animals each) to analyze microvessel density (MVD), microvessel area (MVA) and microvessel size (MVS). Microvascular corrosion casting was performed after 7 and 12 d (5 animals each) to analyze vessel diameter (VD), intervascular distance (IVD), interbranching distance (IBD), and branching angle (BA). Further on, sprout and pillar density as hallmarks of sprouting and intussusceptive angiogenesis were analyzed. Pectoral skin isles from the contralateral side served as controls. A significantly increased MVD was found after 7 and 12 d (p each <0.001). MVA was significantly increased after 3, 7 and 12 d (p each <0.001) and a significantly increased MVS was analyzed after 3 and 7 d (p each <0.001). VD and IVD were significantly increased after 7 and 12 d (p each <0.001). For IBD, a significantly increase was measured after 7 d (p < 0.001). For IBA, sprout and pillar density, no significant differences were found (p each ≥0.05). Significant changes in the vascular architecture of free flaps after successful microvascular anastomosis were seen. Since there was no evidence for sprout and pillar formation within the free flaps, the increased MVD and flap revascularization might be induced by the receiving site.

A New Procedure for Wrapped-Negative Pressure Wound Therapy for Congestion After Arterialized Venous Flap Surgery

Negative pressure wound therapy (NPWT) is a method for treating wound. However, there are no case reports using NPWT for treating congestion after arterialized venous flap. Therefore, this study reported favorable outcomes after using a single-use NPWT system for managing congestion. A 39-year-old man had his index finger caught by a press machine. The finger had a soft tissue defect at the ventral part. An arterialized venous flap taken from the right forearm was transplanted. Perfusion of the flap was favorable, but on postoperative day 5, congestion and the edema of the flap were found. Then, NPWT was initiated. The congestion and edema in the flap were improved without complications such as flap necrosis and wound infection. At 4 months postoperatively, the morphology of the finger was favorable. In this study, NPWT was speculated to force the deeper blood vessels within the flap to dilate with inducing drainage and the simultaneous reduction in excess blood flow to the cortical layer, resulting in the improvement of congestion. Negative pressure wound therapy was used for treating congestion after the transplantation of arterialized venous flap, and the wound was favorably managed.

Evidence based review of negative pressure wound therapy

Vacuum-assisted closure, sometimes referred to as microdeformational wound therapy or most commonly negative pressure wound therapy (NPWT), has significantly improved wound care over the past two decades. NPWT is known to affect wound healing through four primary mechanisms (macrodeformation, microdeformation, fluid removal, and alteration of the wound environment) and various secondary mechanisms (including neurogenesis, angiogenesis, modulation of inflammation, and alterations in bioburden) which are described in this review. In addition, the technique has many established uses, for example in wound healing of diabetic and pressure ulcers, as well as burn and blast wounds. This therapy also has many uses whose efficacy has yet to be confirmed, for example the use in digestive surgery. Modifications of the traditional NPWT have also been established and are described in detail. This therapy has various considerations and contraindications which are summarized in this review. Finally, future perspectives, such as the optimal cycling of the treatment and the most appropriate interface material, are touched upon in the final segment. Overall, despite the fact that questions remain to be answered about NPWT, this technology is a major breakthrough in wound healing with significant potential use both in the hospital but also in the community.

Tadalafil therapy and severe chronic foot wound resolution

We report an unanticipated medication effect resulting in near-complete wound healing in a patient after beginning tadalafil therapy of 20 mg thrice daily. This patient was treated for 50 years with state-of-the art acute and then chronic wound interventions after a traumatic farm machinery accident which resulted in a devascularised foot wound. This infection was both life- and limb-threatening. The patient had undergone multiple vascular and plastic surgeries and antimicrobial therapies in addition to hospitalisations for sepsis. Limb amputation was being considered, when his urologist placed him on daily phosphodiesterase-5 inhibitor therapy, prior to unrelated urologic surgery. Remarkably, his foot wound underwent near-complete resolution and has been stable for 2 years.

PHDs inhibitor DMOG promotes the vascularization process in the AV loop by HIF-1a up-regulation and the preliminary discussion on its kinetics in rat

BACKGROUND

The Arterovenous Loop (AV Loop) model is a vascularization model in tissue engineering research, which is capable of generating a three dimensional in vivo unit with cells as well as the supporting vessels within an isolation chmaber. In our previous studies the AV loop in the isolation chamber was discovered to undergo hypoxia, characterized by Hypoxia Inducible Factor (HIF) up-regulation. The vascularization followed the increase of HIF-α temporally, while it was spatially positively correlated with the HIF-α level, as well. This study aims to prove that HIF-1a up-regulation is the stimulus for vascularization in the AV loop model.

METHOD

The AV loop model in rats was created by interposing a femoral vein graft into the distal ends of the contralateral femoral artery and vein, and the loop was embeded in fibrin matrix and fixed in isolation chamber. PHD (prolyl hydroxylases) inhibitor DMOG (Dimethyloxallyl Glycine) was applied systemically in the rats in 40 mg/KG at day 0 and day 3 (DMOG-1), or in 15 mg/KG at day 8, day10 and day12 (DMOG-2). Two weeks later the specimens were explanted and underwent morphological and molecular evaluations.

RESULTS

Compared to the control group, in the DMOG-2 group the HIF-1α positive rate was siginicantly raised as shown in immunohistochemistry staining, accompanied with a smaller cross section area and greater vessel density, and a HIF-1α accumulation in the kidney. The mRNA of HIF-1α and its angiogenic target gene all increased in different extends. Ki67 IHC demostrate more positive cells. There were no significant change in the DMOG-1 group.

CONCLUSION

By applying DMOG systemically, HIF-1α was up-regulated at the protein level and at the mRNA level, acompanied with angiogenic target gene up-regulateion, and the vascularization was promoted correspondingly. DMOG given at lower dosage constantly after one week tends to have better effect than the group given at larger dosage in the early stage in this model, and promotes cell proliferation, as evidenced by Ki67 IHC. Thus, this study proves that HIF-1a up-regulation is the stimulus for vascularization in the AV loop model and that the process of the vessel outgrowth can be controlled in the AV Loop model utilizing this mechanism.