Prof. Amit Gefen
Research
Three-dimensional shape-conformation performances of wound dressings tested in a robotic sacral pressure ulcer phantom
Performances of wound dressings are primarily a function of the dressing technology, which determine the modes of action of the dressings and their effectiveness. Nonetheless, in any real-world clinical scenario, the dressing structure always interacts with the individual wound characteristics and the specific environment acting on the wound. Specifically, effective exudate retention by dressings requires close dressing-wound contact, immediately and continuously after application as any spaces may allow for exudate pooling. In this work we tested the effectiveness of dressings, with a claimed 3D-shape-conformation technology, in minimizing dressing-wound gaps. Using our phantom system combined with a 3D laser scanning and bespoke software, we reconstructed dressing shapes after simulated use and calculated the goodness-of-fit between the dressing and the wound geometry. Our approach and technology are a cornerstone for development of testing standards which incorporate the clinical practice aspects and a high degree of realism while facilitating reproducibility and precision of laboratory tests
How influential is the stiffness of the foam dressing on soft tissue loads in negative pressure wound therapy?
Negative pressure wound therapy (NPWT) is clinically effective in managing both acute and chronic wounds. In this study we have developed a computational modelling framework for better understanding of the mechanobiology of tissues at the peri-wound and wound-bed under NPWT. We specifically developed a three-dimensional open wound finite element (FE) model that contains viscoelastic skin, adipose and skeletal muscle tissue components for determining the states of tissue strains and stresses in and around the wound when subjected to NPWT without primary suture closure. This FE modelling further facilitates studies of the influence of the foam dressing (FD) properties such as its stiffness on the dynamic strain and stress states generated in the tissues. Our computational simulation data demonstrated that the strain state induced at the peri-wound tissues, particularly skin, can be more effectively controlled by adjusting the pressure level than by varying the stiffness of the foam dressing.
A computational model for evaluating the efficacy of protective vests in preventing non-penetrating internal combat-related injuries
Torso injuries are common in a combat environment. Although penetrative injury results with internal organ damage that may be fatal, it should be noted that even non-penetrative blunt trauma might cause severe and fatal tissue damage, since blocking projectiles by an armor is accompanied by immense amounts of energy absorbed in the consequently injured tissues.
Current methods used for evaluating the efficacy of protective armors are not accurate and do not provide analysis and description of the pattern of deformations and stresses that develop in the tissues during the impact. Our objective is to develop an efficient platform for comparing performances of armor designs using finite-element modelling.
The simulations resemble non-penetrating ballistic impacts in an anatomically-realistic torso model while examining different types of armors and projectiles. The performance of each armor is quantitatively evaluated based on biomechanical parameters.
This study has immediate practical implications. Using this innovative approach it will be possible to considerably shorten the development and procurement processes of efficient protective gear and consequently improve protection capabilities for soldiers.
Physiological measurements of facial skin response under personal protective equipment
Medical device-related pressure ulcers (MDRPUs) were traditionally associated with skin-contacting medical devices applied to patients, eventually causing tissue damage. The coronavirus-2019 pandemic has brought a new variant of MDRPUs: facial skin irritation or damage associated with extended use of protective personal equipment (PPE), e.g. facemasks and respirators. In this context, we report here a comprehensive experimental evaluation including facial contact forces, skin temperatures and sub-epidermal moisture (SEM) measurements pre/post-PPE usage, to determine how these physiological parameters change under the effects of surgical facemasks and KN95 respirators and whether such potential changes can explain the commonly reported skin irritation or damage. We found that a surgical mask is potentially less irritating to facial skin than the KN95 respirator, as it applies lower forces and facilitates faster return of facial temperatures to their basal levels. Further, we demonstrated that use of dressing cuts for padding under a KN95 respirator considerably reduced localized forces and did not worsen the thermal and SEM readings at the skin-device contact sites. This study provides a basis for improvement of PPE designs, as it describes physiological measurement methodologies for quantitative comparisons of the effects of different PPE types on facial skin status.
