- Email: [email protected]
Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds
JBUR-4977; No. of Pages 6 burns xxx (2017) xxx–xxx
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/burns
Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 54 burn wounds A. Tan a,b,*, F.A. Pedrini a,c, G. Oni a, Q. Frew a,b, B. Philp a, D. Barnes a, P. Dziewulski a a
St Andrew Centre for Plastics and Burns, CM1 7ET, United Kingdom St Andrews Anglia Ruskin University Hall Lane, CM1 1SQ, United Kingdom c Scuola di Medicina e Chirurgia, Polo didattico Murri, Via Massarenti 9, 40138 Bologna, Italy b
article info
abstract
Article history:
Introduction: The assessment of burn depth can be challenging even to the experienced burn
Accepted 12 June 2016
clinician. Clinical assessment is most widely used to determine burn depth. Because of this subjective nature, various imaging modalities have been invented. The use of photospec-
Keywords:
tometry as a novel technique in burn wound depth analysis has been previously described
Spectrophotometric intracutaneous
but the literature is very limited.
analysis
Methodology: We carried out a single blinded non-randomized comparative study of healing
Healing potential burn wounds
potential of 50 burn wounds between tissue spectrophotometry analysis versus clinical
Clinical applicability
evaluation. Results: ScanOSkinTM technology has an overall sensitivity of 75% and specificity of 86% in predicting healing potential of wounds. Analysis of Inter Rater Agreement (IRA) using Kappa calculations showed strengths of agreement varied from fair to moderate in perfusion and burn depth. IRA for assessing pigmentation however, was poor and this was reflected in user feedback. Conclusion: There is a potential role for ScanOSkinTM tissue spectrophotometric analysis in burn depth assessment. Future studies comparing several imaging modalities with ScanOSkin1, KingdombAngila account costs comparison may be useful for future health resources planning. # 2016 Elsevier Ltd and ISBI. All rights reserved.
1.
Background
The assessment of burn depth can be challenging even to the experienced burn clinician [1]. Clinical acumen combining history and physical examination of the wound remains the
mainstay. Accurate assessment is vital to optimize burn wound care and reduce patient morbidity such as infection risks, delayed healing and increased hypertrophic scarring [2]. Various imaging modalities have been created as adjuncts to increase accuracy in burn depth assessment. A variety of
* Corresponding author at: Burns Unit St Andrew, E220, Broomfield Hospital, Court Road, CM1 7ET Essex, United Kingdom E-mail address: [email protected] (A. Tan). http://dx.doi.org/10.1016/j.burns.2016.06.018 0305-4179/# 2016 Elsevier Ltd and ISBI. All rights reserved.
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
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diagnostic tools have been reported in the literature including laser Doppler [3], various dye techniques [4,5], thermography [6,7], and ultrasonography [8]. Although each modality has its unique advantages, often factors such as financial resources, logistical challenges and clinician preferences greatly influence the decision to use of one method over another if any at all. The first non-touch intra-cutaneous tissue spectrophotometric analysis was described as having potential in the assessment of burn depth 1988 [9]. Previously validated against the laser Doppler imaging (LDI), it has an accuracy of 87% [10]. This technology has been modified and advanced in the form of combining digital photography using a standard digital single-lens reflex (DSLR) camera with dedicated accessories (lens that filters through light of wavelengths 400–1000 nm during image capture) and accompanying computer software named ScanOSkinTM (Leniomed Ltd, England and Wales). Using the standard DSLR camera with the aforementioned lens attached, a picture is taken of the burn wound. ScanOSkin TM software processes the picture taken using an embedded proprietary algorithm to produce two additional images revealing information on the blood flow in the wound bed as well as melanin and haemosiderin. A set of three images– ‘original clinical picture’, ‘perfusion picture’ and ‘pigmentation picture’ to help the clinician determine burn depth. This device has been advertised to be particularly helpful in discriminating mid dermal (partial thickness or grade IIa) from deep dermal (deep partial thickness or grade IIb) burn wounds. In theory, the more superficial the burn wound is, the greater the dermal perfusion seen and the less haemosiderin from damage vessels will be seen. The combination of images showing a mild pink wound base, strong perfusion and little pigmentation indicates a superficial partial thickness wound (grade IIa) whereas a combination of pink wound base, low perfusion and high pigmentation indicates a deep partial thickness wound (grade IIb). Tehrani first compared and validated the use of non-touch spectrophotometric intracutaneous analysis against the LDI in the assessment of burn depth in a case series of nine patients in 2009 [11]. More recently in a study that compared a trio of non-invasive imaging modalities for burn assessment, BurkeSmith concluded that non-touch spectrophometric has advantages over LDI but acknowledged refinement in technology is required to improve interpretation of images [12]. Although tissue spectrophotometric analysis has been described as having potential to aide burn depth assessment, its accuracy in predicting wound healing potential has not been correlated with clinical outcomes of burn wound. We present our prospective case series correlating actual wound outcomes with retrospective blinded evaluation of acute burn wounds using the ScanOSkinTM analysis tool and postulate that it has a role as a potential adjunct in burn depth evaluation.
2.
burn wounds presenting within 48 h and up to 5 days of injury to the burn clinic of a regional burn centre were taken using the prototype photo spectrometry camera ScanOSkin1. All wound blisters were de-roofed followed by consented photos for medical record keeping and wound monitoring. We excluded wounds which were infected and those with delayed presentation beyond 5 days.(Fig. 1) The ScanOSkinTM camera consists of a standard Digital SLR camera (Canon EOS Digital Rebel 1000D, CANON, London, UK) with an additional filter lens and a flash exposure-reading device attached to the top of the camera. This lens filters through light of wavelength of 400–1000 nm, the length that is absorbed by haemosiderin and melanin of the skin. Distance of camera lens to wound taken was in accordance to manufacture’s recommendation of between 50 cm and 1 m. Overexposure or under exposure of photos resulted in black images (i.e. failed picture). Throughout the duration of the study, a single operator performed photography of all the burn wounds. Each burn wound in continuity was considered as a single wound. All identifiable characteristics on photos such as patient identity and facial features were removed. The images taken were analysed through the ScanOSkinTM software to provide sets of 3 images; clinical picture, perfusion of wound, and pigmentation seen (Fig. 2). Images generated from ScanOSkinTM of the wounds were shown to three experienced burn clinicians and they were asked to evaluate images and give one of three management outcomes; ‘conservative’, ‘surgical’, or ‘conservative with a
Fig. 1 – Selection criteria.
Methodology
This clinical service evaluation was approved by our institutional health care review board (ref: CA 14-95) and was conducted over a period of 2 months. Photographs of acute
Fig. 2 – A set of triple images generated by ScanOSkin software. Clinical picture (left), perfusion picture (middle), pigmentation picture (right).
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
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period of observation’. All three clinicians were blinded to the clinical findings noted on assessment, history of burn and patient details. We then correlated their finding with the actual clinical assessment of burn wound (those with healing potential of 3 weeks and those that took >3 weeks to heal) and outcomes. Using actual wound healing times as the reference standard, we calculated the sensitivity and specificity of ScanOSkin in predicting healing potential of burn wound as defined above. Wilcoxon test was used to determine the influence of timing of picture taken (<24 h, 24–48 h, 48 h) on the accuracy of assessment. Inter-rater agreement (IRA) was calculated for the assessment of clinical images, pigmentation and perfusion using the Landis and Koch classification [13] of Kappa values. Finally, we analysed user satisfaction using a standardized feedback questionnaire (Fig. 3).
3.
Results
3.1.
Image capture
A total of 42 patients were included in this study, with a total number of 50 burn wounds. 50 clinical pictures were processed by ScanOSkin1, and corresponding perfusion and pigmentation images were generated using computation software. A total of 150 images was created in the form of 50 sets of triple images. These images were presented to three senior burn surgeons who were blinded to the history of injury. Their predicted outcomes guided by ScanOSkinTM were compared to actual clinical outcomes of patients.
3.2.
Burn demographics
The location of burn wounds are shown in Fig. 1, with 22 out of 50 burn wounds being on the upper limbs (44%). The median total burn surface area (TBSA) was 1% (range 0.5–30%). Burn types included scalds (58%), flame (20%), contact (14%), chemical (6%)
Table 1 – Summary burn demographics. Patient demographics Gender M F
30 12
Age (years) Mean
21.8
Burn demographics TBSA (%) Median (SD) Range
1 (2) 0.5–30
Mechanism of injury Flame Scald Contact Chemical Electrical
10 29 7 3 1
Depth Superficial partial thickness Mixed depth
23 27
Outcomes Healing times (days) Median (SD) Range
15(11.6) 7–61
Management Conservative Surgery Conservative to surgery
46 1 3
(20%) (58%) (14%) (6%) (2%)
and electrical (2%). Thirty-three wounds healed in 3 weeks, whilst 17 wounds took > 3 weeks to heal. 46 wounds were managed conservatively and 4 underwent surgery (Table 1).
3.3.
Data analysis
Using the ScanOSkinTM software with details of the burns blinded to the assessors, in predicting the healing potential of the burn wound we note the use of this prototype photospectrometry analysis had a sensitivity of 75% and a specificity of 86%.(Table 2) Using the Wilcoxon test, accuracy of assessment using ScanOSkinTM was good for images taken <24 h and those between 24 and 48 h. Beyond 48 h up to 5 days, accuracy of assessment using remained good apart for that of Clinician C ( p = 0.0348). We measured IRA using the statistical measurement kappa, k. Strength of agreement varied from fair to moderate in perfusion and burn depth assessment using the Landis and Koch [13] classification. IRA for assessing pigmentation however, was poor (k value ranging between 0.011 and 0.244) and this was reflected in user feedback (Table 3).
Table 2 – Sensitivity and specificity (with 95% CI limits). Value (lower and upper limit 95% CI)
Fig. 3 – User feedback form.
Sensitivity Specificity Accuracy
0.75 (0.24, 0.96) 0.86 (0.72, 0.93) 0.87
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
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Table 3 – Inter-rater agreement, kappa values. Comparison
Kappa
Weighted kappa
Strength of inter rater agreement
Pigmentation Surgeon A and B Surgeon B and C Surgeon A and C
0.129 0.244 0.011
0.159 0.398 0.015
Poor Fair Poor/worse than expected due to chance alone
Perfusion Surgeon A and B Surgeon B and C Surgeon A and C
0.217 0.354 0.511
0.290 0.455 0.487
Fair Fair Moderate
Depth Surgeon A and B Surgeon B and C Surgeon A and C
0.455 0.491 0.577
0.402 0.473 0.556
Moderate Moderate Moderate
Regarding user feedback, all three senior burn clinicians found it a useful tool and would readily use it if it were available. All agreed the portability feature and the price of the prototype make its use advantageous in comparison to LDI. 2 out of 3 clinicians commented about the difficulty in interpreting pigmentation density and suggested some form of quantification of pigmentation would be useful.
4.
Discussion
The need for an early assessment of burn wound depth is underscored by the fact that there is shorter hospital stay, reduced healing times, reduced mortality rates, reduced infection rates and earlier return to work in wounds of indeterminate depth if surgical excision and skin grafting is undertaken compared to the approach of conservative management [14–18]. Overestimation of depth results in unnecessary surgery. Likewise, underestimation results in prolonged hospital stay, increased infection risk and hypertrophic scarring [15,19]. Furthermore, preservation of viable dermis has been shown to aid healing [20]. The determination of burn depth and healing potential of wound to spontaneously heal in less than 21 days largely relies on the clinician’s assessment which is primarily visual evaluation [21]. The accuracy of clinical evaluation was quoted to be 50% in inexperienced surgeons [22], and ranges from 64% to 76% in experienced surgeons [1]. Burn tissue biopsies and histological analysis with tissue staining were early traditional techniques used in burn depth assessment [23,24] which have since fallen out of favour in clinical practice [1] as tissue biopsies became expensive, required expert pathologist, was deemed invasive and caused permanent scars at biopsy sites [23,25]. Following this, attempts to develop multiple modalities to aid the clinician with burn depth assessment or healing potential of wound have since been made. Tissue spectrophotometric analysis was first described by Anselmo and Zawacki in 1973 [26]. Using infrared light to differentiate between open from thrombosed veins, this was used to represent superficial from deep burns respectively. They showed that computer enhanced images could distinguish superficial from deep burns, and this was further
enhanced through an automated process even more by taking pictures of the burn wound using green, red, and infrared light and then ‘‘subtracting’’ the surface features seen with the green and red light from the infrared detected image [27]. Heimbach developed a probe that emitted infrared light and which could also detect reflected light. The output from the probe was computed as ratios of reflected light. This was then validated for use of burn depth evaluation against clinical assessment of two senior burn surgeons. They showed this technique was more accurate than clinical assessment in predicting wounds that had healing potential of more than 3 weeks [1]. Refinements such as the introduction of a colour palette and a more user-friendly computation program enables characterization of wounds into those likely to, unlikely to and definitely not going to heal in 3 weeks [9,28]. Our unit has previously validated the use of tissue spectrophotometric analysis in burn depth assessment against the Moor LDI in 2009 in a case series of nine patients, and concluded it has a sensitivity of 86% and a potential for wider applications by burn centres [11]. Since then, user friendly focused modifications have been made in the form of an attachable infrared filtration lens to the standard DLSR camera and a ‘user friendly’ computation program known as ScanOSkinTM. Whilst spectrophotometry has been previously compared to the LDI and thermographic camera, to our knowledge it has not been compared to clinical evaluation. We also assessed IRA, sensitivity and specificity of tissue spectrometry which was not undertaken in the previous study in 2009. Furthermore, our paper reaffirms previous findings from the very limited available literature that spectrophotometry does have a potential role as an adjunct in burn depth assessment. Our study is unique in that it is the largest prospective case series using the latest computation program for spectrophotometric tissue analysis in burn depth assessment and correlating with healing potential. This is a follow up on our previous study in 2009 and we feel our findings reaffirm the potential role of tissue photospectrometry in burn depth assessment. We have shown that ScanOSkinTM technology has an overall sensitivity of 75% and specificity of 86% in predicting clinical outcomes (conservative management versus surgical intervention intervention). ScanOSkinTM is not useful for prediction of erythema only or full thickness burns. In erythema, skin is not breached. In full thickness acute burns, the leathery eschar prevents visualization of underlying structures. Both these burn depth have unique characteristics that are easily identified through clinical assessment alone. Much of the difficulty in any burn depth assessment lies in discerning the different depths of dermal burns (superficial, mid and deep) as these have very different management needs and prognosis. In our unit, it is current standard of care to obtain clinical photos of initial burn wound for clinical record keeping and to monitor burn wound progress. ScanOSkinTM is particularly useful as it does not add cost or time burden. It provides instantaneous images for processing and is easily portable in the form of a detachable lens on the DLSR camera. Unlike LDI which requires the subject to position themselves so that burn wounds are at right angles to the scanner, a special lens is mounted on a standard digital camera allows the operator
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
JBUR-4977; No. of Pages 6 burns xxx (2017) xxx–xxx
flexibility when obtaining images. In paediatric burns, instantaneous image capture negates need for sedation or a general anaesthesia. As the initial set up cost is estimated to be in the region of £10 000 and with almost negligible running cost, this places ScanOSkinTM at a fraction of the cost of LDI [12]. A recent prospective study comparing LDI, infrared thermography and spectrophotometric intracutaneous analysis (ScanOSkinTM) described a positive experience with ScanOSkinTM and concluded there were clear advantages in terms of cost of equipment purchase and acceptability to patients [12]. Sozen et al. suggested that the principles of burn wound management should be applied at primary and secondary centres and not just specialist burn centres [29]. In a non-burn specialist peripheral hospital, ScanOSkinTM is a cheaper alternative to LDI. A portable low maintenance device such as this may aid communication between peripheral hospitals and specialist burn centres, avoid unnecessary referrals to specialist care, improve outpatient wound care by peripheral hospitals and therefore, better utilize burn resources. The number of years of experience of the three burn clinicians ranged from 10 to 25 years. The general consensus was that the tissue photo spectrometry analysis and its accompanying ScanOSkinTM software was a useful tool as an adjunct to the clinical assessment of burn depth wounds. In particular, the portability feature and the price of the prototype make its use advantageous in comparison to a LDI. However, we note that correlation of pigmentation density and burn depth is not always consistent. Regarding IRA, our study showed strength of agreement varied from fair to moderate in perfusion and burn depth assessment, but was poor in assessing pigmentation. In a study by Hop et al. in 2014, they showed that IRA of photographic assessment of burn wound (particularly size of burn) by burn specialists was good but concluded that the use of clinical photographs alone in the assessment of burns was inadequate [30]. We feel the added features of perfusion analysis and pigmentation correlation with depth offered by ScanOSkinTM will improve current photographic assessment. We acknowledge that there are limitations to this study in that the blinded evaluation was done retrospectively. One of the biggest challenges is the lack of quantification of density, understanding the relationship between reflectance and dynamic microcirculatory changes within the burn wound with time. Therefore, it can be argued that this method is still a subjective form of assessment. We note that interpretation of pigmentation density can be further improved with stratified pixel quantification in accordance to burn depth. Currently, external Joint Photographic Expert Group (JPEG) pixel quantification applications can be used for this purpose. However, we feel that a calibration of pixels density that is incorporated into the current software will potentially provide an objective measurement of burn depth.
5.
Conclusion
The preference for types of imaging modality used is often influenced by availability of financial resources, logistical considerations and access to burn specialist care on site.
5
Currently in the UK, LDI remains the commonest imaging adjunct in most burn units, although clinical assessment remains the mainstay technique for burn depth evaluation. From our experience, the potential role for ScanOSkinTM tissue spectrophotometric analysis in assessment of burn depth, in particular dermal burns is promising. However, future studies comparing several imaging modalities in parallel including ScanOSkinTM, taking into account long term cost-benefit analysis may be useful for health resources planning.
Conflicts of interest The authors have no conflicts of interest to declare.
Funding No funding was received.
Acknowledgement We would like to thank Mr Matthieu Le-Chevrac, CEO Leniomed1 required prototype loan.
references
[1] Heimbach DM, Afromowitz MA, Engrav LH, Marvin JA, Perry B. Burn depth estimation – man or machine. J Trauma 1984;24(5):373–8. [2] Cubison TC, Pape SA, Parkhouse N. Evidence for the link between healing time and the development of hypertrophic scars (HTS) in paediatric burns due to scald injury. Burns 2006;32(8):992–9. [3] Gill P. The critical evaluation of laser Doppler imaging in determining burn depth. Int J Burns Trauma 2013;3(2):72–7. [4] Sheridan RL, Schomaker KT, Lucchina LC, Hurley J, Yin LM, Tompkins RG, et al. Burn depth estimation by use of indocyanine green fluorescence: initial human trial. J Burn Care Rehabil 1995;16(6):602–4. [5] Still JM, Law EJ, Klavuhn KG, Island TC, Holtz JZ. Diagnosis of burn depth using laser-induced indocyanine green flourescene: a preliminary clinical trial. Burns 2001;27(4):364–71. [6] Renkielska A, Kaczmarek M, Nowakowski A, Grudzin´ski J, Czapiewski P, Krajewski A, et al. Active dynamic infrared thermal imaging in burn depth evaluation. J Burn Care Res 2014;35(5):e294–303. [7] Mazurek MJ, Frew Q, Sadeghi AM, Tan A, Syed M, Dziewulski P. A pilot study of a hand-held camera in a busy burn centre: prediction of patient length of recuperation with wound temperature. Burns 2015;42(3):614–9. [8] Iraniha S, Cinat ME, VanderKam VM, Boyko A, Lee D, Jones J, et al. Determination of burn depth with noncontact ultrasonography. J Burn Care Rehabil 2000;21(4):333–8. [9] Afromowitz MA, Callis JB, Haeimbach DM, DeSoto LA, Norton MK. Multispectral imaging of burn wounds: a new clinical instrument for evaluating burn depth. IEEE Trans Biomed Eng 1988;35(10):842–50. [10] Yeong EK, Hsiao TC, Chiang HK, Lin CW. Prediction of burn healing time using artificial neural networks and reflectance spectrometer. Burns 2005;31(4):415–20.
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[11] Tehrani H, Moncrieff M, Philip B, Dziewulski P. Spectrophotometric intracutaneous analysis: a novel imaging technique in the assessment of acute burn depth. Ann Plast Surg 2008;61(4):437–40. [12] Burke-Smith A, Collier J, Jones I. A comparison of noninvasive imaging modalities: Infrared thermography, spectrophotometric intracutaneous analysis and laser Doppler imaging for the assessment of adult burns. Burns 2015;41(8):1695–707. [13] Landis JR, Koch GG. An application of hierarchical kappatype statistics in the assessment of majority agreement among multiple observers. Biometrics 1977;33(2):363–74. [14] Engrav LH, Heimbach DM, Reus JL, Harnar TJ, Marvin JA. Early excision and grafting vs. nonoperative treatment of burns of indeterminant depth: a randomized prospective study. J Trauma 1983;23(11):1001–4. [15] Xiao-Wu W, Herndon DN, Spies M, Sanford AP, Wolf SE. Effects of delayed wound excision and grafting in severely burned children. Arch Surg 2002;137(9):1049–54. [16] Burke JF, Quinby WC, Bondoc Jr CC. Primary excision and prompt grafting as routine therapy for the treatment of thermal burns in children. Surg Clin North Am 1976;56(2):477–94. [17] Mohammadi AA, Bakhshaeekia AR, Marzban S, Abbasi S, Ashraf AR, Mohammadi MK, et al. Early excision and skin grafting versus delayed skin grafting in deep hand burns (a randomised clinical controlled trial). Burns 2011;37(1):36–41. [18] Ong YS, Samuel M, Song C. Meta-analysis of early excision of burns. Burns 2006;32(2):145–50. [19] Gore D, Desai M, Herndon DN, Abston S, Evans EB. Comparison of complications during rehabilitation between conservative and early surgical management in thermal burns involving the feet of children and adolescents. J Burn Care Rehabil 1988;9(1):92–5.
[20] Janzekovic Z. Once upon a time . . . how west discovered east. J Plast Reconstr Aesthet Surg 2008;61(3):240–4. [21] Wallace DL, Hussain A, Khan A, Wilson YT. A systematic review of the evidence for telemedicine in burn care: with a UK perspective. Burns 2012;38(4):465–80. [22] Hlava P, Moserova J, Konigova R. Validity of clinical assessment of the depth of a thermal injury. Acta Chir Plast 1983;25(4):202–8. [23] Heimbach D, Engrav L, Grube B, Marvin J. Burn depth: a review. World J Surg 1992;16(1):10–5. [24] Hoeksema H, Van de Sijpe K, Tondu T, Hamdi M, Van Landuyt K, Blondeel P, et al. Accuracy of early burn depth assessment by laser Doppler imaging on different days post burn. Burns 2009;35(1):36–45. [25] Monstrey S, Hoeksema H, Verbelen J, Pirayesh A, Blondeel P. Assessment of burn depth and burn wound healing potential. Burns 2008;34(6):761–9. [26] Anselmo V, Zawacki B. Infrared photography as a diagnostic tool for the burn ward. Proc Soc Photo Optical Instr Eng 1973;8:181. [27] Anselmo V, Zawacki B. Multispectral photographic analysis. A new quantitative tool to assist in the early diagnosis of thermal burn depth. Ann Biomed Eng 1977;5:179–93. [28] Afromowitz MA, Van Liew GS, Heimbach DM. Clinical evaluation of burn injuries using an optical reflectance technique. IEEE Trans Biomed Eng 1987;34(2):114–27. [29] Sozen I, Guldogan CE, Kismet K, Sabuncuoglu MZ, Yasti AC. Outpatient burn management and unnecessary referrals. Ulus Travma Acil Cerrahi Derg 2015;21(1):27–33. [30] Hop MJ, Moues CM, Bogomolova K, Nieuwenhuis MK, Oen IM, Middelkoop E, et al. Photographic assessment of burn size and depth: reliability and validity. J Wound Care 2014;23(3):144–5. 148–52.
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/burns
Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 54 burn wounds A. Tan a,b,*, F.A. Pedrini a,c, G. Oni a, Q. Frew a,b, B. Philp a, D. Barnes a, P. Dziewulski a a
St Andrew Centre for Plastics and Burns, CM1 7ET, United Kingdom St Andrews Anglia Ruskin University Hall Lane, CM1 1SQ, United Kingdom c Scuola di Medicina e Chirurgia, Polo didattico Murri, Via Massarenti 9, 40138 Bologna, Italy b
article info
abstract
Article history:
Introduction: The assessment of burn depth can be challenging even to the experienced burn
Accepted 12 June 2016
clinician. Clinical assessment is most widely used to determine burn depth. Because of this subjective nature, various imaging modalities have been invented. The use of photospec-
Keywords:
tometry as a novel technique in burn wound depth analysis has been previously described
Spectrophotometric intracutaneous
but the literature is very limited.
analysis
Methodology: We carried out a single blinded non-randomized comparative study of healing
Healing potential burn wounds
potential of 50 burn wounds between tissue spectrophotometry analysis versus clinical
Clinical applicability
evaluation. Results: ScanOSkinTM technology has an overall sensitivity of 75% and specificity of 86% in predicting healing potential of wounds. Analysis of Inter Rater Agreement (IRA) using Kappa calculations showed strengths of agreement varied from fair to moderate in perfusion and burn depth. IRA for assessing pigmentation however, was poor and this was reflected in user feedback. Conclusion: There is a potential role for ScanOSkinTM tissue spectrophotometric analysis in burn depth assessment. Future studies comparing several imaging modalities with ScanOSkin1, KingdombAngila account costs comparison may be useful for future health resources planning. # 2016 Elsevier Ltd and ISBI. All rights reserved.
1.
Background
The assessment of burn depth can be challenging even to the experienced burn clinician [1]. Clinical acumen combining history and physical examination of the wound remains the
mainstay. Accurate assessment is vital to optimize burn wound care and reduce patient morbidity such as infection risks, delayed healing and increased hypertrophic scarring [2]. Various imaging modalities have been created as adjuncts to increase accuracy in burn depth assessment. A variety of
* Corresponding author at: Burns Unit St Andrew, E220, Broomfield Hospital, Court Road, CM1 7ET Essex, United Kingdom E-mail address: [email protected] (A. Tan). http://dx.doi.org/10.1016/j.burns.2016.06.018 0305-4179/# 2016 Elsevier Ltd and ISBI. All rights reserved.
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
JBUR-4977; No. of Pages 6
2
burns xxx (2017) xxx–xxx
diagnostic tools have been reported in the literature including laser Doppler [3], various dye techniques [4,5], thermography [6,7], and ultrasonography [8]. Although each modality has its unique advantages, often factors such as financial resources, logistical challenges and clinician preferences greatly influence the decision to use of one method over another if any at all. The first non-touch intra-cutaneous tissue spectrophotometric analysis was described as having potential in the assessment of burn depth 1988 [9]. Previously validated against the laser Doppler imaging (LDI), it has an accuracy of 87% [10]. This technology has been modified and advanced in the form of combining digital photography using a standard digital single-lens reflex (DSLR) camera with dedicated accessories (lens that filters through light of wavelengths 400–1000 nm during image capture) and accompanying computer software named ScanOSkinTM (Leniomed Ltd, England and Wales). Using the standard DSLR camera with the aforementioned lens attached, a picture is taken of the burn wound. ScanOSkin TM software processes the picture taken using an embedded proprietary algorithm to produce two additional images revealing information on the blood flow in the wound bed as well as melanin and haemosiderin. A set of three images– ‘original clinical picture’, ‘perfusion picture’ and ‘pigmentation picture’ to help the clinician determine burn depth. This device has been advertised to be particularly helpful in discriminating mid dermal (partial thickness or grade IIa) from deep dermal (deep partial thickness or grade IIb) burn wounds. In theory, the more superficial the burn wound is, the greater the dermal perfusion seen and the less haemosiderin from damage vessels will be seen. The combination of images showing a mild pink wound base, strong perfusion and little pigmentation indicates a superficial partial thickness wound (grade IIa) whereas a combination of pink wound base, low perfusion and high pigmentation indicates a deep partial thickness wound (grade IIb). Tehrani first compared and validated the use of non-touch spectrophotometric intracutaneous analysis against the LDI in the assessment of burn depth in a case series of nine patients in 2009 [11]. More recently in a study that compared a trio of non-invasive imaging modalities for burn assessment, BurkeSmith concluded that non-touch spectrophometric has advantages over LDI but acknowledged refinement in technology is required to improve interpretation of images [12]. Although tissue spectrophotometric analysis has been described as having potential to aide burn depth assessment, its accuracy in predicting wound healing potential has not been correlated with clinical outcomes of burn wound. We present our prospective case series correlating actual wound outcomes with retrospective blinded evaluation of acute burn wounds using the ScanOSkinTM analysis tool and postulate that it has a role as a potential adjunct in burn depth evaluation.
2.
burn wounds presenting within 48 h and up to 5 days of injury to the burn clinic of a regional burn centre were taken using the prototype photo spectrometry camera ScanOSkin1. All wound blisters were de-roofed followed by consented photos for medical record keeping and wound monitoring. We excluded wounds which were infected and those with delayed presentation beyond 5 days.(Fig. 1) The ScanOSkinTM camera consists of a standard Digital SLR camera (Canon EOS Digital Rebel 1000D, CANON, London, UK) with an additional filter lens and a flash exposure-reading device attached to the top of the camera. This lens filters through light of wavelength of 400–1000 nm, the length that is absorbed by haemosiderin and melanin of the skin. Distance of camera lens to wound taken was in accordance to manufacture’s recommendation of between 50 cm and 1 m. Overexposure or under exposure of photos resulted in black images (i.e. failed picture). Throughout the duration of the study, a single operator performed photography of all the burn wounds. Each burn wound in continuity was considered as a single wound. All identifiable characteristics on photos such as patient identity and facial features were removed. The images taken were analysed through the ScanOSkinTM software to provide sets of 3 images; clinical picture, perfusion of wound, and pigmentation seen (Fig. 2). Images generated from ScanOSkinTM of the wounds were shown to three experienced burn clinicians and they were asked to evaluate images and give one of three management outcomes; ‘conservative’, ‘surgical’, or ‘conservative with a
Fig. 1 – Selection criteria.
Methodology
This clinical service evaluation was approved by our institutional health care review board (ref: CA 14-95) and was conducted over a period of 2 months. Photographs of acute
Fig. 2 – A set of triple images generated by ScanOSkin software. Clinical picture (left), perfusion picture (middle), pigmentation picture (right).
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
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period of observation’. All three clinicians were blinded to the clinical findings noted on assessment, history of burn and patient details. We then correlated their finding with the actual clinical assessment of burn wound (those with healing potential of 3 weeks and those that took >3 weeks to heal) and outcomes. Using actual wound healing times as the reference standard, we calculated the sensitivity and specificity of ScanOSkin in predicting healing potential of burn wound as defined above. Wilcoxon test was used to determine the influence of timing of picture taken (<24 h, 24–48 h, 48 h) on the accuracy of assessment. Inter-rater agreement (IRA) was calculated for the assessment of clinical images, pigmentation and perfusion using the Landis and Koch classification [13] of Kappa values. Finally, we analysed user satisfaction using a standardized feedback questionnaire (Fig. 3).
3.
Results
3.1.
Image capture
A total of 42 patients were included in this study, with a total number of 50 burn wounds. 50 clinical pictures were processed by ScanOSkin1, and corresponding perfusion and pigmentation images were generated using computation software. A total of 150 images was created in the form of 50 sets of triple images. These images were presented to three senior burn surgeons who were blinded to the history of injury. Their predicted outcomes guided by ScanOSkinTM were compared to actual clinical outcomes of patients.
3.2.
Burn demographics
The location of burn wounds are shown in Fig. 1, with 22 out of 50 burn wounds being on the upper limbs (44%). The median total burn surface area (TBSA) was 1% (range 0.5–30%). Burn types included scalds (58%), flame (20%), contact (14%), chemical (6%)
Table 1 – Summary burn demographics. Patient demographics Gender M F
30 12
Age (years) Mean
21.8
Burn demographics TBSA (%) Median (SD) Range
1 (2) 0.5–30
Mechanism of injury Flame Scald Contact Chemical Electrical
10 29 7 3 1
Depth Superficial partial thickness Mixed depth
23 27
Outcomes Healing times (days) Median (SD) Range
15(11.6) 7–61
Management Conservative Surgery Conservative to surgery
46 1 3
(20%) (58%) (14%) (6%) (2%)
and electrical (2%). Thirty-three wounds healed in 3 weeks, whilst 17 wounds took > 3 weeks to heal. 46 wounds were managed conservatively and 4 underwent surgery (Table 1).
3.3.
Data analysis
Using the ScanOSkinTM software with details of the burns blinded to the assessors, in predicting the healing potential of the burn wound we note the use of this prototype photospectrometry analysis had a sensitivity of 75% and a specificity of 86%.(Table 2) Using the Wilcoxon test, accuracy of assessment using ScanOSkinTM was good for images taken <24 h and those between 24 and 48 h. Beyond 48 h up to 5 days, accuracy of assessment using remained good apart for that of Clinician C ( p = 0.0348). We measured IRA using the statistical measurement kappa, k. Strength of agreement varied from fair to moderate in perfusion and burn depth assessment using the Landis and Koch [13] classification. IRA for assessing pigmentation however, was poor (k value ranging between 0.011 and 0.244) and this was reflected in user feedback (Table 3).
Table 2 – Sensitivity and specificity (with 95% CI limits). Value (lower and upper limit 95% CI)
Fig. 3 – User feedback form.
Sensitivity Specificity Accuracy
0.75 (0.24, 0.96) 0.86 (0.72, 0.93) 0.87
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
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Table 3 – Inter-rater agreement, kappa values. Comparison
Kappa
Weighted kappa
Strength of inter rater agreement
Pigmentation Surgeon A and B Surgeon B and C Surgeon A and C
0.129 0.244 0.011
0.159 0.398 0.015
Poor Fair Poor/worse than expected due to chance alone
Perfusion Surgeon A and B Surgeon B and C Surgeon A and C
0.217 0.354 0.511
0.290 0.455 0.487
Fair Fair Moderate
Depth Surgeon A and B Surgeon B and C Surgeon A and C
0.455 0.491 0.577
0.402 0.473 0.556
Moderate Moderate Moderate
Regarding user feedback, all three senior burn clinicians found it a useful tool and would readily use it if it were available. All agreed the portability feature and the price of the prototype make its use advantageous in comparison to LDI. 2 out of 3 clinicians commented about the difficulty in interpreting pigmentation density and suggested some form of quantification of pigmentation would be useful.
4.
Discussion
The need for an early assessment of burn wound depth is underscored by the fact that there is shorter hospital stay, reduced healing times, reduced mortality rates, reduced infection rates and earlier return to work in wounds of indeterminate depth if surgical excision and skin grafting is undertaken compared to the approach of conservative management [14–18]. Overestimation of depth results in unnecessary surgery. Likewise, underestimation results in prolonged hospital stay, increased infection risk and hypertrophic scarring [15,19]. Furthermore, preservation of viable dermis has been shown to aid healing [20]. The determination of burn depth and healing potential of wound to spontaneously heal in less than 21 days largely relies on the clinician’s assessment which is primarily visual evaluation [21]. The accuracy of clinical evaluation was quoted to be 50% in inexperienced surgeons [22], and ranges from 64% to 76% in experienced surgeons [1]. Burn tissue biopsies and histological analysis with tissue staining were early traditional techniques used in burn depth assessment [23,24] which have since fallen out of favour in clinical practice [1] as tissue biopsies became expensive, required expert pathologist, was deemed invasive and caused permanent scars at biopsy sites [23,25]. Following this, attempts to develop multiple modalities to aid the clinician with burn depth assessment or healing potential of wound have since been made. Tissue spectrophotometric analysis was first described by Anselmo and Zawacki in 1973 [26]. Using infrared light to differentiate between open from thrombosed veins, this was used to represent superficial from deep burns respectively. They showed that computer enhanced images could distinguish superficial from deep burns, and this was further
enhanced through an automated process even more by taking pictures of the burn wound using green, red, and infrared light and then ‘‘subtracting’’ the surface features seen with the green and red light from the infrared detected image [27]. Heimbach developed a probe that emitted infrared light and which could also detect reflected light. The output from the probe was computed as ratios of reflected light. This was then validated for use of burn depth evaluation against clinical assessment of two senior burn surgeons. They showed this technique was more accurate than clinical assessment in predicting wounds that had healing potential of more than 3 weeks [1]. Refinements such as the introduction of a colour palette and a more user-friendly computation program enables characterization of wounds into those likely to, unlikely to and definitely not going to heal in 3 weeks [9,28]. Our unit has previously validated the use of tissue spectrophotometric analysis in burn depth assessment against the Moor LDI in 2009 in a case series of nine patients, and concluded it has a sensitivity of 86% and a potential for wider applications by burn centres [11]. Since then, user friendly focused modifications have been made in the form of an attachable infrared filtration lens to the standard DLSR camera and a ‘user friendly’ computation program known as ScanOSkinTM. Whilst spectrophotometry has been previously compared to the LDI and thermographic camera, to our knowledge it has not been compared to clinical evaluation. We also assessed IRA, sensitivity and specificity of tissue spectrometry which was not undertaken in the previous study in 2009. Furthermore, our paper reaffirms previous findings from the very limited available literature that spectrophotometry does have a potential role as an adjunct in burn depth assessment. Our study is unique in that it is the largest prospective case series using the latest computation program for spectrophotometric tissue analysis in burn depth assessment and correlating with healing potential. This is a follow up on our previous study in 2009 and we feel our findings reaffirm the potential role of tissue photospectrometry in burn depth assessment. We have shown that ScanOSkinTM technology has an overall sensitivity of 75% and specificity of 86% in predicting clinical outcomes (conservative management versus surgical intervention intervention). ScanOSkinTM is not useful for prediction of erythema only or full thickness burns. In erythema, skin is not breached. In full thickness acute burns, the leathery eschar prevents visualization of underlying structures. Both these burn depth have unique characteristics that are easily identified through clinical assessment alone. Much of the difficulty in any burn depth assessment lies in discerning the different depths of dermal burns (superficial, mid and deep) as these have very different management needs and prognosis. In our unit, it is current standard of care to obtain clinical photos of initial burn wound for clinical record keeping and to monitor burn wound progress. ScanOSkinTM is particularly useful as it does not add cost or time burden. It provides instantaneous images for processing and is easily portable in the form of a detachable lens on the DLSR camera. Unlike LDI which requires the subject to position themselves so that burn wounds are at right angles to the scanner, a special lens is mounted on a standard digital camera allows the operator
Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018
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flexibility when obtaining images. In paediatric burns, instantaneous image capture negates need for sedation or a general anaesthesia. As the initial set up cost is estimated to be in the region of £10 000 and with almost negligible running cost, this places ScanOSkinTM at a fraction of the cost of LDI [12]. A recent prospective study comparing LDI, infrared thermography and spectrophotometric intracutaneous analysis (ScanOSkinTM) described a positive experience with ScanOSkinTM and concluded there were clear advantages in terms of cost of equipment purchase and acceptability to patients [12]. Sozen et al. suggested that the principles of burn wound management should be applied at primary and secondary centres and not just specialist burn centres [29]. In a non-burn specialist peripheral hospital, ScanOSkinTM is a cheaper alternative to LDI. A portable low maintenance device such as this may aid communication between peripheral hospitals and specialist burn centres, avoid unnecessary referrals to specialist care, improve outpatient wound care by peripheral hospitals and therefore, better utilize burn resources. The number of years of experience of the three burn clinicians ranged from 10 to 25 years. The general consensus was that the tissue photo spectrometry analysis and its accompanying ScanOSkinTM software was a useful tool as an adjunct to the clinical assessment of burn depth wounds. In particular, the portability feature and the price of the prototype make its use advantageous in comparison to a LDI. However, we note that correlation of pigmentation density and burn depth is not always consistent. Regarding IRA, our study showed strength of agreement varied from fair to moderate in perfusion and burn depth assessment, but was poor in assessing pigmentation. In a study by Hop et al. in 2014, they showed that IRA of photographic assessment of burn wound (particularly size of burn) by burn specialists was good but concluded that the use of clinical photographs alone in the assessment of burns was inadequate [30]. We feel the added features of perfusion analysis and pigmentation correlation with depth offered by ScanOSkinTM will improve current photographic assessment. We acknowledge that there are limitations to this study in that the blinded evaluation was done retrospectively. One of the biggest challenges is the lack of quantification of density, understanding the relationship between reflectance and dynamic microcirculatory changes within the burn wound with time. Therefore, it can be argued that this method is still a subjective form of assessment. We note that interpretation of pigmentation density can be further improved with stratified pixel quantification in accordance to burn depth. Currently, external Joint Photographic Expert Group (JPEG) pixel quantification applications can be used for this purpose. However, we feel that a calibration of pixels density that is incorporated into the current software will potentially provide an objective measurement of burn depth.
5.
Conclusion
The preference for types of imaging modality used is often influenced by availability of financial resources, logistical considerations and access to burn specialist care on site.
5
Currently in the UK, LDI remains the commonest imaging adjunct in most burn units, although clinical assessment remains the mainstay technique for burn depth evaluation. From our experience, the potential role for ScanOSkinTM tissue spectrophotometric analysis in assessment of burn depth, in particular dermal burns is promising. However, future studies comparing several imaging modalities in parallel including ScanOSkinTM, taking into account long term cost-benefit analysis may be useful for health resources planning.
Conflicts of interest The authors have no conflicts of interest to declare.
Funding No funding was received.
Acknowledgement We would like to thank Mr Matthieu Le-Chevrac, CEO Leniomed1 required prototype loan.
references
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Please cite this article in press as: Tan A, et al. Spectrophotometric intracutaneous analysis for the assessment of burn wounds: A service evaluation of its clinical application in 50 burn wounds. Burns (2017), http://dx.doi.org/10.1016/j.burns.2016.06.018