title: Blood pressure changes after high- and low-salt diets: are intermittent arm measures and beat-by-beat finger measures equivalent?
abstract: The assessment of sodium sensitivity requires to measure the difference in mean arterial pressure (MAP) at the end of sodium-loading (SLoad) and sodium-depletion (SDepl) maneuvers with an arm-cuff manometer. Aim of this study is to evaluate whether MAP measuring devices based on the volume-clamp method at the finger can also be used for assessing sodium sensitivity. Sixty-eight normotensive volunteers underwent SLoad and SDepl diets in random order. MAP was simultaneously measured at the end of each diet with arm (Spacelabs 90207) and finger (Portapres model-2) cuff devices. The sodium sensitivity was assessed as the difference in MAP at the end of SLoad and SDepl diets (ΔMAP), and as salt-sensitivity index (SSI; SSI = ΔMAP divided by the difference in urinary-sodium-excretion rate at the end of the diets). Discrepancies between finger and arm-cuff devices in ΔMAP or SSI were evaluated by Bland and Altman analysis. Even if discrepancies between devices had null-fixed bias, results showed a significant proportional bias and large limits of agreement (between -25 and 25 mm Hg for ΔMAP, between -196 and 180 mm Hg mol(-1) per day for SSI). The SSI distribution over the group was larger, flatter and less symmetric if derived from finger-cuff rather than arm-cuff devices, and this influenced substantially the identification of salt-sensitive individuals. Therefore, the response of MAP to SLoad/SDepl diets and consequently the assessment of the salt-sensitivity condition depends importantly on the measurement site, and brachial measures should be preferred for consistency with literature and normative data.
authors.affiliation: IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Castiglioni
authors.affiliation: 1] Department of Cardiology, Istituto Auxologico Italiano, Milan, Italy [2] Department of Health Sciences, University of Milano-Bicocca, Milan, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Parati
authors.affiliation: IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Rienzo
authors.affiliation: Fondazione Don Carlo Gnocchi, Parma, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Brambilla
authors.affiliation: Fondazione Don Carlo Gnocchi, Parma, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Brambilla
authors.affiliation: Fondazione Don Carlo Gnocchi, Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gualerzi
authors.affiliation: Fondazione Don Carlo Gnocchi, Parma, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Lazzeroni
authors.affiliation: Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Coruzzi
mesh_terms: D000328:Adult; D001794:Blood Pressure; D005260:Female; D006801:Humans; D008297:Male; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*
chemical_list: D017673:Sodium Chloride, Dietary