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Three Part Question

In a [patient with a burn] is there one [method of assessment of size] that is most [accurate to assess surface area of the wound]?

Clinical Scenario

A 30 year-old female is brought to the emergency department with extensive burns after having been trapped in a burning car. After initial resuscitation of the patient you attempt to assess the surface area of skin affected by the burn in order to guide the volume of fluid required for resuscitation. You wonder which method of surface area assessment is the best tool for assessing the surface area of her burns.

Search Strategy

Medline using the OVID interface 1966-May 2009.
EMBASE 1980-week 22 2009.
Google scholar.
References
Medline search:[burn$.mp OR exp Burns OR heat injur$.mp OR thermal injur$.mp OR scald.mp] AND [assess$.mp OR estimat$.mp OR size.mp OR exp Body Surface Area/ or surface area.mp OR SA.mp OR BSA.mp OR TBSA.mp OR Lund Browder.mp OR rule of nines.mp OR serial halving.mp] LIMIT to clinical trial, all and English language and humans.

EMBASE search: [exp Burn/ OR burn$.mp. OR scald.mp. OR exp Scald/ OR heat injur$.mp. OR thermal injur$.mp.] AND [[assess$.mp. OR estimat$.mp. OR measur$.mp.] AND [size.mp. OR body surface area.mp. OR exp Body Surface/ OR tbsa.mp. OR bsa.mp. OR sa.mp.]] OR [exp Diagnostic Accuracy/ OR exp Measurement/ OR lund browder.mp. OR rule of nines.mp. OR serial halving.mp.]LIMIT to human and english language and "diagnosis (sensitivity)".
Google scholar searched for first three pages of results using each of the terms, "Lund and Browder", "rule of nines", "serial halving" and "burns assessment"

Search Outcome

1518 papers were found on the Medline search, of which 1 was relevant.
727 papers were found on the EMBASE search, 2 were relevant, 1 one was unique.
3 papers were found using Google scholar, 1 of which was already in the EMBASE search result.
1 further relevant paper was found from the references of papers used. 5 papers were therefore available and are summarised in the table below:

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Wachtel TL et al, 2000, USA	24 members of staff from the unit, with a variety of backgrounds,Burn area chart drawings of 26 different patients admitted to one burns unit were redrawn by an artist. Ten of the pictures were selected at random. The drawings were duplicated on 6 different forms - 1 was the original Lund and Browder chart, 3 were modified Lund and Browder charts and two represented the Rule of Nines. Planimeter was used to determine accurate % of each area of burn on each drawing.	Experimental	Variability of estimates for burn assessment methods. Planimeter was used to determine accurate % of each area of burn on each drawing.	The Lund and Browder charts were less variable than the 'rule of nines' charts. Differences were calculated with paired t-tests and were statistically significant with a p<0.05.	The staff would have been more familiar with the Lund and Browder chart as this is usually used on the burns unit. Fails to assess the accuracy of translating burns on a patient into a two-dimensional representation on a chart.
			Time taken for surface area estimation.	The 'Rule of Nines' charts take a shorter time to complete.
Knaysi G et al, 1968, USA	Three volunteers were made up to simulate patients with burns and four doctors estimated the size of the 'burns' using the 'rule of nines'. The gold standard size was measured by wrapping cling film around the patient then applying masking tape to the affected area. The wrap and tape were then removed and the surface area measured using a planimeter.	Experimental	Volunteer A percentage SA	Measured - 28.3%. Mean estimate 29.8%, range 25-36%.	Very small numbers. Not real patients.
			Volunteer B percentage SA	Measured - 11.9%. Mean estimate 18.8%, range 17-22%
			Volunteer B percentage SA	Measured - 30.9%. Mean estimated 33.5%, range 27-38%.
Nichter L, Williams J, Bryant C, Edlich R 1985 USA	30 physicians with a variety of experience in dealing with patients with burns. A slide was shown of a volunteer made up to simulate burns over his anterior surface. The physicians documented the burns onto a Lund and Browder chart and then estimated the size using the 'rule of nines'. The gold standard was measured using computer program where data was inputted by tracing over a special pad.	Experimental	Estimated burn size	Mean 21.1% +/- 6.4%	Only one subject used. Model is likely to perform poorly on circumferential burns. Surface area of the regions of Lund and Browder charts do not correspond exactly with the percentage surface attributed to them if measured with a planimeter.
			Documented burn size on chart	Mean 12.1% +/- 1.5%
			Burn size estimated by computer	1375 sq.cm, 10.8%
			Burn size measured by cut-out	1387 sq.cm.
Nichter L et al, 1985, USA	27 physicians with a variable amount of experience in managing patients with burns. The physicians had to review a completed Lund and Browder chart and estimate the size of burn represented. This drawing also had the surface area measured using a computer with data entry via a graphic pad.	Experimental	Physician estimate vs. computer measurement	Mean of 42% vs. measurement of 29.6%.	Small study with only one chart compared.
Smith J et al, 2005, UK	125 members of local emergency services and military paramedical staff. All attended training in using either 'rule of nines' or serial halving as a method of assessing burn size. They then had one minute to assess the burn size of each of 10 volunteers who had been made up to simulate burns affecting from 6-61% of their surface area using the technique that they had been shown. The gold standard was formed by the consensus of a group of seven experts.	Educational Intervention	Difference between outcomes in management of patients in terms of requiring intravenous fluid or not.	Good correlation with the expert consensus and no significant difference in outcome demonstrated between the assessment techniques.	Data very poorly presented in a series of small tables. Due to the difficulty of comparing the an exact percentage from the 'rule of nines' with a more approximate 'less than 50%' or 'less than 25%' from the serial halving technique the authors have discarded most of the data available and simplified it whether the patient would receive intravenous fluids or not. A cut-off of 25% total surface area was used.

Comment(s)

Estimating the size of burns can be difficult to do well. The percentage of total surface area affected is an important figure as it has bearing on whether or not the patient should be referred to a specialist Burns Centre for management. It is also used to decide if patients require intravenous fluids and in formulae to calculate the requirements for fluid resuscitation. It is relatively difficult to measure the surface area of an irregularly shaped three dimensional object at any time and pretty much impossible in an acute situation with an unwell patient. It may also be difficult to differentiate simple erythema from partial thickness burns in the immediate presentation. There are four main methods of estimating the percentage of a patients body surface area that is involved in a burn: Lund and Browder charts form a fairly detailed diagram with percentage surface areas of different parts of the body, dependent on age, that can be combined for a total figure(1); the Rule of Nines chart splits the body into 11 areas of 9% and the perineum makes up the final 1%(3); serial halving invoves dividing the surface area of the patient into areas of 50% and deciding if the burn covers more or less than this area. This process is continued for a further two times if necessary to get an approximate value of the percentage surface area affected; for smaller areas the palmar surface of the patient's hand is taken to represent 1% of their total body surface area and used to aid estimation. There have also been a couple of studies using computers to calculate the surface area affected from an image of the patient. Although there are several papers comparing different groups of physicians estimates for percentage areas of burns there were only a few papers, found in this search, directly comparing the different methods used. Due to the impracticality of having several physicians independently assess a real patient with burns, various alternatives were used. Various gold standards were used, the best of which involved measuring the surface area of the burn, although event these studies used formulae to calculate the overall surface area rather than measuring it directly. The literature suggested that there was significantly less variation in the estimates made using the Lund and Browder chart from the schematic burns than using the Rule of Nines technique, although the variation remained substantial. There also appeared to be less variation and greater accuracy in documenting the size of the burns graphically than in converting this to a percentage surface area. The 'rule of nines' technique appears to be quicker to use and does not require a special chart as long as the physician can recall the attributed surface areas percentages. Serial halving provides a very approximate result which can be used quickly in the field to establish whether or not intravenous access is required with reasonable consistency. Once a burn has been mapped to a two-dimensional diagram then a computer or planimeter can accurately calculate the percentage surface area affected. Interestingly, when this technique is used to measures the surface areas of the different regions on a blank Lund and Browder chart, they do not correspond with the values that they are purported to represent. This intrinsic error means that there is a limit to how accurately the chart could ever be interpreted. It is not difficult to imagine a computer program than could provide a manipulatable three-dimensional figure on screen that could be drawn onto and provide an estimate of percentage burn size based on the height, weight and age of the patient. This may improve the accuracy and consistency of estimates but would require access to the computer and software and may still leave problems of documentation in the medical notes and communication with other hospitals. The question that leads on from this discussion is whether more accurate assessment of burn size would actually result in an clinical benefit for patients or whether an rough estimate and then titration of treatment according to response is as good.

Clinical Bottom Line

The Lund and Browder chart allows more consistent estimates of percentage surface area from drawings of burns than the Rule of Nines. No evidence was found of a benefit of one form of estimation over another in clinical practice.

Level of Evidence

Level 3 - Small numbers of small studies or great heterogeneity or very different population.

References

1. Wachtel TL. Berry CC. Wachtel EE. Frank HA. The inter-rater reliability of estimating the size of burns from various burn area chart drawings. Burns (2000)p156-170.
2. Lund CC, Browder NC The estimation of areas of burns Surg Gynecol Obstet 1944; 79: 352-8
3. Sakson, JA A simplified chart for estimating burn areas Am J Surg 1959; 98: 693-4
4. Knaysi G, Crikelair G, Cosman B. The Rule of Nines: Its History and Accuracy. Plastic & Reconstructive Surgery 1968; 41 (6): 560-3.
5. Nichter L, Williams J, Bryant C, Edlich R. Improving the Accuracy of Burn-Surface Estimation. Plastic & Reconstructive Surgery 1985; 76 (3): 428-32.
6. Nichter L, Bryant C, Edlich R. Efficacy of Burned Surface Area Estimates Calculated From Charts - The Need for a Computer-based Model. The Journal of Trauma 1985; 25 (6) 477-81.
7. Smith J, Maylon A, Scerri G, Burge T. A comparison of serial halving and the rule of nines as a pre-hospital assessment tool in burns. British Journal of Plastic Surgery 2005; 58: 957-67.