Vascular reactivity during haemodialysis and isolated ultrafiltration: thermal influences.
BACKGROUND
The present study was performed to assess the role of the extracorporeal blood temperature in the disparate cardiovascular response between isolated ultrafiltration and combined ultrafiltration-haemodialysis.


METHODS
In twelve stable dialysis patients (21-77 years), blood pressure and heart rate (Finapres) as well as forearm vascular resistance and venous tone (strain-gauge plethysmography) were measured during 1-h isolated ultrafiltration and 1-h combined ultrafiltration-haemodialysis (bicarbonate, sodium 141 mmol/l) at a fixed ultrafiltration rate of 0.91 l/h. The sequence of both treatment modalities was randomly defined within each patient. Serving as his or her own control, each patient was studied at two different dialysate temperatures: 37.5 and 35.0 degrees C.


RESULTS
At a dialysate temperature of 35.0 degrees C extracorporeal blood cooling during combined ultrafiltration-haemodialysis was comparable to isolated ultrafiltration. The cardiovascular response in isolated ultrafiltration was characterized by a significant increase in both forearm vascular resistance and venous tone, while heart rate even decreased. As a result, blood pressure remained unchanged or even increased. In contrast, during combined ultrafiltration-haemodialysis at a dialysate temperature of 37.5 degrees C the increase in forearm vascular resistance was only small and insignificant, while venous tone decreased significantly. Heart rate tended to increase. Combined ultrafiltration-haemodialysis at a dialysate temperature of 35.0 degrees C was also associated with a small increase in forearm vascular resistance. However, venous tone remained stable while heart rate decreased. At both dialysate temperatures, blood pressure was well maintained.


CONCLUSIONS
We conclude that differences in cardiovascular reactivity between isolated ultrafiltration and combined ultrafiltration-haemodialysis are only partially explained by differences in the extracorporeal blood temperature. In addition, especially venous reactivity is improved by lowering the dialysate temperature.
van Kuijk
W H
WH
Department of Nephrology, University Hospital Maastricht, The Netherlands.
Luik
A J
AJ
de Leeuw
P W
PW
van Hooff
J P
JP
Nieman
F H
FH
Habets
H M
HM
Leunissen
K M
KM
D000328:Adult; D000368:Aged; D001769:Blood; D001794:Blood Pressure; D001808:Blood Vessels / Q000503:physiopathology*; D002319:Cardiovascular System / Q000503:physiopathology; D005112:Extracorporeal Circulation; D005260:Female; D005542:Forearm / Q000098:blood supply; D006339:Heart Rate; D006439:Hemodynamics; D006440:Hemofiltration; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D013696:Temperature; D014655:Vascular Resistance; D014661:Vasoconstriction; D014680:Veins / Q000503:physiopathology