Myoglobin and troponin concentrations are increased in early stage deep tissue injury

Troponins and Skeletal Muscle Pathologies

Skeletal muscles account for ~30-40% of the total weight of human body and are responsible for its most important functions, including movement, respiration, thermogenesis, and glucose and protein metabolism. Skeletal muscle damage negatively impacts the whole-body functioning, leading to deterioration of the quality of life and, in severe cases, death. Therefore, timely diagnosis and therapy for skeletal muscle dysfunction are important goals of modern medicine. In this review, we focused on the skeletal troponins that are proteins in the thin filaments of muscle fibers. Skeletal troponins play a key role in regulation of muscle contraction. Biochemical properties of these proteins and their use as biomarkers of skeletal muscle damage are described in this review. One of the most convenient and sensitive methods of protein biomarker measurement in biological liquids is immunochemical analysis; hence, we examined the factors that influence immunochemical detection of skeletal troponins and should be taken into account when developing diagnostic test systems. Also, we reviewed the available data on the skeletal troponin mutations that are considered to be associated with pathologies leading to the development of diseases and discussed utilization of troponins as drug targets for treatment of the skeletal muscle disorders.

The theory and practice of pressure ulcer/injury risk assessment: a critical discussion

Pressure ulcer/injury (PU) risk assessment is widely considered an essential component in clinical practice. It is a complex and broad concept that includes different approaches, such as clinical judgement, using standardised risk assessment instruments, skin assessments, or using devices to measure skin or tissue properties. A distinction between PU risk assessment and early detection is important. PU risk measures the individual's susceptibility to developing a PU under a specific exposure (primary prevention), and early detection includes the assessment of early (sub)clinical signs and symptoms to prevent progression and to support healing (secondary prevention). PU risk is measured using prognostic/risk factors or prognostic models. Every risk estimate is a probability statement containing varying degrees of uncertainty. It therefore follows that every clinical decision based on risk estimates also contains uncertainty. PU risk assessment and prevention is a complex intervention, where delivery contains several interacting components. There is a huge body of evidence indicating that risk assessment and its outcomes, the selection of preventive interventions and PU incidence are not well connected. Methods for prognostic model development and testing in PU risk research must be improved and follow state-of-the-art methodological standards. Despite these challenges, we do have substantial knowledge about PU risk factors that helps us to make better clinical decisions. An important next step in the development of PU risk prediction might be the combination of clinical and other predictors for more individualised care. Any prognostic test or procedure must lead to better prevention at an acceptable cost.

Myoglobin-derived iron causes wound enlargement and impaired regeneration in pressure injuries of muscle

The reasons for poor healing of pressure injuries are poorly understood. Vascular ulcers are worsened by extracellular release of hemoglobin, so we examined the impact of myoglobin (Mb) iron in murine muscle pressure injuries (mPI). Tests used Mb-knockout or treatment with deferoxamine iron chelator (DFO). Unlike acute injuries from cardiotoxin, mPI regenerated poorly with a lack of viable immune cells, persistence of dead tissue (necro-slough), and abnormal deposition of iron. However, Mb-knockout or DFO-treated mPI displayed a reversal of the pathology: decreased tissue death, decreased iron deposition, decrease in markers of oxidative damage, and higher numbers of intact immune cells. Subsequently, DFO treatment improved myofiber regeneration and morphology. We conclude that myoglobin iron contributes to tissue death in mPI. Remarkably, a large fraction of muscle death in untreated mPI occurred later than, and was preventable by, DFO treatment, even though treatment started 12 hr after pressure was removed. This demonstrates an opportunity for post-pressure prevention to salvage tissue viability.

Biomarkers for the early detection of pressure injury: A systematic review and meta-analysis

BACKGROUND

Pressure injury imposes a significant burden for patients and healthcare systems and the majority of pressure injuries are preventable. The early identification of pressure injury is critical for its prevention. As an objective measure, biomarkers have preliminarily shown the potential to identify individuals at risk for developing pressure injury before it is visually observed to occur. However, these results have not been synthesized.

OBJECTIVE

To assess and synthesise the predictive effect of different biomarkers in the early detection of pressure injury formation.

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

PubMed, EMBASE, CINAHL Complete and the Cochrane Library were comprehensively searched for articles up to June 2021. No restrictions were applied to study design type, language, country, race or date of publication.

REVIEW METHODS

Two reviewers independently extracted data from all original eligible studies using a specified data extraction form, resolved disagreements through discussion and the involvement of an additional reviewer. Methodological quality of all included studies was independently appraised by two authors with the Joanna Briggs Institute (JBI) Critical Appraisal Checklist and the Newcastle-Ottawa Quality Assessment Scale (NOS). Heterogeneity of each study was estimated using the I² statistic, and the data was synthesized using StataSE15.

RESULTS

Eight observational studies involving 10595 participants were included. The overall pooled area under curve (AUC) and the 95% confidence intervals (CIs) of Serum albumin (Alb) was 0.66(0.62-0.70), and the Serum haemoglobin (Hb) was 0.67(0.60-0.74). The AUC and 95% CI of C-reactive protein (CRP) was 0.62(0.50-0.74), Braden score was 0.56 (0.429-0.691), Waterlow score was 0.729(0.654-0.803), Alb with Waterlow was 0.741(0.694-0.787), and the combination of Hb, CRP, Alb, Age and Gender was 0.79(0.682-0.898). Besides, the chemokine interferon-γ-induced protein of 10kd/CXCL10, cytokine interferon-α, tumor necrosis factor-alpha (TNF-α), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-15 (IL-15) and combination of creatine kinase (CK), myoglobin (Mb), heart-type fatty acid binding protein (H-FABP) and CRP may prove potential for detecting pressure injury.

CONCLUSION

The findings suggest the combination of Hb, CRP, Alb, Age and Gender is superior to other biomarkers. However, the predictive effect of biomarkers needs to be confirmed by more researches and patient-level data.

Serum Myoglobin Is Associated With Postoperative Acute Kidney Injury in Stanford Type A Aortic Dissection

Background

The correlation between rhabdomyolysis and postoperative acute kidney injury has been reported in several surgical procedures. As a good predictor of rhabdomyolysis-related acute kidney injury, an elevated serum myoglobin level was often observed after total aortic arch replacement combined with frozen elephant trunk implantation. However, the correlation between serum myoglobin and acute kidney injury in such patients had not been established.

Methods

Totally 398 stanford type A aortic dissection patients who underwent total aortic arch replacement combined with frozen elephant trunk implantation were enrolled in this retrospective study. The correlations between serum myoglobin and acute kidney injury as well as the 30-day mortality were assessed.

Results

Overall, 268(67.3%) patients had acute kidney injury (KDIGO stage 1 or higher) and 75(18.8%) had severe acute kidney injury (KDIGO stage 2&3). Patients who developed acute kidney injury had higher level of perioperative serum myoglobin than patients without acute kidney injury. After adjusting for known acute kidney injury risk factors, logarithmically transformed preoperative serum myoglobin [OR = 1.58 (95% CI, 1.26–1.95), P < 0.001] and postoperative day 1 serum myoglobin [OR = 3.47 (95%CI, 2.27–5.29), P < 0.001] were associated with severe acute kidney injury. These correlation persisted after adjustment for decline in filtration via change in serum creatinine (ΔCr) and biomarkers of cardiac and kidney injury, including N-terminal prohormone of brain natriuretic peptide, cardiac troponin I, creatine kinase-MB, serum creatinine and Cystatin C. Compared with the clinical model, sMb considerably improved the risk discrimination and reclassification for AKI.

Conclusion

For stanford type A aortic dissection patients underwent total aortic arch replacement with frozen elephant trunk implantation, serum myoglobin can improve postoperative acute kidney injury risk classification. Rhabdomyolysis may be an important supplement to the existing knowledge on the mechanism of acute kidney injury.

Genetic modification of limbs using ex vivo machine perfusion

Genetic engineering is a promising tool to repair genetic disorders, improve graft function or to reduce immune responses towards the allografts. Ex vivo organ perfusion systems have the potential to mitigate ischemic-reperfusion injury, prolong preservation time or even rescue organ function. We aim to combine both technologies to develop a modular platform allowing the genetic modification of vascularized composite (VC) allografts. Rat hind limbs were perfused ex vivo under subnormothermic conditions with lentiviral vectors. Specific perfusion conditions such as controlled pressure, temperature and flow rates were optimized to support the genetic modification of the limbs. Genetic modification was detected in vascular, muscular and dermal limb tissues. Remarkably, skin follicular and interfollicular keratinocytes as well as endothelial cells (ECs) showed stable transgene expression. Furthermore, levels of injury markers such as lactate, myoglobin and lactate dehydrogenase (LDH) as well as histological analyses showed that ex vivo limb perfusion with lentiviral vectors did not cause tissue damage and limb cytokine secretion signatures were not significantly affected. The use of ex vivo VC perfusion in combination with lentiviral vectors allows an efficient and stable genetic modification of limbs representing a robust platform to genetically engineer limbs towards increasing graft survival after transplantation.

Our contemporary understanding of the aetiology of pressure ulcers/pressure injuries

In 2019, the third and updated edition of the Clinical Practice Guideline (CPG) on Prevention and Treatment of Pressure Ulcers/Injuries has been published. In addition to this most up‐to‐date evidence‐based guidance for clinicians, related topics such as pressure ulcers (PUs)/pressure injuries (PIs) aetiology, classification, and future research needs were considered by the teams of experts. To elaborate on these topics, this is the third paper of a series of the CPG articles, which summarises the latest understanding of the aetiology of PUs/PIs with a special focus on the effects of soft tissue deformation. Sustained deformations of soft tissues cause initial cell death and tissue damage that ultimately may result in the formation of PUs/PIs. High tissue deformations result in cell damage on a microscopic level within just a few minutes, although it may take hours of sustained loading for the damage to become clinically visible. Superficial skin damage seems to be primarily caused by excessive shear strain/stress exposures, deeper PUs/PIs predominantly result from high pressures in combination with shear at the surface over bony prominences, or under stiff medical devices. Therefore, primary PU/PI prevention should aim for minimising deformations by either reducing the peak strain/stress values in tissues or decreasing the exposure time.

Pressure Relieving Support Surfaces: a Randomised Evaluation 2 (PRESSURE 2): using photography for blinded central endpoint review

Background

PRESSURE 2 is a randomised evaluation of the clinical and cost-effectiveness of two types of mattress for the prevention of pressure ulcers (PUs). The primary clinical endpoint was time to development of a category ≥2 PU. The current ‘gold standard’ for PU identification is expert clinical assessment. Due to the mattress appearance, a blinded assessment of the endpoint is not possible. This poses a risk to the internal validity of the study. A possible approach is to use photographs of skin sites, with central blinded review. However, there are practical and scientific concerns including patients’ consent to photographs, burden of data collection, photograph quality, data completeness and comparison of photographs to the current ‘gold standard’. This paper reports the findings of the PRESSURE 2 photographic validation sub-study.

Method

Where consent was obtained, photographs were taken of all category ≥2 PUs on the first presentation to assess over-reporting, and for the assessment of under-reporting, a random sample of 10% patients had an assessment by an independent clinical assessor who also photographed two skin sites. The staff were trained in taking and transferring photographs using standardised procedures and equipment. A card included in the photograph recorded participant details and a ‘greyscale’ for correction of white balance during processing. Three blinded reviewers assessed the photographs and rated how confident they were in their assessment.

Results

The trial recruited 2029 patients; 85% consented to photography, and 532 photographs were received and used in the blinded central review. The level of confidence varied by skin classification with more confidence observed when the skin was assessed as being less severe than a category ≥2 PU. Overall, there was a very good reliability compared to the gold standard expert clinical assessment (87.8%, kappa 0.82).

Conclusion

Study findings have usefully informed the scientific and practical issues of blinded assessment of PU status to reducing the risk of bias in medical device trials. The reliability of central blinded expert photography was found to be ‘very good’ (PABAK). Photographs have been found to be an acceptable method of data validation for participants. Methods to improve the quality of photographs would increase the confidence in the assessments.

Trial registration

ISRCTN Registry ISRCTN01151335. Registered on 19 April 2013

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.

Sub-epidermal moisture measurement: an evidence-based approach to the assessment for early evidence of pressure ulcer presence

This paper aims to discuss the literature pertaining to early pressure-shear induced tissue damage detection, with emphasis on sub-epidermal moisture measurement (SEM). The current method for pressure detection is visual skin assessment (VSA); however, this method is fraught with challenges. Advances in early detection of pressure ulcers are reported in the literature and mainly involve measuring inflammation markers on weight-bearing anatomical areas in order to capture the first signs of tissue damage. One novel technique currently in use is SEM measurement. This biophysical marker is the product of plasma that leaks as a response to local inflammation arising due to pressure-shear induced damage over bony prominences. The early detection of tissue damage is beneficial in two different ways. First, it enables early intervention when the damage is still microscopic and reversible and, therefore, has the potential to prevent further aggravation of healthy surrounding tissue. This arises by avoiding the causation of the problem and stopping the knock-on effect of inflammation, especially when the rapid pressure ulceration pathway of deformation is in place. Second, when the slow ischaemic-reperfusion related mechanism is undergoing, cell death can be avoided when the problem is identified before the cell reaches the "death threshold," completely averting a pressure ulcer.