Li-Tao Cheng

Visceral fat, arterial stiffness, and endothelial function in peritoneal dialysis patients.

BACKGROUND The relationship between overweight or obesity and mortality in peritoneal dialysis (PD) patients remains controversial. Both pulse-wave velocity (PWV) and endothelial dysfunction are related to an increased risk of cardiovascular disease. However, the association between PWV, endothelial dysfunction, and visceral adipose tissue in PD patients is not well-understood. METHODS One hundred and sixteen PD patients were enrolled in this cross-sectional study. The overall fat ratio and visceral-fat level of PD patients were measured by multiple-frequency bioelectrical impedance analysis (BIA). Carotid-femoral pulse-wave velocity (C-F PWV) was measured as an indicator of aortic stiffness. Endothelial function was evaluated by brachial-artery flow-mediated dilation (FMD). The association between these monitored parameters was assessed by statistical analyses. RESULTS Bivariate correlation analysis showed that C-F PWV was positively correlated with visceral-fat level (r = 0.343, P < .001), whereas FMD was negatively correlated with visceral-fat level (r = -0.354, P < .01). Multiple regression analysis indicated that age, diabetic status, visceral-fat level, and duration of dialysis were determinants of PWV (adjusted R(2) = 0.316, P < .001), whereas visceral-fat level and glucose load were the determinants of FMD (adjusted R(2) = 0.130, P < .01). CONCLUSION Visceral-fat level was an independent predictor of PWV and FMD in PD patients, and could be considered one of the risk factors for cardiovascular disease in PD patients.

Residual Renal Function and Volume Control in Peritoneal Dialysis Patients

Background: Fluid overload is not uncommon in patients on continuous ambulatory peritoneal dialysis (CAPD). Previous studies suggested that residual renal function (RRF) played an important role in maintaining fluid balance. However, good fluid status should be a balance between fluid intake and removal. Therefore, in the present study, we investigated the effect of RRF on patients’ fluid status after focusing on the balance between fluid intake and removal in CAPD patients. Methods: In this cross-sectional study, 195 stable CAPD patients in a single center were included. Patients were divided into three groups according to their urine output: anuric group with urine ≤100 ml/day, oliguric group with urine ≤400 ml/day and UO >400 ml group with urine >400 ml/day. Fluid status was evaluated by bioimpedance analysis and mean arterial pressure (MAP). The sodium removal and plasma sodium concentration were also measured. All the patients were educated to try to achieve good volume control by focusing on salt and fluid intake and their removals. Results: There were 51, 31 and 113 patients in anuric, oliguric and UO >400 ml group, respectively. Anuric patients were older and had been on CAPD longer than that of the oliguric and UO >400 ml patients (p < 0.05). The urine output in the three groups were 9.28 ± 22.68, 236.13 ± 75.43 and 1,013.34 ± 541.54 ml/day, respectively (p < 0.001). Bioimpedance analysis showed that the differences of extracellular water, intracellular water and total body water were not statistically significant among the three groups. However, there was significant difference in MAP among the three groups (MAP in anuric, oliguric and UO >400 ml groups were 93.27 ± 13.35, 96.63 ± 9.94 and 102.36 ± 13.70 mm Hg, p < 0.01), and UO >400 ml group had higher MAP than anuric and oliguric groups (p < 0.05). The total sodium removal (renal + peritoneal) in anuric, oliguric and UO >400 ml groups were 96.44 ± 60.18, 98.95 ± 73.82 and 134.64 ± 72.44 mmol/day, respectively (p < 0.01). The UO >400 ml group also had higher plasma sodium concentration than anuric and oliguric groups (plasma sodium in the three groups were 137.49 ± 3.43, 137.82 ± 2.63 and 139.15 ± 3.30 mmol/l, respectively; p < 0.01). Conclusions: This study showed that extracellular water among anuric, oliguric and UO >400 ml groups was not significantly different, which suggested that RRF may be not so important as expected in maintaining good volume status. The higher blood pressure in patients with higher RRF and higher sodium and fluid removal in the present study suggested restricting salt and fluid intake might be more important for better blood pressure control in CAPD patients.

Stepwise increase in the prevalence of isolated systolic hypertension with the stages of chronic kidney disease

BACKGROUND Hypertension is common in patients with chronic kidney disease (CKD), and isolated systolic hypertension (ISH) accounts for most patients with inadequate blood pressure (BP) control. However, it remains unclear whether the prevalence of ISH would increase with the advancement of CKD. METHODS CKD patients of stages 3, 4 and 5 were recruited (n = 324). Based on office systolic BP (SBP) and diastolic BP (DBP), they were classified into any of the four hypertensive subtypes: normotension (SBP/DBP <140/90 mmHg), isolated diastolic hypertension (IDH, SBP <140 mmHg and DBP >or=90 mmHg), ISH (SBP >or=140 mmHg and DBP <90 mmHg) and systolic-diastolic hypertension (SDH, SBP/DBP >or=140/90 mmHg). RESULTS The control rate was 45.7% at stage 3, which decreased with the advancement of CKD (control rate was 51.9%, 40.4% and 38.6% in stage 3, 4 and 5, respectively; P < 0.05). The prevalence of IDH changed from 5.0% to 5.3% and 0% from stage 3 to 4 and 5, while there was no significant change in the prevalence of SDH (15.0%, 14.9% and 15.7% at stage 3, 4 and 5, respectively). There was a stepwise increase in the prevalence of ISH with the stages of CKD (it was 28.1%, 39.4% and 45.7% in stage 3, 4 and 5, respectively). Logistic regression showed that age and CKD stages [compared with stage 3, stage 4 and 5 had 2.57 (95% CI 1.04-6.33) and 3.68 (95% CI 1.09-12.47) folds higher risk to develop ISH, respectively] were independent predictors of ISH. CONCLUSION The prevalence of ISH increased correspondingly with advanced stages of CKD, which may partially contribute to the increased cardiovascular mortality during the progress of CKD.

Serum Uric Acid and Endothelial Dysfunction in Continuous Ambulatory Peritoneal Dialysis Patients

Background: Endothelial dysfunction is an early predictor of cardiovascular events. Hyperuricemia has been shown to be associated with increased cardiovascular mortality. It remains unclear if serum uric acid (UA) is associated with endothelial dysfunction in peritoneal dialysis patients. Methods: In this cross-sectional study, the relationship of UA and endothelial dysfunction was investigated in 189 stable peritoneal dialysis patients. The clinical and laboratory data were collected. Endothelial function was estimated by flow-mediated dilatation (FMD) of the brachial artery and expressed as percentage change relative to baseline diameter. Results: UA levels did not differ between 93 male and 96 female patients (416.31 ± 86.93 vs. 395.52 ± 87.47 μmol/l, p > 0.05). Patients were grouped into three tertiles on the basis of their serum UA levels. Systolic blood pressure (p = 0.007), serum phosphate (p = 0.005), high-sensitive C-reactive protein (hs-CRP) (p < 0.001), and FMD (p = 0.016) were all different among UA tertiles. FMD was found to be related with UA (p = 0.002) and hs-CRP (p = 0.006) in a Pearson’s correlation analysis. Multivariate regression analysis showed that only UA was an independent determinant of FMD (β = –0.237, p = 0.036). Conclusion: There was an independent correlation between UA and FMD, and a higher UA level was related to worse endothelial function which may contribute to hypertension and cardiovascular morbidity.

Correlation between Pulse Wave Velocity and Fluid Distribution in Hemodialysis Patients

Background: In this study, we focused on whether volume overload plays a role in the development of arterial stiffness. Methods: Seventy-three prevalent hemodialysis patients were enrolled in a cross-sectional study. Arterial stiffness was assessed by carotid-femoral pulse wave velocity (PWV), and volume overload was assessed by bioimpedance analysis. Results: Patients were divided into a high PWV group and a low PWV group based on the median of PWV. Age, systolic blood pressure, pulse pressure (PP), extracellular water/total body water ratio (ECW/TBW), diabetic status (all p < 0.01), and history of cardiac events (p < 0.05) were significantly higher in the high PWV group (n = 37) than in the low PWV group. In the correlation analysis, PWV was positively associated with PP, systolic blood pressure, ECW/TBW, age, history of cardiac events, and diabetes (all p < 0.01). Multiple regression analysis showed that PWV was independently related to PP and ECW/TBW (p < 0.01). Conclusion: Volume overload plays an important role in the development of arterial stiffness in hemodialysis patients.

Pulse Wave Velocity Is Associated with Metabolic Syndrome Components in CAPD Patients

Background: Overall, the proportion of deaths due to cardiovascular disease (CVD) reached 40–50% in dialysis patients. Pulse wave velocity (PWV) reflects arterial stiffness and may provide an integrated index of vascular status and CVD risk. Individual components of the metabolic syndrome (MetS) are well-established cardiovascular risk factors. Thus we conducted a cross-sectional study in continuous ambulatory peritoneal dialysis (CAPD) patients to explore the association of MetS components with PWV. Methods: Prevalent CAPD patients (n = 148, 63 M/85 F) were categorized according to the number of traits of the MetS into one of three groups (No MetS, Risk of MetS, MetS). Due to the effect of peritoneal dialysis (PD), waist circumference was not assessed. Aortic stiffness was assessed by carotid-femoral PWV (C-F PWV). Results: Patients’ MetS trait numbers were positively associated with C-F PWV (r = 0.301, p < 0.01), pulse pressure (r = 0.256, p < 0.01), systolic blood pressure (r = 0.233, p < 0.01), and serum albumin (r = 0.205, p < 0.05). In a multivariate regression analysis, PWV was independently determined by age (p < 0.01) and MetS score (p = 0.01). Adjusted R2 of the model was 0.24. Conclusion: MetS traits were closely associated with an increased C-F PWV, even after adjustment for confounders. This suggests that commonly recognized MetS criteria are useful also when predicting CVD in CAPD patients.

Design and challenges of the Randomized Evaluation of Normal versus Augmented Level Replacement Therapy (RENAL) Trial: high-dose versus standard-dose hemofiltration in acute renal failure

Background/Aims: The optimal dose of renal replacement therapy (RRT) in acute renal failure (ARF) is uncertain. Methods: The Randomized Evaluation of Normal versus Augmented Level Replacement Therapy Trial tests the hypothesis that higher dose continuous veno-venous hemodiafiltration (CVVHDF) at an effluent rate of 40 ml/kg/h will increase survival compared to CVVHDF at 25 ml/kg/h of effluent dose. Results: This trial is currently randomizing critically ill patients in 35 intensive care units in Australia and New Zealand with a planned sample size of 1,500 patients. This trial will be the largest trial ever conducted on acute blood purification in critically ill patients. Conclusion: A trial of this magnitude and with demanding technical requirements poses design difficulties and challenges in the logistics, conduct, data collection, data analysis and monitoring. Our report will assist in the development of future trials of blood purification in intensive care. This study was registered with ClinicalTrials.gov (NCT00221013).

The Prevalence of Left Ventricular Hypertrophy in Chinese Hemodialysis Patients Is Higher Than That in Peritoneal Dialysis Patients

Background. Left ventricular hypertrophy (LVH) is common in dialysis patients, and an independent predictor of mortality. While recent studies have shown no differences in mortality between the two most common dialysis modalities, hemodialysis (HD) and peritoneal dialysis (PD), their impact on LVH is controversial. We thus performed cardiac ultrasound studies in prevalent dialysis patients receiving either HD or PD and compared LVH. Methods. We included 48 HD and 62 PD patients receiving treatment for at least three months in our dialysis center. All patients underwent echocardiographic examination and blood pressure measurements immediately following therapy. Volume status was assessed by bioelectrical impedance analysis. Results. There was no baseline difference in demographics or comorbidities between HD and PD patients. As expected, extracellular water (ECW) in post-HD patients was significantly lower than that in pre-HD and PD patients, while cardiac output (CO) and systolic blood pressure (SBP) were higher in pre-HD than that in post-HD or PD patients. There was no significant difference in CO or SBP between post-HD and PD patients. Left ventricular mass index (LVMI) was markedly higher in HD patients as compared to PD patients. Thus, the prevalence of LVH according to the Framingham criteria was 68.8% in HD patients and 45.2% in PD patients. Subgroup analysis showed similar results in the patients who had been on single-modality dialysis for at least two years and in the anuric patients. Finally, in a linear regression model (r2 = 0.364, p < 0.001), SBP, treatment modality (to be in HD), and ECW were all independent predictors of LVMI. Conclusions. In a cross-sectional analysis of prevalent Chinese patients, we found a higher LVMI and a higher prevalence of LVH in HD than in PD patients. As LVMI was associated with high blood pressure and volume overload, we suggest that in these patients, PD may preserve more physiological hemodynamics even during long-term therapy.

Strong Association between Nutritional Markers and Arterial Stiffness in Continuous Ambulatory Peritoneal Dialysis Patients

Background: Malnutrition is a predictor of cardiovascular disease in dialysis patients, but the mechanisms remain unknown. We investigated links between nutritional markers and arterial stiffness in continuous ambulatory peritoneal dialysis patients. Methods: We evaluated the relationship between arterial stiffness evaluated by pulse-wave velocity (PWV) and four estimates of nutritional status (serum albumin, handgrip strength [HGS], subjective global assessment [SGA], and bioelectrical impedance analysis phase angle [PA]) in 124 PD patients. Results: Malnourished patients exhibited a significantly higher PWV than those classified as well-nourished by SGA (p < 0.05). Furthermore, PWV correlated negatively with albumin, HGS and PA (p < 0.001, respectively). PWV was also correlated with age, systolic blood pressure, and C-reactive protein. In multivariate regression analysis, albumin, HGS, SGA and PA were each independently associated with PWV after adjustment. Conclusions: The significant association between each nutritional marker and PWV in PD patients was independent of inflammation and diabetic state, suggesting that malnutrition may contribute to vascular dysfunction.

Seasonal Variation in Blood Pressure of Patients on Continuous Ambulatory Peritoneal Dialysis

Background: A seasonal variation in blood pressure (BP) has been observed in hemodialysis and renal transplant patients. However, this phenomenon in continuous ambulatory peritoneal dialysis (CAPD) patients, whose hemodynamics are different from hemodialysis patients, has not been reported before. In addition, the contribution of extracellular water (ECW) in the seasonal variation in BP is not clear. Methods: All stable CAPD patients (n = 122) dialyzed in a single center from January 1, 2003 to December 12, 2004 were studied. Systolic blood pressure (SBP), diastolic blood pressure (DBP), weight and ECW (by bioimpedance analysis) were measured in every patient. Climatic data were obtained from the Beijing Weather Bureau. These data were pooled together and grouped according to the calendar month. Results: In general, an apparent seasonal variation in BP was observed in CAPD patients. BP began to decrease from spring and reached the lowest level in summer, then increased from autumn and reached its peak in winter. The seasonal variation in BP in male patients was similar to that in female patients, but in comparison to non-diabetic patients there was no apparent seasonal variation in the BP of diabetic patients. SBP and DBP negatively correlated with the average atmospheric temperature (r = –0.768, p < 0.001 and r = –0.764, p < 0.001, respectively). BP also negatively correlated with rainfall and humidity, but this correlation disappeared when temperature was controlled in partial correlation analysis. Weight and ECW fluctuated throughout the year but showed no seasonal variation. Conclusion: On the whole there was an apparent seasonal variation in blood pressure in CAPD patients. As opposed to non-diabetic patients, there was no apparent seasonal variation in BP in diabetic patients. The seasonal variation in BP was influenced more by temperature than rainfall and humidity, and the change in ECW was not seasonal, suggesting that other mechanisms such as total peripheral resistance might play a more important role in this phenomenon.