Intradialytic exercise with blood flow restriction: Something to add to hemodialysis adequacy? Findings from a crossover study

Effects of Different Exercises on Physical Function, Dialysis Adequacy, and Health-Related Quality of Life in Maintenance Hemodialysis Patients: A Systematic Review and Network Meta-Analysis

BACKGROUND

Clinical guidelines recommend exercise training for patients undergoing maintenance hemodialysis (MHD). However, the effectiveness of different types of exercise remains uncertain.

OBJECTIVES

The aims of the study were to compare and rank the effect of different types of exercise on walking capacity, cardiorespiratory fitness, dialysis adequacy, and health-related quality of life (HRQOL) in patients undergoing MHD.

METHODS

Eight databases (four English and four Chinese) were searched from inception to January 1, 2022. Randomized controlled trials evaluating the efficacy of different exercises for patients undergoing MHD were included. Two independent reviewers screened the literature, extracted data, assessed the risk of bias, and evaluated the certainty of evidence. A frequentist random-effect network meta-analysis was conducted.

RESULTS

Ninety trials with 4,084 participants comparing 15 types of exercise were included, reporting on the six-minute walking test (45 trials), peak oxygen uptake (22 trials), dialysis adequacy (30 trials), and HRQOL (23 trials). Network meta-analysis showed that the most effective intervention for walking capacity was intradialytic aerobic exercise combined with blood flow restriction with a mean difference and 95% confidence interval of 97.35 (11.89-182.81), for peak oxygen uptake it was non-intradialytic combined aerobic and resistance exercise with a value of 4.35 (2.25-6.44), for dialysis adequacy it was intradialytic combined aerobic and resistance exercise with a value of 0.17 (0.06-0.28), for the physical component summary of HRQOL it was intradialytic aerobic exercise with a value of 4.93 (2.31-7.54), and for the mental component summary of HRQOL it was non-intradialytic combined aerobic and resistance exercise with a value of 6.36 (0.45-12.27). Ultimately, intradialytic combined aerobic and resistance exercise could improve all the above outcomes compared to usual care.

CONCLUSIONS

This study concluded that intradialytic combined aerobic and resistance exercise is optimal for MHD patients due to its significant positive effects on multiple outcomes. Walking capacity can be further enhanced by combining blood flow restriction with exercise. For improving dialysis adequacy, intradialytic exercise proves to be more effective than non-intradialytic exercise. Further well-designed clinical trials are needed to investigate the effects of exercise with varying durations, intensities, and frequencies.

Effect of intra-dialytic physical exercise on depression in prevalent hemodialysis patients

Background

Depression is associated with morbidity, death, diminished quality of life, decreased longevity, and even suicidal ideation in hemodialysis patients. Intra-dialytic exercise is considered as integral component of the clinical care management of hemodialysis patients as it improves hemodialysis effectiveness, reducing systemic inflammation, increasing exercise tolerance, decreasing depression and improving quality of life. The objective of this study was to assess the effect of intra-dialytic physical exercise on depression and physical activity in prevalent hemodialysis patients. This prospective cohort research comprised 50 hemodialysis patients maintained on regular hemodialysis 3 times/week with duration since starting dialysis (1–5 years), not practicing any previous physical activity, suffering from depressive symptoms, not maintained on antidepressants and separated into two groups: group I underwent intra-dialytic exercise for 3 months and group II was matched in age and gender but did not undertake any exercise.

Results

Hamilton depression rating scale was significantly decreased in group I after completing the exercise program compared to baseline (P = 0.000), while there was no significant change in group II. Serum tumor necrosis factor alpha significantly decreased in group I compared to baseline (P = 0.000), while there was no significant change in group II. A positive correlation was found between serum tumor necrosis factor alpha and Hamilton depression rating scale (r = 0.676), (P = 0.000). Physical activity tests; 6-min walk test, rapid assessment of physical activity and peak volume of oxygen consumption were significantly improved in group I compared to baseline (P = 0.000), while there was no statistically significant difference in group II. Serum phosphorus and parathyroid hormone levels were significantly decreased in group I compared to baseline (P < 0.01), while urea reduction ratio was significantly increased in group I compared to baseline (P = 0.000), but there was no significant change in group II.

Conclusions

Intra-dialysis exercise can improve depression and physical performance in hemodialysis patients. As positive correlation was found between serum tumor necrosis factor alpha and Hamilton depression rating scale, so tumor necrosis factor alpha may be considered as marker of depression in hemodialysis patients. Intra-dialytic exercise can improve dialysis efficacy by improving urea reduction ratio.

Potential implications of blood flow restriction exercise on patients with chronic kidney disease: a brief review

Combining blood flow restriction (BFR) with exercise is considered a relevant, helpful method in load-compromised individuals and a viable replacement for traditional heavy-load strength training. BFR exercise may be particularly useful for those unable to withstand high mechanical stresses on joints resulting in skeletal muscle dysfunction, such as patients with chronic kidney disease (CKD). Current literature suggests that BFR training displays similar positive health benefits to exercise training alone for CKD patients, including maintenance of muscle strength, glomerular filtration rate maintenance, uremic parameters, inflammatory profile, redox status, glucose homeostasis, blood pressure adjustments, and low adverse reports. In this review of nine studies in CKD patients, we clarify the potential safety and health effects of exercise training with BFR compared to exercise training alone and recommend insights for future research and practical use. Furthermore, we introduce relevant gaps in this emerging field, providing substantial guidance, critical discussion, and valuable preliminary conclusions in this demographic of patients. However, based on the limited studies in this area, more research is necessary to determine the optimal BFR exercise programming.

A Useful Blood Flow Restriction Training Risk Stratification for Exercise and Rehabilitation

Blood flow restriction training (BFRT) is a modality with growing interest in the last decade and has been recognized as a critical tool in rehabilitation medicine, athletic and clinical populations. Besides its potential for positive benefits, BFRT has the capability to induce adverse responses. BFRT may evoke increased blood pressure, abnormal cardiovascular responses and impact vascular health. Furthermore, some important concerns with the use of BFRT exists for individuals with established cardiovascular disease (e.g., hypertension, diabetes mellitus, and chronic kidney disease patients). In addition, considering the potential risks of thrombosis promoted by BFRT in medically compromised populations, BFRT use warrants caution for patients that already display impaired blood coagulability, loss of antithrombotic mechanisms in the vessel wall, and stasis caused by immobility (e.g., COVID-19 patients, diabetes mellitus, hypertension, chronic kidney disease, cardiovascular disease, orthopedic post-surgery, anabolic steroid and ergogenic substance users, rheumatoid arthritis, and pregnant/postpartum women). To avoid untoward outcomes and ensure that BFRT is properly used, efficacy endpoints such as a questionnaire for risk stratification involving a review of the patient’s medical history, signs, and symptoms indicative of underlying pathology is strongly advised. Here we present a model for BFRT pre-participation screening to theoretically reduce risk by excluding people with comorbidities or medically complex histories that could unnecessarily heighten intra- and/or post-exercise occurrence of adverse events. We propose this risk stratification tool as a framework to allow clinicians to use their knowledge, skills and expertise to assess and manage any risks related to the delivery of an appropriate BFRT exercise program. The questionnaires for risk stratification are adapted to guide clinicians for the referral, assessment, and suggestion of other modalities/approaches if/when necessary. Finally, the risk stratification might serve as a guideline for clinical protocols and future randomized controlled trial studies.

Exercise training for adults undergoing maintenance dialysis

BACKGROUND

Dialysis treatments weigh heavily on patients' physical and psychosocial health. Multiple studies have assessed the potential for exercise training to improve outcomes in adults undergoing dialysis. However, uncertainties exist in its relevance and sustainable benefits for patient-important outcomes. This is an update of a review first published in 2011.

OBJECTIVES

To assess the benefits and safety of regular structured exercise training in adults undergoing dialysis on patient-important outcomes including death, cardiovascular events, fatigue, functional capacity, pain, and depression. We also aimed to define the optimal prescription of exercise in adults undergoing dialysis.

SEARCH METHODS

In this update, we conducted a systematic search of the Cochrane Kidney and Transplant Register of Studies up to 23 December 2020. The Register includes studies identified from CENTRAL, MEDLINE, EMBASE, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov as well as kidney-related journals and the proceedings of major kidney conferences.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of any structured exercise programs of eight weeks or more in adults undergoing maintenance dialysis compared to no exercise or sham exercise.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the search results for eligibility, extracted the data and assessed the risk of bias using the Cochrane risk of bias tool. Whenever appropriate, we performed random-effects meta-analyses of the mean difference in outcomes. The primary outcomes were death (any cause), cardiovascular events and fatigue. Secondary outcomes were health-related quality of life (HRQoL), depression, pain, functional capacity, blood pressure, adherence to the exercise program, and intervention-related adverse events.

MAIN RESULTS

We identified 89 studies involving 4291 randomised participants, of which 77 studies (3846 participants) contributed to the meta-analyses. Seven studies included adults undergoing peritoneal dialysis. Fifty-six studies reported aerobic exercise interventions, 21 resistance exercise interventions and 19 combined aerobic and resistance training within the same study arm. The interventions lasted from eight weeks to two years and most often took place thrice weekly during dialysis treatments. A single study reported death and no study reported long-term cardiovascular events. Five studies directly assessed fatigue, 46 reported HRQoL and 16 reported fatigue or pain through their assessment of HRQoL. Thirty-five studies assessed functional capacity, and 21 reported resting peripheral blood pressure. Twelve studies reported adherence to exercise sessions, and nine reported exercise-related adverse events. Overall, the quality of the included studies was low and blinding of the participants was generally not feasible due to the nature of the intervention. Exercise had uncertain effects on death, cardiovascular events, and the mental component of HRQoL due to the very low certainty of evidence. Compared with sham or no exercise, exercise training for two to 12 months may improve fatigue in adults undergoing dialysis, however, a meta-analysis could not be conducted. Any exercise training for two to 12 months may improve the physical component of HRQoL (17 studies, 656 participants: MD 4.12, 95% CI 1.88 to 6.37 points on 100 points-scale; I² = 49%; low certainty evidence). Any exercise training for two to 12 months probably improves depressive symptoms (10 studies, 441 participants: SMD -0.65, 95% CI -1.07 to -0.22; I² = 77%; moderate certainty evidence) and the magnitude of the effect may be greater when maintaining the exercise beyond four months (6 studies, 311 participants: SMD -0.30, 95% CI 0.14 to -0.74; I² = 71%). Any exercise training for three to 12 months may improve pain (15 studies, 872 participants: MD 5.28 95% CI -0.12 to 10.69 points on 100 points-scale; I² = 63%: low certainty evidence) however, the 95% CI indicates that exercise training may make little or no difference in the level of pain. Any exercise training for two to six months probably improves functional capacity as it increased the distance reached during six minutes of walking (19 studies, 827 participants: MD 49.91 metres, 95% CI 37.22 to 62.59; I² = 34%; moderate certainty evidence) and the number of sit-to-stand cycles performed in 30 seconds (MD 2.33 cycles, 95% CI 1.71 to 2.96; moderate certainty evidence). There was insufficient evidence to assess the safety of exercise training for adults undergoing maintenance dialysis. The results were similar for aerobic exercise, resistance exercise, and a combination of both aerobic and resistance exercise.

AUTHORS' CONCLUSIONS

It is uncertain whether exercise training improves death, cardiovascular events, or the mental component of HRQoL in adults undergoing maintenance dialysis. Exercise training probably improves depressive symptoms, particularly when the intervention is maintained beyond four months. Exercise training is also likely to improve functional capacity. Low certainty evidence suggested that exercise training may improve fatigue, the physical component of quality of life, and pain. The safety of exercise training for adults undergoing dialysis remains uncertain.

Intradialytic Nutrition and Hemodialysis Prescriptions: A Personalized Stepwise Approach

Dialysis and nutrition are two sides of the same coin—dialysis depurates metabolic waste that is typically produced by food intake. Hence, dietetic restrictions are commonly imposed in order to limit potassium and phosphate and avoid fluid overload. Conversely, malnutrition is a major challenge and, albeit to differing degrees, all nutritional markers are associated with survival. Dialysis-related malnutrition has a multifactorial origin related to uremic syndrome and comorbidities but also to dialysis treatment. Both an insufficient dialysis dose and excessive removal are contributing factors. It is thus not surprising that dialysis alone, without proper nutritional management, often fails to be effective in combatting malnutrition. While composite indexes can be used to identify patients with poor prognosis, none is fully satisfactory, and the definitions of malnutrition and protein energy wasting are still controversial. Furthermore, most nutritional markers and interventions were assessed in hemodialysis patients, while hemodiafiltration and peritoneal dialysis have been less extensively studied. The significant loss of albumin in these two dialysis modalities makes it extremely difficult to interpret common markers and scores. Despite these problems, hemodialysis sessions represent a valuable opportunity to monitor nutritional status and prescribe nutritional interventions, and several approaches have been tried. In this concept paper, we review the current evidence on intradialytic nutrition and propose an algorithm for adapting nutritional interventions to individual patients.