Nutritional requirements and parenteral nutrition

Abstract

ENERGY REQUIREMENTS In the context of this discussion it is appropriate to think of a big burn, one of between 30 and 60 per cent of body surface area, where there are likely to be quite extensive areas of full-thickness involvement. In burns of this severity, metabolic rate changes have an important impact on the outcome. Clearly, similar changes occur with smaller burns, but these are of a different order of magnitude and therefore proportionately less important. In a big burn, the metabolic response to injury, already the subject of so much discussion in theliterature, the effect of integumentary damage leading to energy loss from evaporative cooling of water and the not infrequent occurrence of infection leading to fever all contribute to an increase in energy expenditure. The net result is an increase in metabolic rate which will vary with the extent of burn, the stage of the reparative process and the environmental conditions in which the patient is placed (Barr et al., 1968). In terms of energy cost this may amount to much more than 5000 calories per day in an adult weighing 65 kg or more and burned over an area greater than 40 per cent of his body surface (Wilmore, 1972). Comparative figures for the energy requirements in burns are shown in Table I. In normal health there is ample information about the energy expenditure of people in different activities and there is no doubt about how many calories are required in different circumstances to maintain balance. It is more difficult to define protein needs in health. The answer must lie somewhere between the excessive consumption of animal protein found in the affluent industrialized nations and the often extremely poor intake in people in many of the emerging nations. Monroe, who has contributed so much to our knowledge