High Dialysate Calcium Concentration May Cause More Sympathetic Stimulus During Hemodialysis

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Autonomic Nervous System Research

Background:

• Hemodialysis can cause sympathetic overactivity, impacting blood pressure and mortality.
• Low heart rate variability (HRV) and abnormal ankle-brachial index (ABI) are mortality predictors in hemodialysis patients.
• Dialysate calcium concentration (DCa) may influence autonomic responses during hemodialysis.

Purpose of the Study:

• To investigate the effect of high (1.75 mmol/l) versus low (1.25 mmol/l) DCa on HRV and ABI in incident hemodialysis patients.
• To assess the relationship between DCa, sympathetic activity, and hemodynamic changes during dialysis.

Main Methods:

• Assessed HRV (as LF/HF ratio) and ABI pre- and post-hemodialysis.
• Studied 30 incident hemodialysis patients over two consecutive mid-week sessions.
• Compared outcomes between high and low DCa sessions.

Main Results:

• Higher DCa (1.75 mmol/l) was associated with more stable blood pressure compared to lower DCa (1.25 mmol/l).
• Increased sympathetic activity (higher LF/HF ratio) was observed with higher DCa.
• A decrease in ABI post-hemodialysis correlated with heightened sympathetic activity.

Conclusions:

• While higher DCa improves hemodynamic tolerance during hemodialysis, it elevates sympathetic nervous system activity.
• Increased sympathetic activity during hemodialysis is linked to a reduction in ABI.
• The findings suggest a complex interplay between dialysate calcium, autonomic function, and peripheral vascular response in hemodialysis patients.