Muscle Status Response to Oral Nutritional Supplementation in Hemodialysis Patients With Protein Energy Wasting: A Multi-Center Randomized, Open Label-Controlled Trial

Making the invisible visible: imaging techniques for assessing muscle mass and muscle quality in chronic kidney disease

Muscle wasting and low muscle mass are prominent features of protein energy wasting (PEW), sarcopenia and sarcopenic obesity in patients with chronic kidney disease (CKD). In addition, muscle wasting is associated with low muscle strength, impaired muscle function and adverse clinical outcomes such as low quality of life, hospitalizations and increased mortality. While assessment of muscle mass is well justified, the assessment of skeletal muscle should go beyond quantity. Imaging techniques provide the means for non-invasive, comprehensive, in-depth assessment of the quality of the muscle such as the infiltration of ectopic fat. These techniques include computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound. Dual energy X-ray absorptiometry is also an imaging technique, but one that only provides quantitative and not qualitative data on muscle. The main advantage of imaging techniques compared with other methods such as bioelectrical impedance analysis and anthropometry is that they offer higher precision and accuracy. On the other hand, the higher cost for acquiring and maintaining the imaging equipment, especially CT and MRI, makes these less-used options and available mostly for research purposes. In the field of CKD and end-stage kidney disease (ESKD), imaging techniques are gaining attention for evaluating muscle quantity and more recently muscle fat infiltration. This review describes the potential of these techniques in CKD and ESKD settings for muscle assessment beyond that of muscle quantity.

The relationship between skeletal muscle mass and exercise capacity in patients undergoing hemodialysis: An exploratory secondary-analysis

BACKGROUND

Protein-energy wasting is commonly observed in patients undergoing hemodialysis, leading to reduced muscle mass and, in severe cases, sarcopenia, which significantly impacts the patients' quality of life and clinical outcomes. Exercise interventions are frequently employed to address muscle loss in these patients. However, the relationship between exercise capacity and skeletal muscle mass in this context remains uncertain. In this study, researchers conducted a series of body composition analysis and exercise capacity test to explore the relationship between exercise capacity and skeletal muscle mass.

METHODS

This study recruited 32 patients undergoing hemodialysis and analyzed their demographic and clinical parameters. To assess aerobic exercise capacity, the incremental shuttle walking test (ISWT) was conducted, while the handgrip strength test was used to evaluate muscle strength. The patients' body compositions were assessed using the Fresenius Body Composition Monitor, and the appendicular skeletal muscle was scanned using a GE Healthcare Lunar iDXA scanner. Three sequential linear models were employed to model the relationship between ISWT and skeletal muscle mass. Model 1 regressed ISWT against gender and age; Model 2 added handgrip strength, fat tissue index, and Davies comorbidity scores as additional predictors; and Model 3 further included the appendicular skeletal muscle index (appendicular skeletal muscle/height).

FINDINGS

After controlling for age and gender (Model 1: R2  = 0.373), and subsequently including handgrip strength, fat tissue index, and Davies comorbidity score effects (Model 2: R2  = 0.581), the impact of appendicular skeletal muscle on ISWT was found to be non-significant (Model 3: R2  = 0.600).

CONCLUSION

There was no significant correlation observed between exercise capacity and skeletal muscle mass in patients undergoing hemodialysis, indicating the factors influencing exercise capacity in this patient population are complex and that increasing skeletal muscle mass may not necessarily involve solely addressing the improvement of exercise capacity.

Effects of correcting metabolic acidosis on muscle mass and functionality in chronic kidney disease: a systematic review and meta-analysis

Metabolic acidosis unfavourably influences the nutritional status of patients with non-dialysis dependent chronic kidney disease (CKD) including the loss of muscle mass and functionality, but the benefits of correction are uncertain. We investigated the effects of correcting metabolic acidosis on nutritional status in patients with CKD in a systematic review and meta-analysis. A search was conducted in MEDLINE and the Cochrane Library from inception to June 2023. Study selection, bias assessment, and data extraction were independently performed by two reviewers. The Cochrane risk of bias tool was used to assess the quality of individual studies. We applied random effects meta-analysis to obtain pooled standardized mean difference (SMD) and 95% confidence intervals (CIs). We retrieved data from 12 intervention studies including 1995 patients, with a mean age of 63.7 ± 11.7 years, a mean estimated glomerular filtration rate of 29.8 ± 8.8 mL/min per 1.73 m2 , and 58% were male. Eleven studies performed an intervention with oral sodium bicarbonate compared with either placebo or with standard care and one study compared veverimer, an oral HCl-binding polymer, with placebo. The mean change in serum bicarbonate was +3.6 mEq/L in the intervention group and +0.4 mEq/L in the control group. Correcting metabolic acidosis significantly improved muscle mass assessed by mid-arm muscle circumference (SMD 0.35 [95% CI 0.16 to 0.54], P < 0.001) and functionality assessed with the sit-to-stand test (SMD -0.31 [95% CI -0.52 to 0.11], P = 0.003). We found no statistically significant effects on dietary protein intake, handgrip strength, serum albumin and prealbumin concentrations, and blood urea nitrogen. Correcting metabolic acidosis in patients with CKD improves muscle mass and physical function. Correction of metabolic acidosis should be considered as part of the nutritional care for patients with CKD.

Interpretations of the Role of Plasma Albumin in Prognostic Indices: A Literature Review

This review assesses how publications interpret factors that influence the serum or plasma albumin (PA) level in prognostic indices, focusing on inflammation and nutrition. On PubMed, a search for "albumin AND prognosis" yielded 23,919 results. From these records, prognostic indices were retrieved, and their names were used as search strings on PubMed. Indices found in 10 or more original research articles were included. The same search strings, restricted to "Review" or "Systematic review", retrieved yielded on the indices. The data comprised the 10 latest original research articles and up to 10 of the latest reviews. Thirty indices had 294 original research articles (6 covering two indices) and 131 reviews, most of which were from recent years. A total of 106 articles related the PA level to inflammation, and 136 related the PA level to nutrition. For the reviews, the equivalent numbers were 54 and 65. In conclusion, more publications mention the PA level as a marker of nutrition rather than inflammation. This is in contrast to several general reviews on albumin and nutritional guidelines, which state that the PA level is a marker of inflammation but not nutrition. Hypoalbuminemia should prompt clinicians to focus on the inflammatory aspects in their patients.

Dietary protein and muscle wasting in chronic kidney disease: new insights

PURPOSE OF REVIEW

Muscle wasting is an important health problem in chronic kidney disease (CKD) patients. Protein restriction in the diet can be one of the main causes of muscle wasting in this population. In this review, we aimed to investigate the relationship between dietary protein intake and muscle wasting in CKD patients according to recent literature.

RECENT FINDINGS

The one of the main mechanisms responsible for the muscle wasting is the disturbances in skeletal muscle protein turnover. Muscle wasting primarily occurs when the rates of muscle protein breakdown exceed the muscle protein synthesis. Dietary protein intake represents an important role by causing a potent anabolic stimulus resulting a positive muscle protein balance. Compared to studies made in healthy populations, there are very limited studies in the literature about the relationship between dietary protein intake and muscle wasting in the CKD population. Majority of the studies showed that a more liberal protein intake is beneficial for muscle wasting in especially advanced CKD and hemodialysis population.

SUMMARY

Although evaluating muscle wasting in CKD patients, the amount of protein in the diet of patients should also be reviewed. Although excessive protein intake has some negative consequences on this patient group, a more liberated dietary protein intake should be taken into account in this patient group with muscle wasting and especially in dialysis patients.

Barriers and Facilitators to Intradialytic Parenteral Nutrition Implementation Targeting Protein Energy Wasting in Malaysian Hemodialysis Patients

The capacity to deliver intradialytic parenteral nutrition (IDPN) for patients on hemodialysis (HD) diagnosed with protein energy wasting (PEW) in low resource settings is unknown. This study aimed to examine the extent of IDPN practice in HD units in Malaysia, and its implementation to treat PEW. We surveyed pharmacists (n = 56), who are central to parenteral nutrition delivery in Malaysia including IDPN. Seventeen healthcare stakeholders engaging with the Promoting Action on Research Implementation in Health Services (PARIHS) framework used the Likert scale to rate survey outcomes on IDPN implementation to treat PEW, according to the Evidence, Context, and Facilitation elements. IDPN for HD patients was available in 28 of 56 hospitals providing parenteral nutrition services, with only 13 hospitals (23.2%) providing IDPN to outpatients. Outpatient treatment was concentrated to urban locations (12/13) and significantly associated (p < 0.001) with resident nephrologists. The Evidence domain was rated poorly (2.18 ± 0.15) pertaining to IDPN indication when the oral spontaneous intake was ≤20 kcal/kg/day. The Context domain indicated good adherence to international best practice relating to IDPN administration (4.59 ± 0.15) and infusion time (4.59 ± 0.12). Poor adherence was observed in the Facilitation domain on ’Access to pharmacist and dietitian at HD units’ (2.65 ± 0.21) and ’Access to continuous medical education on managing PEW patients on HD’ (2.53 ± 0.15). The IDPN outpatient service was concentrated to urban hospitals with greater manpower resources. The PARIHS evaluation on IDPN implementation to treat PEW revealed facilitators in good practice adherence for prescribing and administration of IDPN but highlighted major barriers relating to IDPN indication and nutrient calculation.

The Effect of Nutrition and Exercise on Body Composition, Exercise Capacity, and Physical Functioning in Advanced CKD Patients

Patients with stages 4 and 5 chronic kidney disease (CKD), and particularly chronic dialysis patients, commonly are found to have substantially reduced daily physical activity in comparison to age- and sex-matched normal adults. This reduction in physical activity is associated with a major decrease in physical exercise capacity and physical performance. The CKD patients are often physically deconditioned, and protein energy wasting (PEW) and frailty are commonly present. These disorders are of major concern because physical dysfunction, muscle atrophy, and reduced muscle strength are associated with poor quality of life and increased morbidity and mortality in CKD and chronic dialysis patients. Many randomized controlled clinical trials indicate that when CKD and chronic dialysis are provided nutritional supplements or undergo exercise training their skeletal muscle mass and exercise capacity often increase. It is not known whether the rise in skeletal muscle mass and exercise capacity associated with nutritional support or exercise training will reduce morbidity or mortality rates. A limitation of these clinical trials is that the sample sizes of the different treatment groups were small. The aim of this review is to discuss the effects of nutrition and exercise on body composition, exercise capacity, and physical functioning in advanced CKD patients.

Disease-related malnutrition in chronic kidney disease

PURPOSE OF REVIEW

Disease-related malnutrition has complex and multifactorial pathophysiology. It is common in patients with chronic kidney disease (CKD) and has a devastating impact on morbidity and mortality. Given the rising numbers of patients diagnosed with CKD, disease-related malnutrition is an escalating clinical challenge. This review summarises current knowledge in relation to the development, screening and treatments for disease-related malnutrition in CKD.

RECENT FINDINGS

New research has identified other potential causes for the development of malnutrition in CKD, including changes in taste and smell, and effects of polypharmacy. Screening and assessment studies have investigated different tools in relation to the new Global Leadership Initiative on Malnutrition (GLIM) criteria. Different modalities of low protein diets and the potential use of pre and probiotics are being explored. Furthermore, the importance of nutritional support, and possibly exercise during dialysis is being examined in terms of reducing anabolic resistance and catabolism.

SUMMARY

Further research is required to better understand the nuances of the pathophysiology of disease-related malnutrition in CKD. This work should inform not only consistent terminology and the application of assessment tools specific to disease-related malnutrition in CKD but also the development of novel interventions that reflect its multifaceted pathophysiology and impact.