Peritoneal Equilibration Test Data Research Articles

ISPD recommendations for the evaluation of peritoneal membrane dysfunction in adults: Classification, measurement, interpretation and rationale for intervention.

A pathophysiological taxonomy: A pathophysiological classification of membrane dysfunction, which provides mechanistic links to functional characteristics, should be used when prescribing individualized dialysis or when planning modality transfer (e.g. to automated peritoneal dialysis (PD) or haemodialysis) in the context of shared and informed decision-making with the person on PD, taking individual circumstances and treatment goals into account. (practice point). Identification of fast peritoneal solute transfer rate (PSTR): It is recommended that the PSTR is determined from a 4-h peritoneal equilibration test (PET), using either 2.5%/2.27% or 4.25%/3.86% dextrose/glucose concentration and creatinine as the index solute. (practice point) This should be done early in the course dialysis treatment (between 6 weeks and 12 weeks) (GRADE 1A) and subsequently when clinically indicated. (practice point). Clinical implications and mitigation of fast solute transfer: A faster PSTR is associated with lower survival on PD. (GRADE 1A) This risk is in part due to the lower ultrafiltration (UF) and increased net fluid reabsorption that occurs when the PSTR is above the average value. The resulting lower net UF can be avoided by shortening glucose-based exchanges, using a polyglucose solution (icodextrin), and/or prescribing higher glucose concentrations. (GRADE 1A) Compared to glucose, use of icodextrin can translate into improved fluid status and fewer episodes of fluid overload. (GRADE 1A) Use of automated PD and icodextrin may mitigate the mortality risk associated with fast PSTR. (practice point). Recognizing low UF capacity: This is easy to measure and a valuable screening test. Insufficient UF should be suspected when either (a) the net UF from a 4-h PET is <400 ml (3.86% glucose/4.25% dextrose) or <100 ml (2.27% glucose /2.5% dextrose), (GRADE 1B) and/or (b) the daily UF is insufficient to maintain adequate fluid status. (practice point) Besides membrane dysfunction, low UF capacity can also result from mechanical problems, leaks or increased fluid absorption across the peritoneal membrane not explained by fast PSTR. Diagnosing intrinsic membrane dysfunction (manifesting as low osmotic conductance to glucose) as a cause of UF insufficiency: When insufficient UF is suspected, the 4-h PET should be supplemented by measurement of the sodium dip at 1 h using a 3.86% glucose/4.25% dextrose exchange for diagnostic purposes. A sodium dip ≤5 mmol/L and/or a sodium sieving ratio ≤0.03 at 1 h indicates UF insufficiency. (GRADE 2B). Clinical implications of intrinsic membrane dysfunction (de novo or acquired): in the absence of residual kidney function, this is likely to necessitate the use of hypertonic glucose exchanges and possible transfer to haemodialysis. Acquired membrane injury, especially in the context of prolonged time on treatment, should prompt discussions about the risk of encapsulating peritoneal sclerosis. (practice point). Additional membrane function tests: measures of peritoneal protein loss, intraperitoneal pressure and more complex tests that estimate osmotic conductance and 'lymphatic' reabsorption are not recommended for routine clinical practice but remain valuable research methods. (practice point). Socioeconomic considerations: When resource constraints prevent the use of routine tests, consideration of membrane function should still be part of the clinical management and may be inferred from the daily UF in response to the prescription. (practice point).

A Model To Estimate Glucose Absorption in Peritoneal Dialysis: A Pilot Study.

Glucose absorption in patients on peritoneal dialysis (PD) may contribute to adverse metabolic effects. Previous studies on glucose absorption were done on patients on continuous ambulatory PD, with a long dwell time. However, the growing majority of contemporary patients on PD perform automated PD with a short dwell time. Moreover, membrane characteristics and dwell time determine small-solute transport across the peritoneal membrane. In our pilot study, we used data from the peritoneal equilibration test (PET) to develop a model to estimate glucose absorption. In six randomly selected patients on PD, we calculated actual glucose absorption from directly measuring effluent glucose concentration. We then used the R programming language to create a nonlinear, least-squared regression model, inputting PET data, D2/D0, and D4/D0 to generate an exponential decay curve. This model was then used to estimate the fraction of glucose remaining in the dialysate at a particular dwell time t (Dt/D0). Daily glucose absorption was calculated by multiplying 1-Dt/D0 with the amount of glucose the patient was exposed to in 24 hours. We observed the mean glucose absorption (89.7±28.8 g/d), as measured from the effluent, very close to our estimate (88.12±28.9 g/d), and the difference between the glucose estimation and actual absorption was not statistically significant (P>0.05), with "W" value of 8. After validating our hypothesis, we randomly selected an independent cohort of 11 patients with ESKD who were on various PD modalities and analyzed their data. We observed that the mean daily glucose absorption of 62.7±24.5 g (27.98-110.35 g), much lower than that reported in the literature, depends on dwell times and membrane characteristics in addition to the amount of glucose absorption in the cohort. Our model provides a simple tool for estimating glucose absorption and caloric load in contemporary patients on PD. Hopefully, the accurate estimation of caloric load and the incorporation of it into the daily caloric intake of the individual will help to reduce metabolic consequences of hyperglycemia and weight gain and improve overall outcomes of PD.

Comparison of peritoneal transport characteristics at the second week and at six months of peritoneal dialysis commencement

Peritoneal equilibration test (PET) is an important tool for managing peritoneal dialysis (PD) prescription. The Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines suggest that the first PET be performed 4-8 weeks after PD commencement. The main reason for this delay is because of the peritoneal membrane might change its character once it is exposed to the glucose based dialysate. In this study, we compared PET 2 weeks after PD commencement to PET after 6 months to evaluate the changes in the peritoneal membrane character with time. This study included 126 patients who underwent PD initiation between March 2007 and December 2011. The PET was performed as per the standard protocol at 2nd week and 6th month after PD initiation. Transport status was categorized as low, low average, high average, and high as per the standard definition. There was no change in transport character in 115 patients (91.2%) between the two PET measurements. When the Early PET at 2nd week and 6th month PET data were analyzed, no significant changes were observed in measured D/P creatinine (0.59 ± 0.14 vs. 0.62 ± 0.14 respectively P = 0.26) and D/D0 Glucose (0.46 ± 0.12 vs. 0.46 ± 0.11, P = 0.65). Using the Bland-Altman analysis the repeatability coefficients were 0.27 and 0.25 for creatinine and glucose values respectively. In our study, the PET performed at the 2nd week are similar to that of the 6th month PET in 91.2% of our patients and the test did not significantly change with time. In conclusion, we could do PET early at 2nd week to assess the peritoneal membrane character and this would help in proper dialysis prescription to the patients.

Severe Peritonitis in Patients Treated With Peritoneal Dialysis: A Case Series Study

Severe peritonitis causing death and/or technique termination (catheter explanted) is one of the most devastating complications of peritoneal dialysis (PD). The aim of this case series study was to reveal the predictors of risk and clinical characteristics of these cases. We included 38 patients with either peritonitis causing death (18 patients, 47%) or catheter removal (20 patients, 53%) in the period 1996-2006. Their last clinical, laboratory and peritoneal equilibration test data before the peritonitis episode and hospitalization data after the start of peritonitis were reviewed. Their median (range) age was 66 (25-85) years, 61% were male, and the median PD duration was 60 (1-144) months. Baseline C-reactive protein (17.5 ± 19.1 mg/L) was substantially higher than in contemporary stable controls from our unit (3.5 ± 4.2 mg/L, P = 0.002). For 14 patients (37%), this was their first episode, with a significantly lower mortality of 14% as opposed to 47% across the whole group (P = 0.002). Almost half the patients (42%) had a causative abdominal condition identified, such as diverticulitis or cholecystitis. Clinical and laboratory data at presentation were variable and not different according to survival. Non-surviving cases had a significantly larger proportion of fast transporters (83 vs. 45%, P = 0.03), a significantly lower estimate of daily protein intake (0.72 vs. 0.88 g/kg/day, P = 0.007), and a significantly higher proportion of non-Gram-positive causative microorganisms (72 vs. 40%, P = 0.019). The patients with severe peritonitis were characterized as older with a longer PD duration, and a higher baseline C-reactive protein. Fast peritoneal transport, lower normalized protein catabolic rate, and non-Gram-positive causative bacteria were associated with mortality.

The Short Pet in Pediatrics

The peritoneal equilibration test (PET) is a 4-hour procedure that is recommended to be performed in children receiving peritoneal dialysis to assist in prescription management. While a shortened version of the PET has been used in adults and reliably characterizes peritoneal membrane transport capacity, no similar experience with children has been reported. Retrospective evaluation of 2-hour and 4-hour PET data obtained from 20 children receiving chronic peritoneal dialysis in a single center. Characterization of membrane transport capacity was based on evaluation of serum and dialysate samples used to determine the dialysate-to-plasma ratio (D/P) of creatinine and the ratio of dialysate glucose to baseline dialysate glucose (D/D(0)). Patient values were compared to pediatric reference data. In all 20 patients, characterization of peritoneal membrane transport capacity using 2-hour D/P and D/D(0) results was identical to that determined using 4-hour data for the same solute. While the creatinine- and glucose-based characterization was discrepant in 14 of 20 patients, in only 1 case was the discrepancy of more than a single transport category. These results support the accuracy of a short PET in children, a procedure that should prove beneficial in terms of patient and staff time.

Increases in peritoneal small solute transport in the first month of peritoneal dialysis predict technique survival

Peritoneal transport of small solutes generally increases during the first month of peritoneal dialysis (PD). The aim of this study was to prospectively evaluate the ability of the peritoneal equilibration test (PET), carried out 1 and 4 weeks after the commencement of PD, to predict subsequent technique survival. Fifty consecutive patients commencing PD at the Princess Alexandra Hospital between 1 February 2001 and 31 May 2003 participated in the study. Paired 1 week and 1 month PET data were collated and correlated with subsequent technique survival. A significant increase was observed in the dialysate : plasma creatinine ratio at 4 h (D/P Cr) between 1 and 4 weeks after the onset of PD (0.55 +/- 0.12 vs 0.66 +/- 0.11, P <0.001). Mean death-censored technique survival was superior in patients who experienced > or =20% rise in D/P Cr during the first month of PD compared with those who did not (2.3 +/- 0.2 vs 1.6 +/- 0.2 years, P <0.05). Using a multivariate Cox proportional hazards model analysis, the significant independent predictors of death-censored technique survival were an increase in D/P Cr of greater than 20% during the first month (adjusted hazard ratio [HR] 0.20, 95% CI 0.05-0.75), the absence of diabetes mellitus, the absence of ischaemic heart disease, body mass index and baseline peritoneal creatinine clearance. A 20% or greater rise in D/P Cr during the first month of commencing PD is independently predictive of PD technique survival. Further investigations of the mechanisms underlying this phenomenon are warranted.

A Comparison of Peritoneal Equilibration Tests Performed 1 and 4 Weeks after PD Commencement

The aim of this study was to prospectively evaluate the ability of a peritoneal equilibration test (PET) performed in the first week of peritoneal dialysis (PD) to predict subsequent transport status, as determined by a PET at 4 weeks and >1 year after PD commencement. Prospective observational study of an incident PD cohort at a single center. Tertiary-care institutional dialysis center. The study included 50 consecutive patients commencing PD at the Princess Alexandra Hospital between 25/2/2001 and 14/5/2003 (mean age 60.9 +/- 12.2 years, 54% male, 92% Caucasian, 38% diabetic). All patients were initially prescribed continuous ambulatory PD. Measurements performed during paired PETs included dialysate-to-plasma ratios of urea (D/P urea) and creatinine (D/P creatinine) at 4 hours, the ratio of dialysate glucose concentrations at 0 and 4 hours (D/D0 glucose), and drain volumes at 4 hours. When paired 1-week and 1-month PET data were analyzed, significant changes were observed in measured D/P urea (0.91 +/- 0.07 vs 0.94 +/- 0.07 respectively; p < 0.05), D/P creatinine (0.55 +/- 0.12 vs 0.66 +/- 0.11, p < 0.001), and D/D0 glucose (0.38 +/- 0.08 vs 0.36 +/- 0.10, p < 0.05). Using Bland-Altman analysis, the repeatability coefficients were 0.17, 0.20, and 0.13, respectively. Agreement between 1-week and 1-month PET measurements with respect to peritoneal transport category was moderate for D/D0 glucose (weighted kappa 0.52), but poor for D/P urea (0.30), D/P creatinine (0.35), and drain volumes (0.20). The PET measurements performed more than 1 year following PD commencement (n = 28) generally agreed closely with 1-month measurements, and poorly with 1-week measurements. Peritoneal transport characteristics change significantly within the first month of PD. PETs carried out during this time should be considered preliminary and should be confirmed by a PET 4 weeks later. Nevertheless, performing an early D/D0 glucose measurement at 1 week predicted ultimate transport status sufficiently well to facilitate early clinical decision-making about optimal PD modality while patients were still receiving PD training. On the other hand, the widespread practice of using measured drain volumes in the first week to predict ultimate transport category is highly inaccurate and not recommended.

Continuous Flow Peritoneal Dialysis: Assessment of Fluid and Solute Removal in a High-Flow Model of “Fresh Dialysate Single Pass”

♦ Background Growing concern over the limited capacity of the peritoneal dialysis (PD) system has revived interest in continuous flow peritoneal dialysis (CFPD), a modality in which continuous circulation of PD fluid is maintained at a high flow rate using two separate catheters or one dual-lumen catheter. The CFPD regimen contrasts the “inflow/outflow” regimen, which requires specific times devoted to filling and draining the peritoneum via a single-lumen catheter. Historical data established CFPD capabilities in providing higher solute clearance and ultrafiltration rate (UFR) using either an open loop system with a single pass of fresh PD fluid, or various external purifications of the spent dialysate. ♦ Objective To compare, in patients with various peritoneal transport patterns, fluid and solute removal achieved during a standardized program of CFPD versus two control schedules: nightly intermittent peritoneal dialysis (NIPD) and nightly tidal peritoneal dialysis (NTPD). This study focused on small solute clearances and UFR using only isotonic PD solution (Dianeal PD1 1.36%; Baxter Healthcare, Castlebar, Ireland). The model of fresh dialysate, single pass, was used to optimize solute gradients and to characterize the impact of a continuous flow regimen on peritoneal transport characteristics. ♦ Methods In a crossover trial, 4-hour CFPD sessions were performed at a fixed dialysate flow rate (100 mL/minute) in 5 patients being treated with automated PD. A hemofiltration monitor (BM25; Baxter Healthcare, Brussels, Belgium) was adapted to the CFPD technique. The peritoneal cavity was filled through a temporary second catheter and simultaneously drained using the permanent peritoneal access. Fluid and solute removal were compared to data obtained from a control period based on 8-hour sessions of NIPD or NTPD using 13 L of isotonic dialysate. ♦ Results High-flow CFPD enhanced the diffusive transport coefficient compared with the alternative flow regimen in patients ranging from low to high transporters. Weekly creatinine clearance increased from 36.9 L (22.3 – 49.6 L) and 37.3 L (27.5 – 45.0 L) with NIPD and NTPD respectively, to 74.9 L (42.3–107.5 L) with CFPD. Mean UFR was 2.44 mL/min with CFPD versus 0.92 and 0.89 mL/min with NIPD and NTPD respectively. The mass transfer area coefficient (MTAC) of creatinine with CFPD was 2.5-fold that obtained from the peritoneal equilibration test data. ♦ Conclusion Our results confirm that CFPD is highly effective in increasing fluid and solute removal. Furthermore, consistent with historical data, our findings indicate that the enhanced solute transfer is not due only to steeper solute gradients, but also depends on increased MTAC in a wide range of peritoneum transport characteristics.

Correlation of Intraperitoneal Antibiotic Pharmacokinetics and Peritoneal Membrane Transport Characteristics

To identify correlations between the pharmacokinetic variables that describe drug disposition in peritoneal dialysis (PD) patients and the measures used to assess dialysis adequacy. This retrospective study re-evaluated data collected during previous pharmacokinetic studies for intraperitoneally administered cefazolin, ceftazidime, and gentamicin in continuous ambulatory peritoneal dialysis (CAPD) patients, and intravenous cefazolin and tobramycin in automated PD patients. Pharmacokinetic variables were compared to creatinine clearance (CCr), Kt/V, and peritoneal equilibration test data using the Pearson product correlation coefficient (r). Prominent correlations were found between renal CCr and renal Kt/V, with renal clearances of CAPD cefazolin and ceftazidime, and automated PD tobramycin and cefazolin (r values ranged from 0.698 to 0.986; p < 0.05). These findings support current peritonitis treatment recommendations that patients with residual renal function may require higher doses or more frequent drug administration.

Unrestricted pore area (A0/δx) is a better indicator of peritoneal membrane function than PET

How to measure the peritoneal exchange in uremic patients treated with peritoneal dialysis (PD) is still a matter of controversy. Most clinics use the peritoneal equilibration test (PET), but from a theoretical point of view, it would be more appropriate to determine the "area" parameter, A0/Deltax. The latter reflects the total unrestricted pore area per centimeter diffusion distance and can be obtained by three-pore analysis using, for example, the PD capacity test (PDC). To evaluate the different estimates of peritoneal function, PET data and the A0/Deltax parameters were compared with the independently determined uptake of a small diffusible tracer, iohexol (molecular weight of 821 D), from the abdominal cavity to blood. Fourteen patients on routine PD underwent determinations of PET and A0/Deltax using PDC. Within a month, the two-hour uptake of iohexol (6 mg/mL) was also determined from the plasma iohexol concentration following abdominal filling. A strong correlation was found between the rate of iohexol plasma concentration increase (k30-120) and A0/Deltax (A0/Deltax = 76,300. k30-120 - 1.56; r2 = 0.799; N = 14) for the 2 L dwell, while the PET data were far less related to iohexol uptake (D/DPurea, r2 = 0.409; D/Pcreatinine, r2 = 0.436; and D/D0glucose, r2 = 0.015, respectively). The "area" parameter, A0/Deltax, is superior to the more widely used routine PET as an indicator of peritoneal membrane function. In addition, the concept of A0/Deltax has the virtue of supplying quantitative information about the peritoneal pathophysiology and physiology.

Peritoneal Accumulation of Age and Peritoneal Membrane Permeability

In continuous ambulatory peritoneal dialysis (CAPD), the peritoneal membrane is continuously exposed to high-glucose-containing dialysis solutions. Abnormally high glucose concentration in the peritoneal cavity may enhance advanced glycosylation end-product (AGE) formation and accumulation in the peritoneum. Increased AGE accumulation in the peritoneum, decreased ultrafiltration volume, and increased peritoneal permeability in long-term dialysis patients have been reported. The purpose of the study was to evaluate the relation between peritoneal membrane permeability and peritoneal accumulation of AGE. Peritoneal membrane permeability was evaluated by peritoneal equilibration test (PET) using dialysis solutions containing 4.25% glucose. Serum, dialysate, and peritoneal tissue levels of AGE were measured by ELISA method using polyclonal anti-AGE antibody. Peritoneal biopsy was performed during peritoneal catheter insertion [new group (group N), n = 18] and removal [long-term group (group LT), n = 10]. Peritoneal catheters were removed due to exit-site infection not extended into the internal cuff (n = 6) and ultrafiltration failure (n = 4) after 51.6+/-31.5 months (13 - 101 months) of dialysis. PET data obtained within 3 months after the initiation of CAPD or before catheter removal were included in this study. Ten patients in group N and 4 patients in group LT were diabetic. Patients in group LT were significantly younger (46.5+/-11.1 years vs 57.5+/-1.3 years) and experienced more episodes of peritonitis (3.5+/-2.1 vs 0.2+/-0.7) than group N. Peritoneal tissue AGE level in group LT was significantly higher than in group N, in both nondiabetic (0.187+/-0.108 U/mg vs 0.093+/-0.08 U/mg of hydroxyproline, p < 0.03) and diabetic patients (0.384+/-0.035 U/mg vs 0.152+/-0.082 U/mg of hydroxyproline, p < 0.03), while serum and dialysate levels did not differ between the groups in both nondiabetic and diabetic patients. Drain volume (2600+/-237 mL vs 2766+/-222 mL, p = 0.07) and D4/D0 glucose (0.229+/-0.066 vs 0.298+/-0.081, p < 0.009) were lower, and D4/P4 creatinine (0.807+/-0.100 vs 0.653+/-0.144, p< 0.0001) and D1/P1 sodium (0.886+/-0.040 vs 0.822+/-0.032, p < 0.0003) were significantly higher in group LT than in group N. On linear regression analysis, AGE level in the peritoneum was directly correlated with duration of CAPD (r = 0.476, p = 0.012), number of peritonitis episodes (r = 0.433, p = 0.0215), D4/P4 creatinine (r = 0.546, p < 0.027), and D1/P1 sodium (r = 0.422, p = 0.0254), and inversely correlated with drain volume (r = 0.432, p = 0.022) and D4/D0 glucose (r = 0.552, p < 0.0023). AGE level in the peritoneal tissue and dialysate were significantly higher in diabetics than in nondiabetics in group LT, while these differences were not found in group N. Serum AGE level did not differ between nondiabetics and diabetics in either group N or group LT. Drain volume and D4/D0 glucose were lower and D4/P4 creatinine and D1/P1 sodium higher in diabetics than in nondiabetics in both groups. Peritoneal accumulation of AGE increased with time on CAPD and number of peritonitis episodes, and was directly related with peritoneal permeability. Peritoneal AGE accumulation and peritoneal permeability in diabetic patients were higher than in nondiabetic patients from the beginning of CAPD.

The Longitudinal Effect of a Single Peritonitis Episode on Peritoneal Membrane Transport in CAPD Patients

To evaluate the longitudinal effect of a single peritonitis episode on peritoneal membrane transport. A prospective longitudinal study. Department of nephrology in a university hospital. Eighteen continuous ambulatory peritoneal dialysis patients with peritonitis. Peritoneal transport for low, middle, and high molecular weight (MW) solutes was evaluated by peritoneal equilibration test (PET). The first PET was performed on the day following the diagnosis of peritonitis. The test was repeated at weeks 1, 2, 4, 12, and 24 and the results were compared to baseline PET data obtained before peritonitis. In addition, dialysate CA125 concentration and leukocyte count were measured. During peritonitis there were significant increases in dialysate-to-plasma (D/P) ratios for all low, middle, and high MW solutes except potassium, and decreases in D4/D0 glucose ratio and ultrafiltration (UF) volume. Over the subsequent 2 weeks, solute transport gradually decreased to the baseline values then remained unchanged during follow-up. Although net UF volume demonstrated a similar course during the study, it did not completely return to the baseline value. No decrease in D/P sodium ratio was found at 60 minutes during the PET performed 24 weeks after peritonitis. The percent change in solute transport during peritonitis compared to baseline value was significantly correlated with a solute's MW (r = 0.776, p = 0.014). The slope of the regression line for D/P ratios versus MW, in double logarithmic scale, before peritonitis (-0.73 +/- 0.09) was steeper than the slope during peritonitis (-0.59 +/- 0.08). These findings indicate that a single peritonitis episode does not permanently affect peritoneal solute transport. However, the loss of net UF that accompanies peritonitis is not completely recovered, probably due to impairment of transcellular water transport. The transport changes associated with peritonitis may be due to the combined effect of increased effective peritoneal surface area and intrinsic permeability. Our findings suggest that the latter mechanism seems to be more important.

Longitudinal changes in peritoneal kinetics: the effects of peritoneal dialysis and peritonitis

Peritoneal infection and poor ultrafiltration continue to be the major causes of treatment failure in CAPD. The combined effects of peritonitis and the continuous exposure to dialysis fluid remain the most likely candidates affecting the peritoneum in the long term. The purpose of this study was to observe the effects of peritonitis and dialysis on longitudinal peritoneal function. The peritoneal equilibration test (PET) was utilized to quantify longitudinal changes in low-molecular-weight solute transfer (D/P(creat)) and ultrafiltration (UF) in 233 patients treated with CAPD. Of these, 166 represented an unselected cohort (Group 1) studied prospectively from commencing treatment for up to 54 months, and 67 were selected patients (Group 2) with PET data available at commencement of the study, having been on dialysis for a minimum of 18 months. PETs were performed either 6-monthly or following peritonitis episodes. Data on the short-term effect of peritonitis kinetics were pooled for groups 1 and 2. Single, isolated episodes (n = 86) had no significant effect on D/P(creat) or UF, whereas recurrences or clusters of infection (n = 70) caused increases in D/P(creat) and reductions in UF, the significance of which increased with the number of episodes. There were significant correlations between both changes in D/P(creat) and UF with the cumulative dialysate leukocyte count, regardless of infecting organism, suggesting that intensity of peritoneal inflammation is also important. Those organisms associated with greater change in peritoneal kinetics, e.g. S. aureus, Pseudomonas, also had the highest neutrophil counts. The longitudinal changes in peritoneal kinetics were analysed for patients in group 1 only. There was a highly significant increase in D/P(creat) after 6 months treatment; this increased further with time on treatment, reaching further significance at 42 and 48 months. There was an associated reduction in UF. In view of the short-term effects of peritonitis on kinetics group 1 was further subdivided into patients who were either peritonitis free or only experienced isolated infections, group 1a, and those that had multiple infection episodes, group 1b. Treatment drop-out, due to death or technical failure occurred at double the rate in group 1b, who also had significantly higher D/P(creat) and lower UF at 1, 6, 12, 18 and 24 months of treatment. Group 1a subsequently caught up, however, indicating that peritonitis is not the only factor influencing long-term changes in peritoneal kinetics. These data suggest that solute transfer increases and UF declines with time on peritoneal dialysis. This process is exacerbated and accelerated by peritonitis, and appears to be proportional to the degree of associated inflammation and number of infections in close proximity.

Changes in Peritoneal Transport during the First Month of Peritoneal Dialysis

To determine if peritoneal transport characteristics change during the initial month of peritoneal dialysis. Retrospective review of peritoneal equilibration test (PET) results in patients who received their first PET during the first two weeks of peritoneal dialysis (early PET group) versus patients who received their first PET between four and 28 weeks after the initiation of dialysis (late PET group). The initial PET values were compared to subsequent PET results obtained approximately seven months after the initial PET. Peritoneal dialysis unit of a tertiary medical center. PET results and calculated mass transfer area coefficient (MTAC) values. Thirty-four peritoneal dialysis patients in the early PET group and 17 peritoneal dialysis patients in the late PET group. In the early PET group, there was a statistically significant increase from the initial to follow-up values for both dialysate-to-plasma (D/P) creatinine and MTAC creatinine (p < 0.01) as well as a significant decrease for four-hour dialysate to initial dialysate ratios (D/Do) glucose (p = 0.08) and MTAC glucose (p < 0.05). In the late PET group, there was no significant change in any of these parameters with time. However, in the late PET group, there was a significant decrease in D/P urea values with time (p < 0.01), but not with MTAC urea. In addition, there were no differences over time in either group for serum albumin or hematocrit values. During the first two weeks of peritoneal dialysis, there tends to be a change in peritoneal transport characteristics in some patients. PET data obtained during this time period should be interpreted as preliminary.

Determination of peritoneal transport characteristics with 24-hour dialysate collections: dialysis adequacy and transport test.

Although the 24-hour collection of dialysate provides a very accurate measure of the adequacy of dialysis, it is not known if it can also determine peritoneal membrane transport characteristics. In this prospective study, 101 24-hour dialysate collections were immediately followed by a standard peritoneal equilibration test (PET). Four- and 24-h dialysate-to-plasma (D/P) ratios were determined for creatinine and urea. The correlation coefficients between these two tests were 0.86 for the adjusted D/P creatinine and 0.71 for the D/P urea, whereas the standard errors of estimate were 0.054 and 0.060, respectively. Patients were classified into one of four transport groups on the basis of the mean and standard deviation of the adjusted D/P creatinine values, and these values were similar to those generated from the PET data. Rates of ultrafiltration were also defined for patients undergoing 2.0- and 2.5-L dwells. A survey of a subset of these patients demonstrated that the 24-h collection was preferred to the PET for determining transport characteristics. Therefore, the 24-h dialysate collection can be used to monitor both peritoneal membrane transport characteristics and adequacy. This technique, which has been named the "dialysis adequacy and transport test," has the potential for significant cost savings when it is used for the routine follow-up of both peritoneal transport and adequacy of dialysis.

The Peritoneal Permeability and Surface Area Index

The value of the peritoneal equilibration test (PET)-derived dialysate-to-plasma creatinine ratio (D/Pcr) as a measure of the peritoneal membrane's diffusive characteristics is obscured by the major role of convection in determining this value, particularly for low transporters. A simple index, derived from PET data, may permit a more accurate clinical measure of peritoneal diffusion.

Assessment of Dialysis Dose by Measured Clearance versus Extrapolated Data

To determine whether estimates of daily dialysis clearance of creatinine and urea, based on data from the 4-hour peritoneal equilibration test, correlate well with daily dialysis clearance measured by 24-hour dialysate collection in chronic ambulatory peritoneal dialysis patients. Prospective study in which each subject collected all dialysate from a 24-hour period and then immediately thereafter underwent a standard peritoneal equilibration test (PET). Daily clearances of creatinine and urea were calculated from 24-hour dialysate collections by standard methods and then were compared with several estimates of 24-hour clearance based on PET data. Single peritoneal dialysis unit of a university teaching hospital. Thirty-six stable patients on continuous ambulatory peritoneal dialysis (CAPD). The estimated values for daily dialysis clearance both overestimated and underestimated the measured 24-hour clearance. The correlation coefficient between the extrapolations and the actual 24-hour clearances ranged from 0.63-0.68. The range of discordance for daily creatinine clearance was from -2530 mL/day to +2199 mL/day. For daily urea clearance, the range of discordance was from -2103 mL/day to +1940 mL/day. The peritoneal membrane transport characteristics of the individual patient did not predict whether the extrapolation overestimated or underestimated the measured daily clearance. Extrapolation of PET data is not a reliable method to estimate the dose of dialysis delivered to the patient. A 24-hour collection of dialysis is necessary for this determination.

Determining Peritoneal Dialysis Prescriptions by Employing a Patient -Specific Protocol

To develop a formula that would permit a rapid and simple calculation of required dialysate volume needed to provide a predetermined daily creatinine clearance. Prospective study of peritoneal dialysis patients followed for 6 months. A primary care teaching hospital in New York. Twenty-six patients beginning peritoneal dialysis entered and completed the study. By employing each patient's measured peritoneal equilibration test (PET) and a standard clearance formula, a patient-specific treatment protocol (PSP) was calculated. The PET 2-hour D/Pcreat was used for continuous cycling peritoneal dialysis (CCPD) and the 4-hour D/Pcreat was used for patients on continuous ambulatory peritoneal dialysis (CAPD) to determine a PSP that would provide a minimum of 6 L of creatinine clearance daily. Patients were followed for 6 months to assess the ability of this approach of maintaining acceptable levels of blood urea nitrogen, creatinine, albumin, and hematocrit over the 6-month period of observation. Our study of 26 patients revealed that only 6 patients (23%) could be treated with the standard prescription of 8 L/day on CAPD. The remaining 77% of our patients required 9-13 L/day for CAPD and 12-21 L/day for CCPD. All patients were free of uremic symptoms and demonstrated acceptable biochemical parameters over a 3-6 month period of observation. A patient-specific protocol utilizing individually derived PET data provides an acceptable and easy to calculate initial treatment prescription for each patient that avoids the necessity for trial and error that has heretofore been employed.