A controlled study of protein-sparing therapy after excision of the rectum: effects of intravenous amino acids and hyperalimentation on body composition and plasma amino acids

Nutritional support of the obese and critically ill obese patient

With the dramatic increase in the prevalence of obesity worldwide and in the United States, it is virtually certain that clinicians will be caring for bariatric and obese nonbariatric patients in increasing numbers. This patient population presents several difficulties from the medical and surgical management perspectives. In particular, nutrition of the bariatric patient and critically ill obese patient is challenging. A clear understanding of the nutritional assessment and unique management strategies available for the bariatric and the critically ill obese patient is essential to provide them with the safest and most effective care.

Effect of feeding malnourished patients for 1 mo on mitochondrial complex I activity and nutritional assessment measurements

BACKGROUND

We showed previously that the activity of complex I (the first enzyme of the electron transport chain) in peripheral blood mononuclear cells decreases with malnutrition and increases to a subnormal value after 1 wk of refeeding, but the traditional markers of nutritional status do not do so.

OBJECTIVE

The aim of this study was to ascertain whether a period of nutritional intervention longer than 1 wk would normalize complex I activity and traditional markers of nutritional status.

DESIGN

Fifteen malnourished patients (7 women and 8 men) with > or =10% body weight loss over the previous 6 mo were studied on the day of their admission to hospital and 7, 14 and 30 d after the beginning of nutritional support. Complex I activity in peripheral blood mononuclear cells, weight, height, body composition, body water compartments, dietary intake, and serum albumin concentrations were measured on each occasion. The results before and during nutritional intervention were compared with values obtained in 30 healthy volunteers (17 women and 13 men).

RESULTS

Complex I activity increased significantly after the first week of refeeding (P < 0.001) and reached a normal value after 1 mo of nutritional supplementation. Among the classic markers of nutritional status, only the ratio of extracellular water to intracellular water tended to decrease over the refeeding period.

CONCLUSION

Complex I activity increases rapidly and is normalized by refeeding at a time when other markers of nutritional status do not change significantly.

Sequential changes in insulin-like growth factor 1, plasma proteins, and total body protein in severe sepsis and multiple injury

BACKGROUND

Our group wanted to test the hypothesis that plasma levels of insulin-like growth factor 1 (IGF-1), transferrin, and prealbumin are useful markers of nutritional progress in severe sepsis and multiple injury.

METHODS

Measurements of IGF-1 and plasma proteins were made in critically ill patients as soon as they were hemodynamically stable and 5, 10, 15, and 21 days later. The magnitude and direction of the measured changes were compared with the magnitude and direction of the change in total body protein in the same time period.

RESULTS

Fourteen patients with severe sepsis and 10 multiply injured patients were studied. As a group they had an increased metabolic expenditure that peaked at 153% of normal and lost approximately 12.0% of total body protein. An early fall in IGF-1 and plasma proteins accompanied a marked acute phase response, and recovery occurred while hypermetabolism and net proteolysis continued. No correlation existed between changes in IGF-1 or plasma proteins and the change in total body protein.

CONCLUSIONS

Plasma levels of IGF-1, transferrin, and prealbumin are not useful for following changes in protein stores early in the course of critical illness.

[In which patients and for which procedures has the efficacy of postoperative artificial nutrition be proven?]

This study reviewed 19 prospective studies for the incidence of postoperative nutritional support on outcome in elective surgery. It compared enteral and parenteral nutrition initiated no more than three days preoperatively or postoperatively and prolonged maximally for one month, to a simple infusion of glucose or saline. As all studies had methodological weaknesses, concerning mainly the sample size, it is impossible to propose relevant recommendations. Nevertheless, among the 11 studies on total parenteral nutritional support (nitrogen and caloric supply with carbohydrates and/or lipids), three of them produced valuable results. As the available data do not show any beneficial effect, a routine postoperative nutritional support cannot be recommended, even in patients at high risk of postoperative complications. However for the latter a possible benefit cannot be totally excluded in some of them. When an alimentation per mouth cannot be started during the 8 to 10 days after surgery, an artificial nutritional support becomes mandatory.

[How to assess and monitor postoperative artificial nutrition?]

Quantitative and qualitative nutritional requirements depend on the level of energetic expenses. Various formulas, especially the tables by Harris and Benedict allow the estimation of the level of energetic expenses with an approximation of 14%. Corrective factors permit an adjustment of the figures, according to the level of body aggression. In complex cases, indirect calorimetry allows a more accurate appraisal of energetic expenses. This technique provides also indications on the utilisation of each substrate and allows therefore to determine the optimal carbohydrate-lipid ratio for each patient. The assessment of the direct benefit of artificial nutritional support relies on anthropometric techniques and at present on body composition appraisal by determination of its impedance. The changes in muscular strength are difficult to assess. Moreover the time course of body weight is not specific for nutritional status. Therefore other biological indicators such as the nitrogen balance, the concentration of plasma proteins and albumin are more often assessed; proteins with a short half-life depend on the body aggression level. The potassium balance, which is easy to obtain in clinical practice, is a relevant indicator for nitrogen balance and protein synthesis. Clinical monitoring includes the checking of hydratation and its impact on the circulatory, respiratory and renal functions. The tolerance of enteral nutrition is appraised by the quality of gastrointestinal function. Biological monitoring includes the electrolyte balance and various variables of carbohydrate, lipidic and proteic metabolisms. It allows to check the absence of hyperglycaemia, hyperlipidaemia and cholestasis. The daily checking of catheters is part of the monitoring of nutritional support.(ABSTRACT TRUNCATED AT 250 WORDS)

[Caloric and nitrogen intake during pre- and post-operative periods. method and duration]

Preoperative nutritional support is analysed from 7 prospective studies. Clinical benefits from nutrient intake and duration are not demonstrable. In one study, preoperative long-chain triglycerides infusions are associated with more postoperative complications. Postoperative nutrition is analysed from 20 articles. No one considers the clinical benefit with regard to quantitative and qualitative intakes.

Predicting postoperative fatigue: importance of preoperative factors

Postoperative fatigue as defined by a 10-point scale (1 = fit, 10 = fatigued) was determined prospectively in 84 patients undergoing major surgery. Results from this scale correlated well with standard psychological assessment of fatigue (Profile of Mood States Questionnaire) (r = 0.767; p < 0.0001). Fatigue values were 3.46 +/- 0.19 arbitrary units (mean +/- SEM) preoperatively; and postoperatively they were 5.61 +/- 0.24 at day 7, 5.02 +/- 0.24 at day 14, 3.74 +/- 0.19 at day 28, and 2.77 +/- 0.18 at day 90. Fatigue during the postoperative period was integrated to give a total fatigue score (332 +/- 14 arbitrary units, range 90-664), and this score was correlated with preoperative and early postoperative factors. The best predictor of postoperative fatigue was preoperative fatigue (r = 0.545; p = 0.001), with lesser correlations with diagnosis (especially cancer); preoperative weight, particularly total body protein (r = 0.317; p = 0.01); and weight loss (r = 0.29; p = 0.03), grip strength (r = 0.352; p = 0.01), and age (r = 0.267; p = 0.01). Postoperative fatigue was not correlated with preoperative anxiety, depression, or hostility, involuntary muscle function, gender, preoperative stress, or changes in total body protein or fat over the two postoperative weeks. It is concluded that patients who present for surgery already fatigued are the ones who are most likely to suffer from prolonged postoperative fatigue, particularly so if they are elderly, suffer from cancer, or have few extra reserves of body protein.

Early parenteral nutrition in patients unconscious because of acute drug poisoning

The author studied the clinical and laboratory effects of early parenteral nutrition (EPN) in patients who were comatose as a result of acute drug poisoning. All patients were unconscious at the time of admission and entry into the study and received our usual conservative therapy for the first 24 hours. Alternate patients received an EPN solution containing amino acids and glucose. Volume, composition, and caloric content of the EPN solution were calculated separately for each patient according to weight and height nomograms. It was found that the group receiving EPN (n = 46) normalized their nitrogen balance sooner and demonstrated a consistent decrease in their creatine phosphokinase level. Serum amino acid values in patients treated with EPN did not change significantly during the treatment trial. The control group (n = 40) demonstrated a significantly lower serum amino acid concentration on the third day of treatment (p < .001), had significantly more pneumonias (p < .05), and their hospitalization time was significantly longer (.01 < p < .05) than the EPN group. There were significantly fewer instances of disseminated intravascular coagulation in the group receiving EPN (p < .05).

Effects of immediate postoperative enteral nutrition on body composition, muscle function, and wound healing

Thirty-two patients undergoing bowel resection were randomized to receive either immediate postoperative nasojejunal feeding with full strength Osmolite solution for 56 hours (n = 16) or routine postoperative hypocaloric fluids and gradual reintroduction of diet (n = 16). Body composition changes were measured at 14 days after operation with in vivo neutron activation analysis, the wound healing response by subcutaneous implantation of Gortex tubes, and muscle function by grip strength, maximum ventilatory volume, and stimulation of the ulnar nerve at the wrist. Postoperative fatigue up to 3 months after operation was assessed using a 10-point analogue. Successful immediate enteral nutrition was established in 12 of the 16 patients. Enterally fed patients had a mean daily caloric intake of 1179 +/- 388 kcal/d (mean +/- SD) over the first 4 postoperative days compared with 382 +/- 71 kcal/d for the controls (p less than 0.0001). The amount of hydroxyproline accumulating in the Gortex tubes was also significantly greater (2.5 +/- 1.1 nmol/g tube vs 1.5 +/- 0.8 nmol/g tube; p less than 0.02). However, the amount and composition of the weight lost was not significantly different. Muscle function was not preserved, and postoperative fatigue occurred to an equal extent in both groups. Complications were similar in both groups, except for a preponderance of bowel obstructions in the controls. The time to passage of first flatus and first bowel motion, although shorter in the fed group, did not reach significance (p = 0.07). We conclude that immediate enteral nutrition is feasible and results in an improved wound healing response.(ABSTRACT TRUNCATED AT 250 WORDS)

The utilisation of peripherally-administered intravenous nutrient solutions

The utilisation of three peripherally-administered intravenous nutritional regimens has been evaluated in 42 patients on the first four days following surgery for colorectal cancer. A standard dextrose-saline (DS) regimen (n = 16) has been compared with an amino-acid (AA) regimen (n = 12) and a regimen consisting of glucose, amino-acid and fat (GAF) (n = 14). Fat and carbohydrate oxidation was calculated pre- and post-operatively using indirect calorimetry. Patients receiving AA showed a fall in carbohydrate oxidation (p < 0.01) and a rise in fat oxidation (p < 0.05) post-operatively, whereas no significant changes in fat and carbohydrate oxidation occurred in the DS and GAF groups. Cumulative nitrogen balance (NB) for the first four post-operative days was significantly better (p < 0.01) in the AA group (-10.3 +/- 3.8 g; mean +/- s.e.m.) than in the DS group (-25.3 +/- 3.1 g), due to an improved NB in the AA group on the first and second days only. Cumulative NB in the GAF group (+7.7 +/- 2.3 g) was significantly better (p < 0.01) than in the other two groups. Where the provision of peripheral intravenous nutritional support is desired, the use of a combination of glucose, amino-acid and fat is recommended.

Influence of preoperative intravenous nutrition upon hepatic protein synthesis and plasma proteins and amino acids

The influence of 3 and 7 days of preoperative intravenous nutrition (IVN) on the capacity for protein synthesis in liver and on concentrations of plasma proteins and amino acids were investigated in patients with gastrointestinal malignancy. Thirty patients with gastrointestinal neoplasms who had lost more than 5 kg of weight over 3 months were randomized into three groups to receive preoperatively: (a) no IVN, (b) IVN for 3 days (0.18 gN/kg/day as amino acid; 30 kcal/kg/day as glucose), or (c) IVN for 7 days. Free access to a hospital diet was available to all patients including 10 patients who had not lost weight who served as controls. In the three groups of patients who had lost weight, median transferrin and fibronectin were lower than for controls, whereas other proteins and amino acids were comparable. After feeding, samples of liver were obtained peroperatively and the potential rates of protein synthesis were calculated from the in vitro incorporation of (14C)-leucine, into protein. Preoperative IVN significantly increased the potential rate of protein synthesis in liver after 3 days. Plasma amino acids were comparable with controls whereas in the unfed-group concentrations suggested utilization of alanine and breakdown of muscle. Three days of IVN also increased plasma fibronectin and IgA but increases of prealbumin, IgM, and complement C3 were only significant in the group fed for 7 days. On the 7th postoperative day plasma proteins were decreased similarly in each group. This study shows that concentrations of several plasma proteins, in preoperative patients reflect net rates of hepatic protein synthesis and are susceptible to depletion during starvation and repletion by 3 or 7 days of IVN.

The effects of an anabolic steroid and peripherally administered intravenous nutrition in the early postoperative period

Sixty patients undergoing colorectal surgery for malignancy were randomized to receive the anabolic steroid stanozolol (n = 30) or to a control group (n = 30). Patients were further randomized to receive on the first 4 postoperative days a) a standard dextrose-saline regimen (DS), b) an amino acid regimen (AA), or c) a glucose-amino acid-fat regimen (GAF) via a peripheral vein. Fat and carbohydrate oxidation rates were calculated pre- and postoperatively using indirect calorimetry. Postoperative nitrogen balance (NB) in patients receiving amino acids was significantly improved (p less than 0.02) by the administration of stanozolol. Fat and carbohydrate oxidation rates were not significantly affected by stanozolol. Patients in the stanozolol and control AA groups showed a fall in carbohydrate oxidation (p less than 0.01) and a rise in fat oxidation (p less than 0.05) postoperatively, whereas no significant changes in fat and carbohydrate oxidation occurred in the two DS and two GAF groups. Cumulative NB for the first 4 postoperative days was significantly better (p less than 0.01) in the two AA groups than in the two DS groups, due to an improved NB in the two AA groups on the 1st and 2nd days only. Cumulative NB in the two GAF groups was significantly better (p less than 0.01) than in all the other groups. This study shows that stanozolol improves postoperative NB in patients receiving amino acids alone, whereas the provision of a more complete nutritional regimen containing glucose, amino acids, and fat results in a positive NB unaffected by stanozolol.

Relative importance of amino acid infusion as a means of sparing protein in surgical patients

We performed isotopic infusions in 51 surgical patients to investigate the effectiveness of different substrates to conserve protein. All patients were initially studied in the basal state and then the effects of glucose infusion (GL, N = 13), lipid infusion (LIP, N = 11), or amino acid infusion (AA, N = 17) were determined. Ten patients receiving total parenteral nutrition (TPN) were also studied. The basal value for net protein catabolism (NPC) in GL patients was 1.53 +/- 0.4 (SEM) g/kg/day decreasing to 1.39 +/- 0.4 g/kg/day during glucose infusion (p less than 0.01). The basal NPC in the LIP group was 2.04 +/- 0.4 g/kg/day decreasing to 1.72 +/- 0.3 g/kg/day during lipid infusion (p less than 0.01). In the TPN patients the NPC was 0.79 +/- 0.46 g/kg/day whereas in the AA patients the basal value for NPC was 1.37 +/- 0.14 g/kg/day decreasing to -0.77 +/- 0.11 g/kg/day during amino acid infusion (p less than 0.0005). From our study we conclude that: (1) All substrates commonly used in intravenous feeding have the capacity to spare protein. (2) Protein sparing was more pronounced when a balanced amino acid infusion was used than with either glucose or lipid infusion alone. (3) This effect is not solely due to insulin secretion as larger insulin responses were seen with both GL and TPN patients. (4) These results may have implications for peripheral vein feeding with amino acid solutions where there is a contraindication for full TPN or the lack of resources for administering it.

The immediate and long-term effects of postoperative total parenteral nutrition on body composition

The short and long-term effects of postoperative total parenteral nutrition (TPN) on body composition were studied in a randomised series of patients undergoing major colorectal surgery. Ninety-two patients (colorectal cancer: 50, ulcerative colitis or Crohn's disease: 42) were grouped according to diagnosis and clinical inflammatory activity. TPN was given for 9.7 +/- 1.1 days. The complication rate was not changed by the TPN. Nitrogen balance was studied during the first week. Body weight, total body potassium, triceps skinfold, serum albumin and body water were measured before and at intervals up to 24 weeks after the operation. Cumulative nitrogen balance in control patients at 7 days after surgery was -47.3 g. Patients given TPN balanced nitrogen intake and output (cancer patients and patients with quiescent inflammatory bowel disease, IBD) or were in positive balance (patients with active IBD). Weight loss at 1 week after surgery was less in TPN patients compared to controls and this difference remained statistically significant up to 6 months after termination of the nutritional treatment. A similar, although not statistically significant, difference was noted in total body potassium and triceps skinfold. Patients with active IBD regained pre-operative body composition earlier than cancer patients and patients with quiescent IBD. It is concluded that TPN after major colorectal surgery reduces postoperative weight loss and that this effect lasts after termination of the nutritional treatment. In the absence of increased body potassium and increased body water, we conclude that the long-term effect of TPN on body weight is most likely due to preservation of fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative nutritional support in the cancer patient

Cancer patients in whom elective surgical intervention is planned are frequently malnourished. Moreover, the tumor itself may be responsible for additionally altering metabolism in the host, although the mechanisms by which this occurs are not clear. All preoperative cancer patients should be carefully surveyed for indices of malnutrition. Patients with a history of inadequate oral protein and calorie intake, an unintentional weight loss of greater than 10 pounds, or a serum albumin level of less than 3.5 gm per dl should undergo a thorough nutritional assessment, including anthropometric measurements, 24-hour urinary urea nitrogen and creatinine measurements, and recall skin antigen testing. Surgical risk may be predicted by using indices that are sensitive and specific in assessing preoperative parameters of malnutrition. Adequate nutritional support for 7 to 10 days prior to surgery should be provided to all patients falling into the high-risk category and has been shown to significantly reduce the rate of postoperative complications and death in this group. Generally, a serum albumin of less than 3 gm per dl, a recent unintentional weight loss of greater than 10 to 15 per cent of normal body weight, and/or skin test anergy should be considered to designate high risk. In the formulation of a nutritional plan, estimates of daily energy requirements are essential and can be made by use of the Harris-Benedict equation, metabolic cart measurements, and perhaps 24-hour urinary creatinine values. Generally, 30 to 45 kcal per kg of body weight with 1.2 to 1.5 gm of protein per kg of body weight daily, regardless of the route of delivery, will provide adequate nutritional support. Patients should be fed by the enteral route if possible. Although oral intake is preferable, many malnourished cancer patients will be unable to achieve necessary protein and calorie requirements in this manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle function and nutrition

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Is it possible to evaluate the efficacy of amino acid solutions after major surgical procedures or accidental injuries? Evaluation in a randomized and prospective study

Two unbalanced amino acid solutions (essential amino acids, branched-chain amino acids) were compared to a complete and balanced amino acid solution with regard to efficacy of nitrogen balance. Patients were randomized to receive the amino acid solutions over 3 days for each regimen. The patients were examined postoperatively or directly after accidental trauma. Nonprotein calories were given as 40 kcal/kg/day consisting of 50% fat and 50% glucose. Nitrogen was given at the amount of 0.15 g N/kg/day. Unbalanced amino acid solutions gave a 2-fold more negative nitrogen balance than a balanced and complete amino acid solution. However, this difference disappeared and nitrogen balance approached equilibrium irrespective of the amino acid composition of the infused solutions when nitrogen in blood products was accounted for. All patients received a considerable amount of blood products in a comparable but unpredictable way. Blood products corresponded to around 40% of the daily nitrogen intake. Our study demonstrates that it is not possible to test the efficacy of amino acids for nitrogen retention in patients who are in the need of blood-product transfusions. It is likely that amino acids in blood proteins serve as a significant amino acid source that is utilized for resynthesis of body proteins especially in flow-phase patients with high protein breakdown. This fact has not been sufficiently accounted for in the previous literature.

Clinical effects of enteral and parenteral nutrition preceding cancer surgery

Parenteral and enteral nutrition have become major tools in the nutritional management of cancer patients perioperatively. The purpose of this article is to see if there is evidence from prospective controlled trials that parenteral and enteral nutrition preceding cancer surgery are of clinical benefit. From our investigation and from 8 other controlled, randomized clinical investigations the following conclusions can be drawn: Parenteral and enteral nutrition preceding cancer surgery improve nutritional parameters; Parenteral and enteral nutrition preceding cancer surgery may decrease postoperative morbidity and mortality, but this beneficial effect may not be limited to malnourished patients; If enteral nutrition can provide the same amount of proteins and calories as parenteral nutrition can, parenteral and enteral nutrition are equal with regard to clinical effects.

Use of urea kinetics in the nutritional care of the acutely ill patient

In acutely ill patients nitrogen balance is often assessed clinically from measurements of protein intake and urinary urea nitrogen. We have utilized urea kinetic modeling to measure urea generation rates, protein catabolic rates and nitrogen balance in 19 acutely ill patients with varying degrees of renal dysfunction and have studied the effect of varying caloric intake on protein balance during a period of fixed protein intake. In patients with measured creatinine clearances equal to or greater than 50 ml/min there was a highly significant correlation between nitrogen balance estimates derived from urea kinetic modeling and those obtained from urinary urea nitrogen (R = 0.939; p less than 0.001). When creatinine clearance measurements were between 20 to 50 ml/min the correlation between the two estimates was poorer (R = 0.337; p less than 0.001). In patients whose creatinine clearance was below 20 ml/min the correlation between measurements was worse still (R = 0.229; p less than 0.002). To determine the effects of increasing caloric intake on protein catabolic rate seven acutely ill patients were studied. When caloric intake was increased from 27.8 to 34.2 kcal/kg/day while on a fixed protein intake of 1.27 g/kg/day there was a significant fall in protein catabolic rate from 1.39 to 0.99 g/kg/day (p less than 0.002). As urea kinetic modeling takes into account changes in blood urea nitrogen, extrarenal losses of urea and the urinary urea pool, it is the preferred method for measuring protein balance in acutely ill patients particularly those with poor renal function. Serial monitoring of protein catabolic rates permits easy continuous assessment of the effect of increasing caloric intake on protein sparing during parenteral hyperalimentation.

Effect of injury, sepsis, and parenteral nutrition on high-energy phosphates in human liver and muscle

This study examined the effect of varying degrees of resting hypermetabolism and total parenteral nutrition on muscle and hepatic high-energy phosphates. Twelve severely injured patients, five critically ill patients with normal blood pressure, and six severely ill patients on 1 wk of total parenteral nutrition were investigated, and the results were compared with those in 14 normal controls. High-energy phosphates were not significantly changed in liver and muscle after severe injury; lactate and pyruvate levels in both tissues were increased; glycogen levels in the liver were decreased. In critical illness, muscle and hepatic adenosine triphosphate as well as adenosine diphosphate were decreased significantly; energy charge potential dropped; adenosine monophosphate, lactate, and the ratio of lactate to pyruvate were increased. Liver glycogen, but not muscle glycogen, dropped remarkably. The correlation coefficient between hepatic and muscle adenosine triphosphate was 0.61. In patients on 1 wk of total parenteral nutrition, hepatic and muscle high-energy phosphates were not significantly changed before or during total parenteral nutrition. Alterations in the adenosine triphosphate-adenosine diphosphate-adenosine monophosphate system in liver and muscle suggest a low-energy charge in severe injury and critical illness. This would indicate a decreased capacity for biosynthetic reactions and production of storage compounds. The changes of high-energy phosphates in liver are always parallel to changes in muscle.

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.

Effects of an anabolic steroid on plasma amino acids, proteins, and body composition in patients receiving intravenous hyperalimentation

In this controlled trial we have studied the effect of anabolic steroid on ill surgical patients receiving intravenous hyperalimentation. Body composition, plasma proteins, and amino acids were compared in each of two groups of 12 patients before and after 14 days of intravenous feeding. The patients in one group were given 100 mg of nandrolone decanoate at the commencement of study and again one week later. Body weight, muscle (AMC), plasma transferrin, prealbumin, and retinol-binding protein were increased comparably in both groups. An apparent gain in total body nitrogen was not significant. However, anabolic steroid caused greater gain of water requiring a more liberal use of diuretics, but prevented the gains of fat, triglyceride and insulin that occurred in the control group. Most plasma amino acids increased due to intravenous hyperalimentation but decreased in patients given anabolic steroid. It is concluded that in patients who may be in the catabolic phase of recovery anabolic steroid probably enhances amino acid and water uptake by tissues and increases the utilization of fat but, does not promote any greater increase in "visceral" proteins than during intravenous hyperalimentation alone.

The effect of isotonic amino acid infusions on serum proteins and muscle breakdown following surgery

Twenty patients undergoing major surgical procedures received constant infusion (21/day) of either 3.5 per cent amino acid (AA) or 5 per cent dextrose (D5W) solutions in addition to other fluid requirements for 4 postoperative days. Ketosis was evident in AA patients as a mean daily beta-hydroxy butyrate excretion of 2.16 +/- 1.39 mmol and respiratory quotient of 0.708 +/- 0.013 compared with 0.28 +/- 0.45 mmol/day and 0.754 +/- 0.015 respectively in the D5W group. The serum total protein and albumin concentrations (but not those of transferrin and prealbumin) were significantly higher in the AA than the D5W group on day 4. However, the mean fluid balance for days 3 and 4 was significantly less positive in AA patients. The mean daily nitrogen balance of -6.6 +/- 7.7 gN/day in AA patients and -9.5 +/- 5.8 gN/day in D5W patients was not significantly different. Mean daily 3-methyl histidine excretion (38.2 +/- 12.3 mumol/mmol creatinine) in AA patients was significantly higher than in D5W patients (31.2 +/- 10.8 mumol/mmol creatinine). With no improvement in nitrogen balance, an increase in muscle protein breakdown and the possibility that decreased fluid retention explains the higher serum total protein and albumin levels, this study fails to demonstrate improved protein sparing by isotonic amino acid infusions following surgery.

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.

Hyperalimentation in cancer

A growing body of work has been addressed to the hypothesis that because patients with cancer who have poor nutritional status have a worse prognosis, increased nutritional support in these patients will result in better tolerance of surgical interventions, chemotherapy and radiation therapy, and a better outcome from the cancer. Although the hypothesis is an attractive one, there is only a single well-conducted, randomized, prospective trial to date that shows that active nutritional support is of benefit in the therapy of patients with cancer. Based on this review of the literature, it is felt that though cachexia is clearly of negative import in patients with cancer, there is little evidence to support the hypotheses that any nutritional support changes the outcome or the course of therapy of patients with cancer. It seems reasonable to continue the nutritional support to cachectic patients with cancer concomitant with specific anticancer therapy, but supportive nutritional therapy alone with postponement of specific anticancer treatment, as in awaiting weight gain or anabolism, cannot be justified with the current state of the art.

Parenteral nutrition: current status and concepts

Parenteral nutrition is regarded as a form of nutrition in some countries and as an extension of intravenous fluid therapy in others. The optimum clinical application of parenteral nutrition as a form of therapy requires detailed knowledge of the nutrient solutions themselves, including the commonly used solutions such as dextrose, soybean oil emulsion, synthetic crystalline L-amino acid solutions; older solutions such as xylitol, protein hydrolysates; and newer solutions such as glycerides and special purpose amino acid solutions. Additionally, information has accumulated over the past 10 years, leading to the rational use of vitamins and trace elements in parenteral nutrition. Metabolism of the substrates has been correlated with known pathways of intermediary metabolism in normal, starved and stressed subjects. Several new concepts have arisen: a) Infusion of excessive quantities of dextrose results in lipogenesis and increased carbon dioxide production. Hyperalimentation of this type is being replaced by infusion of lesser quantities of dextrose, supplemented by intravenous infusion of lipid as a calorie source. b) Protein hydrolysates and racemic synthetic crystalline amino acid solutions have been replaced by synthetic crystalline L-amino acid solutions. c) A new fat emulsion based on safflower oil is competing successfully with the traditional soybean oil emulsion. d) Newer substrates are being explored. These include branched chain amino acids, keto analogues of amino acids, synthetic glycerides and maltose. e) Deficiencies of essential fatty acids, trace elements and vitamins have been studied in patients on long term parenteral nutrition and their mechanisms elucidated. Official recommendations for intravenous administration of these nutrients have been made. f) Several techniques have been applied in several circumstances, including protein sparing therapy, cyclic nutrition, home therapy, and parenteral nutrition in liver and renal failure. Parenteral nutrition is now used extensively, not only in major hospitals where the resources of a team approach with physician, nurse, pharmacist and dietitian are available, but also in smaller hospitals where all of these facilities may not be at hand. However, whatever the setting, the principles behind the clinical application of parenteral nutrition should be well understood by those involved, including current approaches to safe preparation and infusion of parenteral nutrition solutions.

Parenteral nutrition by peripheral vein

Peripheral parenteral nutrition can provide perioperative nutritional support to patients with inadequate oral intake in whom total parenteral nutrition with hypertonic dextrose administered by a central vein cannot be undertaken because of sepsis, subclavian vein thrombosis, or lack of expertise and familiarity. Peripheral parenteral nutrition may be indicated in patients with marginal nutritional status whose postoperative course and period of starvation are unpredictable and in patients being started on a total enteral nutrition regimen. In patients with increased requirements because of stress or malnutrition who need full nutritional support by a peripheral method, the lipid system is indicated. In certain instances, large enough volumes can be infused to provide sufficient calories and protein for nutritional repletion. Protein-sparing therapy is indicated for nutritional maintenance in patients who do not clearly require full support by total parenteral nutrition but who are taking insufficient calories and protein orally. Peripheral parenteral nutrition avoids the risks of subclavian vein catheterization but requires that adequate peripheral veins are available. The metabolic complications are minimal compared with those of total parenteral nutrition, and the nutritional management of the diabetic patient is greatly simplified. Several techniques of preserving peripheral veins and prolonging their use have been discussed.