| Summary: | 博士 === 國立陽明大學 === 臨床醫學研究所 === 87 === Urea index, Kt/V, has been used as prescription tool in most hemodialysis (HD) centers since Gotch and Sargent developed it from the National Cooperative Dialysis Study. While most nephrologists are using Kt/V values as dialysis prescriptions, some researchers begin to take a grand view of solute removal mass. Ronco et al. demanded in 1994 that a certain amount of solute removal mass per week should be the real target of the treatment. Several other researchers also put their effort in the study of urea removal in order to realize the performance of different regimens. This study is to probe whether solute removal mass can be the target of adequate dialysis, or whether it is insignificant in dialysis evaluation, as some researchers believe, since the patient''s intake and output of nitrogen would be in equilibrium as long as he or she maintains in stable condition.
Like all other papers, the present work uses nitrogen as the surrogate of solute removal for study. Mathematical formulae for easy bedside calculation of nitrogen removal mass were used to avoid the trouble and inconveniences caused by direct measure. The weekly removal mass of urea nitrogen (M) and urea generation rate (G) of 32 conventional HD and 21 CAPD patients were calculated. All the patients were anuria and stable and were under adequate dialysis pursuant to either the criterion of the urea index Kt/V or the clinical requirements. The weekly removal mass of urea nitrogen (MHD = 41.9 + 9.5 gm/week, MCAPD = 38.8 + 11.9 gm/week) and the urea generation rate (GHD = 3.90 + 1.02 mg/min, GCAPD = 3.85 + 1.21 mg/min) of these two groups revealed statistically insignificant (p = 0.119 and p = 0.869, respectively). When the protein nitrogen leaking through peritoneal membrane was considered and added to MCAPD, the nitrogen removal in CAPD (M''CAPD), became pretty close to the urea nitrogen removal mass in HD (42.3 + 13.0 gm/week, p = 0.886). We observed that in stable patients there was no correlation between dialysis dosage and urea removal mass in either CAPD or HD.
Our conclusion is that the urea nitrogen removal mass is in effect similar with PCR (protein catabolic rate). It is meaningful in dialysis evaluation only when it is discussed with BUN level simultaneously. However, in evaluating unstable patients that the removal mass will change at the inception of the dialysis change makes the removal mass more significant than PCR. Another objective of this study is to find an index of adequacy which takes into consideration the effect of decreasing concentration of urea nitrogen in HD and can be used before treatments to quantitate the prescriptions with the same criterion for both hemodialysis and continuous ambulatory peritoneal dialysis.
Through mathematical theories, the removal index was obtained and then compared with the urea index (Kt/V) values of the sample patients. 32 HD and 21 CAPD patients were included. All the patients were dialyzed with optimal urea index values and had been stable for at least one year. The removal index ( HD) in HD for each dialysis was 0.62 + 0.07 and the normalized removal index ( CAPD) in CAPD was 0.59 + 0.11. There was no statistical significance. This result is consistent with the fact that no difference of morbidity or mortality exists between these two modalities. After mathematical manipulation, the removal index in HD can be presented in the form of the urea reduction ratio (URR) which is a retrospective measure to estimate the performance of hemodialysis. It implies that the removal index is able to facilitate the prescriptions for adequate dialysis. The removal index can also be used to explain the reason why the urea index values in HD are always larger than in CAPD.
The study also proved the weakness of urea index (Kt/V). In summary, the value of the removal index not only represents the percentage of urea nitrogen cleared in each dialysis, but also can be obtained predialysis and used as a reference target for either modality of dialysis.
|
|---|
