Wirkungen einer Kohlenhydratkombinationslösung auf den Stoffwechsel bei hochdosierter Kurzzeitinfusion

[Comparison of side effects of infusion of glucose and glucose substitutes at different doses]

Glucose, fructose, sorbitol or xylitol were infused for four hours at different dose levels to metabolically healthy volunteers. The metabolic effects of the so-called glucose substitutes were compared to that of glucose. Even at very high doses (2.0 g/kg bodyweight per hour) of infusion of glucose or fructose a steady state was attained. This, however, was not the case with xylitol or sorbitol at lower doses (i.e. 0.5 g/kg bodyweight per hour), where no steady state was reached. The blood glucose concentration is not influenced by any of the glucose substitutes. During infusion of very high doses of fructose a small increase in serum insulin level is found, however, without any alteration in blood glucose concentration. Glucose as well as glucose substitutes cause an immediate suppression of free fatty acid concentrations in serum. In case of glucose there is a manifold increase in fatty acid concentration after the infusion is terminated. On the other hand, the free fatty acid concentration remains low even several hours following termination of the high-dosed fructose infusion. Theoretically one would expect an increase in triglyceride concentration, at least at the high dosed carbohydrate infusions. In contrast to this theoretical expectation, in the case of glucose and of xylitol a significant reduction of triglyceride concentration in serum was observed. Fructose and sorbitol did not exhibit this effect. Glucose and fructose are well utilized in metabolically healthy subjects. The maximum turnover rates for both polyols are lower. Unlike glucose, the glucose substitutes obviously do not cause any serious disturbation in hormonal regulations. Only in the case of glucose, counterregulation is seen following the termination of the infusion.

[Effect of maltose, following long-term intravenous infusion, on the metabolism]

6 healthy subjects received a 20% electrolyte containing maltose solution over a period of 6 hours. The concentration of maltose rose up to 109 (76-215 mg/100 ml). During the infusion period 3,7 (1,9-7,7) g maltose were excreted. The concentration of glucose and insulin was not altered, although the renal glucose loss was 20,2 (7,5-38,7) g. In the same period 49,8 +/- 13,2 mval potassium and 135,4 +/- 35 mval sodium were eliminated. Maltose induced an osmotic diuresis which was not caused by hyperglycemia. Such a type of osmotic substance has not been described before.

[Changes in serum electrolyte concentration and electrolyte excretion induced through infusion of glucose or glucose-exchange substances]

The metabolic effects of intravenous infusion of glucose, fructose, sorbitol or xylitol were investigated using human volunteers. The infusion period was 4 hours or 48 hours. Serum phosphate concentration decreased quickly and independent on the kind of the carbohydrate used. On the other hand, the serum concentration of potassium or sodium did not show any greater deviations from normal. Considering the renal excretion, greater differences between the single substances were seen. Renal potassium excretion was increased especially during xylitol infusions, and not as much during sorbitol infusions, as compared to infusions with glucose or with fructose. These differences were demonstrated especially for the first 12 hours of the infusions periond. During the infusions of glucose or of fructose an oral substitution of the electrolytes was suggicient. However, during xylitol infusions an intravenous substitution of potassium salts was necessary, despite the fact that the changes in serum concentration were only small. It is emphasized to carefully monitor serum electrolyte concentration and renal electrolyte excretion during long lasting intravenous infusions therapy.

Suitability of non-glucose-carbohydrates for parenteral nutrition

Postoperative parenteral nutrition can only be optimally effective if the characteristics of post-traumatic metabolism are taken into account. Two main possibilities are discussed for the carbohydrate component of parenteral nutrition during this phase: glucose with high doses of insulin or non-glucose carbohydrates (sugar substitutes) possibly in a suitable combination with glucose. The risks as well as the technical and organisational problems involved in the use of them are discussed and the authors prefer the second of the two alternatives. Possible side effects of non-glucose carbohydrates are pointed out and it is shown how these can be avoided by observing dose guidelines. So far a combination of frucose : glucose : xylitol in a ratio of 2 : 1 :1 with a total dose of 0.50 g/kg/hour has been studied most thoroughly. This combination normalises the fat metabolism and improves glucose tolerance without requiring exogenous insulin. Experiences with this combination as well as individual non-glucose carbohydrates on operated patients have been given continuously for up to 7 days and in some cases even for several weeks. No side effects, no deviations from a steady state and no abnormal changes of the laboratory values occurred. The authors are of the opinion that non glucose carbohydrates are necessary if the facilities for frequent blood sugar controls are not available.

[Metabolic effect of a carbohydrate combination during simultaneous amino acid infusion]

During a period of 12 hours, eight normal subjects were infused with an electrolyte containing combined 24% carbohydrate solution of fructose, glucose, and xylitol at a ratio of 2:1:1 (Triofusin E 1000 Pfrimmer) with a rate of supply of 0.6 gm/kg/h. Lamino acids (Aminofusin L 10% carbohydrate-free Pfrimmer) were simultaneously administered at a rate of 0.1 gm/kg/h. The serum substrate concentrations of fructose, glucose and xylitol and their excretion were measured. The utilization of fructose was 99%, of glucose practically 100% and of xylitol 88%. In accordance with the slight glucose increase, the concentration of insulin also showed an only slight increase. An increased serum concentration of oxalate was not observed. Despite the infusion of a glycine containing amino acid mixture, the excretion of oxalic acid even decreased during the infusion. The dilution effect measured by means of hematocrit, hemoglobin, erythrocyte count, total protein, and albumin was between 2 and 5%. The lactate concentration did not change significantly whereas hydroxy butyrate decreased significantly by the end of the infusion indicating the antiketogenic effect. A disturbance of fat metabolism was not observed as was indicated by the concentrations of neutral fat and cholesterol. The decrease of free glycerol cannot be clearly explained. A highly significant reduction of the serum uric acid concentration resulted from an increased renal elimination. The electrolyte concentrations of potassium, sodium, calcium and phosphate showed only slight modifications. The concentration of potassium initially rose significantly within normal ranges. Sodium and chloride remained constant whereas calcium decreased slightly but not significantly and phosphate decreased significantly until the 12th hour. The serum transaminase and bilirubin concentrations did not show any change. During the permanent infusion, a respiratory alkalosis developed. The average urinary excretion was 134 ml per hour, the excretion of potassium was 6 mEq/h, of sodium 15 mEq/h, and of phosphate 27 mg/h. The utilazation of a combined carbohydrate solution was in the same range with or without the simultaneous application of amino acids. The reduction of the uric acid concentration and the absent increase of lactate, bilirubin and oxalate may be considered as an additional desirable effect of the simultaneous application of amino acids.