Clinical use of total nutritional admixtures

The administration of a single mixture of the components of total parenteral nutrition (TPN) constitutes total nutritional admixture (TNA), the safety and efficacy of which in a variety of clinical settings have been confirmed by controlled trials. According to the nitrogen balance and stable isotope methods, TNA is as efficacious as the old system of three bottles with piggyback intravenous fat emulsion in maintaining body nitrogen mass, visceral protein, and liver function. Also, serum concentrations of electrolytes, trace elements, and vitamins can be maintained adequately using the TNA system. The other advantages are the timesaving to the nursing staff, with its hidden savings in cost; the avoidance of a peripheral catheter solely for the infusion of lipid emulsion in addition to the central catheter for TPN in hospitalized patients; and the facility of use in home nutrition programs. The ease of home use has resulted in a greater degree of patient compliance; thus patients receive a mixed-fuel system while avoiding the hazards of a piggyback infusion, with all its potential complications. Among the perceived disadvantages of TNA are a supposed higher frequency of catheter-related sepsis, a view based on in vitro studies that is not borne out by in vivo studies; catheter occlusion by precipitation of calcium salts; and enhanced ability to clear fat and thus fat tolerance with continuous infusion of lipids. Numerous studies have shown that these concerns are unwarranted.