Potassium and Hypertension: A State-of-the-Art Review

Predictors of daytime blood pressure, nighttime blood pressure, and nocturnal dipping in patients with chronic kidney disease

Increasing attention has recently been paid to discrepancies between office and ambulatory blood pressure (BP) control in patients with chronic kidney disease (CKD), but information on mechanisms underlying circadian BP variations in CKD remains scarce. We described circadian BP patterns and their predictors in patients with CKD stages 1 to 5 referred for kidney function testing in a French tertiary hospital: 1122 ambulatory BP measurements from 635 participants. Factors associated with daytime and nighttime systolic BP (SBP) as well as with nocturnal SBP dipping (ratio of average nighttime to daytime SBP) were analyzed with linear mixed regression models. Participants (mean age 55 ± 16 years; 36% female, mean GFR 51 ± 22 mL/min/1.73m2) had a mean daytime and nighttime SBP of 130 ± 17 and 118 ± 18 mm Hg, respectively. The prevalence of impaired dipping (nighttime over daytime SBP ratio ≥ 0.9) increased from 32% in CKD stage 1 to 68% in CKD stages 4-5. After multivariable adjustment, measured GFR, diabetes, and sub-Saharan African origin were more strongly associated with nighttime than with daytime SBP, which led to significant associations with altered nocturnal BP dipping. For a 1 SD decrease in measured GFR, nighttime BP was 2.87 mmHg (95%CI, 1.44-4.30) higher and nocturnal SBP dipping ratio was 1.55% higher (95%CI, 0.85-2.26%). In conclusion, the prevalence of impaired nocturnal BP dipping increases substantially across the spectrum of CKD. Along with sub-Saharan African origin and diabetes, lower measured GFR was a robust and specific predictor of higher nighttime BP and blunted nocturnal BP decline.

Diet to Stop Hypertension: Should Fats be Included?

PURPOSE OF REVIEW

International guidelines emphasize advice to incorporate dietary measures for the prevention and in the management of hypertension. Current data show that modest reductions in weight can have an impact on blood pressure. Reducing salt and marine oils have also shown consistent benefit in reducing blood pressure. Whether other dietary constituents, in particular the amount and type of fat that play important roles in cardiovascular prevention, influence blood pressure sufficiently to be included in the management of hypertension is less certain. In this review, we provide a summary of the most recent findings, with a focus on dietary patterns, fats and other nutrients and their impact on blood pressure and hypertension.

RECENT FINDINGS

Since reducing salt consumption is an established recommendation only corollary dietary advice is subject to the current review. Population studies that have included reliable evaluation of fat intake have indicated almost consistently blood pressure lowering with consumption of marine oils and fats. Results with vegetable oils are inconclusive. However dietary patterns that included total fat reduction and changes in the nature of vegetable fats/oils have suggested beneficial effects on blood pressure. Plant-based foods, dairy foods and yoghurt particularly, may also lower blood pressure irrespective of fat content. Total fat consumption is not directly associated with blood pressure except when it is part of a weight loss diet. Consumption of marine oils has mostly shown moderate blood pressure lowering and possibly greatest effect with docosahexaenoic acid-rich oil.