A systematic review of the evolution of laser Doppler techniques in burn depth assessment

A Deep Learning Image-to-Image Translation Approach for a More Accessible Estimator of the Healing Time of Burns

OBJECTIVE

An accurate and timely diagnosis of burn severity is critical to ensure a positive outcome. Laser Doppler imaging (LDI) has become a very useful tool for this task. It measures the perfusion of the burn and estimates its potential healing time. LDIs generate a 6-color palette image, with each color representing a healing time. This technique has very high costs associated. In resource-limited areas, such as low- and middle-income countries or remote locations like space, where access to specialized burn care is inadequate, more affordable and portable tools are required. This study proposes a novel image-to-image translation approach to estimate burn healing times, using a digital image to approximate the LDI.

METHODS

This approach consists of a U-net architecture with a VGG-based encoder and applies the concept of ordinal classification. Paired digital and LDI images of burns were collected. The performance was evaluated with 10-fold cross-validation, mean absolute error (MAE), and color distribution differences between the ground truth and the estimated LDI.

RESULTS

Results showed a satisfactory performance in terms of low MAE ( 0.2370 ±0.0086). However, the unbalanced distribution of colors in the data affects this performance.

SIGNIFICANCE

This novel and unique approach serves as a basis for developing more accessible support tools in the burn care environment in resource-limited areas.

A novel method for objectively, rapidly and accurately evaluating burn depth via near infrared spectroscopy

The accurate and objective evaluation of burn depth is a significant challenge in burn wound care. Herein, we used near infrared spectroscopy (NIRS) technology to measure the different depth of thermal burns in ex vivo porcine models. Based on the intensity of the spectral signals and the diffuse reflection theory, we extracted the optical parameters involved in functional (total hemoglobin and water content) and structural (tissue scattered size and scattered particles) features that reflect the changes in burn depth. Next, we applied support vector regression to construct a model including the optical property parameters and the burn depth. Finally, we histologically verified the burn depth data collected via NIRS. The results showed that our inversion model could achieve an average relative error of about 7.63%, while the NIRS technology diagnostic accuracy was in the range of 50 μm. For the first time, this novel technique provides physicians with real-time burn depth information objectively and accurately.

Application of OCT-Derived Attenuation Coefficient in Acute Burn-Damaged Skin

BACKGROUND AND OBJECTIVES

There remains a need to objectively monitor burn wound healing within a clinical setting, and optical coherence tomography (OCT) is proving itself one of the ideal modalities for just such a use. The aim of this study is to utilize the noninvasive and multipurpose capabilities of OCT, along with its cellular-level resolution, to demonstrate the application of optical attenuation coefficient (OAC), as derived from OCT data, to facilitate the automatic digital segmentation of the epidermis from scan images and to work as an objective indicator for burn wound healing assessment.

STUDY DESIGN/MATERIALS AND METHODS

A simple, yet efficient, method was used to estimate OAC from OCT images taken over multiple time points following acute burn injury. This method enhanced dermal-epidermal junction (DEJ) contrast, which facilitated the automatic segmentation of the epidermis for subsequent thickness measurements. In addition, we also measured and compared the average OAC of the dermis within said burns for correlative purposes.

RESULTS

Compared with unaltered OCT maps, enhanced DEJ contrast was shown in OAC maps, both from single A-lines and completed B-frames. En face epidermal thickness and dermal OAC maps both demonstrated significant changes between imaging sessions following burn injury, such as a loss of epidermal texture and decreased OAC. Quantitative analysis also showed that OAC of acute burned skin decreased below that of healthy skin following injury.

CONCLUSIONS

Our study has demonstrated that the OAC estimated from OCT data can be used to enhance imaging contrast to facilitate the automatic segmentation of the epidermal layer, as well as help elucidate our understanding of the pathological changes that occur in human skin when exposed to acute burn injury, which could serve as an objective indicator of skin injury and healing.

Paediatric chemical burns: a clinical review

Although they account for a small proportion of burns in paediatrics, injuries from chemicals can be just as devastating as other mechanisms of burn injury. At least 25,000 chemicals exist which can cause burns: in children, they are often caused by household chemicals via accidental exposure. The mechanism by which corrosive substances produce chemical burns highlights the importance of early and plentiful irrigation of the burn area, removal of contaminated clothes and careful clinical assessment. Surgical intervention is uncommon but often follows the principles for thermal burns. This article reviews the aetiology, incidence, clinical presentation, management, complications and prevention of chemical burns. What is Known • Chemical burns in paediatrics are often caused by accidental exposure to chemicals available at home • Differences in the pathophysiology of chemical burns reinforces the need for early irrigation What is New • New irrigation fluids show promise in adults and need further study in children • The nature of chemical cutaneous burns can make assessment of wound depth difficult. Laser Doppler Imaging (LDI) is an accurate technique that can be used clinically to determine burn depth in thermal burns and is an area of future interest in the assessment of chemical burns.

Optical imaging of collagen fiber damage to assess thermally injured human skin

Surgery is the definitive treatment for burn patients who sustain full-thickness burn injuries. Visual assessment of burn depth is made by the clinician early after injury but is accurate only up to 70% of the time among experienced surgeons. Collagen undergoes denaturation as a result of thermal injury; however, the association of collagen denaturation and cellular death in response to thermal injury is unknown. While gene expression assays and histologic staining allow for ex vivo identification of collagen changes, these methods do not provide spatial or integrity information in vivo. Thermal effects on collagen and the role of collagen in wound repair have been understudied in human burn models due to a lack of methods to visualize both intact and denatured collagen. Hence, there is a critical need for a clinically applicable method to discriminate between damaged and intact collagen fibers in tissues. We present two complementary candidate methods for visualization of collagen structure in three dimensions. Second harmonic generation imaging offers a label-free, high-resolution method to identify intact collagen. Simultaneously, a fluorophore-tagged collagen-mimetic peptide can detect damaged collagen. Together, these methods enable the characterization of collagen damage in human skin biopsies from burn patients, as well as ex vivo thermally injured human skin samples. These combined methods could enhance the understanding of the role of collagen in human wound healing after thermal injury and potentially assist in clinical decision-making.

The Added Benefit of Combining Laser Doppler Imaging With Clinical Evaluation in Determining the Need for Excision of Indeterminate-Depth Burn Wounds

Background Managing indeterminate-depth burn wounds remains challenging. Laser Doppler Imaging (LDI) has been validated for burn wound depth and can influence the clinical assessment. Our study investigated the value of LDI as an adjunct in determining the need for excision. Methods Seventy American Burn Association (ABA)-verified burn centers were surveyed. A controlled pre-test assessment without LDI and post-test assessment with LDI of 100 indeterminate-depth burn wounds was conducted to evaluate the influence on the clinical judgment among different health professionals. Relative risk, analysis of variance (ANOVA), paired t-test, and intention-to-treat were used for analysis. A p-value [Formula: see text] 0.05 was considered significant.  Results Among 32 burn centers, three confirmed using LDI. Six thousand grader-image interactions were analyzed. There was a significant difference in the predictive accuracy for pre-LDI and post-LDI assessments when all graders were considered (51.9% ± 7.0 vs. 72.9% ± 7.9; p < 0.0001). Post-LDI assessment added 20.9% more accuracy than the pre-LDI assessment. The post-LDI assessment was 1.4 times more likely to correctly predict the need for excision and skin-grafting than the pre-LDI assessment. All groups had an improved performance post-LDI: Group 1 (physicians), 51.9 ± 7.5 versus 76.4±5; Group 2 (nurses), 52.1 ± 6.1 versus 72.7±7.7; and Group 3 (others), 51.7 ± 9.2 versus 68.6 ± 10.1. No statistical difference was observed between groups (p = 0.92).  Conclusion LDI makes the clinical examination of indeterminate-depth burn wounds more accurate. For every five LDI evaluations performed, one assessor changed their treatment plan as a result of this imaging technique. LDI is cost-effective and increases the accuracy of determining the severity of indeterminate-depth burn wounds.

Comparison of Deep Transfer Learning Techniques in Human Skin Burns Discrimination

While visual assessment is the standard technique for burn evaluation, computer-aided diagnosis is increasingly sought due to high number of incidences globally. Patients are increasingly facing challenges which are not limited to shortage of experienced clinicians, lack of accessibility to healthcare facilities and high diagnostic cost. Certain number of studies were proposed in discriminating burn and healthy skin using machine learning leaving a huge and important gap unaddressed; whether burns and related skin injuries can be effectively discriminated using machine learning techniques. Therefore, we specifically use transfer learning by leveraging pre-trained deep learning models due to deficient dataset in this paper, to discriminate two classes of skin injuries—burnt skin and injured skin. Experiments were extensively conducted using three state-of-the-art pre-trained deep learning models that includes ResNet50, ResNet101 and ResNet152 for image patterns extraction via two transfer learning strategies—fine-tuning approach where dense and classification layers were modified and trained with features extracted by base layers and in the second approach support vector machine (SVM) was used to replace top-layers of the pre-trained models, trained using off-the-shelf features from the base layers. Our proposed approach records near perfect classification accuracy in categorizing burnt skin ad injured skin of approximately 99.9%.

Discordance between histologic and visual assessment of tissue viability in excised burn wound tissue

The regenerative capacity of burn wounds, and the need for surgical intervention, depends on wound depth. Clinical visual assessment is considered the gold standard for burn depth assessment but it remains a subjective and inaccurate method for tissue evaluation. The purpose of this study was to compare visual assessment with microscopic and molecular techniques for human burn depth determination, and illustrate differences in the evaluation of tissue for potential regenerative capacity. Using intraoperative visual assessment, patients were identified as having deep partial thickness or full thickness burn wounds. Tangential excisions of burn tissue were processed with hematoxylin and eosin to visualize tissue morphology, lactate dehydrogenase assay to ascertain cellular viability, and Keratin-15 and Ki67 to identify epidermal progenitor cells and proliferative capacity, respectively. RNA from deep partial and full thickness burn tissue as well as normal tissue controls were submitted for RNA sequencing. Lactate dehydrogenase, Keratin-15, and Ki67 were found throughout the excised burn wound tissue in both deep partial thickness burn tissues and in the second tangential excision of full thickness burn tissues. RNA sequencing demonstrated regenerative capacity in both deep partial and full thickness burn tissue, however a greater capacity for regeneration was present in deep partial thickness compared with full thickness burn tissues. In this study, we highlight the discordance that exists between the intraoperative clinical identification of burn injury depth, and microscopic and molecular determination of viability and regenerative capacity. Current methods utilizing visual assessment for depth of injury are imprecise, and can lead to removal of viable tissue. Additionally, hematoxylin and eosin microscopic analysis should not be used as the sole method in research or clinical determination of depth, as there are no differences in staining between viable and nonviable tissue.

Burn Wound Healing and Tissue Engineering

In 2016 the American Burn Association held a State of the Science conference to help identify burn research priorities for the next decade. The current paper summarizes the work of the sub-committee on Burn Wound Healing and Tissue Engineering. We first present the priorities in wound healing research over the next 10 years. We then summarize the current state of the science related to burn wound healing and tissue engineering including determination of burn depth, limiting burn injury progression, eschar removal, management of microbial contamination and wound infection, measuring wound closure, accelerating wound healing and durable wound closure, and skin substitutes and tissue engineering. Finally, a summary of the round table discussion is presented.

The effect of ambient lighting on Laser Doppler Imaging of a standardized cutaneous injury model

OBJECTIVE

The aim of this study was to investigate the potential confounding effects of four different types of ambient lighting on the results of Laser Doppler Imaging (LDI) of a standardized cutaneous injury model.

METHODS

After applying a mechanical stimulus to the anterior forearm of a healthy volunteer and inducing a wheal and arteriolar flare (the Triple response), we used a Laser Doppler Line Scanner (LDLS) to image the forearm under four different types of ambient lighting: light-emitting-diode (LED), compact fluorescent lighting (CFL), halogen, daylight, and darkness as a control. A spectrometer was used to measure the intensity of light energy at 785 nm, the wavelength used by the scanner for measurement under each type of ambient lighting.

RESULTS

Neither the LED nor CFL bulbs emitted detectable light energy at a wavelength of 785 nm. The color-based representation of arbitrary perfusion unit (APU) values of the Triple response measured by the scanner was similar between darkness, LED, and CFL light. Daylight emitted 2 mW at 785 nm, with a slight variation tending more towards lower APU values compared to darkness. Halogen lighting emitted 6 mW of light energy at 785 nm rendering the color-based representation impossible to interpret.

CONCLUSIONS

Halogen lighting and daylight have the potential to confound results of LDI of cutaneous injuries whereas LED and CFL lighting did not. Any potential sources of daylight should be reduced and halogen lighting completely covered or turned off prior to wound imaging.

Prospects of Laser Doppler flowmetry application in assessment of skin microcirculation in diabetes

This review includes results of scientific and clinical use of laser Doppler flowmetry (LDF) in patients with diabetes mellitus. LDF is a non-invasive method for the quantitative evaluation of microcirculation, which can assess microcirculatory rhythms and conduct functional tests with various impacts, allowing the exploration of regulatory mechanisms of microcirculation. LDF reveals specific diabetes changes in the regulatory function of microcirculation. Microcirculation disturbances, which are traditionally associated with the pathogenesis of complications, also occur in patients with early disorders of carbohydrate metabolism and may precede the manifestation of diabetes. However, this method is still not applied in clinical practice. In this review, we analysed factors limiting the implementation of LDF in practical medicine and suggest ways to improve its clinical significance.

Poor methodological quality and reporting standards of systematic reviews in burn care management

The methodological and reporting quality of burn-specific systematic reviews has not been established. The aim of this study was to evaluate the methodological quality of systematic reviews in burn care management. Computerised searches were performed in Ovid MEDLINE, Ovid EMBASE and The Cochrane Library through to February 2016 for systematic reviews relevant to burn care using medical subject and free-text terms such as 'burn', 'systematic review' or 'meta-analysis'. Additional studies were identified by hand-searching five discipline-specific journals. Two authors independently screened papers, extracted and evaluated methodological quality using the 11-item A Measurement Tool to Assess Systematic Reviews (AMSTAR) tool and reporting quality using the 27-item Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Characteristics of systematic reviews associated with methodological and reporting quality were identified. Descriptive statistics and linear regression identified features associated with improved methodological quality. A total of 60 systematic reviews met the inclusion criteria. Six of the 11 AMSTAR items reporting on 'a priori' design, duplicate study selection, grey literature, included/excluded studies, publication bias and conflict of interest were reported in less than 50% of the systematic reviews. Of the 27 items listed for PRISMA, 13 items reporting on introduction, methods, results and the discussion were addressed in less than 50% of systematic reviews. Multivariable analyses showed that systematic reviews associated with higher methodological or reporting quality incorporated a meta-analysis (AMSTAR regression coefficient 2.1; 95% CI: 1.1, 3.1; PRISMA regression coefficient 6·3; 95% CI: 3·8, 8·7) were published in the Cochrane library (AMSTAR regression coefficient 2·9; 95% CI: 1·6, 4·2; PRISMA regression coefficient 6·1; 95% CI: 3·1, 9·2) and included a randomised control trial (AMSTAR regression coefficient 1·4; 95%CI: 0·4, 2·4; PRISMA regression coefficient 3·4; 95% CI: 0·9, 5·8). The methodological and reporting quality of systematic reviews in burn care requires further improvement with stricter adherence by authors to the PRISMA checklist and AMSTAR tool.

Use of a selective enzymatic debridement agent (Nexobrid®) for wound management: Learning curve

AIM

To evaluate the efficacy of Nexobrid^® in the initial management of burns and lessons learned with the procedure.

METHODS

From January 27^th 2015 until January 25^th 2016, 25 patients aged between 18-94 years old with deep partial and full thickness burns were treated with Nexobrid^® covering 1%-30% of their total body surface area (TBSA). The debridement was applied in the first 96 h post-injury following the protocol suggested for Nexobrid^®. In patients with burns of more than 15% TBSA a second application of Nexobrid^® was performed. After the removal of the product - 4 h post application and after a 2 h period of wet dressing - we used several products to cover the wound like Suprathel^®, Biobrane^®, Mepitel^® with wet dressing, silver sulphadiazine 1% cream, and in some cases even autografts. We treated patients with inhalation injury as well. All the procedures were done under deep sedation, regional blocks in extremities or general anaesthesia in the intensive care unit room or in the operating theatre.

RESULTS

After these first 25 cases, we have observed that patients with partial thickness burns treated with Nexobrid^®, experienced great benefits in the reduction of the need for autografting compared with the standard of care. This is because after selective enzymatic debriding of the burn scar we can distinguish different wound beds, which can coexist in the same patient, and we also managed to associate each one to its ability to epithelize. In major burns, besides the improvement in wound healing, we observed an important improvement in their general state. This may be because SIRS significantly improved through a bloodless debridement of necrotic tissue, decreasing the requirements of vasoactive drugs and fluid resuscitation. Circumferential burns also benefited from enzymatic debridement, observing a decrease in the number of compartment syndromes and the need for escharotomies. At present, we have not observed a positive effect in the evolution and outcome of major burns with inhalation injury.

CONCLUSION

The introduction of Nexobrid^® shows significant improvement in burn treatment. Cumulative experiences are necessary to adapt its application in all Burns Centres.

[Icrocirculatory changes I bulbar conjunctiva in various diseases]

The article presents a literature review of the latest achievements in visualizing microcirculation and studying anatomical and physiological characteristics of microcirculation in the bulbar conjunctiva in various diseases.

Civilian blast-related burn injuries

There is limited English literature describing the experience of a civilian hospital managing blast-related burn injuries. As the largest regional burn unit, we reviewed our cases with the aim of identifying means to improve current management. A 6-year retrospective analysis of all patients coded as sustaining blast-related burns was conducted through the unit's burns database. Medical case notes were reviewed for information on burn demographics, management and outcomes. 42 patients were identified. Male to female ratio was 37:5. Age range was 12-84 years, (mean=33 years). Total body surface area (%TBSA) burn ranged from 0.25% to 60%, (median=1%). The most common burn injury was flame (31/42, 73.8%). Gas explosions were the most common mechanism of injury (19 cases; 45.2%). 7/42 cases (16.7%) had full ATLS management pre-transfer to the burns unit. The Injury Severity Score (ISS) ranged from 0-43 (median=2). 17/42 (40.4%) patients required admission. 37/36 (88.1%) patients were managed conservatively of which 1 patient later required surgery due to deeper burns. 5/42 (11.9%) patients required surgical management at presentation and these were noted to be burns with >15% TBSA requiring resuscitation. One case required emergency escharotomies and finger amputations. All patients survived their burn injuries. Blast-related burn injuries are generally uncommon in the civilian setting. Following proper assessment, most of these cases can be deemed as minor injuries and managed conservatively. Improvement in burns management education and training at local emergency departments would provide efficient patient care and avoid unnecessary referrals to a burns unit.

Burns: dressings

INTRODUCTION

Burns are classified according to depth. This overview concerns the treatments for partial-thickness burns, which can be expected or have the potential to heal spontaneously (superficial partial-thickness and mid-dermal partial-thickness burns). Injuries that involve the deeper part of the dermis and require surgical treatments to achieve healing are not the focus of this overview.

METHODS AND OUTCOMES

We conducted a systematic overview and aimed to answer the following clinical question: What are the effects of treatments for partial-thickness burns? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2014 (Clinical Evidence overviews are updated periodically; please check our website for the most up-to-date version of this review).

RESULTS

At this update, searching of electronic databases retrieved 322 studies. After deduplication and removal of conference abstracts, 193 records were screened for inclusion in the overview. Appraisal of titles and abstracts led to the exclusion of 160 studies and the further review of 33 full publications. Of the 33 full articles evaluated, two systematic reviews and two RCTs were added at this update. We performed a GRADE evaluation for 30 PICO combinations.

CONCLUSIONS

In this systematic overview, we categorised the efficacy for 10 interventions, based on information relating to the effectiveness and safety of alginate dressing, biosynthetic dressing, chlorhexidine-impregnated paraffin gauze dressing, hydrocolloid dressing, hydrogel dressing, paraffin gauze dressing, polyurethane film, silicone-coated nylon dressing, silver-impregnated dressing, and silver sulfadiazine cream.