The effect of environmental temperature on the metabolism and nutrition of burned patients.

The nutrition of patients with extensive burns usually requires daily intakes of fats, proteins and carbohydrates with a total calorific value in excess of 4000 kcal together with supranormal amounts of water and various ions, mainly sodium. These calorie requirements by a patient confined to bed are approximately those required by a normal adult male performing hard manual work. Recognition of the reasons for these large calorie requirements arose from the studies of Caldwell, Osterholm, Sower & Moyer (1959) with burned rats, who showed that these animals had a high rate of evaporation of water from the surface of the burned area. As the evaporation of water is an energy-consuming process, requiring j80 kcal/l, a burned patient losing 86 ml of water/h by evaporation from the burned surface requires 1200 kcal of energyld for this process alone. Precise measurements of the rate of evaporation of water from the burned surface have been made by Harrison, Moncrief, Duckett & Mason (1964), Roe & Kinney (1964), Barr, Birke, Liljedahl & Plantin (1968) and Zawacki, Spitzer, Mason & Johns (1970) using scales with a sensitivity of about 2 g. A change in body-weight over a period of 30 min indicated the total water loss from the body. I n patients with burns of moderate severity between one-quarter and one-third of this water loss is from the lungs, the remainder from the burned area. In patients with very extensive burns the respiratory loss of water is only a small proportion of the total loss. Average values for the rate of water loss by evaporation from numerous burned patients with burns of different severity are shown in Table I. The energy requirements for this evaporation of water are also shown and may be compared with the evaporative water loss in a normal person (mainly via the respiratory tract) and the energy production by a normal 70 kg male in the basal and moderately active states. At the time of these increased requirements for calories for the evaporation of water, the patients showed substantially increased metabolic rates (see Davies & Liljedahl, 1971). In patients with burns of about 25y0 of the body surface the metabolic rate was about 50% above normal during the first 2 weeks after burning