Effective negative pressure wound therapy for open wounds: The importance of consistent pressure delivery

The Evolution of Commercial Negative Pressure Wound Therapy Systems over the Past Three Decades

Significance: Since the introduction of the first commercial negative pressure wound therapy (NPWT) system nearly three decades ago, several key technological innovations have led to the wide adoption of the therapy. This is a review of the history and innovation of commercial NPWT systems for adjunctive management of open wounds. Recent Advances: Technical modifications have broadened NPWT options to include innovative dressing interfaces, tubing configurations, power sources, capability of topical wound solution instillation or irrigation, canister versus canister-free configurations, smart technology, and disposable versus larger reusable therapy units. While these options complicate product selection, they have greatly expanded the potential to manage a wide variety of wounds in patients who previously may not have been candidates for NPWT. Critical Issues: Basic yet mandatory requirements of NPWT include delivering an accurate level of negative pressure to the wound bed, maintaining a seal, removing wound surface exudate through the dressing interface, and patient adherence to prescribed therapy. Meeting these requirements is challenging in the face of variable wound types, wound locations, exudate levels, and exudate viscosity. While there are a growing number of marketed NPWT systems, each may have different characteristics and performance. Evaluating the functionality of each system and relevant accessories is complicated, especially as additional manufacturers enter the market. Understanding the key innovations and specific challenges they are intended to solve may aid health care providers in selecting appropriate NPWT technologies for patients. Future Directions: Evolving technology, including artificial intelligence, will likely play a major role in redefining NPWT safety, simplicity, and reliability.

Application of near-infrared spectroscopy to assess the effect of the cupping size on the spatial hemodynamic response from the area inside and outside the cup of the biceps

Cupping therapy is a popular intervention for improving muscle recovery after exercise although clinical evidence is weak. Previous studies demonstrated that cupping therapy may improve microcirculation of the soft tissue to accelerate tissue healing. However, it is unclear whether the cupping size could affect the spatial hemodynamic response of the treated muscle. The objective of this study was to use 8-channel near-infrared spectroscopy to assess this clinical question by assessing the effect of 3 cupping sizes (35, 40, and 45 mm in inner diameter of the circular cup) under -300 mmHg for 5 min on the muscle hemodynamic response from the area inside and outside the cup, including oxyhemoglobin and deoxy-hemoglobin in 18 healthy adults. Two-way factorial design was used to assess the interaction between the cupping size (35, 40, and 45 mm) and the location (inside and outside the cup) and the main effects of the cupping size and the location. The two-way repeated measures ANOVA demonstrated an interaction between the cupping size and the location in deoxy-hemoglobin (P = 0.039) but no interaction in oxyhemoglobin (P = 0.100), and a main effect of the cup size (P = 0.001) and location (P = 0.023) factors in oxyhemoglobin. For the cupping size factor, the 45-mm cup resulted in a significant increase in oxyhemoglobin (5.738±0.760 μM) compared to the 40-mm (2.095±0.312 μM, P<0.001) and 35-mm (3.134±0.515 μM, P<0.01) cup. Our findings demonstrate that the cupping size and location factors affect the muscle hemodynamic response, and the use of multi-channel near-infrared spectroscopy may help understand benefits of cupping therapy on managing musculoskeletal impairment.

Extracellular vesicle-derived silk fibroin nanoparticles loaded with MFGE8 accelerate skin ulcer healing by targeting the vascular endothelial cells

BACKGROUND

Reduced supplies of oxygen and nutrients caused by vascular injury lead to difficult-to-heal pressure ulcers (PU) in clinical practice. Rapid vascular repair in the skin wound is the key to the resolution of this challenge, but clinical measures are still limited. We described the beneficial effects of extracellular vesicle-derived silk fibroin nanoparticles (NPs) loaded with milk fat globule EGF factor 8 (MFGE8) on accelerating skin blood vessel and PU healing by targeting CD13 in the vascular endothelial cells (VECs).

METHODS

CD13, the specific targeting protein of NGR, and MFGE8, an inhibitor of ferroptosis, were detected in VECs and PU tissues. Then, NPs were synthesized via silk fibroin, and MFGE8-coated NPs (NPs@MFGE8) were assembled via loading purified protein MFGE8 produced by Chinese hamster ovary cells. Lentivirus was used to over-express MFGE8 in VECs and obtained MFGE8-engineered extracellular vesicles (EVs-MFGE8) secreted by these VECs. The inhibitory effect of EVs-MFGE8 or NPs@MFGE8 on ferroptosis was detected in vitro. The NGR peptide cross-linked with NPs@MFGE8 was assembled into NGR-NPs@MFGE8. Collagen and silk fibroin were used to synthesize the silk fibroin/collagen hydrogel. After being loaded with NGR-NPs@MFGE8, silk fibroin/collagen hydrogel sustained-release carrier was synthesized to investigate the repair effect on PU in vivo.

RESULTS

MFGE8 was decreased, and CD13 was increased in PU tissues. Similar to the effect of EVs-MFGE8 on inhibiting ferroptosis, NPs@MFGE8 could inhibit the mitochondrial autophagy-induced ferroptosis of VECs. Compared with the hydrogels loaded with NPs or NPs@MFGE8, the hydrogels loaded with NGR-NPs@MFGE8 consistently released NGR-NPs@MFGE8 targeting CD13 in VECs, thereby inhibiting mitochondrial autophagy and ferroptosis caused by hypoxia and accelerating wound healing effectively in rats.

CONCLUSIONS

The silk fibroin/collagen hydrogel sustained-release carrier loaded with NGR-NPs@MFGE8 was of great significance to use as a wound dressing to inhibit the ferroptosis of VECs by targeting CD13 in PU tissues, preventing PU formation and promoting wound healing.

A robotic venous leg ulcer system reveals the benefits of negative pressure wound therapy in effective fluid handling

We applied a market-leading, single-use negative pressure wound therapy device to a robotic venous leg ulcer system and compared its fluid handling performance with that of standard of care, superabsorbent and foam dressings and compression therapy. For each tested product, we determined a metrics of retained, residual, evaporated and (potential) leaked fluid shares, for three exudate flow regimes representing different possible clinically relevant scenarios. The single-use negative pressure wound therapy system under investigation emerged as the leading treatment option in the aspects of adequate fluid handling and consistent delivery of therapeutic-level wound-bed pressures. The superabsorbent dressing performed reasonably in fluid handling (resulting in some pooling but no leakage), however, it quickly caused excessive wound-bed pressures due to swelling, after less than a day of simulated use. The foam dressing exhibited the poorest fluid handling performance, that is, pooling in the wound-bed as well as occasional leakage, indicating potential inflammation and peri-wound skin maceration risks under real-world clinical use conditions. These laboratory findings highlight the importance of advanced robotic technology as contemporary means to simulate patient and wound behaviours and inform selection of wound care technologies and products, in ways that are impossible to achieve if relying solely on clinical trials and experience.

Within-patient randomised clinical trial exploring the development of microskin implantation in the treatment of pressure ulcers

Pressure injury often seriously affects the life quality of aged patients, especially the long-term bedridden casualties. Widely adopted by different disciplines, negative pressure suction has its role in pressure injury. Microskin implantation has been demonstrated powerful in increasing the expansion ratio of donor area-derived skin and accelerating wound healing by forming "skin islands". The study was designed to evaluate the efficacy and safety of additional use of bedside microskin implantation in the palliative care of pressure injury of aged patients who cannot tolerate surgical treatment as a supplement for standard negative pressure suction. An open-label within-patient RCT was conducted in aged patients with pressure injury. Sixteen patients were enrolled. After granulation tissues formed, half of a pressure injury was randomised to receive the negative pressure suction as the control group, and the other half exposed to additional bedside microskin implantation as the experimental group. Efficacy was evaluated within 1 month after treatment, and the primary endpoints included the wound healing rate and pressure ulcer scale for healing (PUSH) scores. The secondary outcomes included survival rate of implanted microskin, pain intensity assessment, satisfaction surveys from patients or their family, and pressure ulcer healing complications. Sixteen patients completed the study. After 14 days of operation, 5.63 ± 1.78 out of 10 pieces of implanted microskin survived and formed neonatal epithelium. The wound healing rates of the control group and the experimental group at 1 month were (26.17 ± 9.03%) and (35.95 ± 16.02%), respectively (P < .01). The mean PUSH score before the surgery was 12.38 ± 2.23. At 1 month after surgery, the mean difference of PUSH score from baseline was 2.13 ± 0.96 in the control group and 2.81 ± 0.83 in the experimental group (P < .01). The treatment of microskin implantation did not cause additional pain or complications to the patients. Accompanied by a better ulcer status, the majority of patients or their guardians have a high degree of acceptance towards the microskin implantation. Bedside microskin implantation could accelerate wound healing with lower PUSH scores. As a complementary palliative treatment, supplementary microskin implantation is effective and well tolerated.

Mechanical and contact characteristics of foam materials within wound dressings: Theoretical and practical considerations in treatment

In the treatment of acute and chronic wounds, the clinical performance of a given foam-based dressing, and, ultimately, the wound healing and cost of care outcomes are strongly influenced by the mechanical performance of the foam material/s within that dressing. Most aspects of the mechanical performance of foam materials, for example, their stiffness, frictional properties, conformability, swelling characteristics and durability, and the overall mechanical protection provided by a foam-based dressing to a wound strongly depend on the microstructure of the foam components, particularly on their microtopography, density and porosity. This article, therefore, provides, for the first time, a comprehensive, self-inclusive compilation of clinically relevant theoretical and practical considerations, based on published analytical and experimental research as well as clinical experience related to the mechanical performance of foams in foam-based wound dressings. The current bioengineering information is useful for establishing understanding of the importance of mechanical properties of foams in foam-based dressings among clinicians and researchers in industry and academia, and other potential stakeholders in the wound care field, for example, regulators and buyers. This information is also particularly important for the development of standardised test methods for the evaluation of foam-based wound dressings and resulting standard mechanical performance metrics for these dressings.