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Gefen A. The influence zone: a critical performance measure for negative pressure wound therapy systems. BRITISH JOURNAL OF NURSING (MARK ALLEN PUBLISHING) 2022; 31:S8-S12. [PMID: 35980923 DOI: 10.12968/bjon.2022.31.15.s8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
This article provides an introduction to the theory of, what is termed, the 'influence zone' in the context of negative pressure wound therapy (NPWT). It is a quantitative bioengineering performance measure for NPWT systems, to indicate their effectiveness, namely, how far from the wound bed edges a specific system is able to deliver effective mechano-stimulation into the periwound, and at which intensity. The influence zone therefore provides objective and standardised metrics of one of the fundamental modes of action of NPWT systems: the ability to effectively and optimally deform both the wound and periwound macroscopically and microscopically. Most important is the mechanical deformation of the periwound area to activate cells responsible for tissue repair, particularly (myo)fibroblasts. Notably, the influence zone must extend sufficiently into the periwound to stimulate (myo)fibroblasts in order that they migrate and progress the wound healing process, facilitating the formation of scar tissue, without overstretching the periwound tissues so as not cause or escalate further cell and tissue damage. The inclusion of the influence zone theory within research to investigate the efficacy of NPWT systems facilitates systematic comparisons of commercially available and potentially new systems. This approach has the capacity to guide not only research and development work, but also clinical decision-making. Recently published research found that inducing an effective influence zone first and foremost requires continuous delivery of the intended pressure to the wound bed.
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Affiliation(s)
- Amit Gefen
- Professor of Biomedical Engineering, The Herbert J Berman Chair in Vascular Bioengineering, Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Israel
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Orlov A, Gefen A. Effective negative pressure wound therapy for open wounds: The importance of consistent pressure delivery. Int Wound J 2022; 20:328-344. [PMID: 35818745 PMCID: PMC9885467 DOI: 10.1111/iwj.13879] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Accepted: 06/14/2022] [Indexed: 02/03/2023] Open
Abstract
Two distinct design concepts exist for single-use negative pressure wound therapy systems: Canister-based versus canisterless. The canister-based technology provides intrinsic stable delivery of the intended negative pressure, because exudate is constantly transferred from the wound into a canister, thereby preventing dressing saturation. In contrast, with a canisterless system, where delivery of the negative pressure depends on continuous evaporation of wound fluids from its dressing, loss of the intended wound-bed pressure may occur due to dressing saturation. To investigate whether these two designs differ in their mechanobiological effect with respect to magnitudes and distributions of tissue strain fields under the absorptive dressing, termed the influence zone, we integrated computational modelling with an animal study. This influence zone must be of biologically influential strain levels and extend sufficiently into the peri-wound for stimulating fibroblasts to migrate and progress the healing. We found that an effective influence zone requires continuous delivery of the intended pressure to the wound-bed. Loss of negative pressure at the wound-bed below 40 mmHg adversely lowered the peri-wound stimulation around a 120 × 70 mm sized wound to less than one-third of the baseline stimulation, and further pressure decreases to 20 mmHg or lower resulted in complete lack of peri-wound mechano-stimulation.
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Affiliation(s)
- Aleksei Orlov
- Department of Biomedical Engineering, Faculty of EngineeringTel Aviv UniversityTel AvivIsrael
| | - Amit Gefen
- Department of Biomedical Engineering, Faculty of EngineeringTel Aviv UniversityTel AvivIsrael
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Orlov A, Gefen A. The potential of a canister‐based single‐use negative‐pressure wound therapy system delivering a greater and continuous absolute pressure level to facilitate better surgical wound care. Int Wound J 2022; 19:1471-1493. [PMID: 35048527 PMCID: PMC9493241 DOI: 10.1111/iwj.13744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 12/05/2021] [Accepted: 12/14/2021] [Indexed: 02/06/2023] Open
Affiliation(s)
- Aleksei Orlov
- Department of Biomedical Engineering, Faculty of Engineering Tel Aviv University Tel Aviv Israel
| | - Amit Gefen
- Department of Biomedical Engineering, Faculty of Engineering Tel Aviv University Tel Aviv Israel
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Zeybek B, Li S, Silberschmidt VV, Liu Y. Wound contraction under negative pressure therapy measured with digital image correlation and finite-element analysis in tissue phantoms and wound models. Med Eng Phys 2021; 98:104-114. [PMID: 34848029 DOI: 10.1016/j.medengphy.2021.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 10/25/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
The purpose of this study is to demonstrate the capabilities of finite-element (FE) models to predict contraction of wounds managed with negative pressure wound therapy (NPWT). The features of wounds and surrounding tissues were analysed to gain insights into the mechanical effects of NPWT on them. 3D digital image correlation (DIC) measurement of soft tissue phantoms was used to investigate the effect of wound thickness, size, and shape, which were further compared with results of FE simulations. It was noticed that with an increased NP level the difference between DIC and FE in wound contraction became more pronounced, particularly for the thick wounds. In addition, the locations of the wounds were evaluated to predict their contraction characteristics, based on surrounding tissue structures, in 3D using the developed FE models. It was demonstrated that features and location of wounds influenced their deformations differently for the same pressure levels. Overall, this study, involving a combined experimental and computational approach, allowed the important insights into mechanical effects of NPWT.
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Affiliation(s)
- Begum Zeybek
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, United Kingdom
| | - Simin Li
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, United Kingdom
| | - Vadim V Silberschmidt
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, United Kingdom
| | - Yang Liu
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, United Kingdom; Centre of Biological Engineering, Loughborough University, United Kingdom.
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Huang R, Xu L, Wang Y, Zhang Y, Lin B, Lin Z, Li J, Li X. Efficient fabrication of stretching hydrogels with programmable strain gradients as cell sheet delivery vehicles. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 129:112415. [PMID: 34579924 DOI: 10.1016/j.msec.2021.112415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/05/2021] [Accepted: 08/30/2021] [Indexed: 01/21/2023]
Abstract
Fabricating functional cell sheets with excellent mechanical strength for tissue regeneration remains challenging. Therefore, we devised a novel 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-hydroxy-succinimide crosslinked hydrogel carrier composed of gelatin (Ge) and beta-cyclodextrin (β-CD) that promoted the adhesion and proliferation of keratinocytes (Kcs) compared with those cultured on a Ge hydrogel due to significantly higher pore size, porosity, and stiffness, as confirmed using field emission scanning electron microscopy (FE-SEM) and shear wave elastography (SWE). Upon exposure to a programmable gradient microenvironment, cells displayed a stress/strain-dependent spatial-temporal distribution of extended cellular phenotypes and cytoskeletons. The promoted proliferation of Kcs and the increased retention of the undifferentiated cell phenotype on Ge-β-CD composite hydrogels under a 15% strain led to the accelerated detachment of cell sheets with retained cell-cell junctions. Moreover, the stretch-triggered upregulated expression of phosphorylated yes-associated protein (YAP) 1 suggested that this effect might be associated with the mechanical stimulation-induced activation of the YAP pathway.
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Affiliation(s)
- Rong Huang
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China
| | - Lirong Xu
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China
| | - Yan Wang
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China
| | - Yuheng Zhang
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China
| | - Bin Lin
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China
| | - Zhixiao Lin
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China
| | - Jinqing Li
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China.
| | - Xueyong Li
- Department of Burn and Plastic Surgery, Second Affiliated Hospital, Air Force Medical University, Xi'an 710038, China.
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Sachs D, Wahlsten A, Kozerke S, Restivo G, Mazza E. A biphasic multilayer computational model of human skin. Biomech Model Mechanobiol 2021; 20:969-982. [PMID: 33566274 PMCID: PMC8154831 DOI: 10.1007/s10237-021-01424-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 01/12/2021] [Indexed: 11/26/2022]
Abstract
The present study investigates the layer-specific mechanical behavior of human skin. Motivated by skin’s histology, a biphasic model is proposed which differentiates between epidermis, papillary and reticular dermis, and hypodermis. Inverse analysis of ex vivo tensile and in vivo suction experiments yields mechanical parameters for each layer and predicts a stiff reticular dermis and successively softer papillary dermis, epidermis and hypodermis. Layer-specific analysis of simulations underlines the dominating role of the reticular dermis in tensile loading. Furthermore, it shows that the observed out-of-plane deflection in ex vivo tensile tests is a direct consequence of the layered structure of skin. In in vivo suction experiments, the softer upper layers strongly influence the mechanical response, whose dissipative part is determined by interstitial fluid redistribution within the tissue. Magnetic resonance imaging-based visualization of skin deformation in suction experiments confirms the deformation pattern predicted by the multilayer model, showing a consistent decrease in dermal thickness for large probe opening diameters.
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Affiliation(s)
- David Sachs
- ETH Zurich, Institute for Mechanical Systems, Zürich, Switzerland
| | - Adam Wahlsten
- ETH Zurich, Institute for Mechanical Systems, Zürich, Switzerland
| | - Sebastian Kozerke
- University and ETH Zurich, Institute for Biomedical Engineering, Zürich, Switzerland
| | - Gaetana Restivo
- Department of Dermatology, University Hospital Zürich, Zürich, Switzerland
| | - Edoardo Mazza
- ETH Zurich, Institute for Mechanical Systems, Zürich, Switzerland
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, Experimental Continuum Mechanics, Dübendorf, Switzerland
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Lin D, Kao Y, Chen C, Wang H, Chiu W. Negative pressure wound therapy for burn patients: A meta-analysis and systematic review. Int Wound J 2021; 18:112-123. [PMID: 33236845 PMCID: PMC7949461 DOI: 10.1111/iwj.13500] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 12/11/2022] Open
Abstract
Negative pressure wound therapy (NPWT), which has been applied in various medical specialties to accelerate wound healing, has been the object of a few investigations. We explored the effectiveness of NPWT and the possibility of its inclusion in burn management guidelines. Randomised controlled trials comparing NPWT with non-NPWT treatments for burn wounds were extracted from PubMed. For the risk of bias analysis, all included studies were evaluated according to the Cochrane risk of bias tool and the approaches outlined in the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) Handbook. Outcomes such as graft take rate in the first week, infection rate, and overall complication rate were analysed. Six studies that included a total of 701 patients met our inclusion criteria. Qualitative analysis revealed that the NPWT group had a significantly better overall graft rate in the first week (P = 0.001) and a significantly lower infection rate (P = 0.04). No significant difference in the overall complication rate was found. Our results indicate that NPWT is a safe method for stimulating healing and lowering the infection rate of burn wounds. NPWT can be part of general burn management, and its incorporation into burn treatment guidelines is recommended.
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Affiliation(s)
- Dai‐Zhu Lin
- College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Yu‐Chien Kao
- College of MedicineTaipei Medical UniversityTaipeiTaiwan
| | - Chiehfeng Chen
- Division of Plastic Surgery, Department of SurgeryTaipei Municipal Wanfang Hospital, Taipei Medical UniversityTaipeiTaiwan
- Department of Public HealthTaipei Medical UniversityTaipeiTaiwan
- Cochrane TaiwanTaipei Medical UniversityTaipeiTaiwan
| | - Hsian‐Jenn Wang
- Division of Plastic Surgery, Department of SurgeryTaipei Municipal Wanfang Hospital, Taipei Medical UniversityTaipeiTaiwan
| | - Wen‐Kuan Chiu
- Division of Plastic Surgery, Department of SurgeryTaipei Municipal Wanfang Hospital, Taipei Medical UniversityTaipeiTaiwan
- Department of Surgery, School of MedicineCollege of Medicine, Taipei Medical UniversityTaipeiTaiwan
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