Amino acid losses during hemodialysis with polyacrylonitrile membranes: effect of intradialytic amino acid supplementation on plasma amino acid concentrations and nutritional variables in nondiabetic patients

ESPEN practical guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease

BACKGROUND AND AIMS

Hospitalized patients often have acute kidney disease (AKD) or chronic kidney disease (CKD), with important metabolic and nutritional consequences. Moreover, in case kidney replacement therapy (KRT) is started, the possible impact on nutritional requirements cannot be neglected. On this regard, the present guideline aims to provide evidence-based recommendations for clinical nutrition in hospitalized patients with KD.

METHODS

The standard operating procedure for ESPEN guidelines was used. Clinical questions were defined in both the PICO format, and organized in subtopics when needed, and in non-PICO questions for the more general topics. The literature search was from January 1st, 1999 until January 1st, 2020. Each question led to one or more recommendation/statement and related commentaries. Existing evidence was graded, as well as recommendations and statements were developed and agreed upon in a multistage consensus process.

RESULTS

The present guideline provides 32 evidence-based recommendations and 8 statements, defining how to assess nutritional status, how to define patients at risk, how to choose the route of feeding, and how to integrate nutrition with KRT. In the final online voting, a strong consensus was reached in 84% at least of recommendations and 100% of statements.

CONCLUSION

The presence of KD in hospitalized patients identifies a highly heterogeneous group of subjects with widely varying nutrient needs and intakes. Considering the high nutritional risk related with this clinical condition, an individualized approach consisting of nutritional status evaluation and monitoring, frequent evaluation of nutritional requirements, and careful integration with KRT should be planned to avoid both underfeeding and overfeeding. Practical recommendations and statements were developed, aiming at defining suggestions for everyday clinical practice in the individualization of nutritional support in this patient setting. Literature areas with scarce or without evidence were also identified, thus requiring further basic or clinical research.

Revisiting Intradialytic Parenteral Nutrition: How Can We Apply the Evidence in Clinical Practice?

Intradialytic parenteral nutrition (IDPN) remains a controversial nutrition support practice in hemodialysis. Multiple reviews and evidence-based clinical practice guidelines have been published in the past 20 years. Despite essentially looking at the same evidence, conclusions and recommendations vary significantly, leading to widespread uncertainty among clinicians on the value of and indications for IDPN. This paper aims to bring a clinical perspective to the current state of evidence and clinical practice, recognizing the strengths and weaknesses of current evidence and the clinical questions that remain unanswered, as well as providing guidance for using IDPN in clinical practice. IDPN should be considered a strategy to complement spontaneous oral intake in clinically stable patients receiving maintenance hemodialysis or who have or are at risk of malnutrition and who have substantial but not adequate protein and/or energy intake. There is a clear need for robust randomized controlled trials evaluating the impact of IDPN in appropriately selected patients. Additionally, future trials should include patient-centered outcome measures such as appetite, spontaneous oral intake, quality of life, and reliable measures of nutritional status.

Intradialytic parenteral nutrition for patients on hemodialysis: when, how and to whom?

Hemodialysis is associated with high morbidity and mortality rates as well as low quality of life. Altered nutritional status and protein-energy wasting are important indicators of these risks. Maintaining optimal nutritional status in patients with hemodialysis is a critical but sometimes overlooked aspect of care. Nutritional support strategies usually begin with dietary counseling and oral nutritional supplements. Patients may not comply with this advice or oral nutritional supplements, however , or compliance may be affected by other complications of progressive chronic kidney disease. Intradialytic parenteral nutrition (IDPN) may be a possibility in these cases, but lack of knowledge on practical aspects of IDPN delivery are seldom discussed and may represent a barrier. In this review, we, as a consensus panel of clinicians experienced with IDPN, survey existing literature and summarize our views on when to use IDPN, which patients may be best suited for IDPN, and how to effectively deliver and monitor this strategy for nutritional support.

Amino Acid Homeostasis and Fatigue in Chronic Hemodialysis Patients

Patients dependent on chronic hemodialysis treatment are prone to malnutrition, at least in part due to insufficient nutrient intake, metabolic derangements, and chronic inflammation. Losses of amino acids during hemodialysis may be an important additional contributor. In this study, we assessed changes in plasma amino acid concentrations during hemodialysis, quantified intradialytic amino acid losses, and investigated whether plasma amino acid concentrations and amino acid losses by hemodialysis and urinary excretion are associated with fatigue. The study included a total of 59 hemodialysis patients (65 ± 15 years, 63% male) and 33 healthy kidney donors as controls (54 ± 10 years, 45% male). Total plasma essential amino acid concentration before hemodialysis was lower in hemodialysis patients compared with controls (p = 0.006), while total non-essential amino acid concentration did not differ. Daily amino acid losses were 4.0 ± 1.3 g/24 h for hemodialysis patients and 0.6 ± 0.3 g/24 h for controls. Expressed as proportion of protein intake, daily amino acid losses of hemodialysis patients were 6.7 ± 2.4% of the total protein intake, compared to 0.7 ± 0.3% for controls (p < 0.001). Multivariable regression analyses demonstrated that hemodialysis efficacy (Kt/V) was the primary determinant of amino acid losses (Std. β = 0.51; p < 0.001). In logistic regression analyses, higher plasma proline concentrations were associated with higher odds of severe fatigue (OR (95% CI) per SD increment: 3.0 (1.3; 9.3); p = 0.03), while higher taurine concentrations were associated with lower odds of severe fatigue (OR (95% CI) per log2 increment: 0.3 (0.1; 0.7); p = 0.01). Similarly, higher daily taurine losses were also associated with lower odds of severe fatigue (OR (95% CI) per log2 increment: 0.64 (0.42; 0.93); p = 0.03). Lastly, a higher protein intake was associated with lower odds of severe fatigue (OR (95% CI) per SD increment: 0.2 (0.04; 0.5); p = 0.007). Future studies are warranted to investigate the mechanisms underlying these associations and investigate the potential of taurine supplementation.

Amino acid availability enhanced through glucose coadministration of amino acid supplementation during hemodiafiltration: two case reports

Background

Intravenous administration of amino acid (AA) formulation (IVAA) as intradialytic parenteral nutrition is widely used for malnourished patients with end-stage kidney disease (ESKD) treated with hemodialysis (HD) or hemodiafiltration (HDF). Although various therapy recipes such as AA compositions or simultaneous administration of glucose and/or lipids have been attempted, the specific effects of each recipe on AA behaviors and metabolic consequences have not been well investigated. To clarify the effect of simultaneous glucose administration with IVAA, we investigated the behavior of AAs, insulin as a metabolic hormone, and energy-related metabolites during an HDF session in two patients.

Case presentation

We aimed to determine the effect of IVAA with or without simultaneous glucose administration. The plasma levels of AAs, branched-chain AAs (leucine, isoleucine, and valine), major nonessential AAs (alanine and glutamine with glutamate), insulin, glucose, and ketone bodies were measured before HDF and at the second hour (prior to the meal in the HDF session). Lost AAs in the spent dialysate were also measured for the first two hours during the HDF session.

Conclusion

In the absence of glucose administration, plasma AA levels and the loss of AAs in the dialysate increased owing to IVAA, with the increase in plasma levels in ketone bodies occurring because of scarce secretion of plasma insulin. In the presence of glucose administration, plasma levels and the loss of AA decreased even when the same amount of AAs was injected, possibly because of the profound secretion of insulin with a decrease in ketone bodies. The present findings suggest that the metabolic effects of simultaneous glucose administration on IVAAs enhanced AA uptake into the body during HDF sessions, which might increase the effectiveness of IVAAs.

An increase in circulating levels of branched-chain amino acids during hemodialysis with regard to protein breakdown: three case reports

Background

Hemodialysis (HD) is a protein catabolic event. However, the amino acid (AA) kinetics during HD sessions involved in protein breakdown have not been well investigated in patients with and without diabetes mellitus (DM).

Case presentation

Three patients (two patients with DM and one patient without DM) underwent fasting HD. Plasma levels of branched-chain AAs (BCAA; leucine, isoleucine, and valine), major non-essential AAs (alanine and glutamine, including glutamate), insulin, and ketone bodies were measured every hour during each HD session. After the start of the HD session, the plasma levels of insulin and all BCAAs dropped simultaneously. There was a significant subsequent increase in the plasma level of leucine and isoleucine levels, while valine levels remained constant. However, the recovery in levels of BCAAs during HD indicated a profound amount of BCAAs entering the blood from body tissues such as muscles. BCAAs may have surpassed their removal by HD. Ketone body levels increased continuously from the start of the sessions and reached high values in patients with DM. Synchronous changes in insulin depletion and an increase in the levels of ketone bodies may indicate disruption of energy metabolism.

Conclusions

This is the first report to demonstrate the time course of the changes in circulating levels of BCAAs and related metabolites in energy homeostasis during HD. An increase in BCAA levels during HD was found to be due to their transfer from the body tissue which suggested protein breakdown.

Chronic Kidney Disease and Nutrition Support

Individuals with chronic kidney disease (CKD), particularly those undergoing maintenance dialysis, are prone to protein-energy wasting (PEW), the latter of which can be ameliorated with different methods of nutrition support. Dietary counseling guided by dietitians is the key for preventing and managing PEW in CKD. If dietary counseling per se fails to meet the recommended energy and protein requirements, the addition of oral nutrition supplements (ONSs) would be necessary. When these initial measures cannot attain the recommended energy and protein requirements, nutrition support, including enteral tube feeding or parenteral nutrition (PN), should be considered as a viable option to improve nutrition status. Partial PN, comprising intraperitoneal PN (IPPN) and intradialytic PN (IDPN) therapies, may be attempted as supplemental nutrition support in patients with PEW requiring peritoneal dialysis and hemodialysis, respectively. Despite the debatable effectiveness of IPPN for patients undergoing peritoneal dialysis, it remains a feasible means in these patients. The indications for IPPN in patients undergoing peritoneal dialysis include inadequate dietary intake of energy and protein, and barriers of oral intake and other forms of enteral supplementation such as issues with suitability, tolerance, and compliance. Nonetheless, in the case of spontaneous dietary consumption of energy and protein meeting the difference between the IDPN provision and the nutrition targets, the use of IDPN is rational. In patients with PEW and malfunctioning gastrointestinal tract, as well as those whose enteral intake (with or without partial PN) is below the recommended nutrient requirements, total PN becomes a relevant nutrition intervention.

ESPEN guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease

Acute kidney disease (AKD) - which includes acute kidney injury (AKI) - and chronic kidney disease (CKD) are highly prevalent among hospitalized patients, including those in nephrology and medicine wards, surgical wards, and intensive care units (ICU), and they have important metabolic and nutritional consequences. Moreover, in case kidney replacement therapy (KRT) is started, whatever is the modality used, the possible impact on nutritional profiles, substrate balance, and nutritional treatment processes cannot be neglected. The present guideline is aimed at providing evidence-based recommendations for clinical nutrition in hospitalized patients with AKD and CKD. Due to the significant heterogeneity of this patient population as well as the paucity of high-quality evidence data, the present guideline is to be intended as a basic framework of both evidence and - in most cases - expert opinions, aggregated in a structured consensus process, in order to update the two previous ESPEN Guidelines on Enteral (2006) and Parenteral (2009) Nutrition in Adult Renal Failure. Nutritional care for patients with stable CKD (i.e., controlled protein content diets/low protein diets with or without amino acid/ketoanalogue integration in outpatients up to CKD stages four and five), nutrition in kidney transplantation, and pediatric kidney disease will not be addressed in the present guideline.

Hemodialysis-Nutritional Flaws in Diagnosis and Prescriptions. Could Amino Acid Losses be the Sharpest "Sword of Damocles"?

This review aims to highlight the strengths and weaknesses emerging from diagnostic evaluations and prescriptions in an intent to prevent progression over time of malnutrition and/or protein-energy wasting (PEW) in hemodialysis (HD) patients. In particular, indications of the most effective pathway to follow in diagnosing a state of malnutrition are provided based on a range of appropriate chemical-clinical, anthropometric and instrumental analyses and monitoring of the nutritional status of HD patients. Finally, based on the findings of recent studies, therapeutic options to be adopted for the purpose of preventing or slowing down malnutrition have been reviewed, with particular focus on protein-calorie intake, the role of oral and/or intravenous supplements and efficacy of some classes of amino acids. A new determining factor that may lead inexorably to PEW in hemodialysis patients is represented by severe amino acid loss during hemodialysis sessions, for which mandatory compensation should be introduced.

Amino acid losses are lower during pre-dilution on-line HDF than HD of the same Kt/V for urea

In this study, we investigated differences in amino acid losses between HD and pre-dilution on-line HDF with equal Kt/V for urea to determine which modality removes less amino acids from extravascular pools and ensures better nutrition. The subjects were patients receiving pre-dilution on-line HDF (n = 10) or HD (n = 10) at this hospital. Dialysis time was 4 h for all patients. In patients on HD, the blood flow rate was 200 mL/min and the dialysate flow rate was 463 ± 29.3 mL/min. In patients on pre-dilution on-line HDF, the blood flow rate was 240 ± 20 mL/min, the dialysate flow rate was 565.0 ± 42.5 mL/min, and the substitution flow rate (substitution volume) was 252.8 ± 26.4 mL/min (57.0 ± 6.0 L). Kt/V for urea was comparable between patients on HD and patients on pre-dilution on-line HDF (1.46 ± 0.25 vs. 1.46 ± 0.31). Amino acid loss and clear space were evaluated. Patients on pre-dilution on-line HDF lost significantly less glutamine and arginine (p < 0.01 and p = 0.032) and significantly less nonessential amino acids (NEAAs) than patients on HD (p = 0.013). They also had significantly lower clear space of total amino acids (TAAs), NEAAs, essential amino acids (EAAs), and branched-chain amino acids (BCAAs) than patients on HD (Total AA p = 0.019, NEAA p = 0.018, EAA p = 0.024, BCAA p = 0.042). When Kt/V for urea is equal, pre-dilution on-line HDF ensures better nutrition than does HD.

A successful pregnancy and parturition in a patient with anuria undergoing maintenance hemodialysis for 6 years: a case report of a 3-year-follow-up

Background

Pregnancies in hemodialysis patients are uncommon and difficult to study. Although the chance of a successful pregnancy and parturition in hemodialysis women has increased over the years, it still remains extremely low with a high maternal and fetal mortality and morbidity rate.

Case presentation

We reported a case of successful pregnancy and parturition in a 22-year-old Chinese female in uremic stage of chronic renal failure and undergoing maintenance hemodialysis (three sessions a week) for 6 years. At the 22nd gestational week, she was diagnosed as pregnant by ultrasound, and started an enhanced hemodialysis routine (Five sessions a week). At the 32nd gestational week, she got hospitalized and received hemodialysis more frequently (seven sessions a week). Based on the initial diagnoses, including uremic stage of chronic renal failure, stage-3 hypertension, single pregnancy of 32nd gestational week, single umbilical artery and polyhydramnios, a drug therapy consisting of compound amino acid, fructosediphosphate sodium, 10 % L-carnitine, erythropoietin, polyferose, amlodipine, isosorbidedinitrate, low-molecular weight-heparin, multivitamins and folic acid was given, and daily examination of the mother and fetus was performed. Under the joint efforts of various departments, the patient underwent caesarean section at the 34th gestational week due to progressive uterine contraction and gave birth to a female, well-being baby weighing 1470 g. It has been more than 3 years since the parturition. The mother has returned to the previous hemodialysis routine, and the child has been growing up healthily.

Conclusion

Although pregnancy in hemodialysis patients is rare, with a high rate of risks. Patients could still gain a good outcome, if we intensify hemodialysis and enhance the collaboration between the patient, nephrologists, obstetricians, neonatologist, nutritionists, and other departments.

The Effects of Parenteral Amino Acid Therapy on Protein Carbamylation in Maintenance Hemodialysis Patients

OBJECTIVE

Protein carbamylation is a urea-driven post-translational protein modification associated with mortality in dialysis patients. Free amino acids (AAs) are competitive inhibitors of protein carbamylation and animal studies suggest increasing AA concentrations reduces carbamylation burden. We hypothesized that AA therapy in maintenance hemodialysis patients would reduce carbamylation, carrying the potential to improve clinical outcomes.

DESIGN

Prospective pilot clinical trial (NCT1612429).

SETTING

The study was conducted from March 2013 to March 2014 in outpatient dialysis facilities in the Boston metropolitan area.

SUBJECTS AND INTERVENTION

We enrolled 23 consecutively consenting hemodialysis subjects, infusing the first 12 individuals with 250 cc of AAs 3 times per week postdialysis over 8 weeks. The remaining 11 subjects served as controls.

MAIN OUTCOME MEASURE

Change in carbamylated albumin (C-Alb), a measure of total body carbamylation burden, between baseline and 8 weeks was the primary outcome.

RESULTS

The treated and control groups had similar clinical characteristics and similar baseline C-Alb levels (mean ± SE 9.5 ± 2.4 and 9.3 ± 1.3 mmol/mol, respectively; P = .61). The treated arm showed a significant reduction in C-Alb compared with controls at 4 weeks (8.4% reduction in the treated arm vs. 4.3% increase in controls; P = .03) and the effect was greater by 8 weeks (15% reduction in the treated vs. 1% decrease in controls; P = .01).

CONCLUSION

In this pilot study, AA therapy appeared safe and effective at reducing C-Alb levels in hemodialysis patients compared with no treatment. The impact of reduced protein carbamylation on clinical outcomes should be further investigated.

Gut bacterial translocation may aggravate microinflammation in hemodialysis patients

BACKGROUND/AIMS

Bacterial translocation (BT) promotes microinflammation in predialysis patients with end-stage renal disease (ESRD). However, the change in BT has not been reported in ESRD patients undergoing regular hemodialysis treatment. The present study investigated whether hemodialysis promotes gut BT and microinflammation.

METHODS

The blood, gut, and dialysate of hemodialysis patients were analyzed using bacterial 16S rDNA amplification and DNA pyrosequencing to determine the presence of bacteria and alteration in gut microbiomes. High-sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6), and endotoxin were also determined. Plasma D-lactate was tested for gut permeability.

RESULTS

Bacteria were present in the plasma of 12 out of 52 ESRD patients. The majority of the bacteria detected in the blood were also distributed in the gut of ESRD patients on the basis of the phylogenetics of the blood and gut microbial specimens in the patients. In patient, groups treated with and without hemodialysis, the plasma hs-CRP, IL-6, and endotoxin levels differed between the positive and negative plasma bacterial DNA. In patients who were positive in blood bacteria, the bacterial DNA concentration was positively correlated with plasma levels of CRP and IL-6. The ESRD patients who underwent hemodialysis had a different flora and showed slightly higher levels of hs-CRP, IL-6, and plasma endotoxin, compared with those in ESRD patients who did not undergo hemodialysis.

CONCLUSION

ESRD, rather than hemodialysis, primarily contributes to BT and microinflammation in ESRD patients. Hemodialysis may exaggerate microinflammation in ESRD patients to some extent.

Prevention and treatment of protein energy wasting in chronic kidney disease patients: a consensus statement by the International Society of Renal Nutrition and Metabolism

Protein energy wasting (PEW) is common in patients with chronic kidney disease (CKD) and is associated with adverse clinical outcomes, especially in individuals receiving maintenance dialysis therapy. A multitude of factors can affect the nutritional and metabolic status of CKD patients requiring a combination of therapeutic maneuvers to prevent or reverse protein and energy depletion. These include optimizing dietary nutrient intake, appropriate treatment of metabolic disturbances such as metabolic acidosis, systemic inflammation, and hormonal deficiencies, and prescribing optimized dialytic regimens. In patients where oral dietary intake from regular meals cannot maintain adequate nutritional status, nutritional supplementation, administered orally, enterally, or parenterally, is shown to be effective in replenishing protein and energy stores. In clinical practice, the advantages of oral nutritional supplements include proven efficacy, safety, and compliance. Anabolic strategies such as anabolic steroids, growth hormone, and exercise, in combination with nutritional supplementation or alone, have been shown to improve protein stores and represent potential additional approaches for the treatment of PEW. Appetite stimulants, anti-inflammatory interventions, and newer anabolic agents are emerging as novel therapies. While numerous epidemiological data suggest that an improvement in biomarkers of nutritional status is associated with improved survival, there are no large randomized clinical trials that have tested the effectiveness of nutritional interventions on mortality and morbidity.

Depressive symptoms and dietary adherence in patients with end-stage renal disease

Depressive symptoms may be associated with fluid and dietary non adherence which could lead to poorer outcomes. The purpose of this study was to examine the relationship between depressive symptoms and fluid and dietary adherence in 100 patients with end-stage renal disease (ESRD) receiving haemodialysis. A descriptive, cross-sectional design with a convenience sample of 100 patients with ESRD receiving maintenance haemodialysis completed instruments that measured self-reported depressive symptoms and perceived fluid and dietary adherence. Demographic and clinical data and objective indicators of fluid and diet adherence were extracted from medical records. As many as two-third of these subjects exhibited depressive symptoms and half were non adherent to fluid and diet prescriptions. After controlling for known covariates, patients determined to have moderate to severe depressive symptoms were more likely to report non adherence to fluid and diet restrictions. Depressive symptoms in patients with ESRD are common and may contribute to dietary and fluid non adherence. Early identification and appropriate interventions may potentially lead to improvement in adherence of these patients.

[Efficacy of oral supplementation during dialysis in patients with chronic renal failure]

Protein-calorie malnutrition is common in hemodialysis patients and is a powerful predictor of morbidity and mortality. Nutritional supplementation, administered orally or parenterally, especially during dialysis, may compensate for the relatively inadequate protein and energy intake and improves net protein anabolism in chronic hemodialysis patients. Intradialytic oral nutrition seems preferable to intradialytic parenteral nutrition (IDPN) due to its lower cost and persistence of its anabolic effects after infusion is stopped, and because IDPN induces a higher increase in serum glucose and insulin levels and a greater reduction in serum ghrelin concentrations. Further larger scale randomized, controlled trials of nutritional interventions should be performed in maintenance dialysis patients to assess their efficacy regarding quality of life, morbidity, and mortality.

The effect of resistance exercise to augment long-term benefits of intradialytic oral nutritional supplementation in chronic hemodialysis patients

BACKGROUND

Resistance exercise combined with intradialytic oral nutrition (IDON) supplementation improves net protein balance in the acute setting in chronic hemodialysis patients. We hypothesized that combination of long-term resistance exercise and IDON would improve markers of muscle mass and strength further compared with IDON alone.

METHODS

Thirty-two participants (21 male; mean age, 43 ± 13 years) on chronic hemodialysis were randomly assigned to IDON plus resistance exercise (NS + EX), or IDON (NS) alone for 6 months. IDON consisted of a lactose-free formula consisting of protein, carbohydrate, and fat. Three sets of 12 repetitions of leg-press were completed before each dialysis session in the NS + EX arm. Primary outcome measurement was lean body mass. Muscle strength and other nutritional parameters were measured as secondary outcomes.

RESULTS

Of 32 participants, 22 completed the 6-month intervention. There were no statistically significant differences between the study interventions with respect to changes in lean body mass and body weight, when comparing NS + EX to NS. There were also no statistically significant differences in any of the secondary outcomes measured in the study. Body weight (80.3 ± 16.6 kg, 81.1 ± 17.5 kg, and 80.9 ± 18.2 kg at baseline, month 3, and month 6, respectively; P = .02) and 1-repetition maximum (468 ± 148 lb, 535 ± 144 lb, and 552 ± 142 lb, respectively; P = .001) increased statistically significantly during the study for all patients combined.

CONCLUSION

This study did not show further benefits of additional resistance exercise on long-term somatic protein accretion above and beyond nutritional supplementation alone. When both treatments groups were combined, body weight and muscle strength improved during the study.

New insights into the role of anabolic interventions in dialysis patients with protein energy wasting

PURPOSE OF REVIEW

Patients on maintenance dialysis commonly develop protein-energy wasting (PEW), which is associated with poor survival. There have been several advances in anabolic interventions aimed at improving PEW in these patients in recent years.

RECENT FINDINGS

Oral or parenteral nutritional supplementation, especially if administered during dialysis, improves net protein anabolism in chronic hemodialysis patients. These beneficial effects have been extended to long-term benefits in recent clinical trials. Resistance exercise, alone or combined with intradialytic oral nutrition supplementation, also improves net protein balance in the acute setting although recent studies indicated a limited beneficial effect of long-term exercise alone on muscle protein accretion in chronic hemodialysis patients. Anabolic agents such as growth hormone and androgens have been shown to exert significant benefits on visceral protein stores, muscle mass and strength. Ghrelin, a hormone with combined orexigenic and anti-inflammatory effects, is a potential new nutritional intervention in maintenance dialysis patients.

SUMMARY

Existing anabolic therapeutic strategies have proven to be effective in improving PEW in maintenance dialysis patients. Combined anabolic interventions and several new and established anabolic hormones represent further promising nutritional interventions. Large-scale randomized controlled trials examining the effects of anabolic interventions on mortality and morbidity are still lacking.

Intradialytic hyperalimentation as adjuvant support in pregnant hemodialysis patients: case report and review of the literature

Pregnancy in chronic dialysis patients is unusual and associated with many complications. Infants are often born both prematurely and small for gestational age. We report a case of a 36-year-old diabetic hemodialysis patient G4P3 who had prolonged hyperemesis gravidarum, for whom intradialytic parenteral nutrition (IDPN) was started at week 14 and continued throughout her pregnancy. She delivered a 3.5-kg baby girl at the 36th week of gestation by cesarean section. We discuss the use of IDPN as adjunct therapy for pregnant dialysis patients.

Impact of new technologies on metabolic care in the intensive care unit

PURPOSE OF REVIEW

Technological innovations in the ICU have lead to extraordinary advances in modern critical care. Renal replacement therapy (RRT) innovations and ventricular assist devices (VAD) are now becoming common interventions in the ICU environment. The purpose of this article is to describe the impact of RRT and VAD on critical care medicine with particular reference to metabolic care.

RECENT FINDINGS

Continuous venovenous hemofiltration and slow low efficient daily dialysis are effective modalities of RRT in hemodynamically unstable patients. These continuous forms of RRT can result in accentuated protein and nutrient losses but also provide an opportunity for intradialytic parenteral nutrition support. VAD patients typically have cardiac cachexia and develop chronic critical illness syndrome. Intensive metabolic support, incorporating trophic, concentrated, semielemental enteral nutrition, supplemental parenteral nutrition, and intensive insulin therapy is a rational strategy to implement in VAD patients. Unfortunately, there is insufficient evidence at this time to support the routine use of these nutritional interventions with RRT and VAD.

SUMMARY

Patients requiring RRT or VAD are at high nutritional risk, which negatively affects ICU outcome. Prompt nutritional risk assessment and early optimization of metabolic care is crucial in this patient population.

Intradialytic nutritional support

PURPOSE OF REVIEW

Intradialytic nutritional support has been used for more than 30 years both in critically ill patients with acute renal failure and during maintenance hemodialysis. Present knowledge allows better estimation of its metabolic and nutritional efficacy, as well its effect on patient outcome.

RECENT FINDINGS

Recent data showed that intradialytic nutritional support is able to counteract these effects of dialysis on protein metabolism and to improve both nitrogen and energy balance. In maintenance hemodialysis patients, the improvement of nutritional status during nutritional support was shown to improve long-term survival. In critically ill patients with acute renal failure, protein sparing is one of the main therapeutic goals. The effect of nutritional support on patient outcome is not demonstrated. Recent data, however, showed that the improvement of nitrogen balance may be associated with a better outcome.

SUMMARY

Current information helps to better assess the effects of intradialytic nutritional support, to clarify the nutritional management of renal failure patients and to provide recommendations. Future research should focus on the possible means to improve the efficacy of nutritional support, either by modifying its components of by associating anabolic or anticatabolic agents.

Intradialytic parenteral nutrition does not improve survival in malnourished hemodialysis patients: a 2-year multicenter, prospective, randomized study

Although intradialytic parenteral nutrition (IDPN) is a method used widely to combat protein-calorie malnutrition in hemodialysis patients, its effect on survival has not been thoroughly studied. We conducted a prospective, randomized trial in which 186 malnourished hemodialysis patients received oral nutritional supplements with or without 1 year of IDPN. IDPN did not improve 2-year mortality (primary end point), hospitalization rate, Karnofsky score, body mass index, or laboratory markers of nutritional status. Instead, both groups demonstrated improvement in body mass index and the nutritional parameters serum albumin and prealbumin (P < 0.05). Multivariate analysis showed that an increase in prealbumin of >30 mg/L within 3 months, a marker of nutritional improvement, independently predicted a 54% decrease in 2-year mortality, as well as reduced hospitalizations and improved general well-being as measured by the Karnofsky score. Therefore, although we found no definite advantage of adding IDPN to oral nutritional supplementation, this is the first prospective study demonstrating that an improvement in prealbumin during nutritional therapy is associated with a decrease in morbidity and mortality in malnourished hemodialysis patients.

Intradialytic parenteral nutrition: comparison of olive oil versus soybean oilbasedlipid emulsions

Lipid, oxidative and inflammatory parameters are frequently altered in dialysis patients and may be worsened by intravenous lipid emulsions (ILE). We assessed the efficacy and tolerance of olive as compared with standard soybean oil-based ILE during intradialytic parenteral nutrition (IDPN). IDPN mixtures containing amino acids, glucose, and either olive oil (OO group,n17) or soybean oil-based ILE (SO group,n18) were administered in a 5-week randomized, double-blind study. On days 0 and 35, patients' nutritional status was assessed by BMI, normalized protein catabolic rate, predialytic creatinine, serum albumin and transthyretin; lipid metabolism by plasma LDL- and HDL-cholesterol, triacylglycerols, phospholipids, apo A-I, A-II, B, C-II, C-III, E and lipoprotein (a); oxidative status by α-tocopherol, retinol, selenium, glutathione peroxidase, malondialdehyde and advanced oxidized protein products; inflammatory status by serum C-reactive protein, orosomucoid, IL-2 and IL-6. No serious adverse event was observed. Significant changes were observed from day 0 to day 35 (P<0·05): nutritional criteria improved (albumin in OO; albumin, transthyretin and creatinine in SO); LDL-cholesterol, apo B, C-II, C-III and apo A-I/A-II ratio increased in both groups. HDL-cholesterol decreased in OO; apo E increased and lipoprotein (a) decreased in SO; α-tocopherol/cholesterol ratio increased in OO; malondialdehyde decreased in both groups; IL-2 increased in both groups. The between-group comparison only showed the following differences: α-tocopherol/cholesterol increased in OO; lipoprotein (a) decreased in SO. From these data, it was concluded that OO- and SO-based IDPNs similarly improved nutritional status and influenced plasma lipid, oxidative, inflammatory and immune parameters.

Nutritional Supplementation in Adult Patients on Hemodialysis

At the beginning of the 1980s, nutritional status appeared as a key element of quality of life, health care requirements, and survival during chronic renal failure. In patients on dialysis, malnutrition is a major determinant of survival, and its management appears to be a key element in terms of outcome. Recommendations for the nutritional management of patients on hemodialysis have been elaborated by the National Kidney Foundation (NKF) and the European Society of Parenteral and Enteral Nutrition (ESPEN).

An anti-inflammatory and antioxidant nutritional supplement for hypoalbuminemic hemodialysis patients: a pilot/feasibility study

BACKGROUND

A low serum albumin concentration < 3.8 g/dL, a marker of malnutrition-inflammation complex syndrome, is observed in approximately half of all maintenance hemodialysis (MHD) patients in the United States and is strongly associated with increased mortality.

OBJECTIVES

We hypothesized that a novel oral nutritional intervention with anti-inflammatory and antioxidant properties taken during routine dialysis sessions is well tolerated and corrects hypoalbuminemia in MHD patients.

DESIGN

Controlled clinical study.

SETTING

An outpatient dialysis facility affiliated with a tertiary care community medical center with six equally distributed hemodialysis shifts and 163 MHD patients.

PATIENTS

Among all MHD outpatients of three selected HD shifts (n = 81 patients), 21 subjects had a serum albumin level < 3.8 g/dL. One patient who was hospitalized before the intervention was excluded. The other three dialysis shifts, with 82 MHD outpatients including 20 hypoalbuminemic subjects, were observed as concurrent controls.

INTERVENTION

The nutritional intervention included one can of Oxepa and one can of Nepro to be taken together orally during each routine hemodialysis session for 4 weeks. Each can contains 237 mL fluid. Oxepa provides 355 calories and 14.8 g protein per can, includes maltodextrin, medium-chain triglycerides, borage oil, and refined and deodorized fish oil, and is designed for critically ill patients with inflammation and oxidative stress. Each can of Oxepa includes 1,020 mg gamma-linolenic acid, 3,100 mg caprylic acid, 1,080 mg eicosapentaenoic acid, 75 mg taurine, 2,840 IU vitamin A activity, 75 IU vitamin E, and 200 mg vitamin C. Nepro provides 475 calories and 16.7 g protein per can; includes high-oleic safflower oil, corn syrup solids, and fructo-oligosaccharides; and is tailored for the nutritional needs of MHD patients. Oxepa and Nepro also contain L-carnitine, 43 mg and 62 mg, respectively.

MAIN OUTCOME MEASURES

Serum albumin pretrial and posttrial.

RESULTS

Studied outpatients (12 men and 8 women) were aged 60.4 +/- 13.0 (SD) years. Three patients had started MHD treatment between 1.5 and 3 months before the intervention. Nine patients were diabetic. Preintervention serum albumin, 3.44 +/- 0.34 g/dL (mean +/- SD) increased to 3.68 +/- 0.34 g/dL (P = .001) 4 weeks after the start of the intervention. In 16 patients, serum albumin level increased by 0.2 to 1.3 g/dL, whereas in 4 patients the serum albumin level decreased by 0.2 to 0.6 g/dL. Three patients reported diarrhea, and one diabetic patient had increased serum glucose values. No other side effects were noted. In 20 control outpatients not receiving nutritional intervention, serum albumin did not change from 3.46 +/- 0.20 to 3.47 +/- 10.44 g/dL (P = .47).

CONCLUSIONS

In hypoalbuminemic MHD patients, a short-term in-center nutritional intervention with one can of Nepro and one can of Oxepa during HD is practical, convenient, well-tolerated, and associated with a significant increase in serum albumin level. Well-designed randomized placebo-controlled clinical trials are needed to verify the safety and effectiveness of this nutritional intervention and its impact on clinical outcome in hypoalbuminemic MHD patients.

Plasma free amino acids and their metabolites in Taiwanese patients on hemodialysis and continuous ambulatory peritoneal dialysis

BACKGROUND

The high prevalence of protein-energy malnutrition is a critical issue for patients with end stage renal disease (ESRD) on hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). Levels of plasma and intracellular amino acids are significant indicators of protein metabolism and nutritional status assessment. We measured plasma FAAs in patients on maintenance dialysis and to provide information in monitoring the therapeutic strategy, particularly in AA supplementary therapy or protein restriction.

METHODS

Fifty-five patients with ESRD were investigated, 25 on HD (male : female=14 : 11; 48-67 y) and 30 on CAPD (male : female=17 : 13; 45-64 y). The subjects had been on dialysis for an average of 13 months (range, 9 to 22 months). Their plasma FAAs (including their intermediate metabolites) were measured by ion exchange chromatography before and after HD or during CAPD and were compared with data obtained from 20 age- and sex-matched healthy controls.

RESULTS

The total plasma FAA levels (urea and free ammonia, NH3 were excluded) in pre-HD samples (3911 +/- 709 micromol/l) was significantly higher than in the other groups (2570 +/- 378 in control, 3210 +/- 640 in post-HD, and 3468 +/- 271 in CAPD samples). The mean plasma FAA concentrations differed significantly between pre-HD and controls and between pre-HD and CAPD samples (p<0.05). No significant differences were found among the other group comparisons. Comparing individual FAA concentrations, only citrulline differed significantly among all groups (p<0.05), whereas serine, glutamine, beta-alanine, beta-aminoisobutyric acid, and gamma-aminobutyric acid were not different. Concentrations of some FAAs involved in the urea cycle, e.g., arginine, aspartic acid, citrulline, and ornithines, and solutes urea and NH3, were significantly increased. Ratios of tyrosine/phenylalanine and valine/glycine ratios were markedly reduced in all patients on dialysis compared with controls.

CONCLUSION

FAAs either from dietary uptake or protein catabolism are substantially retained in the plasma of patients with ESRD, possibly producing higher levels of the waste products (urea and NH3) through the urea cycle and ammonia metabolism in liver. Maintenance dialysis can effectively eliminate excess FAAs in plasma, as there was a 17.9% reduction post-HD. The abnormalities in FAA metabolism found in patients with ESRD necessitate careful consideration of dialysis and dietary measures.

Membrane Biocompatibility Does Not Affect Whole Body Protein Metabolism during Dialysis

BACKGROUND

Protein-calorie malnutrition is present in 30-50% of dialysis patients. The lack of biocompatibility of the dialysis membrane, which results in low-grade inflammation, could be responsible for this malnutrition. We investigated whether protein-energy malnutrition could be partly due to incompatibility of the dialyzer during the dialysis session.

METHODS

Five patients were dialyzed during 2 periods of 3 weeks (cross-over) with either a single-use low-flux polysulfone or cellulose triacetate (biocompatible) or a single-use cuprophan (bio-incompatible) membrane. As a measure of whole body protein metabolism, a primed constant infusion of L-[1-(13)C]-valine was used during a 4-hour dialysis session.

RESULTS

Cuprophan was a more powerful activator of the complement system than other membranes. Protein metabolism parameters during both study protocols were not different and resulted in the same protein balance during polysulfone/cellulose triacetate (-15 +/- 3) and cuprophan (-13 +/- 2 micromol/kg/h) dialysis.

CONCLUSION

In stable hemodialysis patients with no apparent complications, protein metabolism during dialysis is not affected by the compatibility of the dialysis membrane.

Intradialytic amino acids supplementation in hemodialysis patients with malnutrition: results of a multicenter cohort study

OBJECTIVE

Prospective evaluation of the effect of 6-month-long intradialytic amino acids (AA) supplementation on selected nutritional variables in malnourished hemodialysis (HD) patients.

DESIGN

Multicenter, prospective, (nonrandomized, noncontrolled) observational study.

SETTING

Thirty-one HD units affiliated with academic centers and tertiary-care hospitals.

PATIENTS

Adult patients treated by HD for at least 6 months. Inclusion criteria were: serum albumin concentration < or =39 g/L and at least 4% loss of body weight during the last 6 months in otherwise stable HD patients. From a cohort of 133 patients who were enrolled, 97 (54 men and 43 women) were eligible for the analysis.

INTERVENTION

Intradialytic AA supplementation with 500 mL 10% solution per HD session for a period of 6 months.

MAIN OUTCOME MEASURES

Serum albumin concentration, modified Subjective Global Assessment (SGA) score, body mass index (BMI), mid-arm circumference (MAC), and total lymphocyte count. Measurements were recorded at baseline and after 3 and 6 months of AA supplementation.

RESULTS

Serum albumin concentration increased significantly from the mean 32.5 +/- 4.6g/L at baseline to 36.4 +/- 4.8 g/L at 3 months (P <.001) and 37.1 +/- 4.8 g/L at final observation (P <.001 versus baseline). Significant correlation was observed between frequency of AA supplementation and serum albumin increase (r = 0.41; P <.0001). Rate of improvement negatively correlated significantly with baseline concentration of serum albumin (r = - 0.42; P <.0001). SGA score significantly improved from median of 16 points at baseline to 12 points at 3 months (P <.01) and 11 points at 6 months (P <.01 versus baseline), and this improvement also correlated with the frequency of AA supplementation. Small yet significant increase of MAC was observed at 6 months (from baseline 24.1 +/- 4.3 to 24.8 +/- 4.8 cm; P <.01), whereas BMI remained unchanged.

CONCLUSION

Intradialytic AA supplementation improves selected nutritional parameters of HD patients with malnutrition. The improvement depends on the intensity of supplementation.

Clearance of amino acids by hemodialysis in argininosuccinate synthetase deficiency

We determined the dialytic clearance of amino acids involved in ammoniagenesis and nitrogen excretion in a neonate with argininosuccinate synthetase deficiency who underwent acute hemodialysis. Plasma ammonia and plasma and dialysate amino acid concentrations were obtained at baseline, 30-minute intervals during hemodialysis, and 30 minutes after the completion of hemodialysis. Plasma ammonia concentrations declined by 56% during the 90-minute hemodialysis treatment, whereas arginine, citrulline, glutamine, and glycine concentrations decreased by 65%, 55%, 40%, and 34%, respectively. Mean dialytic clearances for arginine, citrulline, glutamine, and glycine were 24, 282, 263, and 189 mL/min per 1.73 m(2), respectively. The high dialytic clearance of citrulline suggests a novel mechanism of hemodialysis removal of nitrogen. Dialytic clearances of glutamine and glycine may prevent further ammoniagenesis in hyperammonemic patients. However, our data suggest that hemodialysis affects the precursors of alternative pathway removal of ammonia. Further study is needed to optimize the intradialytic and interdialytic dosing of substrates.

Increased albumin and fibrinogen synthesis rate in patients with chronic renal failure

BACKGROUND

Hypoalbuminemia and hyperfibrinogenemia are frequently observed in patients with chronic renal failure (CRF) and are both associated with cardiovascular diseases. The mechanisms responsible for hypoalbuminemia and hyperfibrinogenemia in CRF are unknown.

METHODS

In the present study, both albumin and fibrinogen kinetics were measured in vivo in predialysis patients (N = 6), patients on peritoneal dialysis (N = 7) and control subjects (N = 8) using l-[1-13C]-valine.

RESULTS

Plasma albumin concentration was significantly lower in patients on peritoneal dialysis compared to control subjects (P < 0.05). Plasma fibrinogen was significantly increased in both predialysis patients (P < 0.01) as well as patients on peritoneal dialysis (P < 0.001) in comparison to control subjects. In contrast to albumin, fibrinogen is only lost in peritoneal dialysate and not in urine. The absolute synthesis rates (ASR) of albumin and fibrinogen were increased in patients on peritoneal dialysis (ASR albumin, 125 +/- 9 mg/kg/day versus 93 +/- 9 mg/kg/day, P < 0.05; ASR fibrinogen, 45 +/- 4 mg/kg/day versus 29 +/- 3 mg/kg/day, P < 0.01) compared to control subjects. Albumin synthesis is strongly correlated with fibrinogen synthesis (r2 = 0.665, P < 0.0001, N = 21). In this study, the observed hypoalbuminemia in patients on peritoneal dialysis is likely not explained by malnutrition, inadequate dialysis, inflammation, metabolic acidosis, or insulin resistance. We speculate that peritoneal albumin loss is of relevance.

CONCLUSION

Synthesis rate of albumin and fibrinogen are coordinately up-regulated. Both albumin and fibrinogen are lost in peritoneal dialysis fluid. To compensate protein loss, albumin synthesis is up-regulated, but the response, in contrast to predialysis patients, does not fully correct plasma albumin concentrations in peritoneal dialysis patients. The increase in fibrinogen synthesis introduces an independent risk factor for atherosclerosis, since plasma fibrinogen pool is enlarged.

Practical aspects of intradialytic nutritional support

A critical review of recent international literature related to the use of intradialytic parenteral nutrition is given. The role of intradialytic parenteral nutrition as a therapy in malnourished hemodialysis patients is established and the need for systematic monitoring of this population at high risk of malnutrition is emphasized.

CBQCA assay of primary amine losses during hemodialysis

Nitrogen loss during hemodialysis is an important issue since all steps taken to improve clearance of urea will also increase loss of amino acids and other normally recyclable sources of nitrogen. Most dialyzers exclude albumin and other proteins, which react well with dyes commonly employed to measure protein, but do allow passage of mono- and oligopeptides that go undetected in protein assays. The CBQCA reagent provides a highly sensitive assay of primary amines that will detect amino acids, low molecular weight polypeptides, and high molecular weight proteins. We collected dialysate using a split stream technique from 28 chronic dialysis patients. With bovine albumin as the standard, the CBQCA assay reported 24.3+/-9.8 g albumin-equivalents (mean+/-S.D.) per dialysate whereas a Coomassie blue assay measured 1.19+/-0.78 g. The CBQCA assay values were substantially higher than previously reported amino acid losses. The CBQCA fluorescent assay for amines provides a simple assay for quantifying primary amine losses in dialysate fluid.