McCann L, Feldman C, Hornberger J
Effect of intradialytic parenteral nutrition on delivered
Kt/V
NKF 6th Spring Clinical Meeting (Dallas)
Am J Kidney Dis
(Apr) 29:A11 1997
The dialysis session Kt/V is closely related to the urea reduction
ratio or URR. However, while the pot is being cleaned, someone is
peeing into it; e.g., urea generation during a dialysis session causes
the postdialysis BUN to be higher than expected if one were to
consider urea removal alone. At the 1995 ASN meetings, Kloppenburg et
al, using a stable isotope technique, found that the urea
generation rate increased markedly starting 10 min after ingestion of
a protein (44 g) meal. We tried to follow up on this by looking at
patients who ate during dialysis and compare their V with patients who
were not eating, and did not find much; however, our look at this was
only ad hoc and this subject needs to be studied in a careful fashion.
I have been told anecdotally of at least one patient who had trouble
reaching Kt/V goals and who was in the habit of ingesting a large meal
during dialysis. Anecdotally, in the course of the HEMO study, we had
one patient on IDPN who also had trouble reaching her Kt/V goal.
Now McCann et al report an absolutely beautiful study of 19
patients in a crossover trial whose Kt/V was compared during periods
when they were receiving IDPN and when they were not. Also, IDPN
periods when only lipids, glucose, or AA were used were studied as
well. Kt/V fell from 1.51 to 1.26 when IDPN was used, and this effect
was seen only when AA were included in the solution. Some modeling
was also done, although the results are not reported in the abstract,
and it is claimed that results were consistent with observed findings.
Comment: This appears to be a nicely done study with
important practical implications. When we give blood, we give extra
dialysis and UF to remove the associated K and volume load. I suppose
this means that we should perhaps give some extra dialysis to remove
additional urea generated from administered AA? The therapeutic
implications are not clear, but for those following modeling
parameters, another cause for increased UKM volume has been added to
the list. (John T. Daugirdas, M.D., University of Illinois
at Chicago)
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NKF 6th Spring Clinical Meeting (Dallas)
Basic hemodialysis :
Adequacy, prescription, urea kinetics
CRF by organ system :
Nutrition