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Impaired orthostatic blood pressure (BP) stabilization is prevalent in patients with chronic kidney disease (CKD) and is associated with adverse outcomes. We aimed to test the hypothesis that reduced hemoglobin is an important contributor to orthostatic intolerance in CKD in the present study. This study included 262 patients with non-dialysis-dependent CKD. Seated and standing BP was measured, and orthostatic BP reduction was calculated for both systolic BP (∆ SBP) and diastolic BP (∆ DBP). The association between orthostatic BP reduction and hemoglobin was determined by multiple linear regression models. We also performed mediation analysis to test to what extent the effect of renal dysfunction on impaired orthostatic BP stabilization can be explained by reduced hemoglobin. The mean age of the patients was 57.7 (±14.5) years, and 61.5% were male. Both ∆ SBP and ∆ DBP correlated negatively with estimated glomerular filtration rate (eGFR). With adjustment for age and sex, hemoglobin level was negatively associated with ∆ SBP (β = -1.4, SE = 0.4, P < .001) and ∆ DBP (β = -0.6, SE = 0.2, P = .009). The associations remained significant with further adjustment for additional covariates. When eGFR was introduced as a covariate, it did not eliminate the significance (both P < .05). The associations remained essentially unchanged in a sensitivity analysis excluding those with concurrent erythropoietin use. Mediation analysis demonstrated that reduced hemoglobin accounted for 35.4% (P = .004) of the effect of eGFR on ∆ SBP and 47.7% (P = .032) on ∆ DBP. Our study suggests that reduced hemoglobin is a potentially important contributor to the development of orthostatic hypotension in CKD. [ABSTRACT FROM AUTHOR]

Mechanisms underlying elevated blood pressure in dialysis patients are complex as a variety of non-traditional factors are involved. We sought to explore the association of circulating betaine, a compound widely distributed in food, with blood pressure in dialysis patients. We used baseline data of an ongoing cohort study involving patients on hemodialysis. Plasma betaine was measured by high performance liquid chromatography in 327 subjects. Blood pressure level was determined by intradialytic ambulatory blood pressure monitoring. The mean age of the patients was 52.6 ± 11.9 years, and 58.4% were male. Average interdialytic ambulatory systolic and diastolic blood pressure were 138.4 ± 22.7 mm Hg and 84.4 ± 12.5 mm Hg, respectively. Mean plasma betaine level was 37.6 μmol/L. Multiple linear regression analysis revealed significant associations of betaine with both systolic blood pressure (β = -3.66, P = .003) and diastolic blood pressure (β = -2.00, P = .004). The associations persisted even after extensive adjustment for cardiovascular covariates. Subgroup analysis revealed that the association between betaine and blood pressure was mainly limited to female patients. Our data suggest that alteration of circulating betaine possibly contributes to blood pressure regulation in these patients. [ABSTRACT FROM AUTHOR]

Although ambulatory blood pressure (ABP) monitoring (ABPM) is often considered to have an advantage over dialysis unit blood pressure (BP) in dialysis patients, the exact relationship between these two measurements of BP has not been well determined. In a cohort of 90 Chinese dialysis patients, agreement between dialysis unit BP (predialysis and postdialysis BP) and interdialytic ABP was evaluated using Bland-Altman plots and Lin's concordance correlation coefficient for quantitative analysis, and inter-rater agreement (κ) for qualitative analysis. Limits of agreement between dialysis unit BP and ABP were wide (predialysis systolic BP: -33.5 to 20.9 mm Hg; predialysis diastolic BP: -22.2 to 11.9 mm Hg; postdialysis systolic BP: -25.4 to 26.5 mm Hg; postdialysis diastolic BP: -18.4 to 12.3 mm Hg). Lin's concordance correlation coefficient exhibited a poor agreement with concordance correlation coefficients of 0.75, 0.81, 0.64, and 0.75 for predialysis systolic BP, postdialysis systolic BP, predialysis diastolic BP, and postdialysis diastolic BP, respectively. When BP level was classified into quartiles, an increasing trend for incorrect classification rate was observed with deleterious hypertension, with the highest value in grade 3 hypertension (100% and 75.0% for predialysis and postdialysis BP, respectively). Therefore, these data suggest that agreement between dialysis unit BP and interdialytic ABP is poor in Chinese dialysis patients, and the bias for patients with higher degree of hypertension is more prominent. [ABSTRACT FROM AUTHOR]

The two most commonly used strategies to evaluate dialysis patients' blood pressure ( BP) level are 44-hour and 24-hour ambulatory blood pressure monitoring ( ABPM). The objective of this study was to find an appropriate 24-hour period that correlated well with the 44-hour BP level and determine the differences between these strategies. In a group of 51 dialysis patients, the authors performed 44-hour ABPM and extracted data for a fixed 24-hour ABPM. The fixed 24-hour ABPM started at 6 am on the nondialysis day. A strong correlation was found between all parameters of 44-hour and the fixed 24-hour ABPM, with paired sample t test showing only small magnitude changes in a few parameters. Both 24-hour ABPM and 44-hour ABPM were superior to clinic BP in predicting left ventricular mass index ( LVMI) by multiple regression analysis. It was found that 44-hour ambulatory arterial stiffness index ( AASI), but not 24-hour AASI, had a positive association with LVMI ( r=0.328, P=.021). However, after adjustment for 44 -hour systolic blood pressure, this association disappeared. Fixed 24 -hour ABPM is a good surrogate of 44-hour ABPM to some extent, while 44-hour ABPM can provide more accurate and detailed information. [ABSTRACT FROM AUTHOR]