Danielle L. Kirkman

Anabolic exercise in haemodialysis patients: a randomised controlled pilot study.

BackgroundThe anabolic response to progressive resistance exercise training (PRET) in haemodialysis patients is unclear. This pilot efficacy study aimed to determine whether high-intensity intradialytic PRET could reverse atrophy and consequently improve strength and physical function in haemodialysis patients. A second aim was to compare any anabolic response to that of healthy participants completing the same program.MethodsIn a single blind controlled study, 23 haemodialysis patients and 9 healthy individuals were randomly allocated to PRET or an attention control (SHAM) group. PRET completed high-intensity exercise leg extensions using novel equipment. SHAM completed low-intensity lower body stretching activities using ultra light resistance bands. Exercises were completed thrice weekly for 12xa0weeks, during dialysis in the haemodialysis patients. Outcomes included knee extensor muscle volume by magnetic resonance imaging, knee extensor strength by isometric dynamometer and lower body tests of physical function. Data were analysed by a per protocol method using between-group comparisons.ResultsPRET elicited a statistically and clinically significant anabolic response in haemodialysis patients (PRET—SHAM, mean difference [95xa0% CI]: 193[63 to 324]u2009cm3) that was very similar to the response in healthy participants (PRET—SHAM, 169[−41 to 379]u2009cm3). PRET increased strength in both haemodialysis patients and healthy participants. In contrast, PRET only enhanced lower body functional capacity in the healthy participants.ConclusionsIntradialytic PRET elicited a normal anabolic and strength response in haemodialysis patients. The lack of a change in functional capacity was surprising and warrants further investigation.

Kidney transplantation: a systematic review of interventional and observational studies of physical activity on intermediate outcomes

Kidney transplant patients have decreased quality and longevity of life. Whether exercise can positively affect associated outcomes such as physical functioning, metabolic syndrome, kidney function, and immune function, has only been addressed in relatively small studies. Thus the aim of this systematic review was to determine effects of physical activity level on these intermediate outcomes in kidney transplant patients. We electronically and hand searched to identify 21 studies (6 retrospective assessments of habitual physical activity and 15 intervention studies including 6 controlled trials). After study quality assessment, intermediate outcomes associated with quality and longevity of life were expressed as correlations or percentage changes in addition to effect sizes. Habitual physical activity level was positively associated with quality of life and aerobic fitness and negatively associated with body fat (medium to large effect sizes). Exercise interventions also showed medium to large positive effects on aerobic capacity (10%-114% increase) and muscle strength (10%-22% increase). However, exercise programs had minimal or contradictory effects on metabolic syndrome and immune and kidney function. In kidney transplant patients, physical activity intervention is warranted to enhance physical functioning. Whether exercise impacts on outcomes associated with longevity of life requires further study.

Interaction between intradialytic exercise and hemodialysis adequacy.

Background/Aims: According to mathematical modeling, intradialytic exercise of sufficient intensity and duration implemented in the second half of dialysis should be as efficacious as increasing dialysis time for dialysis adequacy. This assumption has not been tested in vivo. Methods: In this controlled trial, 11 hemodialysis (HD) patients (mean (SD) age 56 (13) years) were recruited. Each patient completed three trial arms in a randomized order: routine care (CONT), increased HD time of 30 min (TIME), and intradialytic exercise (EXER), 60 min of cycling at 90% of the lactate threshold in the last 90 min of HD. The primary outcome was eKt/Vurea. Secondary outcomes included reduction and rebound ratios of urea, creatinine, phosphate and β2-microglobulin. Outcomes were calculated from blood sampling collected pre-, post- and 30 min post-HD and confirmed with dialysate sampling. Results: Exercise was not as efficacious as increased HD time for eKt/Vurea (EXER vs. CONT, mean change (95% CI): 0.03 (-0.05 to 0.12); TIME vs. CONT: 0.15 (0.05-0.26)). Exercise was less efficacious at improving reduction ratios of urea and creatinine. However, exercise was more efficacious than increased dialysis time for phosphate reduction ratio (EXER vs. CONT: 8.6% (0.5-16.7); TIME vs. CONT: 5.0% (-1.0 to 11.1)). Conclusion: This study utilized a rigorously controlled in vivo design to test mathematical models and assumptions regarding dialysis adequacy. Intradialytic exercise towards the end of HD cannot replace the prescription of increased HD time for dialysis adequacy, but may be an adjunctive therapy for serum phosphate control.

The Vascular Endothelium in Chronic Kidney Disease: A Novel Target for Aerobic Exercise.

Endothelial dysfunction occurs in chronic kidney disease (CKD) and increases the risk for cardiovascular disease. The mechanisms of endothelial dysfunction seem to evolve throughout kidney disease progression, culminating in reduced L-arginine transport and impaired nitric oxide bioavailability in advanced disease. This review examines the hypothesis that aerobic exercise may reverse endothelial dysfunction by improving endothelial cell L-arginine uptake in CKD.

Cardiopulmonary exercise testing reveals subclinical abnormalities in chronic kidney disease

Background Reductions in exercise capacity associated with exercise intolerance augment cardiovascular disease risk and predict mortality in chronic kidney disease. This study utilized cardiopulmonary exercise testing to (a) investigate mechanisms of exercise intolerance; (b) unmask subclinical abnormalities that may precede cardiovascular disease in chronic kidney disease. Design The design of this study was cross-sectional. Methods Cardiopulmonary exercise testing was carried out in 31 Stage 3–4 chronic kidney disease patients (60u2009±u200911 years; estimated glomerular filtration rate 43u2009±u200913u2009ml/min/1.73 m2) and 21 matched healthy individuals (healthy controls; 56u2009±u20095 years; estimated glomerular filtration rate>90u2009ml/min/1.73 m2) on a cycle ergometer with workload increased by 15u2009W every minute until volitional fatigue. Breath-by-breath respiratory gas analysis was performed with an automated gas analyzer and averaged over 10u2009s intervals. Results Peak oxygen uptake was reduced in chronic kidney disease compared to healthy controls (17.43u2009±u20091.03 vs 28u2009±u20092.05u2009ml/kg/min; pu2009<u20090.01), as was oxygen uptake at the ventilatory threshold (9.44u2009±u20090.53 vs15.55u2009±u20091.34u2009ml/kg/min; pu2009<u20090.01). A steeper minute ventilation rate/carbon dioxide production slope (32u2009±u20090.8 vs 28u2009±u20091; pu2009<u20090.01) and a lower expired carbon dioxide pressure in chronic kidney disease (27u2009±u20090.6 vs 31u2009±u20090.9 vs 0.9; pu2009<u20090.01) indicated ventilation perfusion mismatching in these patients. The ventilatory cost of oxygen uptake was higher in chronic kidney disease (37u2009±u20090.8 vs 33u2009±u20091; pu2009<u20090.01). Maximum heart rate (134u2009±u20095 vs 159u2009±u20093 bpm) and one-minute heart rate recovery (15u2009±u20091 vs 20u2009±u20092 bpm) were reduced in chronic kidney disease (pu2009<u20090.01). Conclusion This study suggests that both central and peripheral limitations likely contribute to reduced exercise capacity in non-dialysis chronic kidney disease. Additionally, cardiopulmonary exercise testing revealed subclinical cardiopulmonary abnormalities in these patients in the absence of overt cardiovascular disease. Cardiopulmonary exercise testing could potentially be a tool for unmasking cardiopulmonary abnormalities preceding cardiovascular disease in chronic kidney disease.

THE ROLE OF MITOCHONDRIA DERIVED REACTIVE OXYGEN SPECIES IN MICROVASCULAR DYSFUNCTION IN CHRONIC KIDNEY DISEASE

Cardiovascular disease is the leading cause of mortality in chronic kidney disease (CKD). Mitochondrial dysfunction secondary to CKD is a potential source of oxidative stress that may impair vascular function. This study sought to determine if mitochondria-derived reactive oxygen species contribute to microvascular dysfunction in stage 3-5 CKD. Cutaneous vasodilation in response to local heating was assessed in 20 CKD patients [60u2009±u200913 yr; estimated glomerular filtration rate (eGFR) 46u2009±u200913 ml·kg-1·1.73 m-2] and 11 matched healthy participants (58u2009±u20092 yr; eGFR >90 ml·kg-1·1.73 m-2). Participants were instrumented with two microdialysis fibers for the delivery of 1) Ringer solution, and 2) the mitochondria- specific superoxide scavenger MitoTempo. Skin blood flow was measured via laser Doppler flowmetry during standardized local heating (42°C). Cutaneous vascular conductance (CVC) was calculated as a percentage of the maximum conductance achieved with sodium nitroprusside infusion at 43°C. Urinary isofuran/F2-isoprostane ratios were assessed by gas-chromatography mass spectroscopy. Isofuran-to-F2-isoprostane ratios were increased in CKD patients (3.08u2009±u20090.32 vs. 1.69u2009±u20090.12 arbitrary units; P < 0.01) indicative of mitochondria-derived oxidative stress. Cutaneous vasodilation was impaired in CKD compared with healthy controls (87u2009±u20091 vs. 92u2009±u20091%CVCmax; P < 0.01). Infusion of MitoTempo significantly increased the plateau phase CVC in CKD patients (CKD Ringer vs. CKD MitoTempo: 87u2009±u20091 vs. 93u2009±u20091%CVCmax; P < 0.01) to similar levels observed in healthy controls ( P = 0.9). These data provide in vivo evidence that mitochondria-derived reactive oxygen species contribute to microvascular dysfunction in CKD and suggest that mitochondrial dysfunction may be a potential therapeutic target to improve CKD-related vascular dysfunction.

Exercise for Chronic Kidney Disease

and depression in this patient population. 5 Despite current guidelines and favorable evidence, exercise is still not prescribed as part of routine care for CKD patients. The multidisciplinary nephrology team is an integral part of encouraging and integrating physical activity and regular exercise into clinical practice. The nephrology dietitian is especially key because this individual can easily combine counseling for healthy eating habits with the need for exercise. The information provided is aimed to promote physical activity counseling and empower health providers to prescribe exercise a routine part of care for CKD patients.

Patient Education. The importance of exercise for chronic kidney disease patients.

and depression in this patient population. 5 Despite current guidelines and favorable evidence, exercise is still not prescribed as part of routine care for CKD patients. The multidisciplinary nephrology team is an integral part of encouraging and integrating physical activity and regular exercise into clinical practice. The nephrology dietitian is especially key because this individual can easily combine counseling for healthy eating habits with the need for exercise. The information provided is aimed to promote physical activity counseling and empower health providers to prescribe exercise a routine part of care for CKD patients.

The Importance of Exercise for Chronic Kidney Disease Patients

and depression in this patient population. 5 Despite current guidelines and favorable evidence, exercise is still not prescribed as part of routine care for CKD patients. The multidisciplinary nephrology team is an integral part of encouraging and integrating physical activity and regular exercise into clinical practice. The nephrology dietitian is especially key because this individual can easily combine counseling for healthy eating habits with the need for exercise. The information provided is aimed to promote physical activity counseling and empower health providers to prescribe exercise a routine part of care for CKD patients.

Arteriovenous fistula complication following MRI

Health professionals should be aware of medical procedures that cause vascular access complications. This case describes a haemodialysis patient who experienced pain, swelling and bruising over a radiocephalic fistula following MRI. Exactly the same signs and symptoms were evident following a second scan performed 3u2005months later. Plausible explanations include a radio frequency-induced electrical current being formed at the arteriovenous fistula, or varying gradients of the MRI sequence stimulating peripheral nerves, leading to a site of increased tissue stimulation. Of note, a juxta-anastomotic venous stenosis was confirmed by fistulogram 4u2005days after the second scan, although whether this access failure was due to the MRI scan per se could not be ascertained. Nevertheless, these previously undocumented observations suggest that careful patient and fistula monitoring is required when completing MRI scans in those with an arteriovenous fistula.