The goal of this study is to evaluate interdialytic blood pressure changes of the patients in chronic hemodialysis. The main question to be answered is: What is the relative importance of weight gain, the renin angiotensin system, the sympathetic nervous system and inflammatory immune reactivity in the interdialytic hypertension of patients in chronic hemodialysis, The participants will have hemodynamic evaluation (cardiac output and peripheral vascular resistance) at the end of dialysis, ambulatory monitoring of blood pressure in the interdialytic period. Serum samples will be collected at the end of dialysis and before the start of the next dialysis, 2-3 days later.
This is a prospective observational study that will study stable patients in the chronic hemodialysis program of the Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" (INCMNSZ) patients. There will be no modifications in the dialysis prescriptions or treatments and the patients with inclusion criteria will be studied after and before their usual hemodialysis sesion. * Weight changes will be studied after dialysis and before the next dialysis session (2-3 days later) * Serum samples will be obtained at the end of dialysis and before the next session (2-3 days later). * ultrasound estimation of cardiac output and peripheral vascular rersistance will be done after dialysis * Ambulatory blood pressure (ABP) monitoring will be done in the interdialytic period (24-40 hours) between the end of dialysis and the next dialysis session. * If possible there will be a predialysis study of bioimpedance. * Associations of interdialytic weight gain, serum angiotensin II, copeptin levels (surrogate of arginine vasopressin) and norepinephrine levels with ABP, systolic and diastolic blood pressure before and after dialysis will be explored. * Phenotypes of blood pressure (sustained hypertension, nocturnal and diurnal hypertension, dippers, non-dippers, extreme dippers and reverse dippers) determined by ambulatory monitoring will be studied in relation of levels of angiotensin II, inflammatory markers, copeptin and norepinephrine levels. All serum levels will be determined by commercial ELISA kits
Study Type
OBSERVATIONAL
Enrollment
32
There will be no intervention. This is an observational studies and 3 groups will be organized depending on the level of ABP in the interdialytic period
Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán"
Mexico City, Mexico
Cardiac Output
Cardiac output (systolic volume x heart rate) was determined by 2 experienced observers using a Siemens Acuson P500 ultrasound equipment with a phased array transducer . Systolic volume was calculated with the velocity time integral of the flow of the left ventricle outflow tract of the aortic area.
Time frame: Each participant was studied once 1-3 hours after dialysis ended
Interdialytic Weight Change
The weight was determined in 2 ocassions: first, immediately after dialysis and second, 2-3 days later, before the next dialysis. The weight change in this interval is expressed as percentage change of the second measure in relation to the first measure.
Time frame: Interdialytic weight change was studied once, by the difference between the weight at the end of dialysis and the weight 2-3 days later, before the next dialysis.
Systemic Vascular Resistance
Systemic vascular resistance was calculated using MediCalcR using the mean arterial pressure (MAP), the central venous pressure (CVP) anf the cardiac output (CO) and the equation: SVR=\[(MAP-CVP)x79.92\]/CO. Cardiac output (CO= systolic volume x heart rate) and central venous pressure were determined by 2 experienced observers using a Siemens Acuson P500 ultrasound equipment with a phased array transducer. Systolic volume was calculated with the velocity time integral of the flow of the left ventricle outflow tract of the aortic area.
Time frame: Systemic vascular resistance was determined once in the participants 1-3 hours after dialysis
Angiotensin II Serum Levels
Angiotensin serum levels (pg/ml) were determined once at the end of the interdialytic period, before dialysis, using ELISA (my BioSource Cat.# MBS703599)
Time frame: Each participant was studied once. Serum samples taken before dialysis
Monocyte+Neutrophiles/Lymphocyte Ratio (MNLR)
Monocyte+Neutrophile/lymphocyte ratio obtained from peripheral blood counts in samples taken before dialysis (following the end of the interdialytic period).
Time frame: Each participant was studied once. Blood samples taken before dialysis (following the end of the interdialytic period).
Serum Norepinephrine Levels
Interdialytic serum norepinephrine levels determined in blood samples obtained before dialysis (end of interdialytic period) using ELISA (ABCAM, Cat. # AB287789);
Time frame: Each participant was studied once. Serum samples taken before dialysis
Serum Copeptin Levels
The copeptin levels (surrogate for arginine vasopressin) were measured before dialyisis (end of the interdialytic period) using ELISA (Bio-techne/NovusBiological, Cat, # NBP2-69822)
Time frame: Each participant was studied once. Serum samples taken before dialysis
Hypertension Phenotypes
Interdialytic ambulatory blood pressure determined during 24-44 hours using Space Labs Health Care, model 90217A and Contec ABPM50 equipment. Determinations every 30 minutes during daytime and every hour during the night. We are here reporting the phenotypes in the total number of participants (n=32) instead that in each group (groups A n=15, B n=7 and C n=10) because our main interest was to determine the incidence of each phenotyte in stable patients treated with chronic dialysis, rather than in each group that, individually, had few patients
Time frame: Each participant was studied once. Ambulatory blood pressure was monitored or 24-44 hours during the interdialytic perdiod starting 1-3 hours after dialysis
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