Hand burns surface area: A rule of thumb.

INTRODUCTION: Rapid estimation of acute hand burns is important for communication, standardisation of assessment, rehabilitation and research. Use of an individual's own thumbprint area as a fraction of their total hand surface area was evaluated to assess potential utility in hand burn evaluation.

MATERIALS AND METHODS: Ten health professionals used an ink-covered dominant thumb pulp to cover the surfaces of their own non-dominant hand using the contralateral thumb. Thumbprints were assessed on the web spaces, sides of digits and dorsum and palm beyond the distal wrist crease. Hand surface area was estimated using the Banerjee and Sen method, and thumbprint ellipse area calculated to assess correlation.

RESULTS: Mean estimated total hand surface area was 390.0cm2 ±SD 51.5 (328.3-469.0), mean thumbprint ellipse area was 5.5cm2 ±SD 1.3 (3.7-8.4), and mean estimated print number was 73.5±SD 11.0 (range 53.1-87.8, 95% CI 6.8). The mean observed number of thumbprints on one hand was 80.1±SD 5.9 (range 70.0-88.0, 95% CI 3.7), χ2 =0.009. The combined mean of digital prints was 42, comprising a mean of two prints each on volar, dorsal, radial and ulnar digit surfaces, except volar middle and ring (3 prints each). Palmar prints were 15 (11-19), dorsal 15 (11-19), ulnar palm border 3, first web space 2, and second, third and fourth web spaces one each. Using the surface of the palm alone, excluding digits, as 0.5% of total body surface area, the area of one thumbprint was approximated as 1/30th of 1%.

CONCLUSIONS: We have demonstrated how thumbprint area serves as a simple method for evaluating hand burn surface area.