burn area

The proportionate area of skin burned has been used as a guide to burn wound prognosis for a long time, but it was Charles Lund and Newton Browder who attempted to provide a practical means of estimating the total body surface area affected by a burn wound, with particular attention being paid to the effects of variable proportions of body parts with age.

In particular, children have smaller extremities, but larger heads than adults. A series of charts was produced (Lund and Browder 1944 pp. 356-357), and have been in use ever since.

Lund and Browder chart to assess burn area

Source: NHS Clinical Knowledge Summary

A simple method of estimating body surface area affected is used in triage – the rule of nines or the reliance on the use of the patient’s palmar surface area being roughly equivalent to 1% of his/ her body surface area.

Newer tools have been developed to assist clinicians map out burn area, such as the use of 3-D body mapping software (Easton 1997).

Estimates of burn area exclude areas of erythema (Wardrope 1992 p.191) and areas exceeding 20% of the total body surface area in adults are classed as ‘major burn injuries’ – those over 10% are considered serious enough to be appropriately managed in regional burns units (McClance and Huether 2002 pp. 1501-1503).

A study (Wachtel et al 2000) investigating the inter-rater variability of the estimation of burn area found that;

• the 'rule of nines' over-estimates burn size but is a rapid means of assessing burns
• greater variability existed when evaluating 'irregularly shaped' burns; those on the trunk and on the thighs (compared to burns on more defined anatomical areas)
• variability in estimation increased with burn size, but plateaued in large burns, before decreasing with 'extensive' burns

references

• Easton J. (1997), ‘3-D computer display brings precision to burn assessment’, University of Chicago Hospitals (www.uchospitals.edu/news/1997/19971012-burn-chart.html)
• Lund C.C., Browder N.C. (1944), ‘The estimation of areas of burns’, Surgery, Gynaecology, Obstetrics 79:352-358
• McClance K.L., Huether S.E. (2002), ‘Pathophysiology. The biologic basis for disease in adults and children’, 4th Ed Mosby Inc.
• Wardrope J., Smith J.A.R. (1992), ‘The management of Wounds and Burns’, Oxford University Press 
• Wachtel TL, Berry CC, Wachtel EE, Frank HA (2000), 'The inter-rater reliability of estimating the size of burns from various burn area chart drawings', Burns 26:156-170