BP Measurement Techniques

Patients with CKD typically have hypertension. Manual BP measurement in the office setting was used to define hypertension, establish eligibility, and assess BP targets in the epidemiologic studies and early randomized, controlled trials that inform currentmanagement of hypertension.Use of automated oscillometric devices has largely replaced manual BP measurement in the office and clinical trials. These newer devices may reduce the white coat effect and facilitate guideline-adherent measurement protocols. Obtaining BP measurements outside of the office with home and ambulatory BP monitoring is now more common. Out of office BPs are especially important in patients with CKD, because reduced GFR and proteinuria are associated with masked hypertension (normal office BP and elevated BP outside of the office), elevated nighttime BP, and abnormal diurnal variation in BP, all of which are associated with higher risk for target organ damage and adverse outcomes. Also, it is now feasible to routinely measure central BP and central hemodynamics. These measures are of greater importance to patients with CKD given the higher prevalence of increased sympathetic tone, arteriosclerosis, and inflammation as well as impaired sodiumexcretionandendothelial dysfunction,which lead toalterations incentralBPs in this population. In this review,wedescribe variousBPmeasurement techniques andhow theyapply to the careof patientswithCKD. Clin J Am Soc Nephrol 13: 1124–1131, 2018. doi: https://doi.org/10.2215/CJN.12551117 Introduction Hypertension is a strong independent risk factor for cardiovascular disease, with observational studies showing a continuous and linear relationship between BP and cardiovascular risk (1). Hypertension is common in patients with CKD, and it can be a cause or consequence of CKD (2). The prevalence of hypertension in patients with CKD, when defined as BP level $140/90 mm Hg, is inversely related to the eGFR— increasing from 67% in those with eGFR.60 ml/min per 1.73 m2 to 92% in those with eGFR,30 ml/min per 1.73 m2 (2,3). Furthermore, patients with CKD are at higher risk for hypertension-related adverse outcomes, including cardiovascular disease (4). Therefore, management of hypertension is particularly important in patients with CKD. The diagnosis and management of hypertension are still predominantly on the basis of office BPs. However, patients with CKD are prone to abnormal BP patterns when BP is measured outside of the office at home and with ambulatory BP monitoring or when central BPs are assessed. The purpose of this review is to discuss various BP measurement techniques and how they apply to the care of patients with CKD. Automated Office BP Monitoring The diagnosis and optimal management of hypertension necessitate obtaining an accurate assessment of patients’ true hypertensive status and risk of end organ damage. Traditional manual office BPmeasurement relies on the use of aneroid sphygmomanometers. Oscillometric devices, which are more commonly used now, overcome some of the disadvantages of auscultatory measurements (5). Office-based BP measurements, whether using the auscultatory or the oscillometric method, have some inherent limitations, including an inability to assess diurnal variation and the “white coat effect,” a transient increase in BP observed in some patients when a medical professional is present in the room (6,7). Despite these limitations, it is likely that office-based BP measurements will continue to be the primary technique for both the diagnosis and management of hypertension. Current treatment recommendations are on the basis of clinical trials that used office BP measurements. The use of automated office BP devices that take multiple consecutive BP readings with the patient sitting and resting alone has been shown to decrease the white coat response compared with single manual measurements (8). Although some studies have shown that automated office BP shows a stronger correlation with average awake BP on ambulatory BP monitoring compared with routine measurements, this finding is not consistent. In a clinical trial of 555 patients with hypertension who were randomized by clinic to ongoing use of manual office BP or automated office BP, mean manual office BP at baseline was similar in both groups (150/81 versus 150/82 mm Hg) (9). After randomization, mean office BP was significantly lower in clinics randomized to automated compared with manual measurement (136/78 versus Department of