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Volume control, blood pressure and cardiovascular function. Lessons from hemodialysis treatment
Bernard Charra1, Charles Chazot
1Centre de Rein Artificiel, Tassin, France. bcharra@aol.com
Insights
Maintaining sodium balance is crucial for dialysis patients to manage extracellular fluid volume (ECV) and prevent complications like hypertension and left ventricular hypertrophy (LVH). Achieving dry weight helps normalize blood pressure and reduce mortality risk.
Area of Science:
- Nephrology
- Cardiovascular Medicine
- Fluid and Electrolyte Balance
Background:
- Dialysis patients often have positive sodium balance and increased extracellular fluid volume (ECV).
- This ECV overload leads to systemic hypertension, vascular, and cardiac remodeling, notably left ventricular hypertrophy (LVH).
- Hypertension and LVH significantly increase mortality risk in dialysis populations.
Purpose of the Study:
- To discuss the concept of dry weight for managing ECV overload in dialysis patients.
- To evaluate the effectiveness of blood pressure as an indicator for setting dry weight targets.
- To explore alternative tools for ECV assessment due to limitations of current methods.
Main Methods:
- Review of the relationship between sodium balance, ECV, and cardiovascular outcomes in chronic renal failure and dialysis.
- Analysis of the dry weight concept and its reliance on blood pressure monitoring.
- Discussion of the impact of dialysis session duration and dialysate sodium concentration on ECV management.
- Exploration of emerging ECV assessment tools like inferior vena cava diameter, bioimpedance, and blood volume monitoring.
Main Results:
- Positive sodium balance and ECV overload are common in dialysis patients, contributing to hypertension and LVH.
- The dry weight concept aims to normalize blood pressure and ECV, but its achievement can be compromised by factors like shortened dialysis time.
- Intradialytic complications can exacerbate ECV overload, leading to increased thirst, weight gain, and worsening hypertension.
- Limitations in achieving dry weight have spurred the development and investigation of alternative ECV assessment methods.
Conclusions:
- Effective management of sodium balance and ECV is critical for improving outcomes in dialysis patients.
- Blood pressure is a key, albeit sometimes lagging, indicator of ECV status.
- Alternative ECV assessment tools are needed to optimize fluid management and reduce cardiovascular risks in dialysis.
Abstract:
The balance of sodium, through its dietary intake and renal excretion, determines extracellular fluid volume (ECV). Chronic renal failure and dialysis patients present with a positive sodium balance and increased ECV. The consequences are systemic hypertension and vascular and cardiac remodelling, especially left ventricular hypertrophy (LVH). High blood pressure (BP) and LVH increase the mortality risk of dialysis patients. Correction of ECV overload with ultrafiltration has led to the dry weight concept, which is the postdialysis body weight that allows BP to remain normal until the next dialysis session, without the need for antihypertensive medication and despite interdialytic weight gain. Blood pressure is the key indicator of ECV and is used to set the body weight target at each dialysis session. Normalization of BP indicates normalization of ECV, usually with a lag-time. Shortening dialysis time, which increases intradialytic morbidity, compromises the achievement of dry weight and normalization of ECV. Such intradialytic events may also lead to an increase in dialysate sodium concentration, which causes thirst, and greater interdialytic weight gain, positive sodium balance and worsening BP. These complications have led to the development of other tools for ECV assessment, such as inferior vena cava diameter, bioimpedance, and blood volume monitoring; their usefulness is discussed.