Intravenous essential L-amino acids and hypertonic dextrose in patients with acute renal failure. Effects on serum potassium, phosphate, and magnesium

An essential infusion for an essential organ

Essential amino acid-based parenteral nutrition (PN) was found to be superior to hypertonic dextrose for patients with acute renal failure in a classical randomized trial that was published in 1973. However, subsequent trials were not able to duplicate this finding when this formulation was compared to hypertonic dextrose or to standard amino acid-based PN. As a result, this intervention has not been recommended in various guidelines for the nutrition support of patients with renal failure. However, all of these trials were relatively small, and none of them compared the intervention to a true control group-namely, patients who were not receiving any artificial nutrition. Because no trials have compared any form of artificial nutrition to no nutrition support in patients with acute renal failure, there really is no basis on which to make any level 1 evidence-based recommendation. Furthermore, a close look at all of the trials suggests that the essential amino acid-based formulation may be superior to the other types of intravenous nutrient supplementation to which it was compared. To determine whether this should be offered to patients with acute renal failure, we need data from one or more large, well-designed and executed, low risk of bias randomized trial(s) comparing essential amino acid-based PN to no nutrition therapy.

Nutrition support therapy in acute kidney injury: distinguishing dogma from good practice

Acute kidney injury (AKI) is a frequently observed complication in critically ill patients. Its presentation may range from the early risk of renal dysfunction to complete renal failure. Morbidity and mortality in the AKI patient increase with the decline of renal function. Appropriate nutrition therapy is essential in the medical management of the AKI patient. Assessment of nutritional requirements should take into account the patient's underlying complication, comorbid medical conditions, and severity of the renal dysfunction. Various stages of AKI determine the direction of nutrition therapy. Additionally, understanding the macro- and micronutrient modifications and electrolyte and vitamin alterations that should be implemented are vital for better patient outcomes.

The preoperative nutritional assessment of surgical patients with hepatic dysfunction

The precise influence of malnutrition on postoperative complications in patients with hepatic dysfunction is not well known. In phase I of the present study, we evaluated the nutritional status of 102 patients with hepatic dysfunction who were admitted for elective hepatobiliary or pancreatic surgery, and a model for the prediction of postoperative complications was developed using a computer-based stepwise regression procedure. The equation for this Prognostic Nutritional Index for Surgery (PNIS) was calculated by [-0.147 x (% weight change) + 0.046 x (% ideal body weight) + 0.010 x (actual triceps skinfold thickness as a % of standard value) + 0.051 x (hepaplastintest)]. In phase II this model was prospectively tested in 182 patients, including 145 with hepatic dysfunction. A total of 18 patients were classified as having a poor prognosis (PNIS < 5) and all of these patients in fact developed postoperative complications: 128 patients were classified as having an intermediate prognosis (5 < or = PNIS < 10), 23 (18.0%) of whom developed postoperative complications, and none of the 36 patients who were classified as having a good prognosis (PNIS > or = 10) developed any postoperative complications. These results demonstrate the importance of performing a thorough preoperative nutritional assessment of patients with hepatic dysfunction as malnourished patients with PNIS < 10 may need preoperative nutritional management, even when their surgical procedures are not major.

Nutritional support in the critically ill surgical patient

Aggressive nutritional support in the critically ill surgical patient is essential if improved outcome is to be realized. An understanding of the metabolic alterations of trauma and sepsis provides the foundation for a nutritional prescription for the individual patient. Careful nutritional assessment; titration of fluid, electrolytes, and micronutrients; provision of adequate calories and nitrogen to meet metabolic needs; and the selective use of specialized formulations are important components of nutritional management in the ICU.

Nutritional support in surgical practice: Part II

On admission, a group of high-risk patients who are potential candidates for surgery can be identified, in whom prompt initiation of preoperative enteral or parenteral nutrition may reduce postoperative morbidity and mortality irrespective of the nutritional status. Among these are patients with inflammatory bowel disease, gastrointestinal fistulas, and pancreatitis. Substantial nutritional support has little or no direct effect upon the pathogenesis of the disease, but the discontinuance of oral intake may well have a beneficial effect on the basic disease process. Thus, the provision of enteral or parenteral nutrition gives the patient an optimal opportunity to marshal host defenses in support of healing. In organ system failures, e.g., acute renal failure, liver failure, and pulmonary failure, appropriate nutritional support may assist the patient in coping with the abnormal intermediary metabolism resulting from such failure until satisfactory organ system function returns. From this review, it seems reasonably clear that the initially malnourished patient is less able to successfully withstand the adverse effects of vigorous therapy and/or severe illness than is the well-nourished individual. Hence, correction of malnutrition, either before initiating therapy or concomitant with the treatment, is very likely to be beneficial.

Profound hypophosphatemia in the course of acute renal failure

Four of 19 patients with acute renal failure (ARF) requiring dialytic therapy were hypophosphatemic (serum phosphate, 0.8 +/- 0.8 mg/dL) during their illness. The hypophosphatemia could not be attributed to differences in the etiology of renal failure, frequency of dialysis, or residual renal function. No hypophosphatemic patient received phosphate-binding antacids. The hypophosphatemia was related to carbohydrate (CHO) providing a large percentage (greater than 79%) of total calories for a prolonged period. This complication was likely caused by tissue anabolism as well as by CHO-stimulated, insulin-induced intracellular shifts of phosphate. The greater use of parenteral fat as a caloric source and more aggressive phosphate supplementation despite the presence of ARF may help prevent this complication.

Use of essential amino acid/dextrose solutions in the nutritional management of patients with acute renal failure

A review of the literature on the effectiveness of essential amino acid and hypertonic dextrose in the nutritional management of patients with acute renal failure is evaluated critically. Earlier case reports and studies published indicated that the administration of these solutions could lead to lower blood urea nitrogen concentrations, positive nitrogen balance, and various other clinical and metabolic improvements. Recent studies, however, show that various combinations of essential and nonessential amino acids can provide similar results. Some investigators have suggested increasing the concentration of branched-chain amino acids in these solutions to decrease protein catabolism in muscle. Unfortunately, patients with complications such as sepsis, burns, and shock may not benefit from any of these therapies. Further research is needed to elucidate fully the optimal composition of these solutions in severely stressed hypercatabolic patients with this disorder.

Goals of nutritional support in acute infections

Defense mechanisms employed by the host to fight infection are highly dependent on adequate protein synthesis to support phagocytic and lymphoid cell activity as well as immunoglobulin production. Interleukin I is a small, not yet fully characterized protein produced by macrophages which appears to initiate most of the nonspecific metabolic changes observed during infection. These alterations include: increase in the synthesis of visceral proteins, white blood cells, and acute phase globulins; enhanced somatic protein breakdown; sequestering of serum iron and zinc in the liver; and induction of fever. The ability of leukocytes to produce interleukin I is impaired in patients with visceral protein depletion or kwashiorkor-like, hypoalbuminemic malnutrition and can be restored in the healthy unstressed patient within approximately three to five days by feeding. Similarly, in the stressed patient, adequate protein and caloric intake improves the ability to produce interleukin I, which may improve survival. Other defects in host defense in advanced stages of protein malnutrition include lymphopenia, impaired phagocytosis, and deficiencies in fibronectin, immunoglobulins, and complement levels. Thus, the goal of nutritional support is to maintain sufficient amounts of amino acids for visceral protein synthesis required for adequate host defense.

Nutritional support of the critically ill patient

Injury or stress generates a vigorous metabolic response designed to establish the metabolic priorities required for the repair of injured tissues. In this condition, hormones commonly found to be elevated in the plasma include glucagon, catecholamines, glucocorticoids, growth hormone, aldosterone, and antidiuretic hormone. This hormonal profile results in rapid lysis of body protein, an increased rate of fat oxidation, and water and salt conservation. Rates of gluconeogenesis and ureagenesis are accelerated and may result in significant losses in lean body mass, a process that, if allowed to progress, will adversely affect patient survival. Exogenous nutrients provided to the critically ill patient may be poorly tolerated and may result in complications. Dextrose and intravenous fat emulsions provide the major sources of parenteral, nonprotein energy. These energy sources may not be metabolized efficiently in these patients, even though energy expenditure in this condition is increased significantly. Measurement of urinary nitrogen losses yields evidence useful in assessing the patient's degree of stress. In this manner, the patient's energy and protein requirements may be estimated. Formulations of amino acids, including the branched-chain amino acids, in higher concentrations have been reported to have anticatabolic effects and may improve the maintenance of lean body mass in stressed individuals. The stressed patient is prone to metabolic complications and, therefore, requires more careful monitoring of fluid, electrolyte, and acid-base balance, as well as renal, pulmonary, and liver function. Nutritional status is difficult to assess, since negative nitrogen balance may persist and the visceral proteins such as transferrin become altered in stress and, therefore, may not respond to nutritional intervention alone. The goal of nutritional therapy is the preservation of lean body mass by the safe and efficacious provision of metabolic substrate, thus improving patient survival.

Nutritional support in the patient with acute renal failure

Nutritional support in the patient with acute renal failure is of great importance in lessening the degree of catabolism when energy demands are high and may also result in salutary metabolic effects. Overall treatment considerations in the posttraumatic or postsurgical patient with acute renal failure will be discussed, including fluid and electrolyte balance and energy and nutritional considerations. The application of the Giordano and Giovannetti principles to the field of parenteral nutritional support enables modifications of treatment programs of total parenteral nutrition to be applied to patients with acute renal failure. Utilizing an intravenous mixture of eight essential l-amino acids, hypertonic dextrose, and vitamins, we observed salutary biochemical effects in surgical patients. A prospective, randomized double-blind study of that treatment regimen compared to patients receiving hypertonic dextrose and vitamins alone resulted in improved survival and a decreased duration of renal failure in the treated group. Management considerations of these patients and possible application of these principles to other patients in renal failure will be discussed.

Uremic catabolism in a neonate: reversal by parenteral nutrition

Parenteral nutrition (PN), applied in the management of a neonate with severe obstructive uropathy, corrected hyperkalemia and metabolic acidosis within a few days. During the PN lasting for 45 days the renal function improved considerably, as judged on the basis of the serum urea nitrogen concentration and creatinine clearance. The pattern of weight gain of the patient resembled that of catch-up growth. Positive metabolic balances were recorded for nitrogen, potassium calcium, and magnesium during the PN. The eight essential amino acids plus histidine were used as nitrogen source, supplemented periodically with L-alanine. An addition to the amino acids of L-arginine brought the serum aminogram round to a more normal one but did not have any measurable effect on the retention of nitrogen. In certain selected cases PN may thus be used as an adjunct in the management of chronic renal insufficiency even in infancy.

Reduction of operative morbidity and mortality by combined preoperative and postoperative nutritional support

A previously developed and validated predictive nutritional assessment model (Prognostic Nutritional Index) was applied to a heterogenous surgical population. Without knowledge of the then undeveloped PNI, adequate preoperative nutritional repletion (TPN) was provided on clinical indications alone to 50 of 145 patients with the remaining 95 patients receiving no preoperative total parenteral nutrition. Analysis of the two groups found no baseline differences in nutritional status, type and severity of disease and/or operative therapy, and other potentially important variables. In the high-risk stratified group as defined by admission nutritional assessment and calculated PNI (greater than or equal to 50%), adequate preoperative TPN reduced postoperative complications 2.5-fold (p < 0.01), postoperative major sepsis six-fold (p < 0.005) and mortality five-fold (p < 0.01). Clinical "eyeball" evaluation of nutritional status cannot identify high-risk individuals. This nutritional assessment predictive model (PNI) identifies the subset of operative candidates in whom adequate preoperative nutritional support significantly reduces operative morbidity and/or mortality.

Acute renal failure: biochemical evaluation of total parenteral nutrition with essential L-amino acids

Plasma amino acid patterns were studied in three groups: one of 10 healthy subjects used as control, one of five patients in acute renal failure treated by haemodialysis plus a standard high-calorie non-protein diet, and one of five patients with the same clinical condition and treated in the same way except that the total parenteral nutrition consisted of a mixture of carbohydrate and essential L-amino acids. Our results indicate that haemodialysis seems to be responsible for some part of the depletion of amino acids and that their administration reduces this effect both for the essential and for the non-essential amino acids.

[Renal complications after general surgical operations (author's transl)]

Oliguria, an easily recognizable symptom of postoperative acute renal failure, is analyzed schematically in terms of various diagnostic aspects and a pragmatic therapeutic procedure. Differentiation among pre-, intra-, and postrenal disturbances is important. Acute renal failure caused by simultaneous and often severe insufficiency of other organs, especially in combination with septicemia, still has a bad prognosis. Prophylaxis in the form of adequate volume substitution and shock therapy is urgent in each case.

Hypophosphataemia and phosphorus requirements during intravenous nutrition

Seven patients with acute illnesses developed hypophosphataemia whilst receiving intravenous nutrition which included a fat emulsion, Intralipid, a possible source of phosphorus. The authors' observations cast doubt on the bio-availability of the phosphorus contained in the phospholipid content of the fat emulsion. The currently recommended allowance of phosphorus for this type of patient appears to be too low and it is suggested that 0-5-0-75 mmol/kg body weight be provided, preferably as a neutral phosphate solution. Sine hypophosphataemia can occur at various time intervals after starting intravenous nutrition and precede clinical sequelae it is recommended that routine serum phosphate measurements are made in all patients receiving this treatment.

Acute renal failure in children: principles of management

Acute renal failure is a complicated disturb ance, which taxes the clinical skills of the physi cian. This paper reviews the metabolic derange ments, the principles of treatment, the conse quences, and the advances recently made in our understanding of the pathophysiology and man agement of acute renal failure.