Mechanisms and Phenotypes of Hypertension in Patients in Chronic Hemodialysis

Mechanisms and Phenotypes of Hypertension in Patients in Chronic Hemodialysis

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

Inclusion Criteria:

• Patients with more than 3 months in the chronic hemodialysis program in the INCMNSZ and assumed to remained in the program for longer than 3 months
• Stable patients with no change in medication 1 month prior to the study
• Unchanged drug therapy and dialysis prescription for >1 month prior to the studies
• Informed consent to participate in the study

Exclusion Criteria:

• Patients unable to give informed consent or withdrawal of informed consent to the study
• Patients with active infection
• Patients with prosthesis or pacemakers
• Patients with immunosuppressive treatment of more than 10mg Prednisone daily
• Prior nephrectomy
• incomplete collection of data specified in the study protocol