Serial Measurements Increase the Accuracy of Laser Doppler Assessment of Burn Wounds

Agreement of clinical assessment of burn size and burn depth between referring hospitals and burn centres: A systematic review

BACKGROUND

The quality of burn care is highly dependent on the initial assessment and care. The aim of this systematic review was to investigate the agreement of clinical assessment of burn depth and %TBSA between the referring units and the receiving burn centres.

METHODS

Included articles had to meet criteria defined in a PICO (patients, interventions, comparisons, outcomes). Relevant databases were searched using a predetermined search string (November 6th 2021). Data were extracted in a standardised fashion. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach for test accuracy was used to assess the certainty of evidence. The QUADAS-2 tool was used to assess the risk of bias of individual studies as 'high', 'low' or 'unclear'.

RESULTS

A total of 412 abstracts were retrieved and of these 28 studies with a total of 6461 patients were included, all reporting %TBSA and one burn depth. All studies were cross-sectional and most of them comprising retrospectively enrolled consecutive cohort. All studies showed a low agreement between %TBSA calculations made at referring units and at burn centres. Most studies directly comparing estimations of %TBSA at referring institutions and burn centers showed a proportion of overestimations of 50% or higher. The study of burn depth showed that 55% were equal to the estimates from the burn centre. Most studies had severe study limitations and the risk of imprecision was high. The overall certainty of evidence for accuracy of clinical estimations in referring centres is low (GRADE ⊕⊕ОО) for %TBSA and very low (GRADE ⊕ООО) for burn depth and resuscitation.

CONCLUSION

Overestimation of %TBSA at referring hospitals occurs very frequently. The overall certainty of evidence for accuracy of clinical estimations in referring centres is low for burn size and very low for burn depth. The findings suggest that the burn community has a significant challenge in educating and communicating better with our colleagues at referring institutions and that high-quality studies are needed.

Evidence Based Burn Depth Assessment Using Laser-Based Technologies: Where Do We Stand?

Early clinical assessment of burn depth and associated healing potential (HP) remains extremely challenging, even for experienced surgeons. Inaccurate diagnosis often leads to prolonged healing times and unnecessary surgical procedures, resulting in incremental costs, and unfavorable outcomes. Laser Doppler imaging (LDI) is currently the most objective and accurate diagnostic tool to measure blood flow and its associated HP, the main predictor for a patient's long-term functional and aesthetic outcome. A systematic review was performed on non-invasive, laser-based methods for burn depth assessment using skin microcirculation measurements to determine time to healing: Laser Doppler flowmetry (LDF), LDI and laser speckle contrast imaging (LSCI). Important drawbacks of single point LDF measurements are direct contact with numerous small points on the wound bed and the need to carry out serial measurements over several days. LDI is a fast, "non-contact," single measurement tool allowing to scan large burned areas with a 96% accuracy. LDI reduces the number of surgeries, improves the functional and aesthetic outcome and is cost-effective. There is only limited evidence for the use of LSCI in burn depth assessment. LSCI still needs technical improvements and scientific validation, before it can be approved for reliable burn assessment. LDI has proven to be invaluable in determining the optimal treatment of a burn patient. For unclear reasons, LDI is still not routinely used in burn centers worldwide. Additional research is required to identify potential "barriers" for universal implementation of this evidence-based burn depth assessment tool.

The treatment of paediatric burns with concentrated surfactant gel technology: a case series

Objective:

To assess the safety and efficacy of a surfactant-based technology for the management of burns.

Method:

In a retrospective review, paediatric patients with different types of burns were treated with the gel technology. In some patients, the treatment was combined with a topical antimicrobial agent. Primary objectives of the review were the assessment of healing, healing times and ease of use of the material.

Results:

The wounds of 15 paediatric patients with different types of burns, particularly with regard to depth and anatomical location, were evaluated using a retrospective chart review. It was found that the surfactant gel technology, with or without the topical antimicrobial agent, assisted in autolytic debridement, and that time to re-epithelialisation was short and within the range of those obtained with other established treatments.

Conclusion:

The number of patients and wounds in this evaluation is small but the study indicates that the gel technology provides a safe and effective way to treat smaller burns in paediatric patients.

Comparative effectiveness of Biobrane®, RECELL® Autologous skin Cell suspension and Silver dressings in partial thickness paediatric burns: BRACS randomised trial protocol

BACKGROUND

Mixed partial thickness burns are the most common depth of burn injury managed at a large Australian paediatric hospital specialty burns unit. Prolonged time until re-epithelialisation is associated with increased burn depth and scar formation. Whilst current wound management approaches have benefits such as anti-microbial cover, these are not without inherent limitations including multiple dressing changes. The Biobrane® RECELL® Autologous skin Cell suspension and Silver dressings (BRACS) trial aims to identify the most effective wound management approach for mixed partial thickness injuries in children.

METHODS

All children presenting with an acute burn injury to the study site will be screened for eligibility. This is a single-centre, three-arm, parallel group, randomised trial. Children younger than 16 years, with burns ≥ 5% total body surface area involving any anatomical location, up to 48 h after the burn injury, and of a superficial partial to mid-dermal depth, will be included. A sample size of 84 participants will be randomised to standard silver dressing or a Regenerative Epithelial Suspension (RES™) with Biobrane® or Biobrane® alone. The first dressing will be applied under general anaesthesia and subsequent dressings will be changed every 3 to 5 days until the wound is ≥ 95% re-epithelialised, with re-epithelialisation time the primary outcome. Secondary outcomes of acute pain, acute itch, scar severity, health-related quality of life, treatment satisfaction, dressing application ease and healthcare resource use will be assessed at each dressing change and 3, 6 and 12 months post-burn injury.

DISCUSSION

The findings of this study can potentially change the wound management approach for superficial partial to mid-dermal burns in children locally and worldwide.

TRIAL REGISTRATION

The Australian New Zealand Clinical Trials Registry (ACTRN12618000245291) approved prospective registration on 15 February 2018. Registration details can be viewed at https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374272&isReview=true.

Classification of burn injury using Raman spectroscopy and optical coherence tomography: An ex-vivo study on porcine skin

Accurate depth assessment of burn wounds is a critical task to provide the right treatment and care. Currently, laser Doppler imaging is able to provide better accuracy compared to the standard clinical evaluation. However, its clinical applicability is limited by factors like scanning distance, time, and cost. Precise diagnosis of burns requires adequate structural and functional details. In this work, we evaluated the combined potential of two non-invasive optical modalities, optical coherence tomography (OCT) and Raman spectroscopy (RS), to identify degrees of burn wounds (superficial partial-thickness (SPT), deep partial-thickness (DPT), and full-thickness (FT)). OCT provides morphological information, whereas, RS provides biochemical aspects. OCT images and Raman spectra were obtained from burns created on ex-vivo porcine skin. Algorithms were developed to segment skin region and extract textural features from OCT images, and derive spectral wave features from RS. These computed features were fed into machine learning classifiers for categorization of burns. Histological results obtained from trichrome staining were used as ground-truth. The combined performance of RS-OCT reported an overall average accuracy of 85% and ROC-AUC=0.94, in distinguishing the burn wounds. The significant performance on ex vivo skin motivates to assess the feasibility of combined RS-OCT in in vivo models.

A systematic review on the quality of measurement techniques for the assessment of burn wound depth or healing potential

PURPOSE

Reliable and valid assessment of burn wound depth or healing potential is essential to treatment decision-making, to provide a prognosis, and to compare studies evaluating different treatment modalities. The aim of this review was to critically appraise, compare and summarize the quality of relevant measurement properties of techniques that aim to assess burn wound depth or healing potential.

METHODS

A systematic literature search was performed using PubMed, EMBASE and Cochrane Library. Two reviewers independently evaluated the methodological quality of included articles using an adapted version of the Consensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. A synthesis of evidence was performed to rate the measurement properties for each technique and to draw an overall conclusion on quality of the techniques.

RESULTS

Thirty-six articles were included, evaluating various techniques, classified as (1) laser Doppler techniques; (2) thermography or thermal imaging; (3) other measurement techniques. Strong evidence was found for adequate construct validity of laser Doppler imaging (LDI). Moderate evidence was found for adequate construct validity of thermography, videomicroscopy, and spatial frequency domain imaging (SFDI). Only two studies reported on the measurement property reliability. Furthermore, considerable variation was observed among comparator instruments.

CONCLUSIONS

Considering the evidence available, it appears that LDI is currently the most favorable technique; thereby assessing burn wound healing potential. Additional research is needed into thermography, videomicroscopy, and SFDI to evaluate their full potential. Future studies should focus on reliability and measurement error, and provide a precise description of which construct is aimed to measure.

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

Aims. The introduction of laser Doppler (LD) techniques to assess burn depth has revolutionized the treatment of burns of indeterminate depth. This paper will systematically review studies related to these two techniques and trace their evolution. At the same time we hope to highlight current controversies and areas where further research is necessary with regard to LD imaging (LDI) techniques. Methods. A systematic search for relevant literature was carried out on PubMed, Medline, EMBASE, and Google Scholar. Key search terms included the following: “Laser Doppler imaging,” “laser Doppler flow,” and “burn depth.” Results. A total of 53 studies were identified. Twenty-six studies which met the inclusion/exclusion criteria were included in the review. Conclusions. The numerous advantages of LDI over those of LD flowmetry have resulted in the former technique superseding the latter one. Despite the presence of alternative burn depth assessment techniques, LDI remains the most favoured. Various newer LDI machines with increasingly sophisticated methods of assessing burn depth have been introduced throughout the years. However, factors such as cost effectiveness, scanning of topographically inconsistent areas of the body, and skewing of results due to tattoos, peripheral vascular disease, and anaemia continue to be sighted as obstacles to LDI which require further research.

Modeling and Estimating Simulated Burn Depth Using the Perfusion and Thermal Resistance Probe

A new thermal perfusion probe operates by imposing a thermal event on the tissue surface and directly measuring the temperature and heat flux response of the tissue with a small sensor. The thermal event is created by convectively cooling the surface with a small group of impinging jets using room temperature air. The hypothesis of this research is that this sensor can be used to provide practical burn characterization of depth and severity by determining the thickness of nonperfused tissue. To demonstrate this capability the measurement system was tested with a phantom tissue that simulates the blood perfusion of tissue. Different thicknesses of plastic were used at the surface to mimic layers of dead tissue. A mathematical model developed by Alkhwaji et al. (2012, “New Mathematical Model to Estimate Tissue Blood Perfusion, Thermal Contact Resistance and Core Temperature,” ASME J. Biomech. Eng., 134, p. 081004) is used to determine the effective values of blood perfusion, core temperature, and thermal resistance from the thermal measurements. The analytical solutions of the Pennes bioheat equation using the Green's function method is coupled with an efficient parameter estimation procedure to minimize the error between measured and analytical heat flux. Seven different thicknesses of plastic were used along with three different flow rates of perfusate to simulate burned skin of the phantom perfusion system. The resulting values of thermal resistance are a combination of the plastic resistance and thermal contact resistance between the sensor and plastic surface. Even with the uncertainty of sensor placement on the surface, the complete set of thermal resistance measurements correlate well with the layer thickness. The values are also nearly independent of the flow rate of the perfusate, which shows that the parameter estimation can successfully separate these two parameters. These results with simulated burns show the value of this minimally invasive technique to measure the thickness of nonperfused layers. This will encourage further work with this method on actual tissue burns.

Critical review of burn depth assessment techniques: part II. Review of laser doppler technology

The judgment of which wounds are expected to heal within 21 days is one of the most difficult and important tasks of the burn surgeon. The quoted accuracy of 64 to 76% by senior burn surgeons underscores the importance of an adjunct technology to help make this determination. A plethora of techniques have been developed in the last 70 years. Laser Doppler imaging (LDI) is one of the most recent and widely studied of these techniques. The technology provides an estimate of perfusion through the burn wound, the assumption being that a lower perfusion correlates with a deeper wound and, therefore, a longer time to heal. Although some reports suggest accuracy between 96 and 100% and that it does this 2 days ahead of clinical judgment, others have questioned its applicability to clinical practice. This article, the second of a two-part series, has two objectives: 1) a review of the Doppler principle and how the LDI uses it to estimate perfusion; and 2) a critical assessment of the burn literature on the LDI. Part I provides a historical perspective of the different technologies used through the last 70 years to assist in the determination of burn depth. Laser Doppler has brought technology closer to provide a reliable adjuvant to the clinical prediction of healing, yet, caution is warranted. A clear understanding of the limitations of LDI is needed to put the current research in perspective to find the right clinical application for LDI.

Cutaneous microcirculatory assessment of the burn wound is associated with depth of injury and predicts healing time

RATIONALE

Current trends for the treatment of deep partial thickness and full-thickness burns include early excision and skin grafting. In this study we retrospectively evaluated the ability of Laser Doppler Flowmetry (LDF), taken within 24h of the burn to predict: (1) burn wound depth and (2) wounds which would heal in less than 21 days.

METHOD

The Laser Doppler Flowmeter (O2C, LEA Medizintechnik, Germany) was employed to non-invasively measure the cutaneous microcirculation of 173 selected areas on 28 patients who suffered burns.

RESULTS

A distinct association between initial flow (<24h after burn injury) and the clinical assessment of depth of burn wounds was observed. Wounds demonstrating an initial blood flow of >100 AU were, in 93.1% of cases, correctly (positively) predicted for spontaneous healing within 21 days. A blood flow of <100 AU (negatively) predicted in 88.2%, those wounds which would not go on to heal within 21 days. Sequential measurement analysis (<24h, 3 days after injury and 6 days after injury) revealed no significant decrease in skin perfusion velocity or flow rate.

CONCLUSION

LDF can provide immediate results for early determination of burn wound depth and is useful in selecting patients for conservative treatment of their burn wounds.

Noninvasive blood perfusion measurements of an isolated rat liver and an anesthetized rat kidney

A simple, cost effective, and noninvasive blood perfusion system is tested in animal models. The system uses a small sensor to measure the heat transfer response to a thermal event (convective cooling) imposed on the tissue surface. Heat flux data are compared with a mathematical model of the tissue to estimate both blood perfusion and thermal contact resistance between the tissue and the probe. The perfusion system was evaluated for repeatability and sensitivity using isolated rat liver and exposed rat kidney tests. Perfusion in the isolated liver tests was varied by controlling the flow of the perfusate into the liver, and the perfusion in the exposed kidney tests was varied by temporarily occluding blood flow through the renal artery and vein. The perfusion estimated by the convective perfusion probe was in good agreement with that of the metered flow of the perfusate into the liver model. The liver tests indicated that the probe can be used to detect small changes in perfusion (0.005 ml/ml/s). The probe qualitatively tracked the changes in the perfusion in the kidney model due to occlusion of the renal artery and vein.

A phantom tissue system for the calibration of perfusion measurements

A convenient method for testing and calibrating surface perfusion sensors has been developed. A phantom tissue model is used to simulate the nondirectional blood flow of tissue perfusion. A computational fluid dynamics (CFD) model was constructed in Fluent(R) to design the phantom tissue and validate the experimental results. The phantom perfusion system was used with a perfusion sensor based on clearance of thermal energy. A heat flux gage measures the heat flux response of tissue when a thermal event (convective cooling) is applied. The blood perfusion and contact resistance are estimated by a parameter estimation code. From the experimental and analytical results, it was concluded that the probe displayed good measurement repeatability and sensitivity. The experimental perfusion measurements in the tissue were in good agreement with those of the CFD models and demonstrated the value of the phantom tissue system.

Non-Invasive Blood Perfusion Measurements Using a Combined Temperature and Heat Flux Surface Probe

Non-invasive blood perfusion measurement systems have been developed and tested in a phantom tissue and an animal model. The probes use a small sensor with a laminated flat thermocouple to measure the heat transfer and temperature response to an arbitrary thermal event (convective or conductive) imposed on the tissue surface. Blood perfusion and thermal contact resistance are estimated by comparing heat flux data with a mathematical model of the tissue. The perfusion probes were evaluated for repeatability and sensitivity using both a phantom tissue test stand and exposed rat liver tests. Perfusion in the phantom tissue tests was varied by controlling the flow of water into the phantom tissue test section, and the perfusion in the exposed liver tests was varied by temporarily occluding blood flow through the portal vein. The phantom tissue tests indicated that the probes can be used to detect small changes in perfusion (0.005 ml/ml/s). The probes qualitatively tracked the changes in the perfusion of the liver model due to occlusion of the portal vein.

Accuracy of early burn depth assessment by laser Doppler imaging on different days post burn

BACKGROUND

Accurate diagnosis of burn depth is essential in selecting the most appropriate treatment. Early assessment of burn depth by clinical means only has been shown to be inaccurate, resulting in unnecessary operations or delay of grafting procedures. Laser Doppler imaging (LDI) was reported as an objective technique to determine the depth of a burn wound, but the accuracy on very early days post burn has never been investigated yet.

METHODS

In 40 patients with intermediate depth burns, we prospectively evaluated and compared the accuracy of the LDI measurements with the clinical assessments on days 0, 1, 3, 5, 8. Clinical evaluation of the depth of the burn was performed by two observers blinded to the LDI images. Accuracies were assessed by comparison with outcome: healing times longer than 21 days were considered to be equivalent to a biopsy finding of a deep dermal wound. Obviously superficial and full thickness wounds were excluded. LDI flux level was used for LDI prediction of outcome: less than 220PU to predict non-healing at day 21.

RESULTS

The accuracies of burn depth assessments on the day of burn and post burn days 0, 1, 3, 5 and 8 using LDI were 54%, 79.5%, 95%, 97% and 100% compared with clinical assessment accuracies of 40.6%, 61.5%, 52.5%, 71.4% and 100%, respectively. LDI accuracy was significantly higher than clinical accuracy on day 3 (p<0.001) and day 5 (p=0.005). Burn depth conversion was also considered. This is the first study to quantify the advantage of LDI scanning over clinical assessments during these important early after burn days.

Assessment of burn depth and burn wound healing potential

The depth of a burn wound and/or its healing potential are the most important determinants of the therapeutic management and of the residual morbidity or scarring. Traditionally, burn surgeons divide burns into superficial which heal by rapid re-epithelialization with minimal scarring and deep burns requiring surgical therapy. Clinical assessment remains the most frequent technique to measure the depth of a burn wound although this has been shown to be accurate in only 60-75% of the cases, even when carried out by an experienced burn surgeon. In this article we review all current modalities useful to provide an objective assessment of the burn wound depth, from simple clinical evaluation to biopsy and histology and to various perfusion measurement techniques such as thermography, vital dyes, video angiography, video microscopy, and laser Doppler techniques. The different needs according to the different diagnostic situations are considered. It is concluded that for the initial emergency assessment, the use of telemetry and simple burn photographs are the best option, that for research purposes a wide range of different techniques can be used but that, most importantly, for the actual treatment decisions, laser Doppler imaging is the only technique that has been shown to accurately predict wound outcome with a large weight of evidence. Moreover this technique has been approved for burn depth assessment by regulatory bodies including the FDA.

The influence of burn wound dressings on laser Doppler imaging assessment of a standardized cutaneous injury model

The objective of this study was to determine the impact of burn wound dressings on Laser Doppler imaging assessment of a cutaneous injury model. A healthy volunteer was subjected to a standardized mechanical stimulus to produce a triple response. This was scanned under ideal conditions using the moor LDI2 before and after application of the following dressings: GLAD Wrap , Bactigras, Hypafix, Omiderm, DuoDERM, Acticoat, and Avance. The triple response was readily and consistently detected on the LDI blood flow image. Glad Wrap, Bactigras, Hypafix, Omiderm, and DuoDERM all had minimal adverse impact on the Laser Doppler blood flow image. Acticoat and Avance prevented detection of the triple response. In addition, there was a false-positive blood flow image with the Acticoat dressing positioned with the silver colored surface uppermost. Dressings transparent to the near infrared spectrum allowed detection of a standardized cutaneous injury model under ideal conditions. Laser Doppler imaging might therefore be used to assess a burn wound without removal of such a dressing. This would have implications for the selection and use of dressings in the treatment of burn patients, especially in an ambulatory care setting.

Repetitive Ischemia–Reperfusion Injury: A Plausible Mechanism for Documented Clinical Burn-Depth Progression After Thermal Injury

Our previous studies confirmed the phenomenon of burn depth progression despite adequate Parkland formula resuscitation [Kim et al. J Burn Care Rehabil 2001;22960:406-6]. Repetitive ischemia-reperfusion injury (I-R) is a plausible explanation and is suggested by the concomitant swings we have observed in serum base deficit (BD) during resuscitation from burn shock. We chose to explore whether laser Doppler imaging (LDI) evidence of burn depth progression mirrored cycles of I-R (episodic swings in continuously measured BD). Positive findings would support the hypothesis that repetitive episodes of I-R is a factor in burn depth progression despite apparently adequate resuscitation. A total of 14 patients with severe life-threatening burns (median 51% TBSA) underwent continuous BD monitoring using a Paratrend 7 (Malvern PA) during 48 hours of resuscitation. Fluid needs were estimated using the Parkland formula, then were titrated to urine output. The slopes of BD changes were then analyzed. Worsening of BD greater than 0.2 mmol/l/min was noted, and a proportion derived relative to pooled data on 5-minute intervals. In four of the patients, LDI scans were performed on six representative areas sequentially every 4 hours. The analysis of median flux in these LDI images provided real-time determination of burn depth progression. Eight patients eventually died. Only four patients achieved a normal BD within 12 hours of monitoring despite exceeding the Parkland formula estimate and meeting urinary output parameters. Our analysis also showed cyclical peaks and valleys in the BD curve (P < .001), suggesting repetitive I-R insults. All increases in BD preceded changes that could be detected in vital signs or urine output. Finally, LDI confirmed that the burn depths continued to progress despite apparently adequate resuscitation, and also showed that there are similar peaks and valleys in the perfusion of the wounds (P < .0001), which mimic the changes in the BD curve. Responses to fluid resuscitation do not follow a linear pattern in the case of massive burns. These results in repetitive periods of tissue hypoperfusion evidenced by BD alterations and may contribute to progressive deepening of the burn wound.

Burn depths evaluation based on active dynamic IR thermal imaging--a preliminary study

Proper diagnostic assessment of burn wound depth is of the highest importance in selecting the mode of burn wound treatment. Several diagnostic methods--clinical and histopathological evaluation, as well as methods employing IR imaging--static thermography and active dynamic thermography (ADT)--are compared on the basis of in vivo experiments conducted on three domestic pigs (23 burn wounds). ADT is presented here as a new, reliable and quantitative method of assessing burn wound depth on the basis of discrimination of the thermal properties of burnt tissue. In the case of ADT registration of thermal images was performed following thermal pulse excitation. A series of captured infrared images was used as the basis for calculating the thermal time constant tau for each pixel. The parameter values were compared with histopathological and clinical assessments of burn depth. The mean value of tau was found for burns, which heal within 3 weeks (tau=12.08+/-1.94s) and for burns, which did not heal during this period (tau=9.07+/-0.68s), p<0.05. The accuracy, sensitivity and specificity of all the methods tested were compared, the best results coming from ADT. The ADT method is fast, non-invasive and relatively inexpensive, although it still requires further animal experimentation as well as clinical study to confirm the results.

Static thermography revisited--an adjunct method for determining the depth of the burn injury

The aim of the study was to investigate the relationship between the static thermography figure of merit DeltaT (the difference in mean values of skin area temperature for the burn wound area and the unaffected reference skin area) and a means of burn classification which would be most suitable for the choice of treatment. The work was an in vivo animal experiment. Statistical analysis showed a high correlation between the DeltaT parameter and histopathological assessment. With regard to the choice of treatment, the most useful correlation was found to be that between DeltaT and the classification of burn wounds into those healed in 3 weeks and those unhealed. The results of this study have revealed a quantitative criterion DeltaT for burn classification. The study suggests that particular burn centres using static thermography use a DeltaT parameter based on their own values for burn classification so as to group burn wounds into those that healed in 3 weeks and those that did not heal. This criterion should be independent of and replace other classification systems. A criterion for the proper choice of burn treatment would then be made more readily available.

A critical evaluation of the clinimetrics of laser Doppler as a method of burn assessment in clinical practice

The estimation of burn depth, which is essential in the management of burns, has traditionally been conducted using clinical evaluation, which has problems of subjectivity. A number of studies have been conducted assessing the use of laser Doppler to estimate burn depth. Some studies have advocated the use of this instrument in clinical practice. However, careful evaluation of many studies to date reveal a lack of standardization among studies and significant methodological problems that affect the validity of the findings in relation to the clinical management of burns. Although many studies suggest that the use of laser Doppler may be a useful adjunct to clinical evaluation, in a climate of evidence-based medicine when strict scientific principles are considered further studies are needed to show the tool to be valid and consistently reliable for the assessment of burns. Until such time, laser Doppler should remain as a research tool.

Plasma free hemoglobin: a novel diagnostic test for assessment of the depth of burn injury

BACKGROUND

Accurate determination of the depth of burn injury is difficult, even for experienced surgeons. The authors hypothesized that the level of plasma free hemoglobin following burn injury is correlated to the depth of burn injury, and they evaluated this hypothesis in a murine model.

METHODS

Full-thickness and partial-thickness burn injuries of varying sizes were inflicted on 38 and 36 male Wistar rats, respectively. Blood specimens were taken at 0, 15, 30, 45, and 60 minutes after burn injury, and the levels of plasma free hemoglobin were determined spectrophotometrically.

RESULTS

Full-thickness burns cause two times more hemolysis than partial-thickness burns (p < 0.05). A linear correlation was demonstrated between plasma free hemoglobin levels and total body surface area burned in both the full-thickness (r = 0.91, p < 0.001) and partial-thickness burn groups (r = 0.94, p < 0.001). The correlation between the quantity of hemolysis and the total body surface area burned was strongest at 15 minutes after the onset of burn injury. The levels of free hemoglobin peaked rapidly between 15 and 30 minutes after thermal injury and declined thereafter.

CONCLUSIONS

The authors' data suggest that the level of plasma free hemoglobin after burn injury is related to the size and depth of burn injury. This test can potentially be a valuable diagnostic adjunct in the assessment of burns.

A general overview of burn care

The majority of burn victims do not need to be treated in a burn centre. Adequate care can be given by non specialised medical personnel, provided that proper guidelines are followed. The article outlines and reviews these guidelines.

State of the Art in Burn Treatment

Optimal treatment of burn victims requires deep understanding of the profound pathophysiological changes occurring locally and systemically after injury. Accurate estimation of burn size and depth, as well as early resuscitation, is essential. Good burn care includes also cleansing, debridement, and prevention of sepsis. Wound healing, is of major importance to the survival and clinical outcome of burn patients. An ideal therapy would not only promote rapid healing but would also act as an antiscarring therapy. The present article is a literature review of the most up-to-date modalities applied to burn treatment without overlooking the numerous controversies that still persist.