Total parenteral nutrition: practical recommendations and new developments

In this article the general guidelines for a nutrition schedule and new developments in the field of parenteral nutrition are discussed. The present possibilities for parenteral nutrition do not imitate the normal physiologic diet completely. The most frequently used calculation of the energy expenditure is estimated by a formula using weight, height, and age and was developed in healthy persons. It does not always represent the real caloric demands of a patient. Complications, partly due to parenteral nutrition, are noted. In severely ill patients hyperglycaemia and liver function disorders are frequently observed. Parenteral nutrition results in atrophy of the intestinal mucosa. Deficiencies in trace elements and vitamins are diagnosed despite calculated adequate nutritional support because the demands are underestimated. New developments in parenteral nutrition include a better method to determine the nutritional demands in clinical practice, administration of hormones to improve the nitrogen balance, and development of new lipid emulsions and amino-acid solutions. Studies provide more insight into the physiologic process of trace element metabolism, and methods are being developed to define a real deficiency.