Analysis of factors associated with variability in haemodialysis adequacy.
BACKGROUND
Delivered dialysis dose measured as Kt/V is widely accepted as an important factor affecting mortality on haemodialysis. It is currently measured relatively infrequently in most units for pragmatic reasons. We have previously shown that significant variation occurs within individuals which often makes the difference between dialysis that would be considered adequate, and inadequate. The aim of this study is to delineate which factors are responsible for the observed variation.


METHODS
We studied 1109 treatments in 109 patients, mean age 59.9 years, mean dry weight 71.8 kg. Depurated volume (Kt) was measured by ionic dialysance for each treatment. Kt and other relevant treatment-related variables were automatically recorded on a central server. Multivariate analysis using mixed models with backwards elimination was used to analyse the determinants of Kt. Kt/V was not used, in order to avoid introducing error in the determination of V.


RESULTS
The analysis indicated that the following were independent determinants of Kt: blood pump speed, time, minimum and mean arterial line pressure, both maximum and minimum venous line pressures and total ionic mass balance.


CONCLUSIONS
This analysis suggests that the variation in adequacy that occurs within an individual is multifactorial. It confirms the importance of effective vascular access, prescription of and adherence to adequate time on dialysis, and reinforces the impact of degree of sodium removal. In clinical practice absolute control of these variables is not possible in every dialysis session and some degree of variability in Kt is therefore inevitable. Monitoring of adequacy thus requires more frequent assessment of Kt than is currently performed. Online monitoring of ionic dialysance achieves this.
Lambie
Stewart H
SH
Department of Renal Medicine, Derby City General Hospital, Derby, UK.
Taal
Maarten W
MW
Fluck
Richard J
RJ
McIntyre
Christopher W
CW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D019538:Health Care Surveys; D015312:Hemodialysis Solutions; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D008297:Male; D008567:Membranes, Artificial; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009862:Online Systems; D011336:Probability; D006435:Renal Dialysis / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D018570:Risk Assessment; D017749:Total Quality Management; D016896:Treatment Outcome; D006113:United Kingdom
D015312:Hemodialysis Solutions; D008567:Membranes, Artificial