Mendley SR, Schoeller DA, Majkowski NL
Body water determination in children with ESRD
Am Soc Nephrol
J Am Soc Nephrol (abstract)
(Sep) 7:1522 1996
The measurement of V for the purposes of calculating KT/V in adult PD
patients has been a
controversial issue for some time. This abstract addresses the problem in
children. The gold
standard used here is deuterium dilution and 8 children aged 4 - 20 are
studied. The results are
compared with V calculated using the Watson and Friis-Hansen equations, as
well as with bioimpedence
analysis techniques using the equations of Kushner and Davies.
The authors find that both the Watson and Friis-Hansen formulae over-
estimated V to a significant
degree, while the Davies formula under-estimated it significantly. Kushner's
equation was best but,
in individual patients, the error could still be significant and clinically
relevant.
Comment: It is interesting that the Watson formula, which has recently
been found to
under-estimate V in adults on PD, is shown here to over-estimate it in
children. This
over-estimation averaged 6 litres and so was very significant in a population
whose V varied
between 10 and 28 litres. The error is thus relatively much greater than in
adult patients and
greatly erodes one's confidence in using the formula in children. Perhaps
the only good thing to be
said about the Watson formula in this context is that by over-estimating V it
will tend to lead to
children being given more PD than is required rather than less. Such an
error is less likely to do
harm to the patient. Clearly, bioimpedence with Kushner's equation may be
the best way to go in
children, but, in its absence, the Watson equation is safe to use, if not
exactly accurate. A case
could be made for measuring V using bioimpedence once every six months in
children on PD.
(Peter G. Blake, M.D., Victoria Hospital, London,
Ontario)
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Am Soc Nephrol
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CRF in infants and children
Basic peritoneal dialysis :
Chronic PD regimens, adequacy, modeling