Studying the Effect of Dialysate Temperature on Toxin Removal and Hypotension

Cool dialysate, by vasoconstriction, is simple maneuver to control and/or prevent incidence of intra-dialytic hypotension (IDH). During dialysis fluid is continuously removed. IDH occurs when plasma refilling rate is smaller than the set ultra-filtration rate. When plasma refiling rate is small, continuous fluid removal bring patient to the threshold state where patient does not have sufficient fluid in central compartment. This leads to the cascade of events, viz., low blood pressure, muscle cramps, dizziness, being first few manifestation. To minimize the occurrence of such events, clinicians often prescribe cool dialysate resulting in vasoconstriction, which ensures sufficient fluid volume in central body compartment so that continuous fluid loss does not impact patient hemodynamics severely.

It is important to note that vasoconstriction may also inhibit the toxin movement from remote peripheral compartments to central blood compartment, and thus less toxin will be removed. On the other hand warm dialysate leading to vasodilation will mobilize the toxins in remote peripheral compartments and increase the toxin influx in central blood compartment. Few researchers have investigate the effect of dialysate temperature on urea removal, but urea is not a true marker of toxin milieu. In this pilot clinical research, we will compare the effect of dialysate temperature on removal of both small and large sized uremic toxins. Our objective is not to study the effect of dialysate temperature on incidence of IDH, so we will recruit subjects who are stable on dialysis and have no prior history of IDH episodes.

Inclusion criteria

• Adult patients male or female (Age > 21 years, < 70 years)
• Minimum dialysis vintage of 3 months
• Stable on hemodialysis
• Blood access capable of delivering the blood flow rate greater than 250 mL/min

Exclusion criteria

• History of recurring or persistent hypotension in past 1 month
• Pregnant woman
• Severely hypertensive patients (Systolic blood pressure > 180 mmHg and/or Diastolic blood pressure > 115 mmHg)
• Severely hypotensive patients (Systolic blood pressure < 100 mm Hg and/or Diastolic blood pressure < 60 mmHg)
• Paradoxically hypertensive patients whose BP increases by more than 20% of baseline during dialysis (during past 1 month)
• History of recent myocardial infarction or unstable angina (within past 6 months)
• Significant valvular disease, i.e. severe aortic stenosis and moderate-severe mitral regurgitation
• Patients with end stage organ disease e.g. chronic obstructive pulmonary disease (COPD), recent or debilitating cerebrovascular attack (CVA)
• Patient with recent stroke (within past 6 months)
• History of known arrhythmia
• Participation in another clinical intervention trial
• Unable to consent