Cardiac abnormalities and exercise tolerance in patients receiving renal replacement therapy

Estimation of pulmonary artery systolic pressure in hemodialysis patients and its association with cardiorespiratory fitness and pulmonary function

PURPOSE

To evaluate the estimated pulmonary arterial systolic pressure (PASP) through transthoracic echocardiography in hemodialysis (HD) patients and associate it with cardiorespiratory fitness and pulmonary function.

METHODS

This study was a cross-sectional analysis of HD patients that performed evaluations of cardiac function, cardiorespiratory fitness, and pulmonary function, through transthoracic echocardiography, cardiopulmonary exercise test, spirometry, and manovacuometry, respectively. All patients underwent the evaluations on a non-dialysis day.

RESULTS

Thirty-five HD patients were evaluated and separated according to the presence of probable pulmonary hypertension (PH) (estimated PASP ≥ 35 mmHg) or not (estimated PASP < 35 mmHg). Those HD patients with probable PH had the worst cardiorespiratory fitness, evaluated by the peak oxygen consumption (VO_2peak) (17.11 ± 4.40 versus 12.90 ± 2.73 mL/kg/min; p = 0.011), and pulmonary function, evaluated by absolute and predicted of forced vital capacity (FVC) (85.52 ± 12.29 versus 71.38 ± 11.63%; p = 0.005) and absolute and predicted of forced expiratory volume in the first second (FEV₁) (83.37 ± 14.98 versus 69.21 ± 13.48%; p = 0.017). The secondary analysis showed that estimated PASP was correlated with VO_2peak (r = - 0.508; p = 0.002), FVC (r = - 0.450; p = 0.007), and FEV₁ (r = - 0.361; p = 0.033). Moreover, the adjusted odds ratio by HD vintage, dry weight and gender showed that increments in VO_2peak (OR 1.62; CI 95% 1.04-2.54; p = 0.034), FVC (OR 39.67; CI 95% 1.74-902.80; p = 0.021), and FEV₁ (OR 39.54; CI 95% 1.89-826.99; p = 0.018) were associated with 1-fold and 39-fold higher chance, respectively, for not having PH. However, all these associations were lost when age was included in the analysis.

CONCLUSIONS

The HD patients with probable PH had the worst cardiorespiratory fitness and pulmonary function. Exploratory analyses showed that greater cardiopulmonary fitness was associated with better cardiac function. Moreover, increments in cardiorespiratory fitness and pulmonary function may increase the chance of not having PH.

Exercise training for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health problem. In the National Kidney Foundation Disease Outcomes Quality Initiative guidelines it is stressed that lifestyle issues such as physical activity should be seen as cornerstones of the therapy. The physical fitness in adults with CKD is so reduced that it impinges on ability and capacity to perform activities in everyday life and occupational tasks. An increasing number of studies have been published regarding health effects of various regular exercise programmes in adults with CKD and in renal transplant patients.

OBJECTIVES

We aimed to: 1) assess the effects of regular exercise in adults with CKD and kidney transplant patients; and 2) determine how the exercise programme should be designed (e.g. type, duration, intensity, frequency of exercise) to be able to affect physical fitness and functioning, level of physical activity, cardiovascular dimensions, nutrition, lipids, glucose metabolism, systemic inflammation, muscle morphology and morphometrics, dropout rates, compliance, adverse events and mortality.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, CENTRAL, MEDLINE, EMBASE, CINAHL, Web of Science, Biosis, Pedro, Amed, AgeLine, PsycINFO and KoreaMed. We also handsearched reference lists of review articles and included studies, conference proceeding's abstracts. There were no language restrictions.Date of last search: May 2010.

SELECTION CRITERIA

We included any randomised controlled trial (RCT) enrolling adults with CKD or kidney transplant recipients undergoing any type of physical exercise intervention undertaken for eight weeks or more. Studies using less than eight weeks exercise, those only recommending an increase in physical activity, and studies in which co-interventions are not applied or given to both groups were excluded.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of study and data quality were performed independently by the two authors. Continuous outcome data are presented as standardised mean difference (SMD) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Forty-five studies, randomising 1863 participants were included in this review. Thirty two studies presented data that could be meta-analysed. Types of exercise training included cardiovascular training, mixed cardiovascular and resistance training, resistance-only training and yoga. Some studies used supervised exercise interventions and others used unsupervised interventions. Exercise intensity was classed as 'high' or 'low', duration of individual exercise sessions ranged from 20 minutes/session to 110 minutes/session, and study duration was from two to 18 months. Seventeen per cent of studies were classed as having an overall low risk of bias, 33% as moderate, and 49% as having a high risk of bias.The results shows that regular exercise significantly improved: 1) physical fitness (aerobic capacity, 24 studies, 847 participants: SMD -0.56, 95% CI -0.70 to -0.42; walking capacity, 7 studies, 191 participants: SMD -0.36, 95% CI-0.65 to -0.06); 2) cardiovascular dimensions (resting diastolic blood pressure, 11 studies, 419 participants: MD 2.32 mm Hg, 95% CI 0.59 to 4.05; resting systolic blood pressure, 9 studies, 347 participants: MD 6.08 mm Hg, 95% CI 2.15 to 10.12; heart rate, 11 studies, 229 participants: MD 6 bpm, 95% CI 10 to 2); 3) some nutritional parameters (albumin, 3 studies, 111 participants: MD -2.28 g/L, 95% CI -4.25 to -0.32; pre-albumin, 3 studies, 111 participants: MD - 44.02 mg/L, 95% CI -71.52 to -16.53; energy intake, 4 studies, 97 participants: SMD -0.47, 95% CI -0.88 to -0.05); and 4) health-related quality of life. Results also showed how exercise should be designed in order to optimise the effect. Other outcomes had insufficient evidence.

AUTHORS' CONCLUSIONS

There is evidence for significant beneficial effects of regular exercise on physical fitness, walking capacity, cardiovascular dimensions (e.g. blood pressure and heart rate), health-related quality of life and some nutritional parameters in adults with CKD. Other outcomes had insufficient evidence due to the lack of data from RCTs. The design of the exercise intervention causes difference in effect size and should be considered when prescribing exercise with the aim of affecting a certain outcome. Future RCTs should focus more on the effects of resistance training interventions or mixed cardiovascular- and resistance training as these exercise types have not been studied as much as cardiovascular exercise.

Urotensin II immunoreactivity in the human circulation: evidence for widespread tissue release

BACKGROUND

The sources of secretion and clearance of plasma urotensin II (UII) in the human circulation remain uncertain and may be relevant to understanding the role of UII in human physiology and cardiovascular disease.

METHODS

In 94 subjects undergoing clinically indicated cardiac catheterization, we collected blood samples from arterial and multiple venous sites to measure transorgan gradients of plasma UII immunoreactivity.

RESULTS

Net UII release occurred (in descending order of proportional transorgan gradient) across the heart, kidney, head and neck, liver, lower limb, and pulmonary circulations (P < 0.01). Although no specific clearance site was localized, the absence of an overall subdiaphragmatic aorto-caval peptide gradient indicated that there were lower body segment sites of UII clearance as well as secretion. The proportional increase in UII immunoreactivity was significantly correlated across all sites of net peptide release within an individual (P < or = 0.05). In univariate analyses, mixed venous UII concentrations were correlated with diagnosis of acute coronary syndrome and femoral artery oxygen tension and inversely with systolic blood pressure and body mass index. Diagnosis of acute coronary syndrome and body mass index were independent predictors of mixed venous UII immunoreactivity in multivariate analysis. No correlates of net cardiac UII release were identified.

CONCLUSIONS

UII is secreted from the heart and multiple other tissues into the circulation. Related increments in UII immunoreactivity across multiple tissue sites suggest that peptide release occurs via a shared mechanism. Increased UII immunoreactivity is observed in subjects with acute coronary syndrome.

Factors limiting physical working capacity in predialytic uraemic patients

The exercise capacity of 20 predialytic uraemic patients (mean age 43 +/- 12 years) was studied prospectively. Nine of these patients were examined twice in a longitudinal study. The maximal working capacity, measured by standardized exercise test on a bicycle ergometer, averaged 74 +/- 19% of the expected normal. Normal exercise ECG were registered in 16 out of 20 patients. Total hemoglobin/kg body weight (THb) was 67 +/- 16% of the expected normal and serum parathyroid hormone concentration (PTH) was 39 +/- 39 micrograms/l (normal range 0.5-1.5). Partial correlation showed a correlation between exercise capacity and PTH (p less than 0.05). In the longitudinal study the decrease in steady state exercise capacity was correlated to the decrease in THb (p less than 0.05), but not to the increase in PTH. In conclusion, patients with predialytic uraemia have a reduced maximal working capacity, due to several possible factors one of which is a reduced THb. Ischaemic heart disease seems to be of minor importance.

Clinical and demographic predictors of exercise capacity in end-stage renal disease

Patients on maintenance hemodialysis therapy for end-stage renal disease have reduced exercise tolerance. Multiple processes related to uremia and hemodialysis have been implicated in the pathophysiology of this impairment. However, limited data are available to identify the separate and combined effects of clinical factors on the degree of impairment for individuals within this population. For this purpose, data from 193 patients who had undergone exercise testing for two clinical trials were retrospectively analyzed. Univariate and multiple linear regression analyses were used to identify demographic and clinical correlates of peak exercise oxygen uptake (VO2). Peak VO2 averaged 18.5 +/- 6.4 mL/min/kg. On univariate analysis, peak VO2 correlated positively with male sex and hemoglobin, serum albumin, and serum creatinine concentrations and correlated negatively with dialytic age and diagnosis of diabetes or chronic heart failure. In a multiple linear regression model, sex, hemoglobin concentration, age, and diagnosis of diabetes each remained statistically significant. Together, factors included in the model accounted for 41% of the variability in peak VO2 (P = 0.0001). Among factors not correlating significantly with peak VO2 were resting blood pressure, serum carnitine level, and urea clearance assessed by Kt/V. Findings show the range of exercise impairment among clinically stable ambulatory hemodialysis patients, which may be sufficient to interfere with normal daily activities for many of these patients. Although this impairment may be broadly attributable to physiological consequences of uremia, the degree of impairment for individual patients is predicted by demographic factors, coexistent disease, and factors potentially modified by medical therapeutics.

Determinants of left ventricular hypertrophy and systolic dysfunction in chronic renal failure

To evaluate determinants of left ventricular hypertrophy (LVH) and left ventricular (LV) systolic dysfunction in chronic renal failure (CRF), M-mode and two-dimensional echocardiography were performed in 38 undialyzed patients with CRF (serum creatinine > or = 3.4 mg/dL), 54 patients receiving continuous ambulatory peritoneal dialysis, 30 patients receiving hemodialysis, and 59 healthy age- and sex-matched volunteers. Left ventricular (LV) wall thickness and LV dimensions were greatest in dialysis patients, intermediate in CRF patients, and least in control subjects. LV mass index calculated from M-mode measurements was 78.7 g/m2 +/- 14.8 g/m2 in controls, 120.5 g/m2 +/- 28.7 g/m2 in CRF patients, and 136 +/- 45.0 g/m2 in dialysis patients (P < 0.0001). LV fractional shortening and LV velocity of circumferential shortening were lower in dialysis patients than in CRF patients and controls (fractional shortening 36.5% +/- 5.6% in controls, 36.2% +/- 7.2% in CRF patients, and 29.8% +/- 8.9% in dialysis patients; P < 0.0001). Echocardiography was normal in only 24 dialysis patients (29%) and 14 CRF patients (37%) (P = NS). Thirty-nine dialysis patients (46%) and 10 CRF patients (26%) had LVH (P = NS). Thirty dialysis patients (36%) and five CRF patients (13%) had LV systolic dysfunction (P < 0.05). LV hypertrophy with LV systolic dysfunction was present in 15 dialysis patients but no CRF patients (P < 0.05). There were no significant differences between hemodialysis patients and continuous ambulatory peritoneal dialysis patients in M-mode echocardiographic measurements or the frequency of LVH and LV systolic dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in exercise capacity after correction of anemia in patients with end-stage renal failure

Changes in exercise tolerance occurring after correction of anemia with recombinant human erythropoietin in a group of patients with end-stage renal failure were evaluated. Ten patients, aged 29 +/- 11 years, on chronic hemodialysis treatment, with no associated diseases, were evaluated by cardiopulmonary bicycle exercise testing and M-mode, 2-dimensional and pulsed doppler echocardiography before and after anemia correction. After 1 and 3 months of therapy, hemoglobin plasma levels increased from 5.9 +/- 1.2 to 7.7 +/- 1.3 and 9.9 +/- 1.4 g/dl, with a concomitant increase in peak oxygen consumption (VO2) from 21.4 +/- 4.3 to 24.4 +/- 4.3 and 26.6 +/- 4.6 ml/kg/min and of VO2 at the ventilatory threshold from 15.0 +/- 3.7 to 17.3 +/- 3.7 and 16.8 +/- 3.4 ml/kg/min. After 3 months of therapy, systolic blood pressure significantly decreased both at peak exercise (159 +/- 35 to 134 +/- 22 mm Hg) and ventilatory threshold (140 +/- 27 to 123 +/- 19 mm Hg), whereas cardiac index at rest decreased from 3.3 +/- 0.7 to 2.8 +/- 0.5 liters/min/m2 and heart rate from 77 +/- 12 to 70 +/- 10 beats/min. However, no significant relation was found between hemoglobin plasma levels and peak VO2, whereas a significant relation was found between hemoglobin concentration and cardiac index at rest.

Exercise capacity in chronic renal failure patients managed by continuous ambulatory peritoneal dialysis

Exercise capacity is documented to be poor in patients with end stage renal failure undergoing regular hemodialysis, but there is little information about exercise capacity in patients on continuous ambulatory peritoneal dialysis (CAPD). We studied a group of 18 patients undergoing CAPD, with a variety of cardiorespiratory disorders, using a progressive load treadmill exercise test. The influence of intraperitoneal fluid on work capacity was also assessed. The mean maximum oxygen uptake (VO2max) of the CAPD patients was reduced considerably (14.6 ml kg-1 min-1) compared with matched control subjects (33.6 ml kg-1 min-1). This corresponded to the difficulty experienced by these patients in carrying out daily activities. There was no significant change in VO2max or in maximum heart rate with the peritoneal cavity full. We conclude that physical fitness is poor in CAPD patients and that the infusion of dialysis fluid into the peritoneal cavity does not affect physical work capacity further.