Vasoactive hormones during hemodialysis with intermittent ultrafiltration

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Endocrinology

Background:

• Hemodialysis (HD) can cause significant blood volume (BV) fluctuations.
• Understanding the body's compensatory mechanisms during HD is crucial for patient stability.

Purpose of the Study:

• To investigate the correlations between blood volume, blood pressure, heart rate, and various hormones during a specific HD protocol.
• To determine the primary regulatory systems involved in maintaining vascular stability during HD with rapid fluid removal.

Main Methods:

• Studied 10 stable HD patients undergoing a "saw tooth" ultrafiltration (UF) profile.
• Monitored blood volume (BV) using continuous hemoglobinometry.
• Measured plasma levels of renin activity (PRA), aldosterone (ALD), antidiuretic hormone (ADH), epinephrine (E), norepinephrine (NE), atrial natriuretic factor (ANF), cGMP, and cAMP.

Main Results:

• A 25% average decrease in BV occurred without significant changes in blood pressure or heart rate.
• Epinephrine (E), norepinephrine (NE), atrial natriuretic factor (ANF), and antidiuretic hormone (ADH) levels correlated directly with BV changes.
• The renin-aldosterone system (PRA and ALD) did not show significant changes; cGMP decreased with diminished BV.

Conclusions:

• Vascular stability during this HD protocol is primarily maintained by the secretion of catecholamines (epinephrine, norepinephrine) and ADH in response to decreased blood volume.
• The renin-aldosterone system plays a minimal role in immediate blood pressure regulation under these conditions.
• This suggests a critical role for the sympathetic nervous system and ADH in managing fluid shifts during intensive hemodialysis.