Hypertension in Chronic Kidney Disease Part 2

Abstract

Blood pressure (BP) is characterized by high variability, including changes beat-to-beat (very short term), within 24 hours (short term), from day to day (midterm), and between visits spaced by weeks, months, seasons, and even years (long term). These variations can be estimated by means of continuous beat-to-beat BP recordings, repeated conventional office BP measures, 24-hour ambulatory BP monitoring (ABPM), or home BP monitoring (HBPM) over longer time windows (Table). A main advantage of ABPM over other BP measurement techniques is represented by its ability to track BP changes occurring in daily life conditions and during 24 hours, thus allowing assessment of overall BP variability (BPV) as well as identification of its specific components, such as nocturnal hypertension and altered day-to-night BP profiles (ie, morning BP rise, nondipping pattern of BP) which become manifest early in the course of chronic kidney disease (CKD). These alterations are even more significant in subjects with end-stage renal disease (ESRD) mainly, but not exclusively, because of the marked reduction in intravascular volume immediately after hemodialysis followed by the progressive increase in volemia throughout the interdialytic period, 2 combined with an enhanced sympathetic activity. The higher frequency of alterations in 24-hour BP profiles and BPV in subjects with CKD and in those with ESRD not only makes a proper assessment and achievement of BP control more difficult in these subjects but may be prognostically relevant on the background of the evidence from longitudinal and observational studies indicating that increased BPV may predict the development of cardiovascular and renal disease, over and above the contribution of elevated mean BP levels per se 3-11 ( Figure 1). The purpose of this review is to address the currently available evidence on the role of ABPM and HBPM for the assessment and management of alterations in circadian BP profiles and in BPV in patients with CKD. Mechanisms of BPVIn physiological conditions, BP fluctuations occurring on a beat-by-beat basis and within the 24 hours may represent a homeostatic response of neural (ie, central sympathetic drive and its reflex modulation by arterial and cardiopulmonary reflexes), humoral (catecholamines, insulin, angiotensin II, bradykinin, endothelin-1, and nitric oxide), vascular (ie, elastic properties of arteries), and rheological mechanisms (ie, blood viscosity) to environmental (weather changes), behavioral (ie, physical activity, sleep, postural changes), and emotional (ie, psychological stress) stimuli.

Different contribution of SBP and DBP variability to vascular events in patients with stroke

“…Repeated assessment of BP values by patients themselves or relatives may offer a solid base to assess BPV during the long-term follow-up period. 29 There are also known and potential limitations associated with the current analysis. First, the possibility of residual confounding cannot be fully eliminated in an observational study, although several important potential confounders have been controlled in multivariable adjusted models.…”

In Patients with Chronic Kidney Disease Short Term Blood Pressure Variability is Associated with the Presence and Severity of Sleep Disorders

“…However, it is important to note that the time interval considered when calculating BPV, does matter with regards to the association between BPV and various cardiovascular outcomes. For example, when BPV is assessed in a large time range, the association with both CV events and CV mortality is rather strong and significant, whilst if a shorter time range is considered, the association with CV events is less evident [31]. …”

Hypertension in patients on dialysis: diagnosis, mechanisms, and management

“…Although BP is measured frequently in the dialysis treatment environment, aspects related to the measurement technique employed may be unsatisfactory. Several other tools are now available and being used in clinical trials and clinical practice to evaluate and treat elevated BP in chronic kidney disease (CKD) patients 1 , 2. Different levels of BP may be observed in the same patient under distinct situations, which include evaluations before, during, or after the dialysis session, and at home using ambulatory BP measurements (ABPM), being frequently and substantially lower than during dialysis measurements 3…”

“…The National Kidney Foundation - Kidney Diseases Outcomes Quality Initiative guideline established that hypertension in hemodialysis patients is diagnosed when pre-dialysis BP is > 140/90 mmHg or when post-dialysis BP is > 130/80 mmHg,24 but the conventional peridialytic BP recordings may not be accurate. Pre- and post-dialysis BPs measures are obtained by the staff of the dialysis unit, often without the necessary attention to the correct measurement technique 1 , 225…”