burns 39 (2013) 1107–1113

Available online at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/burns

The determination of total burn surface area: How much

difference?

M. Giretzlehner a,*, J. Dirnberger a, R. Owen a, H.L. Haller b, D.B. Lumenta c, L.-P. Kamolz c
a
Research Unit Medical-Informatics, RISC Software GmbH, Johannes Kepler University Linz, Hagenberg, Austria
b
Unfallkrankenhaus Linz, AUVA, Linz, Austria
c
Division of Plastic, Aesthetic and Reconstructive Surgery, Department of Surgery, Medical University of Graz, Austria

article info abstract

Article history: Burn depth and burn size are crucial determinants for assessing patients suffering from
Accepted 7 January 2013 burns [1]. Therefore, a correct evaluation of these factors is optimal for adapting the
appropriate treatment in modern burn care. Burn surface assessment is subject to consid-
Keywords: erable differences among clinicians [2].
Burn assessment This work investigated the accuracy among experts based on conventional surface
Burn size estimation methods (e.g. ‘‘Rule of Palm’’, ‘‘Rule of Nines’’ or ‘‘Lund–Browder Chart’’). The
Burn size determination estimation results were compared to a computer-based evaluation method.
Correct evaluation of burns Survey data was collected during one national and one international burn conference.
Accuracy of estimations The poll confirmed deviations of burn depth/size estimates of up to 62% in relation to the
Objectivity of estimations mean value of all participants. In comparison to the computer-based method, overestima-
Computer-aided methods tion of up to 161% was found.
Computer support We suggest introducing improved methods for burn depth/size assessment in clinical
Documentation of burns routine in order to efficiently allocate and distribute the available resources for practicing
Overestimation burn care.
Deviations of burn size estimations # 2013 Elsevier Ltd and ISBI. All rights reserved.
Improved methods for burn size
assessment

 ‘‘Lund–Browder Chart’’ [5]

1. Introduction
Several studies have been carried out in order to analyze
Burn depth and burn size are crucial determinants for the reliability and adequacy of these methods, e.g. Miller et al.
assessing patients suffering from burns [1]. Therefore a [6] have analyzed the assessment differences between
correct evaluation of these factors is key for adapting the physicians and nurses. Objectivation of TBSA and conse-
appropriate treatment in modern burn care. Burn surface quently improving estimation results has always been an
assessment is subject to considerable differences among issue within the burn community [2]. Neuwalder et al. [7]
clinicians [2]. published a review of computer-aided body surface area
Three established and commonly used estimation meth- determination, Haller et al. [8] and Prieto et al. [9] recently
ods are: published papers on currently available computer-aided 3D
approaches.
 ‘‘Rule of Palm’’ [3] The aim of this study was to investigate assessment
 ‘‘Rule of Nines’’ [4] accuracy of burns below 20% burned surface area among

* Corresponding author. Tel.: +43 7236 3343 672; fax: +43 7236 3343 680.
E-mail addresses: michael@giretzlehner.at, michael.giretzlehner@risc.uni-linz.ac.at (M. Giretzlehner).
0305-4179/$36.00 # 2013 Elsevier Ltd and ISBI. All rights reserved.
http://dx.doi.org/10.1016/j.burns.2013.01.021
1108 burns 39 (2013) 1107–1113

clinical personnel, their variance and accuracy versusa (3) Method(s) used on a regular basis; the possible alternatives
computer-based surface estimation and documentation were:
method. a. ‘‘Rule of Palm’’
b. ‘‘Rule of Nines’’
c. ‘‘Lund–Browder Chart’’
2. Methods d. Others
(4) Profession; possible alternatives were:
We designed a sheet containing three pictures of patients with a. Resident
different burn wound patterns and sizes. In order to provide b. Specialist
different levels of complexity, we selected one patient with c. Nursing staff/allied health professionals
plenty of small disseminated burn areas (2 years-of-age, male), d. Medical students
one with a limited amount of extended regions (35 years-of- e. Others
age, male) and one with a mixture of both (4 years-of-age,
female). The patients are shown in Illustration 1. In order to We provided graphical representations of the ‘‘Rule of
balance an improved response rate versus a more detailed Palm’’, the ‘‘Rule of Nines’’ and a ‘‘Lund–Browder Chart’’ on
questionnaire, we have compromised and only used three the back of the survey sheet. The questionnaire was printed on
cases per sheet, which was distributed in between conference A4 paper (210 mm  297 mm, 80 g/A4) with a high-quality
sessions or during coffee breaks, and immediately recollected color laser printer.
on two occasions during one national (‘‘28. Jahrestagung der Collected data was manually and independently entered in
deutschsprachigen Arbeitsgemeinschaft für Verbrennungsbehan- respective Excel sheets (Microsoft Office, Excel, Version 2010,
dlung, DAV’’) and one international conference (‘‘14th Europe- Richmond, MA, USA) by two persons, and descriptive statisti-
an Burns AssociationCongress, EBA‘‘) in January 2010 and cal data were calculated (mean, median and standard
September 2011, respectively. deviations per total, per conference and per group). The box
Data was collected anonymously, voluntarily and without plot analysis was performed with the statistical software tool R
offering any financial incentives. The survey sheets were (The R Project for Statistical Computing, R Foundation, Vienna,
handed out randomly to conference participants, and a total of Austria).
102 were completed (51 data sets on each conference). For the comparison of burned surface area estimations of
The questionnaire consisted of the following parts: participants to a computer-aided method the established
system ‘‘Burn Case 3D’’, presented by Haller et al. [8] was used.
(1) Description to clarify the aim and process of the survey: A patient-specific 3D model (adapted to height and weight of
‘‘The task is to estimate the total surface area within the real patient according to Dirnberger et al. [10]) was created and
yellow line per patient. The line itself is part of the burn the digital picture was cross-faded. The burns were trans-
area; the estimation should be independent of its burn ferred to the model in three steps as shown in Illustration 2.
depth.’’ The majority of respondents were specialists (total 41,
(2) Estimation of the total burned surface areas (TBSA) using 40.2%; DAV19, 37.3%; EBA 22, 43.1%), followed by others (total
three photographs. The images show three patients with 22, 21.6%; DAV 12, 23.5%; EBA 10, 19.6%), nursing staff (total 21,
outlined burns. The estimations were asked to be given in 20.6%; DAV 10, 19.6%; EBA 11, 21.6%) and residents (total 18,
percentages. 17.6%; DAV 10, 19.6% EBA 8, 15.7%).

Illustration 1 – Pictures of patients with different wound patterns depicted on the questionnaire: patient 1 (2 years-of-age,
male, 12 kg, 87 cm), patient 2 (35 years-of-age, male, 80 kg, 182 cm), patient 3 (4 years-of-age, female, 16 kg, 102 cm).
 burns 39 (2013) 1107–1113 1109

Illustration 2 – Burn wound data transfer from superimposed picture to 3D model by use of ‘‘BurnCase 3D’’. To achieve an
accurate result, the model was cross-faded with the picture in three separate steps. The first picture shows the patient only,
the second picture demonstrates the overlapping of the three-dimensional virtual model. The third and fourth picture
shows the overlapping positions for transferring the marked surfaces on the chest and arm. On the far right picture, the
final result of the transferred areas can be seen.

The preferred methods for burn extent estimation on a difference could be found concerning the ‘‘Lund–Browder
regular basis were headed by ‘‘Rule of Nines’’ (total 57, 38.0%; Chart’’, which was considerably less popular in German-
DAV 26, 38.8%; EBA 31, 37.3%) closely followed by the ‘‘Rule of speaking countries.
Palm’’ (total 56, 37.3%; DAV 28, 41.8%; EBA 28, 33.7%), ‘‘Lund– In sum, the following trends were found: nursing staff/
Browder Chart’’ (total 27, 18.0%; DAV 7, 10.4%; EBA 20, 24.1%) allied health professionals in the non-German-speaking
and others (total 10, 6.7%; DAV 6, 9.0%; EBA 4, 4.8%). countries were more familiar with the use of ‘‘Lund–Browder
For details of coherence between estimation methods and Chart’’ than in German-speaking countries. Both, specialists
profession please refer to Illustrations 3 and 4. and residents of the international conference used the ‘‘Lund–
For each patient mean, median, mode (the number that Browder Chart’’ significantly more often than their colleagues
appears most often in a set of numbers), standard deviation in German-speaking countries. The ‘‘Rule of Palm’’ was more
(SD), the value of standard deviation in relation to the mean commonly used by nursing staff/allied health professionals in
and the resulting overestimation, in relation to the computer- German-speaking countries as compared to all European
based surface determination, are shown in percentages in countries.
Tables 1–3. For details about the disposition of estimated burn When asked to specify their preferred methods for TBSA
extent, please refer to the box plots shown in Illustrations 5 estimation ‘‘on a regular basis’’, the overall dominating ones
and 6. were the ‘‘Rule of Nines’’ and ‘‘Rule of Palm’’. About 51% of the
For detailed description of differences of burn extent EBA and 66.7% of the DAV participants selected only one single
estimations by professional groups, please refer to Illustra- method of TBSA-determination. The majority of the remain-
tions 7 and 8. der (EBA 41.2%; DAV 29.4%) selected (at least) two different
Most participants specified to use the methods ‘‘Rule of methods.
Nines’’ and ‘‘Rule of Palm’’ for %TBSA determination. The
results of both conferences showed high correlations; howev-
er, on the European conference (EBA) the ‘‘Rule of Nines’’ was 3. Discussion
slightly more popular than the ‘‘Rule of Palm’’. A significant
The correct estimation of burn depth and extent are the main
factors for determining burn severity, and should have careful
100%
and accurate estimation by the treating clinicians.
80% Variations of results among the participants were evident
Others
60%
Lund-Browder Chart in all three pictures. The highest standard deviation was
40% observed in the patient with the small scattered areas; the
Rule of Nines
lowest standard deviation in the patient with few large areas,
20% Rule of Palm
which is in conjunction with the current literature [11]. Our
0%
Resident Specialist Nurse/Aendant analyses show high standard deviations in all 3 patients of up
to 62% of the mean burn extent. This can best be shown with
Illustration 3 – Coherence between used estimation Illustration 7, where we have visualized the standard devia-
methods on a regular basis by profession on the national tion range by markers. For the mean burn extent of 9.4%, we
conference DAV. The values represents the percentage of found a huge deviation range from 3.5% to 15.3%. This means
individuals using this method within the professional that it is likely that two different clinicians estimate the same
group in relation to its group size. burn extent one with 3.5% and the other one with 15.3%.
1110 burns 39 (2013) 1107–1113

100%
80%
Others
60%
Lund-Browder Chart
40% Rule of Nines
20% Rule of Palm
0%
Resident Specialist Nurse/Aendant

Illustration 4 – Coherence between used estimation

methods on a regular basis by profession on the
international conference EBA. The values represents the
percentage of individuals using this method within the
professional group in relation to its group size.

In comparison to the estimations done by experts, the

Illustration 5 – Boxplot showing the disposition of
software calculated significantly lower values, which
estimated burn extent in %TBSA for patient 1 on DAV. The
explained the general overestimation as compared to the
burn extent estimations ranged from 1.5 to 30. The
computer analysis in all three patients, which corresponded
spacing between the quartiles indicates the degree of
with other publications, where overestimations of about 50%
dispersion, which is rather high at 5.5 according to a
were common [6–8].
median 8. Skewness demonstrated no statistical
In all three pictures the computer-aided assessed value was
significance. The horizontal line represents the computer
below the lower quartile. Consequently, more than 75 percent
aided value of 3.6%TBSA. The computer-aided value was
of the participants estimated higher values than the comput-
significantly lower than the 25th quartile of the
er-aided method in all pictures. This corresponds to an
distribution.
overestimation of 77% up to 161% compared to the comput-
er-aided method. The overestimation depended on the

Table 1 – Results of patient 1 (2 years-of-age, male, 12 kg, 87 cm) from the national (column 1, DAV) and the international
(column 2, EBA) conference. The third column represents statistical values for all 102 datasets. The fourth column
demonstrating the computer aided determined value. The bottom two lines demarcate the overestimation as compared to
the computer aided determined value.

Table 2 – Results of patient 2 (35 years-of-age, male, 80 kg, 182 cm) from the national (column 1, DAV) and the
international (column 2, EBA) conference. The third column represents statistical values for all 102 datasets. The fourth
column demonstrates the computer-aided determined value. The bottom two lines demarcate the overestimation as
compared to the computer-aided value.
 burns 39 (2013) 1107–1113 1111

Table 3 – Results of patient 3 (4 years-of-age, female, 16 kg, 102 cm)from the national (column 1, DAV) and the
international (column 2, EBA) conference. The third column represents statistical values for all 102 datasets. The fourth
column demonstrates the computer-aided determined value. The bottom two lines demarcate the overestimation as
compared to the computer-aided value.

arrangement, and extent of surface areas. For example, a The software ‘‘Burn Case 3D’’ has been developed with
maximum estimation error of 161%meant that an area of burn surgeons since 2001 and is in clinical use since 8 years.
actual 10% TBSA could be (over-)estimated and fixed at 26.1% During this time plenty of proofs with marked areas on
TBSA. volunteers have been performed (unpublished data). As
described by Dirnberger et al. [10] the standard model is
adapted to height and weight of the real patient. The standard
model consists of more than 100,000 triangles, which have a
close relation to the actual patient’s body surface area. The
concerned area (=burned area) is the sum of the surface areas
of all marked triangles. Since the sum of all triangles equals
100%, the marked area as percentage of total body surface area
is from a mathematical point of view absolutely provable,
which was the ratio for its use in the first place. Moreover, the
verifications with 3D scans of actual persons is currently on
the way.
The computer-aided system is based on standard models
determined by gender, age and body shape. For reasons of
standardization, the surface area is calculated in the same
body posture per time-point. Therefore, changes in posture of
the picture (e.g. flexing of elbows) will result in a minor bias in
the computer model. Well keeping in mind, that in relation to
Illustration 6 – Boxplot showing the disposition of the currently observed inaccuracies and differences by
estimated burn extent in %TBSA for patient 1 on EBA. The currently applied subjective estimation methods, this error
burn extent estimations ranged from 2.5 to 25. The is rather small by comparison in the computer-based model.
spacing between the quartiles indicates the degree of Overall, using a computer-based model nonetheless results in
dispersion, which is rather high at 4.5 according to a an improved accuracy and comparability of burn surface
median of 7. Skewness demonstrated no statistical estimations.
significance. The horizontal line represents the computer On the one hand, due to inadequate superimposition of the
aided value of 3.6%TBSA. The computer-aided value was model and strong distortion of the two-dimensional photo on
significantly lower than the 25th quartile of the the edges of the patients, a minor error needs to be considered.
distribution. On the other hand, some senior surgeons estimated the same
%TBSA as the computer-aided method. We would like to
18 hypothesize that using a computer-aided system could help to
16 compensate estimation errors and most certainly it could assist
14 in improving initial assessments by the less experienced.
12 Resident
10 In the future, we plan to compare the computer-aided system
8 Specialist evaluations to real 3D scans of patients in order to improve
6
4
Nursing staff system accuracy. A mobile version of the computer-aided
2 system is already available and will be tested for telemedicine
mean (DAV) applications in the first-aid/responder sector by paramedics.
With the refinement of software-based calculations still on
Illustration 7 – Variation of burn extent estimations of the way, we do not suggest that the computer-aided method
patient 1 in percent by professional group at national DAV can be regarded as a ‘‘gold standard’’. The question we would
conference (mean W SD). like to raise is whether – in the age of evidence-based medicine
1112 burns 39 (2013) 1107–1113

18 relation to the combined mean value. In comparison to a

16
14 computer-aided method, we found overestimations of
12 Resident %TBSA of up to 161%. Computer-aided systems provide a
10
8 Specialist high potential to improve objectivity and quality of burn
6 Nursing staff assessments in the future, which could ultimately serve as a
4 common data basis for scientific comparisons across
2
various centers and countries. If computer-aided models
mean (EBA) were to be used universally, it does not mean to abandon
our previously used predictive models, but to have at least a
Illustration 8 – Variation of burn extent estimations of
chance to improve them.
patient 1 in percent by professional group at international
EBA conference (mean W SD).
Conflict of interest statement

– we require a more precise and objective way to determine I certify that there is no conflict of interest with any financial
and compare burn surface areas? organization regarding the material discussed in the manu-
The analysis of commonly used surface estimation script.
methods showed up exceptionally high deviations in contrast
to a computer-aided method. If this new technology was to be
used universally, this would raise the question, whether our Acknowledgements
actually used scores like mortality rates, ABSI are still
coherent? It is clearly stated in the literature that all common We would like to thank all participants of the conferences ‘‘28.
manual surface estimation methods do have errors [11–13]. Jahrestagung der deutschsprachigen Arbeitsgemeinschaft für
During the establishment of existing methods plenty of those Verbrennungsbehandlung (DAV) 2010’’ and ‘‘14th European
errors have been incorporated and compensated. This raises Burns Association Congress (EBA) 2011’’ for their voluntary
another question, whether it is good practice to know that we participation in our survey.
are doing things wrong and concomitantly correcting them?
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