Establishment of a novel rat model for deep tissue injury deterioration

Study on an Onset Mechanism of MDRPU by Wearing Elastic Stockings: Numerical Simulation by Two-Dimensional Mechanical Model

As compared with pressure injuries, the mechanism the development of medical device related pressure ulcers (MDRPU) is not revealed enough. According to studies on severity and frequent site of occurrence, MDRPUs are surmised to occur the surface of the skin. In this study, we assess theoretical and experimental analysis by two-dimensional mechanical model for elastic stockings (ES) wear the lower limbs with or without dug into the skin by the wrinkles and curling up of ES. The Finite Element Method (FEM) was used to calculate the stress on the skin and subcutaneous tissue, because of elucidating the mechanism of MDRPU. The FEM used a triple-layered cylindrical model simulating the skin, subcutaneous tissue, and bone. Regarding the interface pressure (compression pressure), two samples were created: the one is applying a uniform pressure of 5.3 kPa on the skin surface simulating the correct wearing of ES, and the other is applying a pressure of 16 kPa on the part of the skin on which ES dug in. The results were as follows: the internal stress on the skin and subcutaneous tissue was maximum at the site where ES dug in, producing stresses of 54 kPa, 50 kPa, and 21 kPa in the circumferential, longitudinal, and radial directions, respectively. The uniform pressure produced an internal stress of 5-9 kPa on the skin surface. Unlike the mechanism of pressure injury formation, we considered compressive strength from tensile of the circumferential and longitudinal directions, furthermore the additive radial pressure at the digging site on the skin due to the wrinkles and curling of ES, which is one of the factor to cause strong external force in the MDRPU formation. (This is secondary publication from Jpn J Phlebol 2021; 32(1): 119-126.).

Improving knowledge of continence care to prevent skin damage associated with incontinence

Older people are at an increased risk of developing skin damage related to incontinence, including pressure ulceration and incontinence-associated dermatitis (IAD). Factors exacerbating risk in older people include: a higher rate of faecal and urinary incontinence, reduced mobility, long-term conditions and changes to skin barrier function, as a result of the ageing process. Nurses have a key role to play in the assessment of continence, IAD prevention and management. This article explores nursing knowledge in relation to continence care on six inpatient wards for older people, and describes the implementation of improvement strategies, in order to reduce voidable harm.

Risk factors for the development and evolution of deep tissue injuries: A systematic review

AIMS

The aim of this systematic review is to identify the current epidemiological evidence indicating the unique risk factors for deep tissue injury (DTI) compared to grade I-IV pressure injury (PI), the proportion of DTI which evolve rather than resolve and the anatomical distribution of DTI.

METHODS

A systematic literature search was undertaken using the MEDLINE and CINAHL Plus databases using the search terms 'Deep tissue injury OR DTI [Title/abstract]'. A google scholar search was also conducted in addition to hand searches of relevant journals, websites and books which were identified from reference lists in retrieved articles. Only peer-reviewed English language articles published 2009-2021 were included, with full text available online.

RESULTS

The final qualitative analysis included nine articles. These included n = 4 retrospective studies, n = 4 prospective studies and n = 1 animal study.

CONCLUSION

The literature indicates that the majority of DTI occur at the heel and sacrum although in paediatric patients they are mainly associated with medical devices. Most DTI are reported to resolve, with between 9.3 and 27% deteriorating to full thickness tissue loss. Risk factors unique to DTI appear to include anaemia, vasopressor use, haemodialysis and nicotine use although it is unclear if these factors are unique to DTI or are shared with grade I-IV PI. Factors associated with deterioration include cooler skin measured using infrared thermography and negative capillary refill. With 100% of DTI showing positive capillary refill in one study resolving without tissue loss (p = 0.02) suggesting this may be an effective prognostic indicator. More prospective studies are required focusing on establishing causal links between risk factors identified in earlier retrospective studies. Ideally these should use statistically powered samples and sufficient follow up periods allowing DTI outcomes to be reached. Further work is also needed to establish reliable diagnostic criteria for DTI in addition to more studies in the paediatric population.

Identification of microRNAs responsive to shear loading in rat skin

Pressure injuries (PIs) are localised skin injuries that result from pressure with or without shear force. Shear force is more destructive than pressure in clinical settings. Therefore, determining the critical external forces is important for selecting the appropriate care to prevent PIs. To quantitatively distinguish pressure and shear loading with high specificity, we focused on microRNAs (miRs). This study aimed to identify the miRs that are distinguishable between pressure with and without shear loading in rat skin. Microarray analysis identified six candidate miRs from the comparisons among the pressure, shear, and unloaded groups. We analysed the expression levels of the candidate miRs in the process of PI development using real‐time reverse transcriptase polymerase chain reaction. In the pressure and shear groups, miR‐92b expressions at 6 hours after loading were 2.3 ± 1.3 and 2.9 ± 1.0, respectively, which were significantly higher than those in the control group (P = .014 and .004, respectively). miR‐877 expression at 6 hours after loading was significantly increased only in the shear group (2.8 ± 0.9) compared with the control group (P = .016). These results indicate that miR‐92b and miR‐877 are promising biomarkers to determine for which external force healthcare professionals should intervene.

Deep tissue injury: a narrative review on the aetiology of a controversial wound

Deep tissue injuries (DTIs) were added to pressure ulcer grading systems in 2009. Since then, they have been associated with the same aetiological processes as other forms of pressure injury (PI). This is despite notable clinical differences in their presentation along with variations in natural history that suggest they are the consequence of processes distinct from those that cause other PIs. Understanding the aetiology of DTIs is essential to guide prevention and treatment in addition to ensuring healthcare governance processes deeply tied to pressure injury are effective and efficient. Current understanding of the aetiology of DTI has significant gaps, with several key challenges impeding progress in this area of PI research, including inconsistent reporting by healthcare services and the limitations of animal and computer models in addition to the ethical barriers to conducting studies on human subjects. Synthesis of early studies with studies undertaken before 2009 is also limited by the variety in definitions of DTI used before that published by the European Pressure Ulcer Advisory Panel, the National Pressure Injury Advisory Panel and the Pan Pacific Pressure Injury Alliance in 2009. To date, few prospective clinical studies have been conducted. This article presents a narrative review on the clinical and animal study evidence indicating contemporary understanding of DTI.

Tazarotene-loaded PLGA nanoparticles potentiate deep tissue pressure injury healing via VEGF-Notch signaling

BACKGROUND AND PURPOSE

New capillaries are essential for deep tissue pressure injury wound healing. Tazarotene is a recently discovered small molecule drug and functions to promote neovascularization and tissue repair. At present, the application of tazarotene in the repair of pressure injuries has not previously been investigated. This study used poly (lactic-co-glycolic acid) (PLGA) as nanoparticle carriers loaded with tazarotene (Ta/PLGA NPs) for drug delivery and to overcome shortcomings associated with the low water solubility, short half-life, easy photolysis and low bioavailability of tazarotene itself.

METHODS

The physicochemical properties, drug release and bioactivity of Ta/PLGA NPs were examined in vitro by transmission electron microscope, spectrophotometry and cell assays. Mouse models of deep tissue pressure injuries (DTPI) were established and the therapeutic effects and mechanisms of Ta/PLGA NPs in local wound repair were studied.

RESULTS

The results showed that Ta/PLGA NPs were of uniform size and distribution and were non-toxic both in vitro and in vivo. In vivo experiments suggested that Ta/PLGA NPs significantly promoted DTPI wound repair through activation of the VEGF/VEGFR-Notch1/DLL4 signaling pathway.

CONCLUSION

This study highlights the potential clinical significance of implementation of tazarotene small molecule drugs in combination with effective biomaterial carriers for the treatment of chronic refractory wounds, such as DTPI.

Vibration inhibits deterioration in rat deep-tissue injury through HIF1-MMP axis

Deep-tissue injury (DTI) is a unique type of pressure ulcer (PU) in which deep-tissue damage expands outwards to the superficial skin. DTI progresses rapidly into a severe PU, despite initially appearing as only a bruise or darkened tissue in the superficial skin. Although some DTI detection methods are available, there is currently no strategy for treating deteriorating DTI. This study investigated the efficacy of vibration therapy for preventing DTI deterioration through down-regulation of the hypoxia-inducible factor-1 matrix metalloproteinase (MMP) axis in rats. We prepared a conventional PU rat model (PU group) and a DTI deterioration rat model (DTI group). The DTI group was further divided into two groups subjected to vibration and control treatments, respectively. Macroscopic and histological features, hypoxia, oxidative stress, apoptosis, and MMP2 and MMP9 activities in compressed skin were analyzed. Hypoxia, oxidative stress, and MMP activity were enhanced in the DTI group compared with the PU group. Vibration remarkably inhibited DTI deterioration, hypoxia, and the expression/activities of MMP2 and MMP9. These results suggest that vibration therapy can effectively attenuate deterioration of DTI. This report provides the first evidence for a therapeutic treatment for deteriorating DTI.