Posttraumatic hypocaloric parenteral nutrition--development and clinical application

The use of hypocaloric parenteral nutrition (HPN) is very common in surgical medicine because it allows for a standardized peripheral venous supply of nutrients. HPN causes very little stress to the posttraumatically labile carbohydrate metabolism-this applies to the use of glucose as well as to sugar substitutes: For example, mean glucose concentrations in serum on glucose administration of 2-3 g/kg/day are between 5.5 and 8.4 mmol/l. The mean dose of amino acids of 1.0-1.2 g/kg/day commonly used in HPN leads to a 50-67% improvement in the N-balance compared to an exclusive water/electrolyte supply or the administration of 2 g of carbohydrates per kg and day. Even a high caloric nutritional therapy leads to no significantly improved N-balances on the first posttraumatic days. HPN is recommended after major surgery and severe trauma in order to better estimate the individual metabolic reaction to nutritional supply prior to any consumption-orientated parenteral nutrition. HPN is also important as an adjunct to early-phase enteral nutrition. Its value after moderate surgical interventions is questionable because studies have yet to confirm HPN's clinical efficacy. HPN should not be used after minor surgery or brief periods of fasting. A possible, but as yet uncertified indication for HPN is the longer-term nutrition of very obese patients.