Evolution of clinical parameters and peritoneal function in a cohort of CAPD patients followed over 7 years

The clinical results and the long-term evolution of some peritonealtransport characteristics were retrospectively analysed in acohort of 23 patients who had been maintained continuously onCAPD for at least 7 years. Several clinical and biological resultslike blood pressure, peripheral nerve conductivity, total protein,and serum phosphorus showed relatively stable values. On the other hand increases were noted in body weight, consumptionof antihypertensive drugs; creati-nine, serum calcium and parathormoneconcentration. Haematocrit, cholesterol, and triglycerides significantly increasedduring the first 2–4 years but returned to the predialysisvalues after 5–7 years. In contrast with patients never exposed to acetate diaysate,there was a continuous loss of peritoneal ultrafiltration from1000 ml/day to 780 ml/day (P<0.05) in patients who had beentreated with acetate. However, peritoneal creatinine clearancesand the D/P creatinine ratios remained constant. The Kt/V urea index declined from 0.88±0.8 during thefirst year to 0.62±0.06 after 7 years (P<0.001). Thiswas due to a decline in contribution of the residual renal Kt/Vurea index from 21.6% at the start to less than 3% after 7 years. A negative correlation between the Kt/V urea index per yearand the hospitalization rate and a positive correlation withthe peripheral nerve conductivity were found. In conclusion, the long-term peritoneal diffusive capacity canremain stable over 7 years in CAPD; in some patients a continuousfall in peritoneal ultrafiltration appears which can be counterbalancedby stimulation of their daily diuresis with high doses of frusemide.Following the Kt/V urea index can be recommended since thisindex is correlated with at least some parameters of morbidityin CAPD patients.     

持续非卧床腹膜透析患者血清肌酐水平的影响因素分析

目的：探讨影响持续非卧床腹膜透析（CAPD）患者血清肌酐水平的因素。方法：选取北京大学第三医院腹透中心200名临床情况稳定的CAPD患者为研究对象。同时收集患者人口学特征、血清肌酐（Scr）及其他生化资料,评估腹膜透析充分性,采用简单相关及多元回归分析探讨影响Scr水平的因素。结果：所有患者平均年龄（61.02±14.81）岁,平均Scr（893±293）μmol/L;简单相关分析显示Scr水平与年龄、总尿素清除指数（TKt/V）、残肾尿素清除指数（RKt/V）、总肌酐清除率（Tccr）及残肾肌酐清除率（Rccr）呈负相关,而与透析剂量、体质指数（BMI）、透析龄呈正相关,差异均具有统计学意义;逐步多元回归分析提示在矫正透析剂量、透析龄及糖尿病等因素后,性别、年龄、Tccr、RKt/V、透析液肌酐浓度/血肌酐浓度（D/PCr）及BMI是影响Scr水平的独立因素（R2=0.659,P〈0.05）。结论：本研究提示在剂量、透析龄及糖尿病等因素后,性别、年龄、营养状况、残余肾功能及腹膜转运功能仍能独立地影响CAPD患者血清肌酐水平。     

Importance of dialysis adequacy in mortality and morbidity of chinese CAPD patients

BACKGROUND: In continuous ambulatory peritoneal dialysis (CAPD), the impact of dialysis adequacy on patient outcome is well established in Caucasian patients but is less clear in Asian patients. Recent evidence suggests that Asian dialysis patients enjoy better overall survival. We hypothesize that dialysis adequacy may be less important in determining outcome for this ethnic group. METHODS: We performed a single-center prospective observational study. From September 1995, we enrolled 150 existing and 120 new CAPD patients. They were followed for up to three years. We monitored dialysis adequacy and nutritional indices, including Kt/V, weekly creatinine clearance (CCr), residual glomerular filtration rate (GFR), normalized protein catabolic rate (NPCR), percentage of lean body mass (%LBM), and plasma albumin level. Clinical outcomes included mortality, technique failure, and duration of hospitalization. RESULTS: The duration of study follow-up was 22.1 +/- 12.3 months. In our study population, 136 were male. Seventy were diabetic (25.9%), and 212 were treated with 6 L exchanges per day (78.5%). The body weight was 59.3 +/- 9.4 kg. Baseline total Kt/V was 1.78 +/- 0.41, peritoneal Kt/V 1.48 +/- 0.36, and median residual GFR 0.98 mL/min (range 0 to 7.45). Two-year patient survival was 83.0%, and technique survival was 72.8%. Multivariate analysis showed that the duration of dialysis, diabetes, %LBM, index of dialysis adequacy (Kt/V or CCr), residual GFR, and requirement of a helper for CAPD exchanges were independent factors of patient survival; serum albumin, adequacy index (Kt/V or CCr), and requirement of a helper were independent factors of technique survival. Duration of dialysis, body weight, requirement of helper, cardiovascular disease, HBsAg carrier, serum albumin, and CCr had independent effects on hospitalization. The peritoneal component of Kt/V or CCr had no independent effect on any outcome parameter. When the prevalent and new CAPD cases were analyzed separately, Kt/V predicted survival only for new CAPD cases. CONCLUSIONS: Our results show that dialysis adequacy has significant impact on outcome of Asian CAPD patients. Although we have excellent medium-term patient and technique survival, this favorable outcome should not prevent health care workers from providing adequate dialysis to Asian patients. The reason of discrepancy in outcome between Asian and Caucasian dialysis patients requires further study.     

Seroprevalence of Helicobacter pylori in Chinese patients on continuous ambulatory peritoneal dialysis

BACKGROUNDS AND AIMS: There is relatively little data on the seroprevalence of Helicobacter pylori in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). This study aims at establishing the seroprevalence of and the factors associated with H. pylori infection in Chinese CAPD patients. METHODS: All CAPD patients from a single dialysis centre were invited to participate in the study. Diagnosis of H. pylori infection was made serologically by the pylori DTect ELISA method. Dyspeptic symptoms were assessed by the Hong Kong Index of Dyspepsia (HKID) Questionnaire. Demographic, clinical and laboratory parameters were correlated with the H. pylori serology results. RESULTS: One hundred and thirty-six Chinese CAPD patients were included in the study. The mean age of the patients was 61.8 +/- 12.5 years with a male to female ratio of 1:1.4. The mean duration of CAPD was 54 +/- 42 months. Thirty-five patients (26%) have positive serology against H. pylori. Nineteen patients had a HKID score of >16. There was no association between H. pylori seropositivity and dyspeptic symptoms (P = 0.62). Patients who were seropositive for H. pylori were significantly older (64.9 +/- 9.5 years vs 60.7 +/- 13.2 years, P < 0.05) and had lower KT/V-values than patients who were seronegative for H. pylori (1.88 +/- 0.3 vs 2.03 +/- 0.3, P < 0.05). Patients with positive or negative H. pylori serological status did not differ in terms of demographic parameters (e.g. sex, duration of CAPD), clinical factors (e.g. bodyweight, body mass index, hepatitis status, use of H(2) antagonists or proton pump inhibitors) and laboratory data (e.g. haemoglobin, serum urea, creatinine, albumin and parathyroid hormone levels). CONCLUSIONS: The seroprevalence of H. pylori infection among Chinese CAPD patients is 26%. Helicobacter pylori seropositivity is not associated with dyspepsia. Older age and lower KT/V-values appear to be associated with the development of H. pylori seropositivity in our dialysis population.     

Kinetic modelling and underdialysis in CAPD patients

Kinetic analysis was performed in all 58 patients undergoingstandard CAPD. The urea distribution volume was estimated fromanthropomorphic measurements (Watson formulae). Normalized proteincatabolic rate (NPCR), daily protein leak (PL), urea and creatinineKt/Vs, clearances and peritoneal mass transfer coefficients(Kp) were calculated from measurements on serum, 24-h urineand PD fluid effluent. The mean total (renal+PD) daily creatinine and urea Kt/Vs (KT/V)were 0.31 (range 0.15–0.79) and 0.31 (0.18/0.65). Therewas no relationship between KT/V and serum urea or Kp. The strongestdeterminant of the urea KT/V was the residual renal urea clearance(KrU)(R=079, P<0.001) which decreased with time on dialysis(R=–0.38, P<0.005). There was a significant correlationbetween the hospital admissions per year and both the urea andcreatinine KT/V and KrU (R=–0.30, –0.32, P<0.05).Patients with urea KT/V<0.25 (n=22) had more hospital admissions/yearthan those with KT/V>0.25 (mean of 2.6 versus 1.5, P<0.05).NPCR correlated with urea KT/V (R=0.62, P<0.001) but notwith serum albumin or the PL. Patients identified by UKM to be less well dialysed have a lowerresidual renal function and are more likely to be hospitalized.Undernutrition in CAPD patients appears to be related to underdialysisrather than protein loss.     

Impact of Residual Renal Function on Dialysis Adequacy in Paediatric CAPD Patients

This study was designed to determine the impact of residual renal function (RRF) on dialysis adequacy indices and clinical outcome parameters in paediatric CAPD patients. Seventeen children on CAPD were included. Residual renal function was described by residual diuresis (UO: urine output), residual renal solute clearances [RR.KT/V (residual renal KT/V), RR.Ccr (residual renal creatinine clearance) and GFR (glomerular filtration rate)]. Pearson's correlation coefficients and multiple linear regression analysis were used in statistical analysis. Mean W.KT/V (weekly KT/V) vas 1.97±0.6 and mean T.Ccr (total Ccr) was 56±32 L/week/1.73 m². Both of these indices were found to be strongly correlated with RRF (GFR, UO, RR.KT/V and RR.Ccr) (p<0.001), but not with peritoneal solute clearances. W.KT/V was found to be influenced essentially by RR.KT/V (p<0.001) and also dialysate fill volume (DV) (p<0.01). T.Ccr was influenced primarily by RR.Ccr (p<0.001) and serum cr levels (p<0.05). In addition significant positive correlations were detected between serum albumin, haemoglobin (Hb), haematocrit (Htc) levels and residual diuresis (p<0.05) and a significant negative correlation was found between mean blood pressure and residual diuresis (p<0.05). It was concluded that the mean values of W.KT/V and T.Ccr were heavily influenced by RRF. Almost all variations in W.KT/V and T.Ccr represented changes in RRF. In addition, anaemia, hypertension and hypoalbuminaemia, which are known as clinical criteria of inadequate dialysis, were found to be influenced by residual diuresis. Thus one of the goals of paediatric nephrologists must be the preservation of renal reserve. Since the rate of decline in RRF was significantly lower in CAPD, it should be the first choice of long-term maintenance dialytic therapy for children who have residual renal reserve.     

Clinical outcome of continuous ambulatory peritoneal dialysis predicted by urea and creatinine kinetics.

The effectiveness of urea kinetics (Kt/V, where K is urea clearance, t is treatment time, and V is the volume of distribution for urea) to assess the adequacy of continuous ambulatory peritoneal dialysis (CAPD) and clinical outcome has not been established prospectively, and cross-sectional clinical studies have been inconclusive. A minimum weekly creatinine clearance of 40 to 50 L is recommended, but the adequacy of this dose is unproven. We introduced a simpler approach to creatinine kinetics in the form of an efficacy number (EN) calculated from data obtained in a standardized 4-h dwell exchange. To determine the most effective model for predicting CAPD adequacy, residual renal function, weekly Kt/V urea, weekly creatinine clearance standardized to body surface area, and EN (liters per gram of creatinine per day) were measured in 18 stable CAPD patients followed prospectively for at least 12 months. Patients were divided into three groups, good (G), intermediate (I), and poor (P), on the basis of uremic symptoms, mortality, hospital days, biochemical indices, and the need for transfer to hemodialysis. When comparing groups G (N = 6) and P (N = 8), weekly Kt/V were 2.3 +/- 0.2 versus 1.5 +/- 0.1 (P less than 0.005), weekly creatinine clearances were 71.5 +/- 8.6 versus 35.1 +/- 1.3 L (P less than 0.001), and EN were 7.4 +/- 0.8 versus 3.6 +/- 0.2 L/g of creatinine/day (P less than 0.005). Creatinine kinetics (weekly clearance and EN) but not urea kinetics could differentiate group I (N = 4) from groups G or P. Both urea and creatinine kinetics predict clinical outcome in CAPD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of diuretics in the preservation of residual renal function in patients on continuous ambulatory peritoneal dialysis

BACKGROUND: Patients on continuous ambulatory peritoneal dialysis (CAPD) are dependent on residual renal function for solute and water clearances, and this declines with time on dialysis. Loop diuretics have been postulated to slow this decline. METHODS: Sixty-one patients new to dialysis were randomly assigned to either furosemide 250 mg every day or no furosemide at the time of CAPD training and were followed prospectively. Urine volume (UV), urea clearance (C(Urea)), and creatinine clearance on cimetidine (C(Cr)) were measured at randomization at six months and at one year. Patients underwent a standard four-hour peritoneum equilibrium test, and total body water was measured by bioelectrical impedance. Results were expressed on an intention-to-treat basis. RESULTS: UV, C(Cr), and C(Urea) were similar at randomization (1020 +/- 104 vs. 1040 +/- 130 mL/24 hours, 4.95 +/- 0.51 vs. 4.07 +/- 0.40 mL/min/1.73 m2, 0.91 +/- 0.09 vs. 0.84 +/- 0.08, diuretic vs. control). UV in the diuretic-treated group increased, whereas in the control group, it declined (+176 vs. -200 mL/24 hours at 6 months and +48.8 vs. -305 mL/24 hours at 1 year, P < 0.05). C(Cr) and C(Urea) declined at a constant rate and were unaffected by diuretic administration (0.12 +/- 0.05 vs. 0.071 +/- 0.04 mL/min/1.73 m2/month, 0.020 +/- 0.01 vs. 0.019 +/- 0.01 per month). Urinary sodium excretion increased in the diuretic group and declined in the control group (+0.72 +/- 0.85 vs. -2.56 +/- 1.31 mmol/24 hours/month, P = 0.04). Body weight rose in both groups (4.3 vs. 3.0 kg), but the percentage of total body weight rose in the control group and remained constant in the diuretic group (52 +/- 2.4 vs. 64 +/- 6.6%, P = 0.10). CONCLUSIONS: Long-term furosemide produces a significant increase in UV over 12 months when on CAPD and may result in clinically significant improvement in fluid balance. However, furosemide has no effect on preserving residual renal function.     

Effects of insulin and amino acids on glucose and leucine metabolism in CAPD patients

This study investigates the basal and insulin-stimulated glucose metabolism, substrate utilization, and protein turnover in eight patients maintained on continuous ambulatory peritoneal dialysis (CAPD) (mean age 39+/-5 yr, body mass index [BMI] 108+/-6) and 14 control subjects (mean age 33+/-4 yr, BMI 103+/-3). Euglycemic insulin clamp studies (180 min) were performed in combination with continuous indirect calorimetry and 1-14C leucine infusion (study I). Postabsorptive glucose oxidation was higher (1.75+/-0.18 versus 1.42+/-0.14 mg/kg per min) and lipid oxidation was lower (0.43+/-0.09 versus 0.61+/-0.12 mg/kg per min) in CAPD patients than in control subjects (P<0.05 versus control subjects). During the last 60 min of euglycemic hyperinsulinemia, the total rate of glucose metabolism was similar in CAPD and control subjects (6.33+/-0.51 versus 6.54+/-0.62 mg/kg per min). Both insulin-stimulated glucose oxidation (2.53+/-0.27 versus 2.64+/-0.37 mg/kg per min) and glucose storage (3.70+/-0.48 versus 3.90+/-0.58 mg/kg per min) were similar in CAPD and control subjects. Basal leucine flux (an index of endogenous proteolysis) was significantly lower in CAPD patients than in control subjects (1.21+/-0.15 versus 1.65+/-0.07 micromol/kg per min). Leucine oxidation (0.13+/-0.02 versus 0.26+/-0.02 micromol/kg per min) and nonoxidative leucine disposal (an index of protein synthesis) (1.09+/-0.16 versus 1.35+/-0.05 micromol/kg per min) were also reduced in CAPD compared with control subjects (P<0.01 versus control subjects). In response to insulin (study I), endogenous leucine flux decreased to 0.83+/-0.08 and 1.05+/-0.05 micromol/kg per min in CAPD and control subjects, respectively (all P<0.01 versus basal). Leucine oxidation declined to 0.06+/-0.01 and to 0.19+/-0.02 micromol/kg per min in CAPD and control subjects, respectively (P<0.01 versus basal). A second insulin clamp was performed in combination with an intravenous amino acid infusion (study II). During insulin plus amino acid administration, nonoxidative leucine disposal rose to 1.23+/-0.17 and 1.42+/-0.09 micromol/kg per min in CAPD and control subjects, respectively (both P<0.05 versus basal, P = NS versus control subjects), and leucine balance, an index of the net amino acid flux into protein, become positive in both groups (0.30+/-0.05 versus 0.40+/-0.07 micromol/kg per min in CAPD and control subjects, respectively) (both P<0.01 versus basal, P = NS versus control subjects). In summary, in CAPD patients: (1) basal glucose oxidation is increased; (2) basal lipid oxidation is decreased; (3) insulin-mediated glucose oxidation and storage are normal; (4) basal leucine flux is reduced; (5) the antiproteolitic action of insulin is normal; and (6) the anabolic response to insulin plus amino acid administration is normal. Uremic patients maintained on CAPD treatment show a preferential utilization of glucose as postabsorptive energy substrate; however, their anabolic response to substrate administration and the sensitivity to insulin are normal.     

Impact of dialysis adequacy on the mortality and morbidity of anuric Chinese patients receiving continuous ambulatory peritoneal dialysis

Dialysis adequacy has a major impact on the outcome of continuous ambulatory peritoneal dialysis (CAPD) patients. However, most studies on peritoneal dialysis adequacy have focused on patients with significant residual renal function. The present study examined the effect of dialysis adequacy on anuric CAPD patients. A single-center prospective observational study on 140 anuric CAPD patients was performed. These patients were followed for 22.0 +/- 11.9 mo. Dialysis adequacy and nutritional indices, including Kt/V, creatinine clearance (CCr), protein equivalent nitrogen appearance, percentage of lean body mass, and serum albumin level were monitored. Clinical outcomes included actuarial patient survival, technique survival, and duration of hospitalization. In the study population, 64 were male, 36 (25.7%) were diabetic, and 59 (42.1%) were treated with 6 L exchanges per day. The body weight was 59.2 +/- 10.2 kg. Average Kt/V was 1.72 +/- 0.31, and CCr was 43.7 +/- 11.5 L/wk per 1.73m(2). Two-yr patient survival was 68.8%, and technique survival was 61.4%. Multivariate analysis showed that DM, duration of dialysis before enrollment, serum albumin, and index of dialysis adequacy (Kt/V or CCr) were independent factors of both patient survival and technique survival. It was estimated that for two patients who differed only in weekly Kt/V, a 0.1 higher value was associated with a 6% decrease in the RR of death (P: < 0.05; 95% confidence interval, 0.92 to 0.99). Serum albumin and CCr were the only independent factors that predicted hospitalization. It was found that even when there is no residual renal function, higher dialysis dosage is associated with better actuarial patient survival, better technique survival, and shorter hospitalization. Dialysis adequacy has a significant impact on the clinical outcome of CAPD patients, and the beneficial effect is preserved in anuric patients as well as in an ethnic group that has a low overall mortality.     

Clinical performance measures: the changing status of peritoneal dialysis.

BACKGROUND: The Peritoneal Dialysis-Clinical Performance Measures Project (PD-CPM) characterizes peritoneal dialysis within the U.S. Current survey results are reported and compared to those of previous years. METHODS: Prevalence data from random national samples of adult peritoneal dialysis (PD) patients participating in the United States End-Stage Renal Disease (ESRD) program have been collected annually since 1995. RESULTS: In 1995, 79% of the respondents used continuous ambulatory peritoneal dialysis (CAPD) rather than automated peritoneal dialysis (APD). The mean hematocrit (Hct) of PD patients was 32% and only 66% of individuals had a measurement of dialysis adequacy reported. The mean weekly Kt/Vurea (wKt/V) and weekly creatinine clearance (wCCr) reported for CAPD patients in 1995 were 1.9 and 67 L/1.73 m2/week, respectively. In 2000 the median age of PD patients was 55 years and 63% were white. The leading cause of ESRD was diabetes mellitus (34%) and 54% of adult PD patients performed some form of APD rather than CAPD. Age, sex, size, hematocrit, peritoneal permeability, dialysis adequacy, residual renal function and nutritional indices did not differ between APD and CAPD patients. The mean hemoglobin (Hb) for the 2000 PD-CPM population was 11.6 +/- 1.4 g/dL (mean +/- 1 SD) and 11% of patients had an average Hb below 10 g/dL. The average serum albumin was 3.5 +/- 0.5 g/dL by the bromcresol green method and 56% of subjects had an average serum albumin equal to or above 3.5 g/dL (or 3.2 g/dL by bromcresol purple). In 2000 85% of patients had a dialysis adequacy measurement reported and the mean calculated wKt/V and wCCr were 2.3 +/- 0.6 and 72.7 +/- 24.9 liters/1.73 m2/week for CAPD patients and 2.3 +/- 0.6 and 71.6 +/- 25.1 L/1.73 m2/week for APD patients. PD subjects had a mean body weight of 76 +/- 19 kg and body mass index (BMI) of 27.5 +/- 6.4 kg/m2. The protein equivalent of nitrogen appearance (nPNA) of these patients was 0.95 +/- 0.31 g/kg/day, their normalized creatinine appearance rate (nCAR) equaled 17 +/- 6.5 mg/kg/day, resulting in a percent lean body mass (%LBM) of 64 +/- 17% of actual body weight. Serum albumin correlated in a positive fashion with BMI, nPNA, nCAR and %LBM, but not with wCCr. CONCLUSIONS: The majority of indicator variables monitored by the PD-CPM have improved since 1995. PD patients have higher hemoglobins and a greater proportion of patients meet the criteria for adequate dialysis. Serum albumin values, however, remain marginal and unchanged over the five-year project. Furthermore, serum albumin values fail to correlate with the intensity of renal replacement therapy and are not strongly correlated with alternative estimates of nutritional status.     

Effects of postdialysis urea rebound on the quantification of pediatric hemodialysis

Urea rebound (UR) causes single pool urea kinetic modeling (UKM), which is based on end-dialysis urea instead of its equilibrated value (Ceq), to erroneously quantify hemodialysis (HD) treatment. We estimated the impact of postdialysis UR on the results of formal variable volume single pool (VVSP) UKM [Kt/V, urea distribution volume (V), urea generation rate (G), normalized protein catabolic rate (nPCR), and urea reduction ratio (URR)] in children on chronic HD. Thirty-eight standard pediatric HD sessions in 15 stable patients (9 female, 6 male) aged 14.5 +/- (SD) 3.28 years were investigated. The HD sessions lasted 3.75 +/- 0.43 h. The single pool urea clearance was 4.84 +/- 1.25 ml/min/kg. All HD sessions were evaluated by VVSP and URR (%) with postdialysis urea taken at the end of HD and with Ceq taken 60 min after the end of HD, incorporating double pool effects and representing true double pool values. The anthropometric V was calculated by Cheek and Mellits formulae for children. VVSP significantly overestimated Kt/V by 0.26 +/- 0.18 U (1.68 +/- 0.36 vs. 1.42 +/- 0.30, p < 0.0001), i.e., 19. 05 +/- 13.07%, G/V (0.20 +/- 0.04 vs. 0.18 +/- 0.04, p < 0.0001), nPCR (1.26 +/- 0.23 vs. 1.18 +/- 0.22 g/kg/day, p < 0.0001), and URR (73.92 +/- 6.49 vs. 69.22 +/- 7.06, p < 0.0001). VVSP significantly underestimated kinetic V in comparison to anthropometric V (18.74 +/- 4.04 vs. 20.76 +/- 4.43 liters or expressed as V/body weight: 58 +/- 8 vs. 65 +/- 9%, p < 0.05), while double pool kinetic V was more accurate (21.45 +/- 4.34 liters, V/body weight: 64 +/- 6%, p > 0.05). We conclude that UR has a significant effect on all results of UKM even after standard pediatric HD, and the degree of this efffect is documented. We suggest an increase of the minimum required prescribed single pool Kt/V in children and reduction of any delivered single pool Kt/V by approxiamtely 0.26 Kt/V U. Overestimation of nPCR by approximately 0.08 g/kg/day and underestimation of V by 8.5% should be kept in mind.     

Lack of correlation between urea kinetic indices and clinical outcomes in CAPD patients

We examined the predictive value of urea kinetics for patient outcomes in CAPD by measuring dialysis index (DI; a means of quantifying CAPD dose using urea kinetics), KT/V and normalized protein catabolic rate (PCRN) on 222 occasions in 76 new patients at the time of starting CAPD and at subsequent six month intervals. We investigated how these indices altered with time and in relation to each other, and how they correlated with a wide range of subsequent patient outcomes. DI, KT/V and PCRN all tended to decrease with time on CAPD (P less than 0.0004, less than 0.0001 and 0.0005, respectively). DI and KT/V were highly correlated with each other (r = 0.89, P less than 0.0001) and both correlated with PCRN (r = 0.57, P less than 0.0001 and r = 0.60, P less than 0.0001, respectively). DI and KT/V both correlated inversely with subsequent values for serum creatinine (P less than 0.0001), urea (P less than 0.0002), potassium (P less than 0.02) and phosphate (P less than 0.002), and directly with bicarbonate (P less than 0.0001). PCRN correlated inversely with serum creatinine (P less than 0.0002) and directly with urea (P less than 0.0001) and with the number of blood transfusions received (P less than 0.03). None of these indices correlated with levels of hemoglobin, PTH, alkaline phosphatase or albumin, or with nerve conduction velocity or any other subsequent clinical outcomes including death, technique failure, hospital days, peritonitis rate and subjective indices of fatigue, pruritus and insomnia. We conclude that the urea kinetic model is predictive of some biochemical outcomes but not of clinical outcomes in CAPD patients.     

A hypothesis: the protein catabolic rate is dependent upon the type and amount of treatment in dialyzed uremic patients

Urea kinetic modelling was performed serially, over 24 months, on 55 patients undergoing hemodialysis and eight patients receiving peritoneal dialysis. The data obtained, together with changes in therapy aimed at increasing or decreasing the normalized dose of dialysis [KT/V (urea)], suggested the dependence of dietary protein intake and protein catabolic rate (PCR; g/kg/d) on the KT/V (urea). The studies also indicated that the nature of this relationship may be dependent upon the dialysis treatment used; dialysis by AN69S membrane hemodialyzers required less KT/V (urea) than hemodialysis by cellulosic membranes to obtain a given PCR. This difference may be explained by the beneficial effect of removal of "middle molecular weight" uremic toxins by the AN69S membrane, which has a different solute clearance profile than the cellulosic membrane. The studies also indicated a similar relationship between PCR and KT/V (urea) for peritoneal dialysis. With this form of therapy, however, it is difficult to obtain a PCR greater than 1 g/kg/d without first achieving very high values for KT/V (urea). It is postulated that this is due to an independent adverse effect of peritoneal dialysate in suppressing appetite. The data presented suggest that the conclusions of the National Cooperative Dialysis Study may be reinterpreted by assigning a major role to the nutritional status of patients in morbidity, with satisfactory nutritional status attained only in patients receiving adequate dialysis which, in turn, ensures control of plasma urea levels. Studies to prove this hypothesis are indicated.     

A novel association between residual renal function and left ventricular hypertrophy in peritoneal dialysis patients

BACKGROUND: Left ventricular hypertrophy (LVH) and dialysis adequacy are both important predictors for mortality in dialysis patients. This study evaluated the association between residual renal function (RRF) and the severity of LVH in endstage renal failure (ESRF) patients undergoing long-term continuous ambulatory peritoneal dialysis (CAPD). METHODS: A cross-section study was performed with left ventricular mass index (LVMi), determined in 158 non-diabetic CAPD patients using echocardiography and its relationship with residual glomerular filtration rate (GFR), peritoneal dialysis (PD) and total weekly urea clearance (Kt/V) and other known risk factors for LVH was evaluated. RESULTS: Twelve patients had no LVH (group I). The remaining 146 patients were stratified [group II (lowest), III and IV (highest)] according to the LVMi (median 207 g/m2; range 103 to 512 g/m2). Across the four groups of patients with increasing LVMi, there was significant decline in GFR (2.27 +/- 1.98 vs. 1.49 +/- 1.58 vs. 1.61 +/- 1.91 vs. 0.80 +/- 1.42 mL/min/1.73 m2; P = 0.011) and total weekly Kt/V (1.98 +/- 0.44 vs. 1.96 +/- 0.38 vs. 1.92 +/- 0.42 vs. 1.71 +/- 0.42; P = 0.037); however, PD Kt/V was similar for all four groups. Patients with better-preserved residual GFR not only had significantly higher total Kt/V, but were less anemic and hypoalbuminemic and had a trend toward lower systolic blood pressure and arterial pulse pressure. Multiple regression analysis showed that other than age, gender, body weight, arterial pulse pressure, hemoglobin and serum albumin, known factors for LVH, residual GFR (estimated mean -7.94; 95% confidence interval -15.13 to -0.74; P = 0.031) was also independently associated with LVMi. CONCLUSIONS: Other than anemia, hypoalbuminemia and arterial pulse pressure, this study demonstrates an important, novel association between the degree of RRF and severity of LVH in ESRF patients undergoing long-term CAPD. Prospective studies are needed to define if indeed there is a cause-effect relationship between this association, to evaluate if a decline in residual GFR is independently associated with an increase in LVMi, and to determine whether treatment directed at preserving RRF will reduce the severity of LVH, improve cardiac performance and hence survival of these patients.     

Preoperative Weight Loss as a Predictor of Long-term Success Following Roux-en-Y Gastric Bypass

BACKGROUND: All patients undergoing gastric bypass surgery at this institution are recommended to achieve a goal of 10% total body weight (TBW) loss prior to surgery. The objective of this study was to determine whether preoperative TBW correlated with 3- and 4-year weight loss outcome. METHODS: This study was conducted prospectively at a large teaching hospital. All adult patients with 3- and 4-year follow-up data since the start of the study in 1998 to September 2007 were included. All data are expressed as mean +/- SD. Pairwise correlation and ordinary least squares regression analysis was used to determine the strength of association between preoperative TBW loss and weight loss at 3 and 4 years. RESULTS: One hundred fifty patients (120 females), age 45.3 +/- 8.9 years, were included. Their body mass indexes (BMIs), preoperatively and after 3 years, were 52.2 +/- 9.8 and 35.4 +/- 8.2 kg/m(2), respectively. There was a significant correlation between preoperative and 3-year TBW lost (9.5 +/- 6.8% vs 31.9 +/- 11.7%, r = 0.302, p = 0.0002) and between excess body weight (EBW) lost preoperatively and after 3 years (16.1 +/- 11.3% vs 55.1 +/- 20.2%, r = 0.225, p = 0.006). Ninety five patients had follow-up data available at 4 years. Their mean preoperative BMI was 52.6 +/- 9.7 kg/m(2) and decreased to 37.5 +/- 9.0 kg/m(2). The TBW loss prior to and after surgery (10.0 +/- 6.5% vs 29.4 +/- 11.5%) was significantly correlated (r = 0.247, p = 0.015). The EBW loss preoperatively and after 4 years correlated positively (17.1 +/- 11.1% vs 50.8 +/- 19.8%, r = 0.205, p = 0.046). CONCLUSION: There is a significant correlation between weight loss attained preoperatively and sustained weight loss at 3 and 4 years.     

Is there any correlation between urea kinetics and the clinical outcomes in CAPD patients?]

Urea kinetic modeling was applied to 19 CAPD patients followed in our outpatient clinics. Serum beta 2-microglobulin was also measured as a marker of large molecular weight substances. Clinical conditions of patients were assessed by both doctors and patients. Patient's assessment were done by the questionnaire. Indices of urea kinetics (KT/V, PCR) and biochemical parameters were compared between well-treated and not well-treated patients judging from patient's and doctor's assessment scores. The rate of peritonitis was significantly higher in the latter group. None of the parameters were different between 2 groups except for serum albumin. There was a significant correlation between serum concentration of albumin and doctor's assessment score (gamma = 0.52). In conclusion, urea kinetic parameters is not a good indicator for adequacy of dialysis in our CAPD population. Serum albumin seems to be one of the indices for adequate dialysis. However, clinical symptoms and signs are more valuable than biochemical parameters for the assessment of adequacy of dialysis.     

KT/V and protein catabolic rate determination from serial urea measurement in the dialysate effluent stream

A bloodless technique of evaluating protein catabolic rate (PCR) and KT/V (K, clearance; T, dialysis time; V, urea distribution volume) in hemodialysis patients is presented based on serial measurement of urea in the dialysate effluent stream. PCR follows from equating urea generation and urea removal over a 7 day cycle, changes in body stores being comparatively negligible: PCR = 0.026 [U1 + U2 + U3]/BWdry + 0.17, where U1 is the amount of urea in mmol appearing in the dialysate for each session in the 7 day period. KT/V is obtained from the slope of the natural logarithm of spent dialysate urea concentration-time plot: KT/V = [- slope.T + 3.delta BW/BWdry]/[1 - 0.01786.T(hr], where delta BW = amount ultrafiltered in liters. The dialysate-based approach was validated and compared with conventional urea kinetic modeling (UKM) for 17 patients studied for three consecutive dialyses. The dialysate-based and UKM values of PCR agreed well when in vivo clearance values based on total dialysate collection were used for UKM. KT/V values agreed poorly on a session-by-session basis but were nearly equivalent when averaged for the three dialyses of the week. These findings lay the foundation for UKM automation with a urea sensor in the effluent dialysate stream.