Comparison of stroke volume measurements during hemodialysis using bioimpedance cardiography and echocardiography.

BACKGROUND: Fluid management remains a major challenge of hemodialysis (HD) care, with serious implications for morbidity and mortality. Intradialytic fluid management is typically guided by blood pressure, an indirect resultant of hemodynamics status. Direct measurements of hemodynamic parameters may improve cardiovascular outcomes by providing rational bases for intervention. We compare stroke volume (SV) measurements using a noninvasive, regional biompedance cardiography device (NiCaS) with Doppler echocardiography (Echo) in HD setting. METHODS: Stroke volumes were simultaneously measured using the devices in 17 patients receiving maintenance HD. Measurements were made during 2 weekly HD treatments, and twice within each HD treatment during the first and last hour of each treatment, for a total of 64 SV measurements. Agreement between devices was assessed using linear regression, a Pearson's correlation coefficient, and a Bland-Altman plot all adjusted for repeated measures within patients. RESULTS: Echo and NiCaS SV mean and 95% CIs were 58.0 (50.1, 65.8) and 56.7 (49.4, 64.0) mL, respectively. NiCaS SV correlated strongly with Echo SV during the first and last hours of treatments (r = 0.93, P < 0.001 and r = 0.92, P < 0.001, respectively). Linear regression of NiCaS on Echo showed a slope of 0.97, 95% CI (0.91, 1.02) which did not differ from 1, P = 0.20. A Bland-Altman plot and 4-Quadrant plot confirmed that the 2 methods produced comparable measurements. CONCLUSION: NiCaS SV measurements are similar to and strongly correlated with Echo SV measurements. This suggests that noninvasive NiCaS technology may be a practical method for measuring SV during HD.

High-density lipoprotein particle pattern and overall lipid responses to a short-term moderate-intensity aerobic exercise training intervention in patients with chronic kidney disease.

BACKGROUND: Chronic kidney disease (CKD) is associated with abnormal lipid profiles and altered high-density lipoprotein (HDL) particle size patterns. Lower levels of the larger, cardioprotective HDL particles found in CKD may play a role in the increased risk for cardiovascular disease in these patients. The current study was designed to assess the effects of short-term moderate-intensity aerobic exercise training on the HDL particle pattern and overall lipid profiles in stage 3 CKD patients. METHODS: Forty-six men and women with stage 3 CKD were randomized to either exercise (EX, n = 25) or control (CON, n = 21). Those in the EX group completed 16 weeks of supervised moderate-intensity aerobic exercise three times per week. Serum total cholesterol, HDL cholesterol (HDL-C), triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), HDL particle size, estimated glomerular filtration rate (eGFR), body composition and peak oxygen uptake (VO2peak) were assessed at baseline and week 16. RESULTS: The rate of compliance in the EX group was 97 ± 7.2%. No change was observed in eGFR over time in either group. There was an 8.2% improvement in VO2peak in the EX group (P = 0.05), while VO2peak decreased in the CON group. HDL-C, TGs, HDL particle size and body composition remained unchanged in both groups. A trend was found for lower total cholesterol (TC) (P = 0.051) and LDL-C (P = 0.07) in the CON group. CONCLUSION: Our findings indicate that a short-term aerobic exercise training intervention in stage 3 CKD patients does not induce changes in HDL particle size or favorable lipid profile modifications.

Blood pressure response to acute and chronic exercise in chronic kidney disease.

AIM: The current study was designed to determine if a relationship exists between acute and chronic blood pressure responses to aerobic exercise in pre-dialysis patients. METHODS: Pre-dialysis kidney patients attended four sessions before being randomized to the treatment (n = 25) or control group (n = 21). In session 1, resting blood pressure was recorded, and these measurements were repeated during the second visit when peak oxygen uptake (VO2peak ) was assessed. In the third and fourth sessions, blood pressures were taken prior to a 40 min walk or period of seated rest. After the 40 min walk or seated rest, blood pressures were monitored for 60 min in the laboratory and for the subsequent 24 h. After session 4, subjects in the treatment group trained aerobically at a moderate intensity, three times per week for 16 weeks. Control subjects were asked to be sedentary. All measurements were repeated after 16 weeks of training or sedentary living. RESULTS: Training increased VO2peak (mL/kg per minute) in the treatment group (baseline 19.6 ± 6.7 vs 21.2 ± 7.7, P < 0.05), with no change in the control (18.0 ± 6.0 vs 17.5 ± 5.7) group. Post-exercise hypotension occurred at baseline prior to training but was unaffected by 16 weeks of training. CONCLUSION: Post-exercise hypotension occurs in pre-dialysis patients following aerobic exercise, but short-term moderate-intensity continuous aerobic training has no effect upon this response. There seems to be no relationship between the acute and chronic blood pressure responses to exercise in pre-dialysis kidney patients.

Short-term aerobic exercise and vascular function in CKD stage 3: a randomized controlled trial.

BACKGROUND: The present study was designed to determine the effect of short-term moderate-intensity exercise training on arterial stiffness in patients with chronic kidney disease (CKD) stage 3. STUDY DESIGN: Randomized controlled trial with a parallel-group design. SETTING & PARTICIPANTS: Testing and training sessions were performed at Springfield College. 46 (treatment group, n=25; control group, n=21) patients with CKD with diabetes and/or hypertension completed the study. INTERVENTION: The aerobic training program consisted of 16 weeks of supervised exercise training at 50%-60% peak oxygen uptake (Vo2peak) 3 times per week, while the control group remained sedentary. Identical testing procedures were performed following the 16-week intervention. OUTCOMES: The primary outcome was arterial stiffness. Secondary outcomes were aerobic capacity, various blood parameters (endothelin 1, nitrate/nitrite, and high-sensitivity C-reactive protein), and health-related quality of life. MEASUREMENTS: Arterial stiffness was assessed with aortic pulse wave velocity (PWV), aerobic capacity by Vo2peak, blood parameters by enzyme-linked immunosorbent assays, and health-related quality of life by the 36-Item Short Form Health Survey (SF-36). Participants attended 4 sessions before being randomly assigned to either the treatment or control group. Participants gave consent during the first session, whereas a graded exercise test with measurement of Vo2peak was completed during the second session. During sessions 3 and 4, aortic PWV was measured at rest prior to 40 minutes of either moderate-intensity exercise training or seated rest. A venous blood sample was obtained prior to exercise or rest and participants completed the SF-36 questionnaire. RESULTS: 16 weeks of training led to an 8.2% increase in Vo2peak for the treatment group (P=0.05), but no changes in aortic PWV . LIMITATIONS: Randomization was not concealed and was violated on one occasion; also, use of an indirect measurement of endothelial function and the short duration of the intervention. CONCLUSIONS: Short-term moderate-intensity exercise training does not alter arterial stiffness in patients with CKD, but seems to reduce endothelin 1 levels.