A patient loses much fluid into tissues which have been burnt, but not actually killed—most of it is lost during the first 8 hours. He loses more fluid this way than by evaporation from the surface of his burns, or into blisters. The loss of this fluid sends him into shock and raises his haematocrit. At the same time he also loses water and electrolytes in his urine, and water through his lungs and his normal skin. Treat him by replacing all this fluid.
Severe injuries, as from a road accident, for example, cause shock immediately, but the shock following a burn develops more slowly. Half an hour after a severe burn a patient may look suprisingly well, but four hours later he will be deeply shocked. Try to prevent this and resuscitate him before he becomes shocked. If you delay, he may die.
A burn of over 15% in an adult, or 10% in a child, causes shock. Burns of this severity always need a drip, lesser ones may do, especially in children. Besides childhood, old age, malnutrition, and anaemia can also reduce a patient’s ability to withstand a burn and increase his liability to shock.
Many formulae are used. Although some centres use plasma and colloids, there is no evidence that a patient does better. They are expensive, so only crystalloids are described here. Give an adult 1 ml offluid for each 1% of his body burnt, for each kilo of his weight. Thus a 60-kg man with a 20% burn needs 60120 = 1,200 ml of fluid. Give a child under six years twice as much. Give him 2 ml offluid for each 1% of his body surface burnt for each kilo of his weight. Thus a 6-kg child with a 20% burn needs 6220 = 240 ml of fluid. Both adults and children need these volumes of fluid once in the first eight hours following the burn, once in the next 16 hours, and once again in the following 24 hours.
This formula is designed for use with Ringer’s lactate or 0.9% saline, or if necessary Darrow’s solution, and is more generous than those designed for use with colloids.
After 48 hours you can usually take a patient’s drip down, but only provided that his urine output is satisfactory and he is drinking well. There is a danger of overhydration if fluids are continued unnecessarily after 48 hours.
Calculate a patient’s fluid needs from the time of the burn, not from the time of admission. If admission is delayed, you will need to give the fluid correspondingly faster (58.8).
The formula above accounts only for the fluid loss from the burn itself, and not for a patient’s ordinary daily fluid requirements (metabolic water needs), which vary with h is size and the ambient temperature and are given in Scale E Fig. 58-6. So give him this volume of fluid in addition to the fluid you give him to treat the shock his burns have caused. Give him his daily fluid requirements (metabolic water needs) as 5% dextrose intravenously, or as water by mouth, as in the next section.