Elemental balances during intravenous hyperalimentation of underweight adult subjects

Obesity and adiposity: the culprit of dietary protein efficacy

Obesity and increased body adiposity have been alarmingly increasing over the past decades and have been linked to a rise in food intake. Many dietary restrictive approaches aiming at reducing weight have resulted in contradictory results. Additionally, some policies to reduce sugar or fat intake were not able to decrease the surge of obesity. This suggests that food intake is controlled by a physiological mechanism and that any behavioural change only leads to a short-term success. Several hypotheses have been postulated, and many of them have been rejected due to some limitations and exceptions. The present review aims at presenting a new theory behind the regulation of energy intake, therefore providing an eye-opening field for energy balance and a potential strategy for obesity management.

Relationships among Dietary Quality, Children's Appetites, Growth Stunting, and Efficiency of Growth in Poor Populations

In Jamica, as in other developing countries less well off, the diets of low-income children are low in energy and protein relative to recommended intakes. Dietary intake is further reduced by anorexia which accompanies infections as well as deficiencies of specific essential nutrients in the diet, such as essential amino acids, potassium, phosphorus, or zinc. Imbalanced diets also limit synthesis of lean tissue and result in growth failure. The results of food-supplementation studies in young children in the developing world have indicated little effect on weight or height gain. In spite of being offered large amounts of dietary energy, the children receive far less than intended because of the anorexia caused by infection, specific nutrient deficiencies, and imbalanced diets. Attention should be paid to nutrient balance (quality) as well as nutrient intake (quantity) in both diets and dietary supplements offered to these children.

Malnutrition in Gastrointestinal Disorders: Detection and Nutritional Assessment

All patients with significant gastrointestinal disease should be clinically assessed for protein calorie malnutrition by using the Subjective Global Assessment. Blood tests for anemia, electrolytes, calcium, phosphorus, magnesium, ferritin, vitamin B₁₂, and folate should be considered for assessment of major micronutrients. Where malabsorption or inflammatory bowel disease is diagnosed, bone mineral density using dual beam x-ray absorptiometry, 25-OH vitamin D levels, and measurement of other vitamins and trace elements should be considered. In addition, in at-risk patients, vitamin and trace element clinical deficiency syndromes should be considered during patient assessment.

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.

Defining, Recognizing, and Reporting Malnutrition

Although malnutrition is a common health and social care problem, there is no universal agreement about its definition, prevalence, or method of identification and report. Fifteen definitions of malnutrition were critically examined to assess their variability. They ranged from descriptions of undernutrition alone to under- and overnutrition, with intakes ranging from dietary protein and energy alone to dietary and nondietary sources of all nutrients and energy. Definitions also varied from non-outcome based to those based on functional, physiological, and/or clinical outcomes. Some definitions relied on the pathways by which malnutrition develops, with one apparently requiring loss of fat-free mass. Also examined were nutrition screening tools, diversely developed for detection of malnutrition, management of malnutrition, and prediction of clinical outcomes or health care usage. Their intended use also varied from specific care settings (hospital, community, care homes) to all settings and from specific age groups to all age groups. With all these definitions and tools, there is considerable scope for confusion and misunderstanding. Therefore, to clarify the burden and significance of malnutrition, guidelines for documenting it in routine practice and reporting it in scientific literature are provided.

Establishing energy requirements for body weight maintenance: validation of an intake-balance method

BACKGROUND

Experimentally establishing a group's body weight maintenance energy requirement is an important component of metabolism research. At present, the reference approach for measuring the metabolizable energy intake (MEI) from foods required for body weight maintenance in non-confined subjects is the doubly-labeled water (DLW)-total energy expenditure (TEE) method. In the current study, we evaluated an energy-intake weight balance method as an alternative to DLW that is more flexible and practical to apply in some settings.

METHODS

The hypothesis was tested that MEI from foods observed in a group of subjects maintaining a constant energy intake while keeping their weight within ±1 kg over 10 days is non-significantly different from DLW-measured TEE (TEEDLW). Six non-obese subjects evaluated as part of an earlier study completed the inpatient protocol that included a 3-day initial adjustment period.

RESULTS

The group body weight coefficient of variation (X ± SD) during the 10-day balance period was 0.38 ± 0.10% and the slope of the regression line for body weight versus protocol day was non-significant at 1.8 g/day (R2, 0.002, p = 0.98). MEI from foods observed during the 10-day balance period (2390 ± 543 kcal/day) was non-significantly different (p = 0.96) from TEE measured by DLW (2373 ± 713 kcal/day); the MEI/TEEDLW ratio was 1.03 ± 0.15 (range 0.87-1.27) and the correlation between MEI from foods and TEEDLW was highly significant (R2, 0.88, p = 0.005).

CONCLUSIONS

A carefully managed 10-day protocol that includes a constant MEI level from foods with weight stability (±1 kg) will provide a group's body weight maintenance energy requirement similar to that obtained with DLW. This approach opens the possibility of conducting affordable weight balance studies, shorter in duration than those previously reported, that are needed to answer a wide range of questions in clinical nutrition. Trial registration The study is registered at http://www.clinicaltrials.gov (NCT01672632; August 20, 2012).

Permissive Underfeeding of the Critically Ill Patient

The rise in the popularity of nutrition support in the 1970s was associated with the concept of "hyperalimentation." This concept was based on the early findings that increased metabolic rates were observed in various disease states such as trauma, sepsis, and burns. The aim was to feed 40% to 100% above the basal metabolic rate to avoid weight loss associated with critical illness. Since that time, several observations have indicated that permissive underfeeding may be beneficial because: (a) the metabolic rate is not markedly increased in most patients with critical illness except burns; (b) weight gain during nutrition support in critical illness is not caused by a gain in nitrogen but fat; (c) energy intake as glucose in excess of needs causes increased carbon dioxide production and a fatty liver; (d) hyperglycemia increases the risk of infective complications; and (e) a controlled trial of preoperative nutrition in which patients received 1000 kcal above the metabolic rate increased infectious complications.

ESPEN guidelines on nutrition in cancer patients

Cancers are among the leading causes of morbidity and mortality worldwide, and the number of new cases is expected to rise significantly over the next decades. At the same time, all types of cancer treatment, such as surgery, radiation therapy, and pharmacological therapies are improving in sophistication, precision and in the power to target specific characteristics of individual cancers. Thus, while many cancers may still not be cured they may be converted to chronic diseases. All of these treatments, however, are impeded or precluded by the frequent development of malnutrition and metabolic derangements in cancer patients, induced by the tumor or by its treatment. These evidence-based guidelines were developed to translate current best evidence and expert opinion into recommendations for multi-disciplinary teams responsible for identification, prevention, and treatment of reversible elements of malnutrition in adult cancer patients. The guidelines were commissioned and financially supported by ESPEN and by the European Partnership for Action Against Cancer (EPAAC), an EU level initiative. Members of the guideline group were selected by ESPEN to include a range of professions and fields of expertise. We searched for meta-analyses, systematic reviews and comparative studies based on clinical questions according to the PICO format. The evidence was evaluated and merged to develop clinical recommendations using the GRADE method. Due to the deficits in the available evidence, relevant still open questions were listed and should be addressed by future studies. Malnutrition and a loss of muscle mass are frequent in cancer patients and have a negative effect on clinical outcome. They may be driven by inadequate food intake, decreased physical activity and catabolic metabolic derangements. To screen for, prevent, assess in detail, monitor and treat malnutrition standard operating procedures, responsibilities and a quality control process should be established at each institution involved in treating cancer patients. All cancer patients should be screened regularly for the risk or the presence of malnutrition. In all patients - with the exception of end of life care - energy and substrate requirements should be met by offering in a step-wise manner nutritional interventions from counseling to parenteral nutrition. However, benefits and risks of nutritional interventions have to be balanced with special consideration in patients with advanced disease. Nutritional care should always be accompanied by exercise training. To counter malnutrition in patients with advanced cancer there are few pharmacological agents and pharmaconutrients with only limited effects. Cancer survivors should engage in regular physical activity and adopt a prudent diet.

Effect of phosphorus supplementation on weight gain and waist circumference of overweight/obese adults: a randomized clinical trial

Background:

Phosphorus status is inversely correlated with body weight; however, the effect of phosphorus supplementation on body weight in a controlled design has not been studied.

Methods:

This is a double-blind, randomized, placebo-controlled trial of 63 adults aged 18–45 years with a body mass index (BMI) of ⩾25 kg m⁻² and normal kidney function at the American University of Beirut. Participants were randomly assigned to the placebo or phosphorus group where daily placebo or phosphorus supplements were ingested with three main meals (breakfast, lunch and dinner) for a period of 12 weeks. Primary outcomes were changes in anthropometric measures, blood metabolites (including lipid profile, glucose and insulin) and subjective appetite scores. The trial is registered with Clinical Trial.gov, NCT02329990.

Results:

Body weight was significantly lower in the phosphorus group when compared with the placebo group (−0.65 kg (95% confidence interval (CI) −1.69 to 0.40) vs 1.13 kg (95% CI 0.19 to 2.06), P=0.01). Similarly, BMI and waist circumference were significantly lower in the phosphorus group when compared with the placebo group (−0.24 kg m⁻² (95% CI −0.59 to 0.12) vs 0.42 kg m⁻² (95% CI 0.05 to 0.78), P=0.01; −3.62 cm (95% CI−4.90 to −2.33) vs 0.38 cm ( 95% CI−0.44 to 1.20), P<0.001; respectively). Several parameters of subjective appetite scores were decreased in the phosphorus-supplemented group.

Conclusions:

Phosphorus supplementation for 12 weeks significantly decreases body weight, BMI, waist circumference and subjective appetite scores. These findings support a promising role of the mineral phosphorus in the prevention and management of obesity, especially abdominal adiposity. The exact mechanisms of action and longer-term effects still need to be elucidated.

Nutrition in the pediatric population in the intensive care unit

Nutrition is an essential component of patient management in the pediatric intensive care unit (PICU). Poor nutrition status accompanies many childhood chronic illnesses. A thorough assessment of the critically ill child is required to inform the plan for nutrition support. Accurate and clinically relevant nutritional assessment, including growth measurements, provides important guidance. Indirect calorimetry provides the most accurate measurement of resting energy expenditure, but is too often unavailable in the PICU. To prevent inappropriate caloric intake, reassessment of the child's nutrition status is imperative. Enteral nutrition is the recommended route of intake. Human milk is preferred for infants.

Refractory celiac disease and EATL patients show severe malnutrition and malabsorption at diagnosis

BACKGROUND & AIMS

Refractory celiac disease type II (RCDII) and EATL (Enteropathy Associated T-cell Lymphoma) are (pre)malignant complications of celiac disease (CD). Data on malnutrition and intestinal absorption is lacking in these patients. Therefore, the aim of the study is to comprehensively assess nutritional status and intestinal absorption capacity of patients with RCDII and EATL, compared with data of newly diagnosed CD patients.

METHODS

Observational study in tertiary care setting in RCDII (n = 24, 63.8 ± 8.2 y), EATL (n = 25, 62.3 ± 5.7 y) and CD patients (n = 43, 45.6 ± 14.8 y). At diagnosis, anthropometry (BMI, unintentional weight loss, fat-free mass index (FFMI), handgrip strength (HGS), nutritional intake, fecal losses and Resting Energy Expenditure (REE)) were assessed.

RESULTS

Low BMI (<18.5) was more often observed in RCDII patients than in CD or EATL patients (in 33%, 12% and 12%, respectively, p = 0.029). EATL patients more frequently had unintentional weight loss (>10%) than CD or RCDII patients (in 58%, 19% and 39% of patients, respectively; p = 0.005/0.082). Energy malabsorption (<85%) was detected in 44% and 33% of RCDII and EATL patients, vs 21.6% in CD (NS). Fecal energy losses were higher in RCDII than in CD patients (589 ± 451 vs 277 ± 137 kcal/d, p = 0.017). REE was underestimated by predicted-REE with>10% in 60% of RCDII, 89% of EATL, and 38% of CD patients (p = 0.006). Low FFMI and HGS were detected in one third and two thirds of all patients, respectively.

CONCLUSIONS

The nutritional status of patients with RCDII and EATL is inferior compared with untreated naïve CD patients at presentation. Both malabsorption as well as hypermetabolism contribute to malnutrition.

Bomb calorimetry, the gold standard for assessment of intestinal absorption capacity: normative values in healthy ambulant adults

BACKGROUND

Intestinal absorption capacity is considered to be the best method for assessing overall digestive intestinal function. Earlier reference values for intestinal function in healthy Dutch adults were based on a study that was conducted in an inpatient metabolic unit setting in a relatively small series. The present study aimed to readdress and describe the intestinal absorption capacity of healthy adults, who were consuming their usual (Western European) food and beverage diet, in a standard ambulatory setting.

METHODS

Twenty-three healthy subjects (aged 22-60 years) were included in the analyses. Nutritional intake (energy and macronutrients) was determined with a 4-day nutritional diary. Subsequently, mean faecal losses of energy (by bomb calorimetry), fat, protein and carbohydrate were determined following a 3-day faecal collection. Finally, intestinal absorption capacity was calculated from the differences between intake and losses.

RESULTS

Mean (SD) daily faeces production was 141 (49) g (29% dry weight), containing 891 (276) kJ [10.7 (1.3) kJ g(-1) wet faeces; 22.6 (2.5) kJ g(-1) dry faeces], 5.2 (2.2) g fat, 10.0 (3.8) g protein and 29.7 (11.7) g carbohydrates. Mean (SD) intestinal absorption capacity of healthy subjects was 89.4% (3.8%) for energy, 92.5% (3.7%) for fat, 86.9% (6.4%) for protein and 87.3% (6.6%) for carbohydrates.

CONCLUSIONS

The present study provides normative values for both stool nutrient composition and intestinal energy and macronutrient absorption in healthy adults on a regular Dutch diet in an ambulatory setting. Intestinal energy absorption was found to be approximately 90%.

Reduced parenteral nutrition requirements following anastomosis of a short residual colonic segment to a short jejunum

A 22-year-old man suffered an acute small bowel infarct leading to extensive bowel resection, resulting in only 20 cm of jejunum to a jejunostomy, although he also had 50 cm of residual colon with a mucous fistula. The patient was out on long-term home parenteral nutrition (PN) but endured high stomal losses of 5-6 L per day and, despite all conventional measures, required 6.1 L of fluid (including PN) and 555 mmol sodium per day. Although body mass index was maintained, he suffered debilitating malaise and recurrent episodes of catheter-related sepsis and also developed persistently abnormal liver function tests. He was considered a potential intestinal transplant patient, but before taking that step, he opted for reanastomosis of his residual colon to his jejunum, ending in a colostomy. At surgery, only 30 cm of additional bowel lengthening could be achieved, but despite this, the patient's stomal losses reduced to 2.5 L per day, intravenous fluid requirements reduced to 4.1 L per day, and liver function normalized. The patient also gained 7.5 kg despite no change in PN caloric prescription, and his quality of life was dramatically enhanced. The case illustrates that even a small length of colon can grant significant improvements, probably via improvements in small bowel transit and adaptive changes, better sodium and water resorption with decreased hyperaldosteronism, and enhanced energy and nitrogen recovery. Reanastomosis of defunctioned colon should therefore always be considered a management option in short bowel syndrome.

Enteral nutrition: better navigation, yet unknown destination?

The nutrition dose truly absorbed by a patient is crucial information in the management or the investigation of nutrition during critical illness. In the present issue of Critical Care, assessment of nutritional losses in stools was studied. These losses together with enteral nutrition lost in gastric fluids and enteral nutrition prescribed but never infused make up the difference between the dose supposedly given to a patient and the amount effectively taken up. Additionally, the optimal dosing and timing of nutrition during critical illness are still debated. When enteral nutrition is insufficient, the options are limited.

Malabsorption and nutritional balance in the ICU: fecal weight as a biomarker: a prospective observational pilot study

INTRODUCTION

Malabsorption, which is frequently underdiagnosed in critically ill patients, is clinically relevant with regard to nutritional balance and nutritional management. We aimed to validate the diagnostic accuracy of fecal weight as a biomarker for fecal loss and additionally to assess fecal macronutrient contents and intestinal absorption capacity in ICU patients.

METHODS

This was an observational pilot study in a tertiary mixed medical-surgical ICU in hemodynamically stable adult ICU patients, without clinically evident gastrointestinal malfunction. Fecal weight (grams/day), fecal energy (by bomb calorimetry in kcal/day), and macronutrient content (fat, protein, and carbohydrate in grams/day) were measured. Diagnostic accuracy expressed in terms of test sensitivity, specificity, positive (PPV) and negative predictive value (NPV), and receiver operator curves (ROCs) were calculated for fecal weight as a marker for energy malabsorption. Malabsorption was a priori defined as < 85% intestinal absorption capacity.

RESULTS

Forty-eight patients (63 ± 15 years; 58% men) receiving full enteral feeding were included. A cut-off fecal production of > 350 g/day (that is, diarrhea) was linked to the optimal ROC (0.879), showing a sensitivity and PPV of 80%, respectively. Specificity and NPV were both 96%. Fecal weight (grams/day) and intestinal energy-absorption capacity were inversely correlated (r = -0.69; P < 0.001). Patients with > 350 g feces/day had a significantly more-negative energy balance compared with patients with < 350 g feces/day (loss of 627 kcal/day versus neutral balance; P = 0.012).

CONCLUSIONS

A fecal weight > 350 g/day in ICU patients is a biomarker applicable in daily practice, which can act as a surrogate for fecal energy loss and intestinal energy absorption. Daily measurement of fecal weight is a feasible means of monitoring the nutritional status of critically ill patients and, in those identified as having malabsorption, can monitor responses to changes in dietary management.

Refeeding syndrome: a literature review

Refeeding syndrome (RFS) describes the biochemical changes, clinical manifestations, and complications that can occur as a consequence of feeding a malnourished catabolic individual. RFS has been recognised in the literature for over fifty years and can result in serious harm and death. Crude estimates of incidence, morbidity, and mortality are available for specific populations. RFS can occur in any individual but more commonly occurs in at-risk populations. Increased awareness amongst healthcare professionals is likely to reduce morbidity and mortality. This review examines the physiology of RFS and describes the clinical manifestations. A management strategy is described. The importance of a multidisciplinary approach is emphasized.

Proposed Recommended Nutrient Densities for Moderately Malnourished Children

Recommended Nutrient Intakes (RNIs) are set for healthy individuals living in clean environments. There are no generally accepted RNIs for those with moderate malnutrition, wasting, and stunting, who live in poor environments. Two sets of recommendations are made for the dietary intake of 30 essential nutrients in children with moderate malnutrition who require accelerated growth to regain normality: first, for those moderately malnourished children who will receive specially formulated foods and diets; and second, for those who are to take mixtures of locally available foods over a longer term to treat or prevent moderate stunting and wasting. Because of the change in definition of severe malnutrition, much of the older literature is pertinent to the moderately wasted or stunted child. A factorial approach has been used in deriving the recommendations for both functional, protective nutrients (type I) and growth nutrients (type II).

ESPEN Guidelines on Parenteral Nutrition: gastroenterology

Undernutrition as well as specific nutrient deficiencies has been described in patients with Crohn's disease (CD), ulcerative colitis (UC) and short bowel syndrome. In the latter, water and electrolytes disturbances may be a major problem. The present guidelines provide evidence-based recommendations for the indications, application and type of parenteral formula to be used in acute and chronic phases of illness. Parenteral nutrition is not recommended as a primary treatment in CD and UC. The use of parenteral nutrition is however reliable when oral/enteral feeding is not possible. There is a lack of data supporting specific nutrients in these conditions. Parenteral nutrition is mandatory in case of intestinal failure, at least in the acute period. In patients with short bowel, specific attention should be paid to water and electrolyte supplementation. Currently, the use of growth hormone, glutamine and GLP-2 cannot be recommended in patients with short bowel.

Total body potassium, fat and water during total parenteral nutrition in Crohn's disease

The body composition was studied by measurement of body weight (BW) and total body potassium (TBK), fat and water in 13 patients with Crohn's disease (CD), who were given altogether 18 courses of total parenteral nutrition (TPN) with nil by mouth each lasting at least 3 weeks. At the start of TPN, one group of steroid-free patients displayed intracellular potassium depletion, as reflected by the ratio TBK/lean body mass (LBM) (group 1). Another group of steroid-free patients showed no depletion of intracellular potassium (group 2). The patients given prednisolone all showed intracellular potassium depletion and were assigned to a separate group (group 3). During the initial 19-44 days of TPN, TBK, LBM and BW increased in group 1. All patients with intracellular potassium depletion (groups 1 + 3) showed an increase in TBK and TBK/LBM during the initial 19-51 days of TPN. For steroid-free patients (groups 1 + 2) there were linear relationships between the rate of energy supply per kg LBM and the 24 h change in BW during the third and fourth weeks of TPN (r = 0.79) and between the 24 h change in BW and LBM during the first 19-44 days of TPN (r = 0.59). A steady state in BW was found on administering 53 kcal/kg LBM/24 h. It is concluded that CD patients with intracellular potassium depletion are likely to be improved in terms of TBK and TBK/LBM by at least 3 weeks of TPN as given in the present study. Steroid-free CD patients with intracellular potassium depletion are, moreover, likely to show an improvement in LBM by at least 3 weeks of TPN, and an increase in their BW during the initial 3-6 weeks of TPN will probably reflect an increase in LBM. The pre-TPN TBK/LBM ratio may be a predictor of the repletion rate of the LBM compartment during TPN of steroid-free wasted CD patients.

Refeeding syndrome: effective and safe treatment with Phosphates Polyfusor

BACKGROUND

Severe hypophosphataemia associated with refeeding syndrome requires treatment with intravenous phosphate to prevent potentially life-threatening complications. However, evidence for replacement regimens is limited and current regimens are complex and replace phosphate inadequately.

AIM

To assess the effectiveness and safety of 50 mmol intravenous phosphate infusion, given as a 'Phosphates Polyfusor', for the treatment of severe hypophosphataemia in refeeding syndrome.

METHODS

Patients with refeeding syndrome and normal renal function received a Phosphates Polyfusor infusion for the treatment of severe hypophosphataemia (< 0.50 mmol/L). The outcome measures were serial serum phosphate, creatinine and calcium concentrations for 4 days following phosphate infusion and adverse events.

RESULTS

Over 2 years, 30 patients were treated. Following treatment, 37% of cases had a normal serum phosphate concentration and 73% had a serum phosphate concentration of > 0.5 mmol/L within 24 h. Ten patients required more than one Phosphates Polyfusor infusion. Within 72 h, 93% of cases had achieved a serum phosphate concentration of > or = 0.50 mmol/L. No patient developed renal failure. Three episodes of transient mild hyperphosphataemia were recorded. Four patients developed mild hypocalcaemia.

CONCLUSIONS

This is the largest published series of the use of intravenous phosphate for the treatment of severe hypophosphataemia (< 0.50 mmol/L), and is the most effective regimen described. All patients had refeeding syndrome and were managed on general wards.

The importance of the refeeding syndrome

In this review we discuss the refeeding syndrome. This potentially lethal condition can be defined as severe electrolyte and fluid shifts associated with metabolic abnormalities in malnourished patients undergoing refeeding, whether orally, enterally, or parenterally. It can be associated with significant morbidity and mortality. Clinical features are fluid-balance abnormalities, abnormal glucose metabolism, hypophosphatemia, hypomagnesemia, and hypokalemia. In addition, thiamine deficiency can occur. We describe which patient groups are more at risk for this syndrome and the clinical management of the condition.

Complications of long-term home total parenteral nutrition: their identification, prevention and treatment

The purpose of this review is to describe the most common complications of home total parenteral nutrition, their identification, treatment and prevention. Data sources were manuscripts and abstracts published in the English literature since 1968. Studies were selected for summarization in this review on the basis of clinical relevance to the practicing clinician. Home total parenteral nutrition is a relatively safe, life-saving method for nutrient delivery in patients with compromised gastrointestinal function. However, numerous complications, with associated morbidity and mortality, involving the delivery system and the gastrointestinal, renal, and skeletal systems may develop. Catheter-related complications are often preventable and treatable when they occur, although renal and bone abnormalities have elusive etiologies.

Complications of long-term home total parenteral nutrition: their identification, prevention and treatment

The purpose of this review is to describe the most common complications of home total parenteral nutrition, their identification, treatment and prevention. Data sources were manuscripts and abstracts published in the English literature since 1968. Studies were selected for summarization in this review on the basis of clinical relevance to the practicing clinician. Home total parenteral nutrition is a relatively safe, life-saving method for nutrient delivery in patients with compromised gastrointestinal function. However, numerous complications, with associated morbidity and mortality, involving the delivery system and the gastrointestinal, renal, and skeletal systems may develop. Catheter-related complications are often preventable and treatable when they occur, although renal and bone abnormalities have elusive etiologies.

Laboratory support of the clinical nutrition service

This article critically reviews the role of the laboratory services in assessment, monitoring and management of complications in patients requiring nutritional support. It has broadly been divided into three sections. (i) Assessment of protein and energy status: whilst it is stressed that clinical judgement and anthropometric measurements are the most effective methods of evaluation of nutritional requirements, laboratory tests which can be of use in assessment of protein energy status are discussed in detail, including an appraisal of the value of each test in various clinical situations. (ii) Assessment of micronutrient and electrolyte status: the clinical justification for assessment of the various micronutrients and electrolytes is considered. A few selected examples are discussed in detail including an evaluation of the tests of status available and examples of situations where measurement may be clinically helpful. (iii) Effective use of the laboratory: this section attempts to guide the clinician in the most appropriate use of laboratory tests, firstly in the assessment of requirement for aspects of nutritional support, secondly in the continued monitoring and evaluation of the support provided, and thirdly in prevention and treatment of metabolic complications. It is emphasised that clinical nutrition is a multidisciplinary topic requiring input from the laboratory in conjunction with other specialities to provide the best available patient care.

Perioperative total parenteral nutrition in malnourished, gastrointestinal cancer patients: a randomized, clinical trial

BACKGROUND

Clinical trials investigating the potential benefits of perioperative total parenteral nutrition (TPN) for reducing the risk of surgery in malnourished cancer patients have yielded controversial results.

METHODS

Ninety elective surgical patients with gastric or colorectal tumors and weight loss of 10% or more of usual body weight were randomly assigned to 10 days of preoperative and 9 days of postoperative nutrition vs a simple control group. The daily per kilogram body weight TPN regimen included 34.6 +/- 6.3 kcal nonprotein and 0.25 +/- 0.04 g nitrogen per kilogram in a volume of 42.6 +/- 7.3 mL of fluid. The glucose-to-fat calorie ratio was 70:30. Control patients did not receive preoperative nutrition but received 940 kcal nonprotein plus 85 g amino acids postoperatively.

RESULTS

Complications occurred in 37% of the patients receiving TPN vs 57% of the control patients (p = .03). Noninfectious complications mainly accounted for this difference, which was 12% vs 34%, respectively (p = .02). Mortality occurred in only 5 of the control group patients (p = .05). The total length of hospitalization for TPN patients was longer than for control (p = .00), whereas the length of postoperative stay in the two groups did not differ significantly.

CONCLUSIONS

This study shows that 10 days of preoperative TPN that is continued postoperatively is able to reduce the complication rate by approximately one third and to prevent mortality in severely malnourished patients with gastrointestinal cancer.

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.

Dietary protein, growth and urea kinetics in severely malnourished children and during recovery

The case mortality for severe malnutrition in childhood remains high, but established best approaches to treatment are not used in practice. The energy and protein content of the diet at different stages of treatment appears important, but remains controversial. The effect on growth, urea kinetics and the urinary excretion of 5-L-oxoproline was compared between a standard infant formula (HP group) provided in different quantities at each stage of treatment and a recommended dietary regimen, which differentiates the requirements of protein and energy during the acute phase of resuscitation (maintenance intake of energy and protein, relatively low protein to energy ratio, LP group) from those during the restoration of a weight deficit (energy and nutrient dense). The energy required to maintain weight was less in the HP than the LP group, but the HP group was not able to achieve as high an energy intake during repletion of wasting because of the high volume which would have had to be consumed. Compared to the LP group, in the HP group during catch-up growth there was significantly greater deposition of lean tissue and higher rates of urea production, hydrolysis and salvage of urea-nitrogen. These, together with higher rates of 5-L-oxoprolinuria, suggest a greater constraint of the formation of adequate amounts of nonessential amino acids, especially glycine, in the face of enhanced demands. Although more effective rehabilitation might be achieved using a standard formula, there is the need to determine the extent to which it might impose metabolic stress compared with the modified formulation.

Fluid and sodium problems in perioperative feeding: what further studies need to be done?

Total parenteral nutrition may induce harmful water and sodium retention. Few efforts have been made to elucidate the mechanisms of this deleterious response to total parenteral nutrition. In this review we discuss the different factors involved in its pathophysiology and possible changes in total parenteral nutrition regimes in order to modulate such a response: reduction of the proportion of non-protein calories given as glucose, restriction of water and sodium, and the possible benefits of pharmaceutical nutritional therapy with glutamine and growth hormone.

Response of severely malnourished patients to preoperative parenteral nutrition: a randomized clinical trial of water and sodium restriction

Preoperative parenteral nutrition (PPN) may be beneficial for severely malnourished patients who are candidates for a major elective surgical procedure. The response to PPN, however, has not been thoroughly investigated. Expansion of the extracellular water compartment may occur in some patients, producing a further decrease in the serum albumin concentration and increasing the postoperative complications. Our aims were to investigate the occurrence of and factors associated with water and sodium retention during PPN and its impact on postoperative respiratory complications. Forty-one patients with gastrointestinal cancer and severe malnutrition (weight loss > 15% and/or serum albumin < 35 g/L) were randomly allocated to two groups receiving isocaloric isonitrogenous PPN for 10 d. The Standard PPN Group (SG, n = 19) received 70% of nonprotein calories as glucose, 45 cc of water.kg-1.d-1, and 140 mEq/d of sodium chloride; and the Modified Group (MG, n = 22) received 70% of calories as fat, 30 cc of water.kg-1.d-1, and no sodium. Weight and albumin changes, diuresis, sodium and water balances, and postoperative complications were recorded. At the end of PPN, the SG showed a higher weight gain (0.8 versus -1.5 kg, P = 0.0001) and albumin decrease (-0.7 versus 2.3 g/L, P = 0.006). Diuresis and sodium balance were greater in the SG (1,230 versus 959 mL/d, P = 0.003 and 40 versus -27 mEq/d, P = 0.001). Weight changes correlated with water (r2 = 0.46, P = 0.001) and sodium (r2 = 0.62, P = 0.0001) balances. Inappropriate responses to PPN in both groups (expansion or depletion of the extracellular water compartment) were associated with a significant increase in pulmonary postoperative complications. During PPN, extracellular water expansion--as determined by increasing weight and lowering of the serum albumin concentration--and aggressive fluid therapy to treat water and sodium depletion seem crucial to the development of postoperative respiratory complications.

Nutritional management of patients with gastrointestinal fistulas

Nutritional support plays a key and integral role in the management of patients with gastrointestinal fistulas. It needs to be instituted early to minimize erosion of body cell mass, to prevent further physiologic deterioration of the patient, and to initiate repletion in an otherwise malnourished patient. Furthermore, it allows for rest of the gastrointestinal tract and facilitates healing of the fistula.