Dialysis unphysiology and sodium balance

Area of Science:

• Nephrology
• Cardiovascular Medicine
• Physiology

Background:

• Current hemodialysis (HD) practices are considered unphysiologic due to fluctuations in blood chemistries and fluid balance.
• Intermittent HD leads to extracellular fluid volume expansion, contributing to hypertension and cardiovascular issues.
• Sodium accumulation during interdialytic periods plays a key role in the pathogenesis of hypertension.

Purpose of the Study:

• To discuss the concept of dialysis "unphysiology" and its implications.
• To explain the mechanisms by which sodium accumulation contributes to hypertension in hemodialysis patients.
• To identify strategies for avoiding positive sodium balance in hemodialysis.

Main Methods:

• Review of existing literature on dialysis physiology and hypertension.
• Analysis of sodium and fluid dynamics during intermittent hemodialysis.
• Discussion of the "lag phenomenon" in blood pressure reduction post-dialysis.

Main Results:

• Intermittent hemodialysis fails to maintain stable blood chemistries, causing fluid shifts and hypertension.
• Accumulated sodium exists in osmotically active (extracellular) and inactive (intracellular) forms, both contributing to hypertension.
• Intracellular sodium accumulation in vascular smooth muscle cells may explain delayed blood pressure reduction.

Conclusions:

• Dialysis unphysiology, particularly positive sodium balance, requires management.
• Strategies to avoid positive sodium balance include dietary sodium restriction, adequate dialysis session length, and appropriate dialysate sodium concentration.
• Addressing sodium balance is crucial for improving cardiovascular outcomes in hemodialysis patients.