Comparison of three PET methods to assess peritoneal membrane transport

The peritoneal equilibration test (PET) is the most widespread method for assessing water and solute transport across the peritoneal membrane. This study compared three methods: traditional PET (t-PET), mini-PET, and modified PET (mod-PET). Non-diabetic adults (n=21) who had been on peritoneal dialysis (PD) for at least three months underwent t-PET (glucose 2.5%-4 h), mini-PET (glucose 3.86%-1 h), and mod-PET (glucose 3.86%-4 h) to determine dialysate-to-plasma concentration ratio (D/P) for creatinine and dialysate-to-baseline dialysate concentration ratio (D/D0) for glucose. Agreement between methods regarding D/P creatinine and D/D0 glucose was assessed using analysis of variance (ANOVA), Pearson's correlation coefficient, and Bland-Altman analysis. D/P creatinine differed between t-PET and mini-PET (P<0.001) and between mod-PET and mini-PET (P<0.01) but not between t-PET and mod-PET (P=0.746). The correlation of D/P creatinine with t-PET vs mod-PET was significant (r=0.387, P=0.009) but not that of t-PET vs mini-PET (r=0.088, P=0.241). Estimated bias was −0.029 (P=0.201) between t-PET and mod-PET, and 0.206 (P<0.001) between t-PET and mini-PET. D/D0 glucose differed between t-PET and mod-PET (P=0.003) and between mod-PET and mini-PET (P=0.002) but not between t-PET and mini-PET (P=0.885). The correlations of D/D0 glucose in t-PET vs mod-PET (r=−0.017, P=0.421) or t-PET vs mini-PET (r=0.152, P=0.609) were not significant. Estimated bias was 0.122 (P=0.026) between t-PET and mod-PET, and 0.122 (P=0.026) between t-PET and mini-PET. The significant correlation of D/P creatinine between t-PET and mod-PET suggested that the latter is a good alternative to t-PET. There was no such correlation between t-PET and mini-PET.

Adecuación en diálisis peritoneal pediátrica: Del test de equilibrio peritoneal a las aquaporinas / Peritoneal dialysis adequacy in pediatrics: From the peritoneal equilibration test to the aquaporins

La evaluación de las características de transporte de solutos y agua del peritoneo es esencial para adecuar la prescripción dialítica en pacientes portadores de enfermedad renal crónica. Existen una serie de modelos para realizar esta evaluación. El test de equilibrio peritoneal (PET) evalúa la capacidad de transporte del peritoneo clasificando a los pacientes en 4 categorías de transportador: alto, promedio alto, promedio bajo y bajo. El short PET realiza la misma evaluación en solo 2 h, y ha sido validado en pacientes pediátricos. Por otro lado, el MiniPET otorga información adicional al evaluar la capacidad de transporte de agua libre por los poros ultrapequeños, y el Accelerated Peritoneal Examination Time (APEX) evalúa el punto de intersección de las curvas de equilibrio de urea y glucosa, y ha sido propuesto como el tiempo de permanencia óptimo para lograr una UF adecuada. Se analiza la información actual sobre estos métodos diagnósticos, en particular los últimos aportes de la literatura respecto al transporte de agua libre vía aquaporinas, que podrían representar una herramienta importante para optimizar el transporte de agua y solutos en pacientes en diálisis peritoneal crónica, en particular respecto al pronóstico cardiovascular.

An evaluation of the characteristics of peritoneal solute and water transport is essential to assess the suitability of prescribing dialysis in patients suffering from chronic renal disease. There are currently a series of models to perform this evaluation. The peritoneal equilibration test (PET) evaluates the peritoneal transport capacity, classifying the patients into four transport categories: high, high-average, low-average, and low. The short PET enables the same evaluation to be made in only 2 hours, and has been validated in paediatric patients. On the other hand, the MiniPET provides additional information by evaluating the free water transport capacity by the ultra-small pores, and the Accelerated Peritoneal Examination Time (APEX) evaluates the time when the glucose and urea equilibration curves cross, and has been proposed as the optimum dwell time to achieve adequate ultrafiltration. An analysis is presented on the current information on these diagnostic methods as regards free water transport via aquaporins, which could be an important tool in optimising solute and water transport in patients on chronic peritoneal dialysis, particularly as regards the cardiovascular prognosis.

Influence of VEGF Genetic Polymorphism on Peritoneal Solute Transport in Pediatric Dialysis Patients

PURPOSE: Genetic and clinical factors can influence the permeability of the peritoneal membrane. The peritoneal equilibration test (PET) is helpful in measuring peritoneal permeability in peritoneal dialysis (PD). We investigated the influence of genetic polymorphism of vascular endothelial growth factor (VEGF) on the PET parameters. METHODS: Pediatric patients who underwent PET within 12 months of initiating PD at Seoul National University Children's Hospital and Samsung Medical Center were selected. The patients with positive history of peritonitis before PET were excluded. The VEGF -2578C/A, -14978T/C, -1154G/A, -634G/C, and +936C/T single-nucleotide polymorphisms were genotyped. RESULTS: The mean 4-hour dialysate-to-plasma ratio for creatinine (D/P creatinine) and the mean 4-hour dialysate glucose to baseline dialysate glucose ratio (D/D0 glucose) were 0.56+/-0.13 and 0.43+/-0.11, respectively. The patients with haplotype CTGGC showed higher 4-hour D/P creatinine (0.67+/-0.12 vs 0.50+/-0.09, P=0.007) and lower 4-hour D/D0 glucose (0.35+/-0.12 vs 0.47+/-0.08, P=0.037) than those without haplotype CTGGC. CONCLUSION: The VEGF genetic polymorphism may influence the peritoneal solute transport.

High Peritoneal Transport Status is Not an Independent Risk Factor for High Mortality in Patients Treated with Automated Peritoneal Dialysis

We undertook this study to elucidate whether baseline peritoneal membrane transport characteristics are associated with high mortality in incident automated peritoneal dialysis (APD) patients. This retrospective study includes 117 patients who started APD at Yonsei University Health System from 1996 to 2008 and had a PET within 3 months of APD initiation. High transporters were significantly older and had a higher incidence of cardiovascular disease. Patient survival for years 1, 3, and 5 were 85%, 64%, and 35% for high transporter and 94%, 81%, and 68% for non-high transporter group (P<0.01). Multivariate analysis revealed that age, diabetes, cardiovascular disease, serum albumin level, and residual renal function were independently associated with high mortality in APD patients. In contrast, high transport status was not a significant predictor for mortality in this population when the other covariates were included. Even though high transport was significantly associated with mortality in the univariate analysis, its role seemed to be influenced by other comorbid conditions. These findings suggest that the proper management of these comorbid conditions, as well as appropriate ultrafiltration by use of APD and/or icodextrin, must be considered as protective strategies to improve survival in peritoneal dialysis patients with high transport.

Factors Related to Baseline Peritoneal Solute Transport Rate in Incident Peritoneal Dialysis Patients:Results from Modified Peritoneal Equilibration Test Using 3.86% Glucose Solution / 대한신장학회잡지

BACKGROUND:The present study was designed to determine factors related to baseline peritoneal small solute transport rate (PSTR) from incident Korean peritoneal dialysis (PD) patients using modified peritoneal equilibration test (PET). METHODS:Incident PD patients whose duration of PD is between 4 weeks and 6 months were enrolled from four major university hospitals in Seoul. Modified PET with 3.86% glucose solution and adequacy test were performed. RESULT: 1) Our PET result from incident Korean PD patients showed results similar to that from the Caucacian patients. 2) The patients were divided into four groups based on the PSTR:serum albumin at time of PET, dip dialysate/plasma sodium, dialysate/plasma albumin ratio and peritoneal albumin excretion were significantly different among the four transport types (p<0.05). 3) D/PAlb was significantly higher in the high transport group than in the low transport. Serum albumin concentration before the onset of PD was not different among the four groups but was significantly different at the time of PET. 4) There was no difference of D/PCr4 between the diabetic (0.72+/-0.10) and the non-diabetic (0.72+/-0.11) groups. 5) PSTR in incidental PD patients was correlated with D/PAlb and dip D/P(Na). CONCLUSION:Our PET results from incidental Korean PD patients turned out to be showed results similar to those from Caucacian patients. There were no differences in age, BSA, BMI, nutrition index, CRP, residual renal function among four transport types in incidental PD patients. PSTR in incidental PD patients was correlated with D/PAlb and dip D/P(Na).

Peritoneal Equilibration test (PET) in Korean Patients - Single Center Experience / 대한신장학회잡지

BACKGROUND: Peritoneal solute transport rate, assessed by PET, varies widely among patients and has been shown to differ significantly among different ethnic groups. The aim of the present study is to investigate the peritoneal transport characteristics in Korean peritoneal dialysis (PD) patients and factors that predict peritoneal transport status. METHODS: Between May 2001 and February 2006, 141 patients on PD performed a standard 4-hour PET within the first 6 months after initiation of PD therapy. RESULTS: Of these 141 patients, there were 71males and 70 females. The mean age of the patients was 51.2+/-12.5 years and the etiology of renal failure was diabetes in 67 patients (47.5%). The mean 4-hour D/P creatinine ratio was 0.68+/-0.11. Compared with a mean of 0.65+/-0.15 as determined by Twardowski et al, our patients have significantly higher mean solute transport rate (p<0.05). Numbers of low (L), low-average (LA), high-average (HA), and high (H) transporters were 15 (10.6%). 68 (48.2 %), 53 (37.6%) and 5 (3.5%), respectively. However, according to our own data, the number of L, LA, HA and H were 18 (12.8%), 42 (29.8%), 64 (45.4%) and 17 (12.1%), respectively, significantly different from those classified by Twardowski et al. In univariate analysis, older age, hypoalbuminemia and lower BMI were predictive of high transport status. Using multiple linear regression, only hypoalbuminemia was independently predictive of higher 4-hour D/Pcr (p=0.000). CONCLUSION: Korean PD patients have a higher mean solute transport rate than Twardowskis data, and serum albumin is an independent predictor of high transport status. Further prospective studies with a large number of patients are needed for evaluating the diversity of peritoneal transport characteristics in different ethnic populations.

Peritoneal Equilibration test (PET) in Korean Patients - Single Center Experience / 대한신장학회잡지

BACKGROUND: Peritoneal solute transport rate, assessed by PET, varies widely among patients and has been shown to differ significantly among different ethnic groups. The aim of the present study is to investigate the peritoneal transport characteristics in Korean peritoneal dialysis (PD) patients and factors that predict peritoneal transport status. METHODS: Between May 2001 and February 2006, 141 patients on PD performed a standard 4-hour PET within the first 6 months after initiation of PD therapy. RESULTS: Of these 141 patients, there were 71males and 70 females. The mean age of the patients was 51.2+/-12.5 years and the etiology of renal failure was diabetes in 67 patients (47.5%). The mean 4-hour D/P creatinine ratio was 0.68+/-0.11. Compared with a mean of 0.65+/-0.15 as determined by Twardowski et al, our patients have significantly higher mean solute transport rate (p<0.05). Numbers of low (L), low-average (LA), high-average (HA), and high (H) transporters were 15 (10.6%). 68 (48.2 %), 53 (37.6%) and 5 (3.5%), respectively. However, according to our own data, the number of L, LA, HA and H were 18 (12.8%), 42 (29.8%), 64 (45.4%) and 17 (12.1%), respectively, significantly different from those classified by Twardowski et al. In univariate analysis, older age, hypoalbuminemia and lower BMI were predictive of high transport status. Using multiple linear regression, only hypoalbuminemia was independently predictive of higher 4-hour D/Pcr (p=0.000). CONCLUSION: Korean PD patients have a higher mean solute transport rate than Twardowskis data, and serum albumin is an independent predictor of high transport status. Further prospective studies with a large number of patients are needed for evaluating the diversity of peritoneal transport characteristics in different ethnic populations.

Peritoneal Equilibration Tests on Continuous Ambulatory Peritoneal Dialysis patients / 대한내과학회지

OBJECTIVES: The peritoneal equilibration test(PET) is routinely performed in adults treated with chronic peritoneal dialysis to assess the peritoneal transport rate and to optimize treatment prescription. This study focuses on the evaluation of characteristics of peri toneal solute transport rates and physical and serological factors affecting peritoneal transport rate performed in our continuous ambulatory peritoneal dialysis(CAPD) patients due to guide adequate peri toneal dialysis form. METHODS: We analyzed 95 PET results which had been tested on the 28th day of CAPD and physical and serological values, such as age, sex, diabetes mellitus, height, weight, body surface area, arterial blood pressure, blood urea nitrogen, creatinine, glucose, cholesterol, triglyceride, total protein, albumin, hematocrit, hemoglo bin, sodium, potassium, phosphate which had been ob tained on the day of PET. RESULTS: 1) According to transport rate, high transport rate group was 9 cases(9.5%), high average transport group 26 cases(27.4%), low average transport rate group 32 cases(33.6%), and low transport rate group 28 cases (29.5%) respectivly. 2) The average of 4hour D/PCr was 0.60, 4hour D/Do glucose was 0.46, and drain volume was 2480ml. Thus the average of peritoneal solute transport rate of total patients was low average transport rate. 3) Factors affecting peritoneal solute transport rate were age, body surface area, plasma albumin, serum creatinine and triglyceride level. CONCLUSION: These findings suggest that high dose peritoneal dialysis form should be used in our CAPD patients because most of them have low average peritoneal transport rate, and age, body surface area, plasma albumin, serum creatinine, and triglyceride level should be consid ered when select the adequate peritoneal dialysis form.

Peritoneal Equilibration Test in Korean Patients Undergoing Continuous Ambulatory Peritoneal Dialysis / 대한신장학회잡지

In order to evaluate the peritoneal transport characteristics in Korean non-diabetic and diabetic end- stage renal disease patients, peritoneal equilibration test(PET) proposed by Twardowski et al. were performed on patients who had been on continuous ambulatory peritoneal dialysis(CAPD) for 2 to 6 months. The results were as follows : 1) Fifty four patients(including 24 diabetics) on CAPD were studied with a mean age of 48.7 years. And male/female ratio was 1 : 1.08. 2) In non-diabetics, the dialysate to dialysate prior to infusion ratio for glucose(D/D0 glu) at 2-, and 4-hour dwell times were 0.61+/-0.09, and 0.39+/-0.10, and the dialysate-to-plasma ratio for creatinine (D/P cr) at 2-, and 4-hour dwell times were 0.40+/-0.11, 0.63+/-0.12, respectively. 3) In diabetic patients, D/D0 glu at 2-, and 4- hour dwell times were 0.60+/-0.09, 0.39+/-0.08, respectively, and D/P cr at same dwell times were 0.50+/-0.08, and 0.71+/-0.08, which were significantly higher than in non-diabetics(por=150mg/dL) and normoglycemic(<150mg/ dL) patients. The values of D/Pcr at 2-, and 4-hour dwell times in hyper-glycemic patients were signficantly higher than in non-diabetic patients (D2/P2 cr : 0.50+/-0.09 vs. 0.40+/-0.11, D4/P4 cr : 0.72+/-0.07 vs 0.63+/-0.12, respectively, p<0.05). 5) Net ultrafiltration did not differ between any of subgroups. 6) In non-diabetic patients, the ranges of D4/P4 cr and D4/D0 glu for high, high average, low average, and low transporters were defined as D4/P4 cr : 0.87-0.75, 0.75-0.63, 0.63-0.51, 0.51-0.39, D4/D0 glu : 0.19-0.29 0.29-0.39, 0.39-0.49, 0.49-0.59, respectively, which were remarkably simliar as suggested by Twardowski et al. In conclusion, the creatinine and glucose transfers assessed by dialysate-plasma ratio of creatinine and glucose are remarkably similar between Korean and North American patients. And the creatinine transport rate in Korean diabetic patient is higher than non-diabetic patient while ultrafiltration is achievable in non-diabetic patient.