Assessment of the burn area
An approximate clinical rule in wide use is the ‘rule of nines’ which acts as a rough guide to body surface area. The examining doctor should assess the total area involved and how much of the area is partial thickness and how much full thickness. As a general rule, an adult with more than 20 per cent of the body surface involved or a child with more than 10 per cent of body surface area involved will require intravenous fluid replacement. However, an intravenous access line may be necessary for adequate analgesia for much smaller areas of burn and many children in particular will require fluid replacement because of vomiting. For smaller percentages than the above, it is necessary to maintain an adequate oral intake of fluid. The prognosis depends upon the percentage body surface area burned. A rough guide is that if the age and percentage add together to a score of 100 then the burn is likely to be fatal. A child may therefore survive a large burn, but even a small burn in an elderly patient is potentially fatal.
Intravenous access in a burnt child may be difficult. Both rectal and intraosseous infusion (into the upper third of the tibia) offer useful alternatives.