Beneficial effects of erythropoietin on haematological parameters, aerobic capacity, and body fluid composition in patients on haemodialysis

Cardiopulmonary exercise testing in patients with end-stage kidney disease: principles, methodology and clinical applications of the optimal tool for exercise tolerance evaluation

Chronic kidney disease (CKD), especially end-stage kidney disease (ESKD), is associated with an increased risk for cardiovascular events and all-cause mortality. Exercise intolerance as well as reduced cardiovascular reserve is extremely common in patients with CKD. Cardiopulmonary exercise testing (CPET) is a non-invasive, dynamic technique that provides an integrative evaluation of cardiovascular, pulmonary, neuropsychological and metabolic function during maximal or submaximal exercise, allowing the evaluation of functional reserves of these systems. This assessment is based on the principle that system failure typically occurs when the system is under stress and thus CPET is currently considered to be the gold standard for identifying exercise limitation and differentiating its causes. It has been widely used in several medical fields for risk stratification, clinical evaluation and other applications, but its use in everyday practice for CKD patients is scarce. This article describes the basic principles and methodology of CPET and provides an overview of important studies that utilized CPET in patients with ESKD, in an effort to increase awareness of CPET capabilities among practicing nephrologists.

Effect of Erythropoietin Treatment on Nutritional Status of Continuous Ambulatory Peritoneal Dialysis Patients

Seventeen patients -10 females, 7 males -mean age 52 years (range: 21–77 years), on CAPD for an average of 35 months (range 10–160 months) were studied. Mean initial dose of EPO was 114±45 U/kg/week subcutaneously (range: 59–209). The dose was adjusted to achieve and maintain a target Hb of 100 g/L and Hct 30%. Fifteen of the patients (88.2%) achieved this target within 6 months [baseline to month 6 changes: Hb 72±10 g/L to 107±12 g/L (p=0.0001); Hct 22±3% to 33±4% (p=0.0001)]. Serum total protein also increased significantly over the time of EPO use (p=0.0133); changes from baseline were significant by the fourth month [68±9 g/L to 72±9 g/L (p=0.0115)]. Serum albumin also increased significantly over time (p=0.0157). The change from the baseline result (37±4 g/L) was statistically significant by month 2 (p=0.0060) and was maintained over the following 4 months [month 6 result: 40±3 g/L (p=0.0180)]. The increase was greater for 8 patients with initial serum albumin <35 g/L (mean change 5.75 g/L) than for the 9 subjects with levels >35 g/L (mean change 0.11 g/L). In a comparison group of 17 patients (matched for age, sex, duration of CAPD, underlying disease and antihypertensive treatment), who did not receive EPO treatment, albumin and protein did not appear to increase over time. Mean body weight increased from 60.9± 14.0 kg at the start to 62.1± 13.9 kg at month 6 (p=0.281) and the absolute lymphocyte count from 1.6±0.8 x 109/L to 1.8±1.0 x 109/L (p=0.0472). Serum potassium, urea, creatinine, phosphorus, cholesterol, tri. glycerides, WBC and platelets did not show significant changes over time. Serum phosphorus increased at the end of the second and third months (from 1.6±0.5 mmol/L to 1.9±0.4 and 1.8±0.4 mmol/L and then decreased at the sixth month (1.7±0.5 mmol/L); this is probably due to an increase in phosphate binders in 9 of 17 patients. An improvement in appetite, sleep and well-being, by patients’ self-assessment, was noted during the treatment.

We conclude that the treatment with EPO is associated with improvement of the nutritional status of patients on CAPD.

Low dose exogenous erythropoietin elicits an ergogenic effect in Standardbred horses

REASONS FOR PERFORMING STUDY

Recombinant human erythropoietin (rhuEPO) causes an increase in red blood cell production and aerobic capacity in other species; however, data are lacking on effects in the horse.

HYPOTHESIS

This study tested the hypothesis that rhuEPO administration would alter red cell volume (RCV), aerobic capacity (VO2max) and indices of anaerobic power.

METHODS

Eight healthy, unfit mares accustomed to the laboratory and experimental protocols were randomly assigned to either a control (CON, n = 4; 3 ml saline 3 times/week for 3 weeks) or EPO group (EPO, n = 4, 50 iu/kg bwt rhuEPO/3 ml saline 3 times/week for 3 weeks). Exercise tests (GXT) were performed on a treadmill (6% incline), 1 week before and 1 week after treatment. The GXT started at 4 m/sec, with a 1 m/sec increase every 60 sec until the horse reached fatigue. Oxygen uptake was measured via an open flow indirect calorimeter. Blood samples were collected before, during (each step) and 2 and 15 min post GXT to measure packed cell volume (PCV), haemoglobin concentration (Hb), blood lactate concentration (LA) and plasma protein concentration (TP). Plasma volume (PV) was measured using Evans Blue dye. Blood volume (BV) and RCV were calculated using PCV from the 8 m/sec step of the GXT.

RESULTS

There were no alterations (P>0.05) in any parameters in CON horses. By week 3, EPO produced increases (P<0.05) in resting PCV (37 +/- 2 vs. 51 +/- 2) and Hb (37%). RCV (26%) and VO2max (19%) increased, but BV did not change (P>0.05) due to decreased PV (-11%, P<0.05). There was a significant increase in velocity at VO2max and LApeak for horses treated with rhuEPO and substantial decrease (P<0.05) in VO2 recovery time when the pretreatment GXT was compared to the post treatment GXT. No differences (P<0.05) were detected for TP, VLA4, run time or Vmax.

CONCLUSIONS

Low dose rhuEPO administration increases RCV and aerobic capacity without altering anaerobic power.

POTENTIAL RELEVANCE

This study demonstrates that rhuEPO enhances aerobic capacity and exercise performance, a question relevant to racing authorities.

Central and peripheral adaptations to physical training in patients with end-stage renal disease

Renal replacement treatment options are life-saving treatments for patients with end-stage renal disease (ESRD). However, prolonged survival in patients with ESRD is associated with various functional and morphological disorders from almost all systems. Anaemia, deconditioning, cardiac dysfunction. impairment of cardiac autonomic control and skeletal muscle weakness and fatigue, primarily because of 'uraemic' myopathy and neuropathy, are the main predisposing factors for their poor functional ability. Physical training is being recommended as a complementary therapeutic modality. There are generally 3 methods of exercise training applied in patients with ESRD: (i) the supervised outpatient programme that is held in a rehabilitation centre; (ii) a home exercise rehabilitation programme; and (iii) exercise rehabilitation programme during the first hours of the haemodialysis treatment in the renal unit. All the available training data show that the application of an exercise training programme in patients with ESRD enhances their physical fitness. This improvement is due to central and mainly peripheral adaptations. Exercise training in these patients increases aerobic capacity, causes favourable left ventricular functional adaptations, reduces blood pressure in patients with hypertension, modifies other coronary risk factors, increases the cardiac vagal activity and suppresses the incidence of cardiac arrhythmias. Moreover, exercise training has beneficial effects on muscle structural and functional abnormalities. These central and peripheral adaptations to exercise training cause an increase in their functional capacity and offer them achance of a better quality of life. Moreover, exercise training improves exercisee tolerance of renal post-transplant patients.

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.

Cardiac disease in chronic uremia: management

Heart disease is a common cause of morbidity in end-stage renal disease (ESRD) patients. The management of heart disease in these patients requires a multidimensional approach to the management of heart failure, coronary disease, and arrhythmias, and to risk factors such as hypertension, anemia, secondary hyperparathyroidism, and electrolyte/acid-base disturbances. Coronary artery disease management includes use of antianginal drugs and revascularization of coronary arteries with angioplasty +/- stent placement or coronary artery bypass grafting. The long-term outcomes of these procedures need to be assessed and improved. Hypertension occupies a major role in the pathogenesis of heart disease in ESRD, and early and adequate control of hypertension is likely to have a major impact on the progression of cardiac disease. This entails the achievement of optimal volume status, combined with the appropriate use of antihypertensive agents such as calcium channel blockers, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, vasodilators, alpha-blockers, and central sympatholytic drugs. In ESRD patients, specific dialysis-related complications such as intradialytic hypotension and pericardial effusion may have additional effects on cardiac function and require attention. The choice of dialysate composition and membrane may influence clinical outcomes with specific effects on cardiac performance.

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)

The effect of treatment with recombinant human erythropoietin on skeletal muscle function in patients with end-stage renal failure treated with regular hospital hemodialysis

The effect of treatment with recombinant human erythropoietin on skeletal muscle was investigated in 11 anemic transfusion-dependent patients on the hospital hemodialysis program. There were no significant changes in anthropomorphic measurements during the study, but the maximum voluntary contraction increased significantly for each muscle group studied (pre-erythropoietin and post-erythropoietin values, respectively, were as follows: biceps, median 170 N [range, 83 to 220 N] v 189 N [range, 89 to 245 N]; triceps, 88 N [range, 59 to 167 N] v 106 N [range, 95 to 185 N]; deltoid, 168 N [range, 78 to 247 N] v 193 N [range, 93 to 290 N]; and quadriceps, 202 N [range, 165 to 300 N] v 265 N [range, 185 to 335 N]; P < 0.05). There were no significant changes in muscle strength in a control group of regular hemodialysis patients. Programmed electrical stimulation of the quadriceps following erythropoietin treatment resulted in both a greater force generated and a longer duration of contraction. Following cessation of the electrical stimulus the relaxation rate for the type II fibers was quicker following erythropoietin therapy. This suggests that some of the benefit observed in physical well-being following correction of the anemia of chronic renal failure with erythropoietin is due to an improvement in voluntary skeletal muscle function.

Recombinant erythropoietin (Epogen) improves cardiac exercise performance in children with end-stage renal disease

To determine the effects of anemia in children with end-stage renal disease, we studied cardiac performance before and 1 and 6 months after recombinant erythropoietin (Epogen). Children with end-stage renal disease were included if they had significant anemia [hematocrit (Hct) < 30%]. Epogen 50 U/kg was given subcutaneously or intravenously three times per week until the Hct was > or = 33%. Echocardiography, cardiac output (acetylene rebreathing), and treadmill (modified Bruce) tests were performed. Boys (9) and girls (9), 11.9 +/- 5.6 years, were given Epogen and the Hct increased (from 21.7 +/- 2.7% to 33.4 +/- 2.1%, P = 0.001). Heart rate decreased (P = 0.04) and stroke volume did not change. Blood pressure did not change. Cardiac thickness, chamber dimensions, left ventricular wall stress, velocity of circumferential fiber shortening, and indices of diastolic function were normal and did not change after Epogen. Exercise time increased (from 10.3 +/- 1.9 to 11.2 +/- 1.9 min, P = 0.01) after 1 month of Epogen. Resting oxygen consumption (VO2) decreased (from 7.8 +/- 1.8 to 6.9 +/- 1.4 ml/min per kg, P = 0.01) 1 month after Epogen and peak exercise VO2 did not change after Epogen. There were no differences in exercise tests between the 1 and 6 month measurements. Exercise tolerance improves after the short-term correction of anemia and there is no further improvement after long-term correction.

Low dose erythropoietin in maintenance haemodialysis: improvement in quality of life and reduction in true cost of haemodialysis

Human recombinant erythropoietin (r-HuEPO) improves quality of life in patients on maintenance haemodialysis, but the haemoglobin (Hb) level necessary to achieve this improvement is unknown. In this study, quality of life, functional capacity and symptoms of 28 haemodialysis patients with an initial Hb of 67 +/- 2 (mean +/- SEM) g/L were assessed after 0, 6 and 12 months of r-HuEPO, the dose of which was titrated to achieve a stable Hb of between 90 and 100 g/L. At six and 12 months Hb was 97 +/- 2 and 93 +/- 2 g/L, and mean r-HuEPO dose between three and six, and between nine and 12 months was 88 +/- 6 and 62 +/- 9 U/kg/week intravenously respectively. There was a significant improvement in level of activity and satisfaction with various aspects of life, and a reduction in fatigue, weakness, dyspnoea, angina and restless legs. Patients were able to walk 50% further in six minutes. The improvement in quality of life and function was similar to that reported from other centres whose target Hb was between 100 and 120 g/L, and where the r-HuEPO dose was 75% higher than in this study. Costs of r-HuEPO therapy were assessed. The drug itself costs +A3681/yr/patient, to which was added the estimated cost of additional dialyses and medications, bringing the total to +A5177/yr/patient. There was, however, a reduction in both hospitalisation by 8.3 days/yr/patient and medical consultation by 3.9 hours/yr/patient. Five patients commenced full-time work, one took up full-time study aimed at finding work, three transferred to home haemodialysis and six fewer patients drew social security benefits. The net cost saving from using low dose r-HuEPO was more than +A1,000/yr/patient.

Effect of recombinant human erythropoietin treatment on blood pressure and some haematological parameters in healthy men

The aim of this study was to evaluate the effect of treatment with subcutaneous injections of recombinant human erythropoietin (rhEpo), 20-40 IU kg-1 body weight, 3 times a week, on resting blood pressure, blood pressure response during submaximal exercise, some haematological parameters, and subjective side-effects in 15 healthy male subjects. RhEpo increased both haemoglobin (Hb) concentration and haematocrit (Hct) significantly, the values for Hb being 152 +/- 4.2 g l-1 before treatment and 169 +/- 9.3 g l-1 (mean values +/- SD) after 6 weeks of rhEpo treatment (P less than 0.001). The corresponding values for Hct were 44.5 +/- 1.5% and 49.7 +/- 1.9% (P less than 0.001), respectively. The systolic and diastolic blood pressure values at rest were unchanged after rhEpo treatment. A marked increase in systolic blood pressure was observed during submaximal exercise at 200 W, the initial and final values being 177 +/- 14.2 mmHg and 191 +/- 19.5 mmHg (P less than 0.01), respectively. Heart rate during exercise at 200 W was significantly lower after rhEpo treatment than before it: 144 +/- 15 beats min-1 compared to 136 +/- 8 beats min-1 (P less than 0.001). The leucocyte count remained unchanged after rhEpo treatment, but there was a significant decrease (P less than 0.05) in the number of lymphocytes. Reticulocyte and platelet counts were unchanged. Serum (S) ferritin decreased from 87.3 +/- 41.8 mmol l-1 to 59.3 +/- 27.8 mmol l-1 after rhEpo treatment (P less than 0.001). Serum-Na, S-K, S-Ca, S-creatinine, S-bilirubin, S-aspartate aminotransferase (ASAT), S-alanine aminotransferase (ALAT), and S-lactate dehydrogenase (LD) were unchanged after rhEpo treatment. No subjective side-effects were reported. In conclusion, low doses of rhEpo increased Hb levels and Hct by more than 10% after 6 weeks. Blood pressure at rest was unchanged, but rhEpo induced a markedly accentuated blood pressure reaction during exercise. A minor decrease in the lymphocyte count was observed, but electrolyte and creatinine levels remained unchanged after rhEpo treatment.