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Isothermic hemodialysis and ultrafiltration
L M Rosales1, D Schneditz, A T Morris
1Division of Nephrology and Hypertension, Beth Israel Medical Center, New York, NY, USA.
Summary
During isothermic hemodialysis, fluid removal (ultrafiltration) leads to heat loss. Approximately 6% of a patient's energy expenditure is removed for every 1% of body weight lost during treatment.
Area of Science:
- Nephrology
- Physiology
- Medical Engineering
Background:
- Patient temperature can increase during hemodialysis due to hemodynamic compensation, peripheral vasoconstriction, and reduced heat loss.
- Maintaining a constant body temperature during hemodialysis is crucial for patient well-being.
Purpose of the Study:
- To analyze heat removal during isothermic hemodialysis.
- To investigate the relationship between ultrafiltration and extracorporeal heat loss.
- To establish a guideline for estimating cooling requirements in isothermic dialysis.
Main Methods:
- Conducted 51 high-efficiency hemodialysis treatments in 27 patients using isothermic dialysis with a Blood Temperature Monitor (BTM).
- Utilized ultrapure water and maintained mean blood flows of 410 mL/min.
- Monitored body weight changes, body water removal, dialysate temperature, and thermal energy removed.
Main Results:
- Dialysate temperature decreased significantly during treatments.
- An average of 187 kJ of thermal energy was removed, representing 28% of estimated energy expenditure.
- A strong correlation (r²=0.91) was found between the percentage of energy expenditure removed and the percentage of body weight removed (H% = -5.6 * W%).
Conclusions:
- Ultrafiltration during isothermic hemodialysis leads to significant extracorporeal heat removal.
- The volume hypothesis of intradialytic heat accumulation is supported.
- A rule of thumb is provided: approximately 6% of energy expenditure must be removed for each 1% of body weight reduction via ultrafiltration.