a method and system for continuously monitoring patient heart rate and blood pressure during hemodialysis and for automatically controlling fluid extraction rate and / or dialysate sodium concentration in the event that blood pressure and / or heart rate indicate onset or impending onset of a patient hypotensive episode . a decrease in patient blood pressure below preselected systolic and / or diastolic low alarm limits automatically initiates a second mode of therapeutic intervention wherein sodium concentration in the dialysate is increased for a predetermined time duration . upon detection of such low blood pressure alarm , or upon detection of an increase in patient heart rate above a preselected alarm limit , the extraction rate of fluids from the patient through the ultrafiltration membrane is reduced in a first mode of therapeutic intervention by reducing such fluid extraction rate to a minimum level . blood pressure and heart rate are thereafter monitored during this second mode of intervention to return ultrafiltration flow rate to its desired or goal level as blood pressure and heart rate indicate return of patient vital signs toward their initial levels .