Elemental balances during intravenous hyperalimentation of underweight adult subjects

The main determinants of nitrogen balance during total parenteral nutrition in critically ill injured patients

Factors influencing nitrogen balance during total parenteral nutrition have been investigated in 34 critically ill injured patients studied during the first 6 days after trauma. Basal nitrogen balance was severely negative (-0.26 +/- 0.12 (SD) g X kg-1), but improved consistently during treatment. Nitrogen intake proved to be the major determinant of a positive, or less negative, nitrogen balance, only secondarily followed by total energy intake corrected to predicted basal energy expenditure, according to multiple regression analysis. The amount of non-protein calories and the non-protein calorie to nitrogen ratio appeared to have little significance on nitrogen balance, when corrected for the two former variables.

Short-term clinical, nutritional, and functional effects of continuous elemental enteral alimentation in children with cystic fibrosis

Ten children with cystic fibrosis, aged 3.5 to 12 years, whose weights were lower than 90% of the expected weight for height, received high-calorie elemental enteral alimentation for four weeks. Clinical, anthropometric, and biochemical evaluations as well as blood gas analyses and chest radiograph scoring were performed in all. Pulmonary function tests were performed in the five older children, and progressive exercise tests in three. These evaluations were done before, immediately after, and two months after termination of therapy. Nutritional therapy resulted in an increase of caloric intake and in dramatic weight gain, which persisted only for a short time and was mainly related to adipose tissue accretion. No functional improvement accompanied the amelioration in nutritional status. This short-term nutritional therapy in malnourished children with cystic fibrosis was effective in increasing relative weight and energy stores, but there was no evidence of any long-term functional benefit.

Energy and protein requirements of general surgical patients requiring intravenous nutrition

General surgical patients require intravenous nutrition either because their gastrointestinal tract is blocked, too short or inflamed or because it cannot cope. Such patients can be grouped into four nutritional/metabolic categories: normal and unstressed; normal and stressed; depleted and unstressed; depleted and stressed. The energy requirements of patients in each of these groups vary according to their energy expenditure. Normally nourished and stressed patients have the highest energy expenditure and therefore require the highest energy input (45-55 kcal.kg-1day-1). Other groups of patients rarely require more than 40 kcal.kg-1day-1. Energy can be given mainly as dextrose although calories needed above 40 kcal kg-1day-1 should be given as fat (unless lipogenesis is desirable). In very stressed patients high rates of glucose infusion can themselves constitute a metabolic stress and fat may play a bigger role as a calorie source. For long term feeding, 1 litre of 10 per cent fat emulsion should be given weekly to avoid essential fatty acid deficiency. The level of nitrogen intake required to maintain a positive nitrogen balance is a lot higher in surgical patients than the suggested recommended dietary allowances for normal subjects. It is dependent not only on the nutritional and clinical state of the patient but also on the levels of energy and nitrogen intake given. When energy intake is below energy needs, normally nourished patients cannot retain nitrogen, although depleted patients can. When energy intake exceeds energy needs, both normally nourished and depleted patients retain nitrogen at levels of nitrogen intake ranging from 250 mg kg-1day-1 (depleted and unstressed) to over 400 mg kg-1day-1 (stressed). Depleted patients can maintain a positive nitrogen balance at lower levels of calorie and nitrogen intake than normally nourished patients and in this respect are analogous to a growing child. In all surgical patients, energy and nitrogen intakes can be manipulated to provide for a controlled maintenance or restoration of either wet lean tissue and/or fat. There is little place for protein sparing therapy or the use of insulin and anabolic steroids to promote nitrogen retention in surgical patients requiring intravenous feeding.

Growth, metabolic response, and development in very-low-birth-weight infants fed banked human milk or enriched formula. I. Neonatal findings

Banked human milk has been widely used, although its composition and nutritional adequacy for preterm infants are uncertain. We randomized 76 healthy infants of less than or equal to 1500 gm birth weight to ad lib feedings of frozen BHM or a protein-mineral-calorie-enriched formula (Similac Special Care) designed to sustain intrauterine accretion rates; BHM contained 2.2 gm fat/100 ml and 60 kcal/100 ml (gross energy). Infants fed BHM ingested more milk (197 vs 165 ml/kg/day) but less gross energy (118 vs 143 kcal/kg/day); grew less rapidly in weight (15 vs 30 gm/day), length (0.7 vs 1.1 cm/wk), and head circumference (0.8 vs 1.2 cm/wk); and were discharged at a lower weight (2200 vs 2348 gm) and older age (61 vs 47 day) than infants fed formula (P less than 0.02). At 37 weeks' postmenstrual age, infants fed BHM were less responsive to Brazelton inanimate stimuli (mean total score 5.0 vs 7.5; P less than 0.02). With few exceptions, blood amino acids, pH, and serum electrolyte values were similar in both groups. The different caloric intake of our feeding groups may explain only part of the large difference in growth rate. Donor milk should not be fed to preterm infants unless it has been analyzed and the feedings shown to provide a nutrient intake considered appropriate to the needs of these infants.

Total parenteral nutrition with F080 in cirrhotics with subclinical encephalopathy

It has been proposed that hepatic encephalopathy and malnutrition in cirrhosis can be reversed by infusion of a protein formula (F080) enriched with branched-chain amino acids (valine, leucine, isoleucine) and containing decreased amounts of aromatic amino acids (phenylalanine, tyrosine, tryptophan). This hypothesis was tested by measuring changes in encephalopathy status, plasma ammonia, amino acid profile, and liver function during seven metabolic balance studies in three patients with cirrhosis and subclinical encephalopathy given increasing amounts (20-100 g/d) of F080. The results showed the following: 1) positive nitrogen balance was achieved only with 80 and 100 g F080/day; 2) plasma ammonia fell during negative, but increased during positive nitrogen balance; 3) plasma tyrosine and cystine fell significantly (p less than 0.05) with all intakes of F080; 4) the abnormal branched-chain to aromatic amino acid ratio was reversed; 5) extracellular volume was expanded in all patients; 6) albumin, bilirubin, prothrombin time became abnormal; and 7) encephalopathy did not significantly change from baseline. It is concluded that, in this population, F080 is an inadequate nutritional formula when given as the sole protein source because it produces hypotyrosinemia and hypocystinemia. The marked changes in the ratio of branched-chain to aromatic amino acids are not accompanied by improvement in encephalopathy.

Calcium and phosphorus metabolism during total parenteral nutrition

Calcium and phosphorus metabolism and balance were studied in 151 patients receiving total parenteral nutrition (TPN). Hypercalciuria was common, with mean (+/- SD) urinary calcium excretion 17.5 +/- 3.9 meq/24 hours (n = 2610). There was a significant positive correlation between urinary calcium excretion and parenteral calcium intake (r = 0.34, p less than 0.001). There was also a positive correlation between calcium balance and parenteral calcium intake (r = 0.61, p less than 0.001) in patients without extra-renal losses. Positive calcium balance was achieved with parenteral calcium intake greater than 15 meq/24 hours. Urinary phosphorus excretion correlated positively with parenteral phosphorus intake (r = 0.50, p less than 0.001). Phosphorous balance also correlated positively with parenteral phosphorus intake (r = 0.78, p less than 0.001). Positive phosphorus balance was achieved with parenteral phosphorus intake above 15 mmol/24 hours. Fifty-three patients received 1,000 IU vitamin D once weekly and showed no significant change in serum calcium. Ninety-eight patients received 1,000 IU vitamin D twice weekly and showed a gradual but significant mean increase over time in serum calcium.

The effects of nitrogen and energy intake on the metabolism of normal, depleted and injured man: Considerations for practical nutritional support

This article illustrates how the nutritional and metabolic effects of a range of protein and energy intakes depend on the clinical state of the patient and how these considerations may be used to provide guidelines for nutritional support. First, it is necessary to define states and mechanisms of malnutrition and then discuss the biochemical processes which underlie nutritional rehabilitation.

Nine year's survival with short bowel syndrome after occlusion of the superior mesenteric artery in an elderly man: a study of periods of parenteral nutrition

A 70-year-old man with severe short bowel syndrome after acute occlusion of the superior mesenteric artery and massive intestinal gangrene was given total and supplementary parenteral nutrition for six periods of 14 to 28 days; he survived for more than 9 years and died from the effects of nutritional depletion. Studies of the blood chemistry and the urinary excretion of nitrogen and electrolytes during the six periods of intravenous nutrition showed that nutritional repletion of nitrogen and electrolytes was achieved without adverse effects on the liver function. The results suggest that intermittent total and supplementary parenteral nutrition may allow nutritional repletion and thereby prolong the survival time in the elderly patient in whom massive intestinal resection has been performed.

Increased ureagenesis and impaired nitrogen use during infusion of a synthetic amino acid formula: a controlled trial

In a controlled trial conducted to assess the biologic value of High Nitrogen Vivonex, we compared this "elemental" diet with predigested protein--Product MJ7041--and with solid food during eight-day balance periods. Each formula was evaluated in three patients with malabsorption and one without it, by measuring apparent absorption of nitrogen and energy, nitrogen balance, and blood and urinary urea nitrogen. Overall energy and nitrogen absorption in the patients with malabsorption was better with either special diet than with solid food; net intestinal uptake of Vivonex tended to be higher but not consistently so in al patients. However, nitrogen balance differed consistently during the three diets; with solid food and MJ7041, retention of absorbed nitrogen was respectively, nine and 16 times greater than with Vivonex. Moreover, institution of each Vivonex period led to a prompt increase in urea nitrogen--a trend quickly reversed by the alternative diets. Although the mechanism for the impairment of nitrogen use caused by High Nitrogen Vivonex is unknown, its low biologic value and tendency to cause azotemia should be kept in mind.

Hyperkalemia in patients on enteral feeding

The amount of potassium (K) in proprietary enteral feeds varies considerably from 2.7-9.2 mmol K+/g N. It has been suggested that up to 7 mmol K+/g N is required by the anabolic patient. The aim of this study was to determine the effect of a proprietary feed (Triosorbon MCT), containing 6.9 mmol K+/g N, on serum and urinary K in 13 patients requiring nutritional support. Serum electrolytes in all patients and urinary electrolytes in 7 were measured both before feeding commenced and when they had achieved an intake of between 2.4 and 3.0 liter/day (102-127 mmol K+/day) of full strength feed for a period of 1 wk. Ther serum K rose in all patients from 4.2 +/- 0.5 mmol/liter (mean +/- SD) before feeding to 5.1 +/- 0.5 after feeding for 1 wk (p less than 0.001; pair-difference t-test). The daily urinary K excretion rose from 37.8 +/- 24.2 mmol/day to 61.8 +/- 26.6 over the same period (p less than 0.001) The serum urea rose from 4.7 +/- 2.0 mmol/liter to 6.3 +/- 3.2 (p less than 0.05). No significant change was observed in other serum electrolytes, creatinine, or urinary electrolytes. During the whole course of feeding (range 1-11 wk) it was necessary to discontinue Triosorbon in 2 patients whose serum K concentration became elevated to greater than 6 mmol/liter. We conclude that the recommended levels of K intake may be too high and that serum K should be carefully monitored during enteral feeding.

Protein and calorie requirements with total parenteral nutrition

Body composition measurements, performed by multiple isotope dilution, were used to determine the protein and caloric requirements of patients receiving total parenteral nutrition (TPN). In addition the relative efficacy of lipid as opposed to carbohydrate calories were evaluated. Patients requiring TPN were randomly allocated to receive one of the following TPN solutions: a) 2.5% amino acid with 25% dextrose b) 5% amino acid with 25% dextrose c) 2.5% amino acid with 12.5% dextrose and a 5% lipid emulsion. The efficacy of each solution was evaluated by determining body composition at the onset,and at two week intervals during the course of TPN. In 204 patients who received TPN for 4447 days, 533 body composition studies were performed to evaluate 308 periods of TPN. In the normally nourished patient, as defined by the pre-TPN body composition, the body composition remained unchanged and normal with the three solutions. In the presence of preexisting malnutrition, two weeks of TPN resulted in a significant increase in body weight, arising primarily from an increase in the body cell mass. To evaluate the relative importance of the various factors responsible for the increase in the body cell mass, a multiple linear regression analysis was performed. The mean daily change in the body cell mass was correlated with the carbohydrate, protein and lipid calories infused and with the nutritional state. The resulting regression equation, which was statistically significant, indicated that the rate at which a depleted body cell mass was restored was related to the lipid and carbohydrate calories infused and to the nutritional state of the patient. Carbohydrate calories were more efficient than lipid calories. However increasing the amino acid concentration from 2.5 to 5% had no effect on the rate at which the body cell mass increased. The repletion rate was also directly related to the severity of malnutrition. Thus the correction of a malnourished individual with TPN is dependent on the severity of malnutrition, the type and amount of calories infused but is not affected by increasing the amino acid concentration from 2.5 to 5%.

Hypocitraturia in patients with gastrointestinal malabsorption

We measured serum and urinary citrate, oxalate, calcium, and magnesium in 22 normal subjects and in 16 patients with malabsorption. The patients had subnormal levels of serum citrate and magnesium during fasting, subnormal 24-hour levels of urinary citrate, magnesium, and calcium, and excessive levels of urinary oxalate. Daily citrate excretion averaged only 15 per cent of normal. The hypocitraturia in the patients resulted from a subnormal filtered load of citrate and abnormally high net tubular reabsorption of the anion. An oral citrate supplement raised both the serum concentration and the filtered load of citrate to normal fasting values, but net tubular reabsorption remained abnormally high and urinary excretion abnormally low. Intramuscular magnesium sulfate, which corrected the hypomagnesemia and hypomagnesuria, had no effect on serum citrate or its filtered load. Nevertheless the injection restored net tubular reabsorption of citrate to normal and partially improved the hypocitraturia. Full correction of the hypocitraturia was achieved by combined treatment with oral citrate and intramuscular magnesium sulfate. Hypocitraturia may contribute to the formation of oxalate stones in these patients, and therefore our treatment may help to prevent this complication.

Effects of two energy: nitrogen ratios in patients with gastroenterological disease and malnutrition

In 10 patients with active gastroenterological disease and protein-malnutrition (weight: 77.3 +/- 2.6 (mean +/- SEM) percent of ideal body weight, serum-albumin levels: 2.59 +/- 0.17 mg/100 ml) a randomized crossover study was performed to assess the effects of two energy:nitrogen ratios on body cell replenishment. After at least 3 days for equilibration, the total parenteral nutrition (TPN) study carried out with 354 +/- 5 mg of casein hydrolysate-nitrogen/kg/day, divided in two 7-day periods during which two nonprotein calorie supplies of 47 +/- 1 kcal/kg/day and 81 +/- 4 kcal/kg/day were given. The same 50 +/- 5% dextrose and fat emulsion energy sources were used in the two periods. Nitrogen (Kjeldahl method) and potassium retention, and weight and serum albumin concentration gains were all significantly better (Student t test) during the hypercaloric regimen than during the normocaloric regimen. In the 10 patients, the protein-sparing effect of nonprotein calories "added" during the hypercaloric regimen was demonstrated and represented 17% of the constant infused nitrogen. The more catabolic patient was prior to TPN, the more energy-dependent was the protein-sparing effect observed (r = +0.638). Preliminary data obtained with 3-methylhistidine urine determination suggests that the protein-sparing effect of "added" calories was due to an increased protein synthesis. Finally, body cell replenishment was better with the higher 230 +/- 6 energy:nitrogen ratio than with the lower 132 +/- 4 energy:nitrogen ratio, which suggests that the hypercaloric TPN regimen was useful in such patients.

[Phosphate-depletion (author's transl)]

The essential and critical role of inorganic phosphate has been known in veterinary medicine and experimental research on animals for decades. However, only recently has the phosphate depletion syndrome found widespread attention by clinicians. Hypophosphatemia is usually observed in the following clinical situations:chronic alcoholism, recovery phase of diabetic ketoacidosis, administration of phosphate-free solutions in parenteral nutrition, severe respiratory alkalosis, and infusion of fructose. Disturbed organ function in hypophosphatemia is the result of a depletion of inorganic phosphate in the cytoplasm of somatic cells. Such phosphate depletion may be due to either of the following mechanisms or a combination of both. (1) Negative external phosphate balance resulting from phosphate loss in urine or feces or (2) translocation of phosphate from the extracellular into the intracellular space with or without concomitant negative external phosphate balance. In principle, phosphate depletion interferes with the function of all somatic cells. In acute phosphate depletion, the clinically most important disturbances are observed in striated muscle (rhabdomyolysis with myoglobinuric acute renal failure), heart muscle (acute heart failure), and hematological systems (hemolysis, disturbed leukocyte and thrombocyte functions). In contrast, in chronic phosphate depletion skeletal abnormalities (osteomalacia) predominate. Organ disturbances are thought to result from diminished synthesis of ATP and other organic phosphate esters and/or from hypoxia secondary to changes in erythrocyte 2,3-DPG.

Multi-element analysis of the living body by neutron activation analysis-application to critically ill patients receiving intravenous nutrition

Neutron activation analysis has been used to determine the total content in the body of N, K, Na, Cl, P and Ca in 25 critically ill surgical patients before and after a 14-day course of intravenous nutrition. Muscle elemental composition was also determined in these patients at the same time as the total body analysis. Over the 14-day period of intravenous feeding the total body contents of all the measured elements increased (2-9.7 per cent) but only the increase in K was statistically significant. Muscle chemistry suggested an intracellular K depletion which was corrected over the study period. The results of the total body multi-element analysis were interpreted to show a mean gain of 1.25 l of extracellular fluid and 0.51 l of intracellular fluid and direct measurement of total body water suggested that this interpretation was probably valid. The first application of the technique to patients with nutritional and metabolic problems has quantified the weight gained by two body compartments during a 2-week period of intravenous nutrition. Its further application should help to solve a number of nutritional and metabolic problems in clinical surgery.

Calcium requirements during total parenteral nutrition in well-nourished individuals

Eleven patients, receiving all nutrition intravenously, were given varying doses of calcium (0-20 mg/kg/day) to determine an optimal level for calcium administration during postoperative parenteral nutrition. During each study period, nitrogen, phosphorus, vitamin, and caloric intakes were constant. Negative calcium balance resulted when less than 2 mg Ca++/kg body weight was given daily. During excessive urinary calcium losses, serum calcium concentration remained in the normal range. Increasing calcium intake to approximately 5 mg/kg/day (500 mg/day) yielded an apparent retention of calcium, as did higher doses. Serum calcium did not rise at this time. Urinary calcium excretion was directly proportional to calcium intake. The preliminary data suggest that a minimum dose of 5 mgCa++/kg/day is necessary to attain equilibrium between intake and urinary output. This value is higher than recent suggestions for calcium replacement during intravenous feeding.

Metabolic studies in total parenteral nutrition with lipid in man. Comparison with glucose

A study was undertaken of patients on a regimen of total parenteral nutrition comparing the nitrogen balance, energy substrates, blood amino acids, immunoreactive insulin, and immunoreactive glucagon levels during the sequential infusion of nonprotein calories as either glucose alone (glucose system) or 83% as Intralipid (Pharmacia Fine Chemicals, Montreal, Canada) and 17% glucose (lipid system). These nonprotein calories were administered with a constant background of amino acids (1 g/kg per day), vitamins, and minerals. Each system was infused for a week at a time and the order of infusion randomized. In some patients whole blood arteriovenous (A-V) levels of amino acids were measured across forearm muscle. During the glucose system there was a significantly higher level of pyruvate, lactate, alanine, and immunoreactive insulin, consistent with glucose being the principal source of energy. In contrast, during the lipid system there was a rise in free fatty acids and ketone bodies with a fall in insulin, suggesting that lipid was now the principal source of energy. Despite these two very diverse metabolic situations the nitrogen balance with both systems was positive to a comparable degree after the establishment of equilibrium. Correspondingly, A-V differences of whole blood amino acid nitrogen showed uptake by muscle to an equivalent degree with both systems. Clinical studies indicated that the lipid system as defined herein could be infused by peripheral vein for up to 43 days with resultant weight gain, elevation of serum proteins, and healing of fistulae. Our studies suggest that for both metabolic and clinical reasons exogenously infused lipid is a suitable source of nonprotein calories.

Phosphate depletion and repletion: relation to parenteral nutrition and oxygen transport

Phosphate depletion occurring during total parenteral nutrition has been frequently reported during the part 4 years. Hypophosphatemia may be associated with confusion, hyperventilation, and neuromuscular irritability, suggesting a total body phosphate deficiency. If inorganic phosphate levels fall below 1.0 mg %, diminished red cell glycolysis occurs with low erythrocyte levels of 2,3 diphosphoglycerate and adenosine triphosphate. Lowered red cell organic phosphates are associated with increased hemoglobin oxygen affinity. If severe hypophosphatemia occurs, hemolytic anemia, which is correctible by phosphate infusion, may result. In addition, leucocyte function is impaired by low levels of serum inorganic phosphate. While recognized as a needed additive, recommended phosphate supplements vary. Different infusion regimens have been suggested over the past 4 years, based primarily on assumed daily requirements. In the 19 trauma patients described who received hyperalimentation as part of their treatment, phosphate administration was calculated retrospectively and prospectively as a function of non-protein calories infused. Four different groups were studied. Group A received no phosphate additive and quickly became severely hypophosphatemic. Group B received from one to 15 meg of potassium acid phosphate per 1,000 K cal and developed a more gradual lowering of serum inorganic phosphate levels. Group C received 15 to 25 meg of potassium acid phosphate per 1,000 K cal and maintained normal phosphate levels throughout the course of treatment. Group D received greater than 25 meq of potassium acid phosphate per 1,000 K cal and gradually increased their serum inorganic phosphate levels. A significant positive correlation was found between serum inorganic phosphate levels, 2,3 diphosphoglycerate levels, adenosine triphosphate levels, and P50 of the oxy-hemoglobin dissociation curve. No patients developed hemolytic or neuromuscular syndromes which were attributable to hypophosphatemia. This study describes a simple method for the maintenance of adequate phosphate levels in patients whose dextrose-protein solutions may vary from day to day, by relating it to non-protein calories. Provision of 20 to 25 meq of potassium dihydrogen phosphate per 1,000 K cal will maintain normal serum levels of inorganic phosphate during total parenteral nutrition.