Peripheral intravenous feeding with isotonic amino acid solutions

Acute ingestion of a ketone monoester, whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of myofibrillar protein synthesis rates in young males: a double-blind randomized trial

BACKGROUND

Ketone bodies may have anabolic effects in skeletal muscle via their capacity to stimulate protein synthesis. Whether orally ingested exogenous ketones can stimulate postprandial myofibrillar protein synthesis (MyoPS) rates with and without dietary protein co-ingestion is unknown.

OBJECTIVES

This study aimed to evaluate the effects of ketone monoester intake and elevated blood β-hydroxybutyrate (β-OHB) concentration, with and without dietary protein co-ingestion, on postprandial MyoPS rates and mechanistic target of rapamycin complex 1 (mTORC1) pathway signaling.

METHODS

In a randomized, double-blind, parallel group design, 36 recreationally active healthy young males (age: 24.2 ± 4.1 y; body fat: 20.9% ± 5.8%; body mass index: 23.4 ± 2 kg/m2) received a primed continuous infusion of L-[ring-2H5]-phenylalanine and ingested one of the following: 1) the ketone monoester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KET), 2) 10 g whey protein (PRO), or 3) the combination of both (KET+PRO). Blood and muscle biopsy samples were collected during basal and postprandial (300 min) conditions to assess β-OHB, glucose, insulin, and amino acid concentrations, MyoPS rates, and mTORC1 pathway signaling.

RESULTS

Capillary blood β-OHB concentration increased similarly during postprandial conditions in KET and KET+PRO, with both being greater than PRO from 30 to 180 min (treatment × time interaction: P < 0.001). Postprandial plasma leucine and essential amino acid (EAA) incremental area under the curve (iAUC) over 300 min was greater (treatment: both P < 0.001) in KET+PRO compared with PRO and KET. KET, PRO, and KET+PRO stimulated postprandial MyoPS rates (0-300 min) higher than basal conditions [absolute change: 0.020%/h; (95% CI: 0.013, 0.027%/h), 0.014%/h (95% CI: 0.009, 0.019%/h), 0.019%/h (95% CI: 0.014, 0.024%/h), respectively (time: P < 0.001)], with no difference between treatments (treatment: P = 0.383) or treatment × time interaction (interaction: P = 0.245). mTORC1 pathway signaling responses did not differ between treatments (all P > 0.05).

CONCLUSIONS

Acute oral intake of a ketone monoester, 10 g whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of postprandial MyoPS rates in healthy young males. This trial was registered at clinicaltrials.gov as NCT04565444 (https://clinicaltrials.gov/study/NCT04565444).

Transdermal Glyceryl Trinitrate to Allow Peripheral Total Parenteral Nutrition: A Double-Blind Placebo Controlled Feasibility Study

Seventy-two consecutive patients requiring total parenteral nutrition (TPN) were randomized to two groups. Group A received daily a peripheral intravenous regimen which provided 10 g nitrogen and 1400 non-nitrogen kcal (5.9 MJ). Group B received daily a peripheral intravenous regimen which delivered 9.4 g nitrogen and 1900 non-nitrogen kcal (8.0 MJ). Each group was further randomized to receive a self-adhesive patch of transdermal glyceryl trinitrate (GTN) or an identical placebo. Infusion survival was the main end-point. For group A, the median time of infusion survival was 74 h (range: 58–100) in the control group compared with 108 h (range: 68–156) in the group that received transdermal GTN (P < 0.001). For group B, the median infusion survival was 67 h (range: 46–92) in the control group compared with 103 h (range: 66–151) in the treatment group (P < 0.001). TPN is feasible via peripheral veins and the incidence of infusion failure can be effectively reduced by transdermal GTN.

Protein sparing therapies in acute illness and obesity: a review of George Blackburn's contributions to nutrition science

Protein sparing therapies were developed to mitigate the harms associated with protein-calorie malnutrition and nitrogen losses induced by either acute illness or hypocaloric diets in patients with obesity. We review the development of protein sparing therapies in illness and obesity with a focus on the pioneering contributions of George Blackburn, MD, PhD. He recognized that protein-calorie malnutrition is a common and serious clinical condition and developed new approaches to its treatment in hospitalized patients. His work with stable isotopes and with animal models provided answers about the physiological nutritional requirements and metabolic changes across a spectrum of conditions with varying degrees of stress and catabolism. This led to improvements in enteral and parenteral nutrition for patients with acute illness. Blackburn also demonstrated that lean body mass can be preserved during weight loss with carefully designed very low calorie treatments which became known as the protein sparing modified fast (PSMF). We review the role of the PSMF as part of the comprehensive management of obesity.

Nutrition support in hospitalised adults at nutritional risk

BACKGROUND

The prevalence of disease-related malnutrition in Western European hospitals is estimated to be about 30%. There is no consensus whether poor nutritional status causes poorer clinical outcome or if it is merely associated with it. The intention with all forms of nutrition support is to increase uptake of essential nutrients and improve clinical outcome. Previous reviews have shown conflicting results with regard to the effects of nutrition support.

OBJECTIVES

To assess the benefits and harms of nutrition support versus no intervention, treatment as usual, or placebo in hospitalised adults at nutritional risk.

SEARCH METHODS

We searched Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE (Ovid SP), Embase (Ovid SP), LILACS (BIREME), and Science Citation Index Expanded (Web of Science). We also searched the World Health Organization International Clinical Trials Registry Platform (www.who.int/ictrp); ClinicalTrials.gov; Turning Research Into Practice (TRIP); Google Scholar; and BIOSIS, as well as relevant bibliographies of review articles and personal files. All searches are current to February 2016.

SELECTION CRITERIA

We include randomised clinical trials, irrespective of publication type, publication date, and language, comparing nutrition support versus control in hospitalised adults at nutritional risk. We exclude trials assessing non-standard nutrition support.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane and the Cochrane Hepato-Biliary Group. We used trial domains to assess the risks of systematic error (bias). We conducted Trial Sequential Analyses to control for the risks of random errors. We considered a P value of 0.025 or less as statistically significant. We used GRADE methodology. Our primary outcomes were all-cause mortality, serious adverse events, and health-related quality of life.

MAIN RESULTS

We included 244 randomised clinical trials with 28,619 participants that met our inclusion criteria. We considered all trials to be at high risk of bias. Two trials accounted for one-third of all included participants. The included participants were heterogenous with regard to disease (20 different medical specialties). The experimental interventions were parenteral nutrition (86 trials); enteral nutrition (tube-feeding) (80 trials); oral nutrition support (55 trials); mixed experimental intervention (12 trials); general nutrition support (9 trials); and fortified food (2 trials). The control interventions were treatment as usual (122 trials); no intervention (107 trials); and placebo (15 trials). In 204/244 trials, the intervention lasted three days or more.We found no evidence of a difference between nutrition support and control for short-term mortality (end of intervention). The absolute risk was 8.3% across the control groups compared with 7.8% (7.1% to 8.5%) in the intervention groups, based on the risk ratio (RR) of 0.94 (95% confidence interval (CI) 0.86 to 1.03, P = 0.16, 21,758 participants, 114 trials, low quality of evidence). We found no evidence of a difference between nutrition support and control for long-term mortality (maximum follow-up). The absolute risk was 13.2% in the control group compared with 12.2% (11.6% to 13%) following nutritional interventions based on a RR of 0.93 (95% CI 0.88 to 0.99, P = 0.03, 23,170 participants, 127 trials, low quality of evidence). Trial Sequential Analysis showed we only had enough information to assess a risk ratio reduction of approximately 10% or more. A risk ratio reduction of 10% or more could be rejected.We found no evidence of a difference between nutrition support and control for short-term serious adverse events. The absolute risk was 9.9% in the control groups versus 9.2% (8.5% to 10%), with nutrition based on the RR of 0.93 (95% CI 0.86 to 1.01, P = 0.07, 22,087 participants, 123 trials, low quality of evidence). At long-term follow-up, the reduction in the risk of serious adverse events was 1.5%, from 15.2% in control groups to 13.8% (12.9% to 14.7%) following nutritional support (RR 0.91, 95% CI 0.85 to 0.97, P = 0.004, 23,413 participants, 137 trials, low quality of evidence). However, the Trial Sequential Analysis showed we only had enough information to assess a risk ratio reduction of approximately 10% or more. A risk ratio reduction of 10% or more could be rejected.Trial Sequential Analysis of enteral nutrition alone showed that enteral nutrition might reduce serious adverse events at maximum follow-up in people with different diseases. We could find no beneficial effect of oral nutrition support or parenteral nutrition support on all-cause mortality and serious adverse events in any subgroup.Only 16 trials assessed health-related quality of life. We performed a meta-analysis of two trials reporting EuroQoL utility score at long-term follow-up and found very low quality of evidence for effects of nutritional support on quality of life (mean difference (MD) -0.01, 95% CI -0.03 to 0.01; 3961 participants, two trials). Trial Sequential Analyses showed that we did not have enough information to confirm or reject clinically relevant intervention effects on quality of life.Nutrition support may increase weight at short-term follow-up (MD 1.32 kg, 95% CI 0.65 to 2.00, 5445 participants, 68 trials, very low quality of evidence).

AUTHORS' CONCLUSIONS

There is low-quality evidence for the effects of nutrition support on mortality and serious adverse events. Based on the results of our review, it does not appear to lead to a risk ratio reduction of approximately 10% or more in either all-cause mortality or serious adverse events at short-term and long-term follow-up.There is very low-quality evidence for an increase in weight with nutrition support at the end of treatment in hospitalised adults determined to be at nutritional risk. The effects of nutrition support on all remaining outcomes are unclear.Despite the clinically heterogenous population and the high risk of bias of all included trials, our analyses showed limited signs of statistical heterogeneity. Further trials may be warranted, assessing enteral nutrition (tube-feeding) for different patient groups. Future trials ought to be conducted with low risks of systematic errors and low risks of random errors, and they also ought to assess health-related quality of life.

An Evaluation of Peripheral Essential Amino Acid Infusion following Major Surgery

To assess postoperative progress 43 patients undergoing major abdominal procedures were randomized to be given normal postoperative electrolyte solutions alone or with the addition of 400 ml of essential amino acids. Postoperative measurements confirmed a nitrogen retention significant at 0.1%. Decreased breakdown of muscle was also shown by measuring the upper arm muscle circumference and by following the grip strength. Those treated had no significant muscle loss postoperatively but there was significant loss in those not receiving amino acids. The intravenous cannulae survived equally well in both groups. There was no demonstrable difference in the overall clinical progress.

Ketogenic enteral nutrition as a treatment for obesity: short term and long term results from 19,000 patients

Background

Only protein diet has been used successfully to prevent loss of lean body mass first in post-surgical and then in obese patients. We studied overweight and obese patients receiving short treatments of an exclusively protein-based nutritional solution as 24-hour enteral infusion.

Methods

19,036 patients (age 44.3 ± 13, M:F = 2:5) with an initial body mass index of 36.5 ± 7.1 underwent 10-day cycles of enteral nutrition through a fine nasogastric tube. The nutritional solution consisted solely of 50–65 g of proteins, plus vitamins and electrolytes. The 24-hour infusion was controlled with a small portable pump. Before and after each 10-day cycle body composition was checked with a Handy 3000 impedance analyzer. At the onset of treatment, average fat mass was 40.9 ± 12.8 kg while body cell mass was 42.7 ± 7.2 kg in males and 27.4 ± 4.6 kg in females.

Results

After an average of 2.5 cycles the patients lost 10.2 ± 7.0 kg of body weight, 5.8 ± 5.5 kg of fat mass and 2.2 ± 3.3 kg of body cell mass. No significant adverse effects were recorded except asthenia and constipation which were easily controlled with therapy. Long-term results were obtained from 15,444 patients and after an average of 362 ± 296 days we found a mean weight regain of 15.4%.

Conclusion

Ketogenic Enteral Nutrition treatment of over 19,000 patients induced a rapid 10% weight loss, 57% of which was Fat Mass. No significant adverse effects were found. The treatment is safe, fast, inexpensive and has good one-year results for weight maintenance.

The role of glucose, long-chain triglycerides and amino acids for promotion of amino acid balance across peripheral tissues in man

The role of amino acids, glucose and lipids in improving amino acid balance in peripheral tissues was evaluated. Primed constant infusion of L-[ring-2H5]phenylalanine in combination with flux measurements of glucose, free fatty acids (FFA) and amino acids across arm and leg tissues were applied in male volunteers after an overnight fast with subsequent primed constant infusions of amino acids (0.2 g N kg-1 body weight day-1), long-chain triglycerides (0.98-1.079 g kg-1 day-1) and glucose (3.13-3.62 g kg-1 day-1). Amino acids and phenylalanine tracer infusion continued for 6 h; the lipid infusion was provided during 2-6 h from the start, and glucose infusion was provided between 4 and 6 h. Flux measurements were performed at steady state before the next infusion started. Arterial concentrations of infused substrates increased during provision, but remained constant thereafter. Plasma insulin increased when glucose was provided, whereas insulin-like growth factor (IGF) I was unchanged during all infusions. Blood flow was unchanged in arm tissue during all infusions, while leg blood flow increased during fat and glucose infusion. FFA and glucose balance were unchanged during amino acid infusion but improved during lipid and glucose infusions. Amino acid balance was negative across arm and leg tissues in the fasted state, but reached balance during amino acid infusion. This effect was equally dependent on protein synthesis and protein degradation without any contribution from lipids and glucose. 3-Methylhistidine release from tissues was not influenced by any substrate. Our results suggest that extracellular amino acid concentrations determine amino acid balance across peripheral tissues independently of non-protein calories, insulin and IGF-I.

Effect of amino acid infusion on glucose production in trauma patients

The relationship between precursor supply and hepatic glucose output (HGO) was examined in 8 control subjects and 12 trauma patients after a fasting period of approximately 60 hours. Glucose kinetics were measured with a primed-constant infusion of [U-14C]glucose and [6-3H]glucose. The basal rate of HGO was 5.45 +/- 0.22 micromol x kg-1 x min-1 in the controls and 13.16 +/- 0.76 micromol x kg-1 x min-1 following trauma (p < 0.001). Four hours after amino acid infusion of 1.3 g x kg-1 x 24 h-1, HGO in the controls was unchanged at 5.35 +/- 0.22 micromol x kg-1 x min-1 but it had decreased to 11.71 +/- 0.67 micromol x kg-1 after trauma (p < 0.001). We conclude that increasing the supply of gluconeogenic precursors does not stimulate HGO in normal subjects after fasting or after severe trauma and that factors other than to availability of amino acids are responsible for the enhanced rate of HGO in trauma patients.

First choice for total parenteral nutrition: the peripheral route

Historically, total parenteral nutrition (TPN) has been administered by the central venous route because of the rapid development of thrombophlebitis when TPN solutions are administered into peripheral veins. The insertion and placement of central venous catheters is, however, associated with morbidity and mortality and is the main cause of TPN-related complications. By avoiding central venous catheterization, TPN can be made safer. Current awareness about the pathophysiology of peripheral vein thrombophlebitis and the use of a number of techniques that prevent or delay onset of peripheral vein thrombophlebitis mean it is now possible to administer TPN via the peripheral route. These techniques and changes in the practice of TPN in recent years (eg, reduction of caloric loads and use of lipid emulsions) mean peripheral parenteral nutrition is a technique that is now applicable to the majority of hospitalized, nutritionally compromised patients for whom intravenous feeding is anticipated for less than 10 to 14 days.

The importance of a source of sufficient protein in postoperative hypocaloric partial parenteral nutrition support

A comparison of postoperative metabolic and nutritional responses to different hypocaloric parenteral nutrition supports was performed in 42 patients with various gastric lesions. Sixteen patients (group A) received 3000 mL of a 5% glucose in water or glucose in saline infusion per day after surgery (approximately 10 kcal/kg per day). Another 14 patients (group B) received 2000 mL of 5% glucose in water or saline plus 1000 mL of 5% amino acid solution per day (approximately 10 kcal/kg per day and 1 g of protein per kilogram per day). The other 12 patients (group C) received 2000 mL of 5% glucose in water or saline plus 500 mL of 5% amino acid solution and 500 mL of 10% fat emulsion (approximately 20 kcal/kg per day and 0.5 g of protein per kilogram per day). After 7 days of study, all three groups were found to have a decrease in body weight, mid-arm circumference, triceps skin-fold, and serum albumin level, and the differences among them were not significant. Groups B and C had significantly less negative mean nitrogen balance than group A (-5.54 +/- 0.63 g/d and -6.07 +/- 0.49 g/d vs -9.20 +/- 0.68 g/d). Group B also had a significantly greater increase of transferrin (from 175.5 +/- 9.9 mg/dL to 185.4 +/- 9.3 mg/dL) than group A and a significantly greater increase in total lymphocyte count (from 956 +/- 113 cells/mm3 to 1196 +/- 176 cells/mm3) than groups A and C.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma-specific proteins: their response to surgical trauma and tumour load, and modification of this response by post-operative metabolic support

Concentrations of plasma proteins with short half-life have been suggested as indicators of nutritional state in surgical patients. Trauma also affects the circulating concentrations of these proteins. Serum concentrations of retinol binding protein (RBP), pre-albumin and transferrin were determined pre- and post-operatively on different supporting regimens. The circulating concentration of these liver proteins displayed no differential effect of the supporting regimen during the first 5 post-operative days. None of the patients with tumour demonstrated any indication of hepatic metastases pre-operatively or at the time of laparotomy but, as a group, had lower pre-operative concentrations of RBP (p < 0.001) and pre-albumin (p < 0.01) than patients with no tumour load. In addition 55% of patients (15:27) with tumour had RBP concentrations <3.5 mg/dl; all of the non-tumour bearing patients (13/13) had RBP concentrations >3.5 mg/dl. RBP and pre-albumin appear to act as non-specific tumour markers, but not to serve a useful function as short-term nutritional markers of post-operative support.

The effect of glucose administration on carbohydrate metabolism after head injury

The role of intravenous infusion of glucose in limiting ketogenesis and the effect of glucose on cerebral metabolism following severe head injury were studied in 21 comatose patients. The patients were randomly assigned to alimentation with or without glucose. Systemic protein wasting, arterial concentrations of energy substrates, and cerebral metabolism of these energy substrates were monitored for 5 days postinjury. Both groups were in negative nitrogen balance, and had wasting of systemic proteins despite substantial protein intake. Blood and cerebrospinal fluid (CSF) glucose concentrations were highest on Day 1, but remained higher than normal fasting levels on all days of study, even in the patients who received no exogenous glucose. Although there were no differences in blood or CSF glucose concentrations in the two groups of patients, the glucose group had higher plasma insulin levels, with a mean +/- standard deviation of 14.8 +/- 7.3 microU/ml compared to 10.3 +/- 4.2 microU/ml in the saline group. The blood concentrations of beta-hydroxybutyrate, acetoacetate, pyruvate, glycerol, and the free fatty acids were higher in the saline group than in the glucose group. Cerebral oxygen consumption was similar in the two groups, while the cerebral metabolism of glucose and of the ketone bodies was dependent on whether glucose was administered. In the glucose group, glucose was the only energy substrate utilized by the brain. In the saline group, the ketone bodies beta-hydroxybutyrate and acetoacetate replaced glucose to the extent of 16% of the brain's total energy production. Cerebral lactate production and CSF lactate concentration were lower in the saline group. These studies suggest that administration of glucose during the early recovery period of severe head injury is a major cause of suppressed ketogenesis, and may increase production of lactic acid by the traumatized brain by limiting the availability of nonglycolytic energy substrates.

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.

Incidence of phlebitis in peripheral parenteral nutrition: Effect of the different nutrient solutions

To determine the influence of peripheral parenteral nutrition (PPN) on the incidence of phlebitis and the effect of simultaneous infusion of lipid emulsion, 68 surgical patients were assigned randomly to 3 nutrition groups: (1) amino-acid 4% solution and dextrose 8% (AA + DX) + Intralipid (IL) 10% in the ratio 1.5:1 (2) AA + DX and IL 20% in the ratio 3:1 (3) AA + DX alone. Group 4 (control group) consisted of 25 patients receiving maintenance solutions and iso-osmotic drugs. No filters were used. The cannulae were studied for 72 hours and the cannula sites were evaluated daily for phlebitis. Mean age of patients was 52.3 +/- 17.7 years, with a similar sex ratio in the 4 groups. One hundred and twenty-five cannulae were studied. At 72 h, the following cumulated phlebitis rates were recorded: 22% in Group 1 (712 mOsm/L), 48% in Group 2 (802.5 mOsm/L), 44% in Group 3 (920 mOsm/L) and 26% in Group 4 (260-314 mOsm/L). The phlebitis incidence was similar in groups 1 and 4 (control) throughout the study. Both Groups 2 and 3 had higher phlebitis rates on days 2 and 3 (II: p < 0.05, III: p < 0.01). It is concluded that PPN with simultaneous IL 10% in the ratio 1.5:1 is no more phlebogenic than the usual maintenance solutions during the first 72 h. This is probably due to the lower osmolality and lower DX and K concentrations of the solution with IL 10%. Intralipid 20% does not have the same protective venous effect. The lower complication rate, the limited need for nursing, and lower costs compared to central parenteral nutrition, make PPN a safe nutrition technique for up to 10 days in patients needing no volume restriction.

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.

Minor role of ketone bodies in energy metabolism by skeletal muscle tissue during the postoperative course

To evaluate changes of peripheral ketone body (KB) metabolism after operation, muscle metabolism in postsurgical patients was studied at 3 hours (SI) and 24 hours (SII) after surgery by the forearm catheter technique. Data were compared to those of equivalent fasted controls (CI, CII). In a manner consistent with enhanced mobilization of endogenous substrate stores, arterial concentrations of free fatty acids (FFA), 3-hydroxybutyrate (3-HOB), and acetoacetate (AcAc) were markedly elevated immediately after surgery. This increase was accompanied by a rise in muscular utilization of AcAc (SI: 0.21 +/- 0.05 mumol/100 g/min; CI: 0.08 +/- 0.05, p less than 0.05) and 3-HOB (SI: 0.24 +/- 0.06 mumol/100 g/min; CI: 0.11 +/- 0.01, p less than 0.05). Surprisingly, on the first postoperative day, concentrations of AcAc and 3-HOB fell below those of fasting controls. Concomitantly, the utilization rate of AcAc by muscle (SII: 0.07 +/- 0.03 mumol/100 g/min; CII: 0.27 +/- 0.04, p less than 0.05) was significantly lower in patients than in controls. Reduction of the fractional extraction rate of AcAc (SI: 38.4 +/- 3.8%; SII: 24.0 +/- 6.1%, p less than 0.05), as well as a net production of 3-HOB by muscle (SII: -0.08 +/- 0.05 mumol/100 g/min; CII: 0.49 +/- 0.13, p less than 0.05) 24 hours after surgery indicated a reduced peripheral capacity for KB removal. Since this finding was related to a significantly higher rate of muscular glycerol production (SII: -0.13 +/- 0.03 mumol/100 g/min; CII: -0.06 +/- 0.02, p less than 0.05), one may suggest that increased intramuscular availability of FFA from triglyceride hydrolysis was responsible for the impairment of peripheral KB utilization. These results indicate that KBs contribute little to energy metabolism in skeletal muscle tissue in the late postoperative phase.

Parenteral nutrition via peripheral veins: a feasibility study

Twenty patients who had undergone uncomplicated surgery of moderate severity were randomly allocated to two groups (both n = 10) who were fed using a peripheral vein for up to six days. Group I received, each day, a nutrient solution providing 10 grams of nitrogen as Perifusin (E Merck Ltd) and 1400 calories as dextrose and Intralipid (Kabivitrum Ltd) with an osmolality of 490 mosmol/kg. Group II received only 15 grams of nitrogen per day as Perifusin with an osmolality of 376 mosmol/kg. The mean (+/- s.e. mean) nitrogen balance over the study was similar in both groups, in Group I being -1.23 +/- 0.89, and in Group II being -1.05 +/- 1.08 g (P greater than 0.05 Mann-Whitney U test). The nutrient mixture given to Group I resulted in elevated levels of serum 3-hydroxybutyrate and lower levels of serum non-esterified fatty acids. These data suggest that lipolysis and ketogenesis were suppressed. There was no significant difference in serum lactate levels in either group. Venous thrombophlebitis at the infusion site was assessed daily using Maddox's criteria, with a minimal degree of inflammation occurring in either group. This preliminary study suggests that a total parenteral feeding regimen may be designed for peripheral vein infusion. Further studies are indicated.

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)

Nutritional and metabolic support following acute hepatic trauma

A patient undergoing partial hepatectomy subsequent to trauma was maintained post-operatively on a specifically tailored total parenteral nutrition regimen. This, despite obviously impaired liver function, allowed adequate nutrition without the expected adverse metabolic sequelae associated with hepatic resection and nitrogen loading. The patient also demonstrated, in the absence of normal hepatic tissue, an ameliorated metabolic response to trauma.

Post operative stimulation of cell mediated immunity

The consequences of altered immuno-competence resulting from anaesthesia and surgery are potentially hazardous to the patient with malignant disease. Malnutrition also produces reduction in cell mediated immunity, a condition which is commonly incurred in patients with neoplastic disorders. Numerous agents have been claimed to stimulate the immune responses but few have proved to be of practical value. This paper reports the use variously of protease inhibitors, using Aprotinin, and post operative nutritional therapy, following major surgical resection for carcinoma - specifically as regards their influence on parameters believed to relate to cell mediated immunity. No clinical, metabolic or immunologic benefit was identified from either method of post operative stimulation of cell mediated immunity, although this study did confirm post operative depression of these parameters. The significance of these changes is unclear but there is no evidence to support an immunological mechanism for either of these approaches being of benefit in clinical practice.

Multidisciplinary treatment of obesity with a protein-sparing modified fast: results in 668 outpatients

Six hundred sixty-eight obese outpatients, 71 per cent (+/- 34) in excess of ideal weight, were enrolled in a multidisciplinary weight control program. The major components of the program included nutrition, education, behavior modification, and exercise. Rapid weight loss was accomplished using a very low calorie (less than 800 kcal) ketogenic diet. Patients adhered to the protein sparing modified fast (PSMF) for 17 +/- 12 weeks and averaged 9 +/- 17 weeks in a refeeding/maintenance program. Mean weight loss was 47 +/- 29 lb (21 +/- 13 kg) at the point of minimum weight and 41 +/- 29 lb (19 +/- 13 kg) at the end of the maintenance period. Systolic and diastolic blood pressure and serum triglycerides fell significantly in men and women. Success in weight loss was greatest in the heaviest patients, those who adhered the longest to the PSMF, and those who stayed the longest in the maintenance program.

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.

The effect of major thermal injury on plasma ketone body levels

Eleven patients with more than 30% total body surface burns were studied during 3 days of starvation and three more days of unrestricted feeding following their injury. All patients developed marked protein mobilization as demonstrated by 3rd day urine nitrogen excretion of 17.1 g daily compared to control excretion of 11.8 g N daily. As a group, the patients failed to mount the expected ketonemic response during their initial period of starvation. Whereas normal fasted controls achieved plasma ketone body levels of 727 +/- 81 mumol/liter, the burn patients responded with an average level of 385 +/- 77 mumol/liter (p less than 0.01).

Insulin-dependent diabetes during the peri-operative period. An assessment of continuous glucose-insulin-potassium infusion, and traditional treatment

Twenty seven insulin-dependent diabetics, and six non-diabetic subjects undergoing elective surgery have been studied. Twelve diabetics received continuous glucose-insulin-potassium (GIK) infusion for at least 4 hours after surgery terminated. Six diabetic patients having morning surgery received a proportion of their morning insulin dose with intravenous glucose (25 g) before surgery and the remaining five operated on in the afternoon received their morning insulin with breakfast. Non-GIK groups were combined and compared with GIK. Postoperative diabetic treatment was the same in both groups. Plasma glucose changes were studied in all patients and other metabolites whenever possible. Mean pre-operative glucose, non-esterfied fatty acid, and 3-hydroxybutyrate concentrations were similar in GIK and non-GIK groups. Four hours postoperatively plasma glucose, and 3-hydroxybutyrate values were lower in the GIK group than in the non GIK group (p less than 0.05) as were mean plasma non-esterfied fatty acid levels. Plasma glucose concentration was also lower in GIK subjects at 72 hours postoperatively (p less than 0.01). At other times measured metabolic variables were similar in both GIK and non GIK groups.

Decreased plasma fibronectin during starvation in man

This study evaluated the effect of 5 days of starvation followed by 5 days of refeeding on immunoreactive plasma and serum fibronectin and associated opsonic activity as studied by peritoneal macrophage monolayer bioassay in 12 healthy women volunteers. The temporal alteration of fibronectin was compared with the serum albumin, total iron-binding capacity, and retinol-binding protein levels. Fibronectin concentration and opsonic activity were also determined in two cachectic patients who were 61 and 78% of their ideal body weight. Prior to starvation, plasma fibronectin was 292 +/- 20 micrograms/ml and serum fibronectin was 182 +/- 16 in all subjects. After 5 days of starvation, immunoreactive fibronectin decreased (p less than 0.05) by 20-25%. This decrease was not great enough to impair opsonic activity as tested by the in vitro macrophage assay. Starvation caused no decrease in serum albumin or total iron-binding capacity, although retinol-binding protein decreased by 35%. During refeeding, subjects were randomized to a diet with (n = 6) and without (n = 6) carbohydrate. After 5 days of refeeding, fibronectin levels were normalized on the carbohydrate-containing diet, but were still low (82% of normal) on the carbohydrate-free diet. Retinol-binding protein did not fully normalize after 5 days of refeeding. In the two cachectic patients, fibronectin levels prior to total parenteral nutrition were 25 and 75% of normal. Thus, starvation can lower fibronectin levels and this protein is rapidly restored with adequate nutrition.

The effect of different carbohydrate intakes on body weight and nitrogen balance during nasogastric feeding after faciomaxillary surgery

In order to assess the effects on body composition of different carbohydrate intakes when nitrogen supply is constant and adequate (9 g/day), we gave either no carbohydrate, sufficient to avoid ketosis (100 g) or at least enough to satisfy energy needs (600 g) to a group of six patients after major faciomaxillary surgery. Each patient was given the different feeds for 3-day periods in a randomised, cross over design. 100 g carbohydrate was effective in avoiding negative nitrogen balance, but weight loss was only prevented when 600 g was used. Differences in water balance suggest that mobilisation and repletion of body glycogen (with associated water) probably account for most of these differences in body weight changes.

Modification of postoperative nitrogen balance with preoperative anabolic steroid

Thirty six patients undergoing abdominal operations were randomly allocated to receive an anabolic steroid, stanozolol (50 mg) or placebo 24 h before surgery. Patients were fasted during the first four postoperative days. During this period the mean daily nitrogen balance was significantly less negative in the stanozolol group (-8.0+/-3.0 gN/day) than in the control group (-10.9+/-4.1 gN/day), although improvement in nitrogen balance was greater in male than in female patients. Muscle catabolism as measured by 3-methylhistidine excretion was similar in both treatment groups. Significant fluid retention occurred in the stanozolol treated group and was more marked in female patients. Improved nitrogen balance in the absence of a measurable change in muscle catabolism suggests that this anabolic steroid acts by improving protein synthesis in the early period after surgery.

[Essential fatty acids in the plasma of severely injured patients under parenteral feeding]

After a heavy injury there are characteristic changes of plasma lipids and lipoproteins. In 7 patients up to 40 days after major injury the fatty acids of cholesteryl esters, phospholipids and triglycerides in plasma under the influence of injury, parenteral nutrition with carbohydrates or fat, and protein-sparing therapy were determined by gas liquid chromatography. These patients' increased requirement for linoleic acid is further increased by up to more than 50 g per day by carbohydrate-rich parenteral nutrition, inhibiting lypolysis of linoleic acid from adipose tissue. Protein-sparing therapy without carbohydrates is not sufficient to cover the patients' increased requirement for linoleic acid. Thus, the early administration of fat emulsions in parenteral nutrition is recommended.

Nitrogen utilization during postoperative, low nitrogen, high caloric parenteral nutrition

Twenty elderly patients having undergone colonic resection were randomized into two regimens of postoperative parenteral nutrition. Fructoglucose satisfied the basal caloric needs of the patients. Amino acids were given as a mixture that provided 0.11 (0.09-0.14; mean and range) g/kg/day of nitrogen only. In half of the patients the energy intake was doubled with fat emulsion. The mean nitrogen-energy ratios in grams of nitrogen/kcal/day were 1:201 and 1:336 in the two groups, respectively. Both regimens were given for three days, starting from the first postoperative day. On the first day, the mean nitrogen balance was negative in both groups. On the third day, the mean balance was slightly positive in the amino acid, fructoglucose plus fat emulsion group, but negative in amino acid plus fructoglucose group. Amino acid concentrations in plasma and urine were markedly elevated in both groups, but relative concentrations in plasma remained rather normal. Apparently, a positive postoperative nitrogen balance can be obtained with restricted amino acid supply, if energy is provided in abundance.

Peripheral vein complications in patients receiving amino acid/dextrose solutions

The incidence and severity of peripheral vein phlebitis was evaluated in patients receiving infusions of amino acids alone (1.4 g/kg/day) (group I), amino acids (1.4 g/kg/day) plus 5% dextrose (group II) and 5% dextrose alone (Group III). Ninety-three patients with carcinoma of the bladder were randomized to receive one of three peripheral parenteral nutrition solutions which were infused predominantly via scalp-vein needles. Peripheral parenteral nutrition solutions contained sodium and potassium chloride as necessary to maintain normal serum electrolyte levels. The osmolality of each solution was calculated. Peripheral intravenous sites were evaluated every 8 hr and at the time of each intravenous site change. The incidence of infiltration, phlebitis and its' severity was recorded and graded zero (no complications) to 4 (severe complications). An intravenous cannula was discontinued if infiltration or a grade 2 or greater phlebitis occurred. The mean osmolality of the solutions were (group I) 450 to 500 mosm/liter, (group II) 713 to 763 mosm/liter and (group III) 369 mosm/liter. The mean duration of infusion was 9.0 + 0.4, 9.1 + 0.4, and 8.7 + 0.5 days, respectively, and the mean number of intravenous site changes were 6.1 + 0.3, 5.8 + 0.3, and 5.6 + 0.3, respectively. Infiltration preceded 57, 56, and 58% of all intravenous site changes and the incidence and severity of peripheral vein phlebitis was similar for all three groups. Sixty patients who received their infusions via plastic indwelling catheters for a mean duration of 2.6 + 1.0, 2,3 + 1.0, and 2.8 + 1.0 days had an 86, 71, and 76% incidence of grade two or greater phlebitis, respectively. There was no significant difference in the incidence of infiltration and phlebitis in patients receiving peripheral parenteral infusions of amino acids alone, amino acids plus dextrose, and 5% dextrose 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.

The metabolic effects of isotonic amino acid infusion in surgical sepsis

28 normally nourished adult male and female patients who had undergone major elective surgery were maintained on dextrose-free isotonic amino acid solutions as their sole nutritional support. In the 6 days after surgery, 15 patients had no septic complications, 9 developed superficial sepsis, and 4 developed a deep seated collection of pus or deep sepsis. Patients without infection developed and maintained a fasting metabolic fuel profile within the first 3 days and increasingly spared protein. Superficial sepsis caused a small depression in serum ketone body concentrations but did not otherwise alter the fasting profile. Moreover nitrogen balances and plasma albumin and transferrin concentrations were unaltered by superficial sepsis which is not the response usually recognised with infection. Metabolic adaptation to the fasting state was lost in patients with deep sepsis and nitrogen losses were increased with greater decreases in plasma albumin and transferrin.

Effects of hypocaloric dextrose and amino acids on body composition and nitrogen balance in rats

Studies were conducted to compare the effects of isocaloric intake of glucose, amino acids, and combinations of these nutrients on nitrogen balance, body composition, and selected metabolic parameters of adult rats. Diets were administered either orally or intravenously at 20% (semi-starvation) of the daily caloric requirement. Although nitrogen balance was improved when all calories were supplied as amino acids when compared to glucose alone, one-half the amino acids could be replaced with glucose without sacrificing nitrogen balance. Animals from the semi-starvation treatment showed similar weight and body composition changes, there was no apparent difference whether the diets were administered orally or intravenously. These results indicate that replacement of at least one-half the calories of an all amino acid hypocaloric diet with glucose does not adversely affect body composition weight change or nitrogen balance, but may reduce blood urea nitrogen, ketosis, and cost of nutritional support.

Nutritional support of the surgical patient

Malnutrition, unfortunately, is not uncommon and malnourished patients suffer increased morbidity and mortality from surgery. Identification of protein-calorie deficient patients can be performed rapidly and inexpensively through standard techniques of nutritional assessment. If the gastrointestinal tract is available, safe and economic nutritional support may be provided by mouth or by tube feeding. If the gastrointestinal tract cannot be utilized, total parenteral nutrition (TPN) may be instituted via a central vein, or in selected instances peripheral amino acids, fat emulsions, or both may suffice. When failure of various organs (heart, kidneys, liver) complicates malnutrition and the underlying surgical condition, adequate nutritional support can and should be provided by adjustment of the amount and content of commercially available nutritional formulations. Optimal surgical care demands the identification and appropriate nutritional support of malnourished patients.

[Protein-sparing effect of various types of peripheral parenteral nutrition]

A randomized clinical study was performed postoperatively in a total of 47 patients comparing three different concepts of peripheral parenteral nutrition. Substituting 1 g amino acids (AA)/kg b.w. daily, the amount of carbohydrates (CH) was changed solely: gr. II no carbohydrates (sole AA-substitution), gr. III 2 g CH/kg b.w. (hypocaloric nutrition) and gr. IV 5 g CH/kg b.w. (basic nutrition). The influence on protein metabolism was examined by cumulative N-balances, various plasma proteins viscerally synthesized and serum amino acids predominantly utilised in peripheral tissues. In comparison to a non-fed-control group (I), hypocaloric nutrition showed the qualitative most favourable protein-sparing effect. Besides, 87% of N-retention serum levels of plasma proteins and amino acids investigated could be normalized completely. Peripheral basic nutrition also had a 88% rate of N-retention, however, only peripherally utilised amino acids were influenced beneficially whereas the plasma proteins remained depleted. Sole AA-substitution neither affected amino acid levels nor plasma proteins, and the N-retention rate was significantly lowered (67%). Possibly this type of therapy increases protein turnover solely, while true protein-sparing took place only with additional CH supply. However, a positive effect on visceral protein synthesis was observed exclusively with hypocaloric nutrition.

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.