The Diurnal Profile of Central Hemodynamics in a General Uruguayan Population.

BACKGROUND: No previous population study assessed the diurnal profile of central arterial properties. METHODS: In 167 participants (mean age, 56.1 years; 63.5% women), randomly recruited in Montevideo, Uruguay, we used the oscillometric Mobil-O-Graph 24-h PWA monitor to measure peripheral and central systolic (SBP), diastolic (DBP), and pulse (PP) pressures and central hemodynamics standardized to a heart rate of 75 bpm, including aortic pulse wave velocity, systolic augmentation (first/second peak × 100), and pressure amplification (peripheral PP/central PP). RESULTS: Over 24 hours, day and night, peripheral minus central differences in SBP/DBP and in PP averaged 12.2/-1.1, 14.0/-0.7, and 9.7/0.2mm Hg and 12.6, 14.7, and 9.5mm Hg, respectively (P < 0.001 except for nighttime DBP (P = 0.38)). The central-to-peripheral ratios of SBP, DBP, and PP were 0.89, 1.00, and 0.70 unadjusted, but after accounting for anthropometric characteristics decreased to 0.74, 0.97, and 0.63, respectively, with strong influence of height for SBP and DBP and of sex for PP. From day (10-20h) to nighttime (0-6h), peripheral (-10.4/-10.5 mm Hg) and central (-6.0/-11.3mm Hg) SBP/DBP, pulse wave velocity (-0.7 m/s) and pressure amplification (-0.05) decreased (P < 0.001), whereas central PP (+5.3mm Hg) and systolic augmentation (+2.3%) increased (P < 0.001). CONCLUSIONS: The diurnal rhythm of central pressure runs in parallel with that of peripheral pressure, but the nocturnal fall in SBP is smaller centrally than peripherally. pulse wave velocity, systolic augmentation, and pressure amplification loop through the day with high pulse wave velocity and pressure amplification but low systolic augmentation in the evening and opposite trends in the morning.

Estimation of Glomerular Filtration Rate Based on Serum Cystatin C versus Creatinine in a Uruguayan Population.

Background. Estimation of glomerular filtration rate (eGFR) from biomarkers has evolved and multiple equations are available to estimate renal function at bedside. Methods. In a random sample of 119 Uruguayans (54.5% women; 56.2 years (mean)), we used Bland and Altman's method and Cohen's kappa statistic to assess concordance on a continuous or categorical (eGFR < 60 versus ≥60 mL/min/1.73 m(2)) scale between eGFRcys (reference) and eGFR derived from serum creatinine according to the Modification of Diet in Renal Disease (eGFRmdrd) or the Chronic Kidney Disease Epidemiology Collaboration equations (eGFRepi) or from both serum cystatin C and creatinine (eGFRmix). Results. In all participants, eGFRmdrd, eGFRepi, and eGFRmix were, respectively, 9.7, 11.5, and 5.6 mL/min/1.73 m(2) higher (P < 0.0001) than eGFRcys. The prevalence of eGFR <60 mL/min/1.73 m(2) was the highest for eGFRcys (21.8%), intermediate for eGFRmix (11.8%), and the lowest for eGFRmdrd (5.9%) and eGFRepi (3.4%). Using eGFRcys as reference, we found only fair agreement with the equations based on creatinine (Cohen's kappa statistic 0.15 to 0.23). Conclusion. Using different equations we reached clinically significant differences in the estimation of renal function. eGFRcys provides lower estimates, resulting in higher prevalence of eGFR <60 mL/min/1.73 m(2).

Quality of the blood pressure phenotype in the GEnotipo, Fenotipo y Ambiente de la hipertensión arterial en UruguaY (GEFA-HT-UY) study.

BACKGROUND: In the ongoing GEnotipo, Fenotipo y Ambiente de la HiperTensión Arterial en UruguaY (GEFA-HT-UY) study, we applied standardized epidemiological methods to determine complex phenotypes including blood pressure (BP). In this report, we present the quality control of the conventionally measured BP. METHODS: Three trained observers measured BP five times consecutively in the seated position at each of two home visits and one clinic visit according to the guidelines of the European Society of Hypertension. On 1 December 2013, 4379 single BP readings in 170 participants were available for analysis. RESULTS: Fewer BP readings than the five planned per contact occurred only at one home visit. Among observers, the frequency of identical consecutive readings for systolic or diastolic BP varied from 0 to 4.2%. The occurrence of odd readings ranged from 0.1 to 0.6%. Only 21.6% of the systolic and diastolic BP readings ended on zero (expected 20%). At home visits, there was a progressive decline in BP from the first to the fifth reading. The average of the five BP readings also decreased from the first to the second home visit (-5.63/-2.34 mmHg). CONCLUSIONS: Our study highlighted the necessity to implement a stringent quality control of the conventionally measured BP. The procedures set up in the GEFA-HT-UY study are resulting in a well-defined BP phenotype, which is consistent with that in other population studies.

24-h ambulatory recording of aortic pulse wave velocity and central systolic augmentation: a feasibility study.

We assessed the feasibility of ambulatory pulse wave analysis by comparing this approach with an established tonometric technique. We investigated 35 volunteers (45.6 years; 51.0% women) exclusively at rest (R study) and 83 volunteers (49.9 years; 61.4% women) at rest and during daytime (1000-2000 h) ambulatory monitoring (R+A study). We recorded central systolic (cSP), diastolic (cDP) and pulse (cPP) pressures, augmentation index (cAI) and pulse wave velocity (PWV) by brachial oscillometry (Mobil-O-Graph 24h PWA Monitor) and radial tonometry (SphygmoCor). We applied the Bland and Altman's statistics. In the R study, tonometric and oscillometric estimates of cSP (105.6 vs. 106.9 mm Hg), cDP (74.6 vs. 74.7 mm Hg), cPP (31.0 vs. 32.1 mm Hg), cAI (21.1 vs. 20.6%) and PWV (7.3 vs. 7.0 m s(-1)) were similar (P0.11). In the R+A study, tonometric vs. oscillometric assessment yielded similar values for cSP (115.4 vs. 113.9 mm Hg; P=0.19) and cAI (26.5 vs. 25.3%; P=0.54), but lower cDP (77.8 vs. 81.9 mm Hg; P<0.0001), so that cPP was higher (37.6 vs. 32.1 mm Hg; P<0.0001). PWV (7.9 vs. 7.4 m s(-1)) was higher (P=0.0002) on tonometric assessment. The differences between tonometric and oscillometric estimates increased (P0.004) with cSP (r=0.37), cAI (r=0.39) and PWV (r=0.39), but not (P0.17) with cDP (r=0.15) or cPP (r=0.13). Irrespective of measurement conditions, brachial oscillometry compared with an established tonometric method provided similar estimates for cSP and systolic augmentation, but slightly underestimated PWV. Pending further validation, ambulatory assessment of central hemodynamic variables is feasible.

Aproximación clínica al consumo de sodio / Clinical approach to sodium consumption

Introducción: el consumo de sodio se vincula directamente a las cifras de presión arterial y adicionalmente incide en el manejo de diversas enfermedades. En el año 2003, la Organización Mundial de la Salud (OMS) propone reducir el consumo poblacional de sal a menos de 5 g/día. En Uruguay no contamos con datos de mediciones directas del consumo de sodio. La medición del sodio en la orina de 24 horas es el método patrón para la determinación del consumo diario, sin embargo es un método poco usado en la prácticaclínica debido en parte a lo engorroso que resulta para el paciente. Objetivo: determinar el consumo de sodio de un grupo de voluntarios a través de la natriuria de 24 horas. Encontrar una relación entre la natriuria de una muestra de orina (spot) y la natriuria de 24 horas. Material y método: se reclutaron estudiantes de cuarto año de la carrera de Doctor en Medicina de la Universidad de la República. Se registraron antecedentes médicos, medidas antropométricas, y de presión arterial en consultorio y se recolectó la orina de 24 horas. El análisis de la relación entre el contenido de sodio en el spot y en la orina de 24 horas serealizó mediante prueba de chi cuadrado.Resultados: 33 de 45 estudiantes completaron el estudio. El consumo promedio de sodio fue de 2,9±1,1 g/día. Una natriuria en el spot mayor a 75 mEq/L se asoció a un consumo de sodiomedido por natriuria de 24 horas mayor de 100 mEq/día (p<0,005), con una sensibilidad de 95% y especificidad de 63%.

Introduction: sodium consumption is closely related to blood pressure rates and it additionally affects the handlingof different diseases. In 2003, the World Health Organization (WHO) encouraged people to reduce the consumption of sodium to under 5 g/day. In Uruguay there is no data resulting from direct measurement of sodium consumption. Measuring sodium in the 24 hour urine is the standard method to determine daily consumption, although this method is rarely used in the clinical practice due to its being bothersome for patients. Objective: to determine sodium consumption for agroup of volunteers through 24 hours natriuria. To find a relationship between spot tests of urine natriuria and 24-hour urine natriuria. Method: fourth year medical students were recruited from the School of Medicine at the University of the Republic. Medical history, anthropometric measures and blood pressure in the polyclinic were recorded and the urine was collected during 24 hours. The analysis of the relationship between the content of sodium in the spot and in the 24- hour urine was performed through square chi.Results: 33 out of 45 students completed the study. Average consumption of sodium was 2.9 2,9±1,1 g/day. Natriuria in the spot greater than 75 mEq/L was associated to sodium consumption measured by 24-hour natriuria greater than 100 mEq/día (p<0,005), with a sensitivity of95% and a specificity of 63%.

Introdução: o consumo de sódio está diretamente relacionado aos valores da pressão arterial e também tem influenciasobre o manejo de varias doenças. Em 2003, a Organização Mundial da Saúde (OMS) lançou uma proposta para reduzir o consumo de sal da população aum valor inferior a 5 g/dia. No Uruguai não estão disponíveis dados de medições diretas do consumo de sal. O método padrão para determinação de consumo diário é o exame da urina de 24 horas; no entanto não é um método muito utilizado na prática clínica por ser muito trabalhoso para o paciente. Objetivo: conhecer o consumo de sódio de um grupo de voluntários determinando a natriúria de 24 horas. Encontrar uma relação entre a natriúria de uma amostra de urina (ôspotõ) e a natriúria de 24 horas. Material e método: foram recrutados estudantes doquarto ano do curso de Medicina da Universidad de la República. Foram registrados sus antecedentes médicos,medidas antropométricas, e pressão arterial no consultório e se realizou a coleta de urina de 24 horas. A análise darelação entre o conteúdo de sódio no ôspotõ e na urina de 24 horas foi realizado utilizando a prova do X quadrado. Resultados: 33 dos 45 estudantes completaram o estudo. O consumo médio de sódio foi de 2,9±1,1 g/dia. Uma natriúria do ôspotõ superior a 75 mEq/L foi associada ao consumo de sódio medido por natriúria de 24 horas superior a 100 mEq/dia (p<0,005), com uma sensibilidadede 95% e especificidade de 63%.