Changes in the Peritoneal Equilibration Test in Selected Chronic Peritoneal Dialysis Patients1

1466 Volume 4 . Number 7 ‘ 1994

Changes in the Peritoneal Equilibration Test in SelectedChronic Peritoneal Dialysis Patients1

Wai-Kei Lo, Alessandra Brendolan, Barbara F. Prowant, Harold L. Moore, Ramesh Khanna,

Zbylut J. Twardowski, and Karl D. Nolph2

W.-K. Lo, A. Brendolan, B.F. Prowant, H.L. Moore, P.

Khanna, Z.J. Twardowski, K.D. Nolph, Division of Ne-phrology, Department of Internal Medicine and DaltonResearch Center, University of Missouri-Columbia, Co-

lumbia, MO

(J. Am. Soc. Nephrol. 1994; 4: 1466-1474)

ABSTRACTFifty-five patients on chronic peritoneal dialysis with

Iwo or more peritoneal equilibration tests (PET) per-

formed between 1983 and 1992 with a mean intervalof 2 1 .9 ± 22.7 months were studied retrospectively.

Repeated PET were performed when transportchanges were suspected rather than routinely. Ac-cording to the initial PET, there were 16 high (HI), 17

high-average (HA), 15 low-average (LA), and 7 low(LO) transporters. There was a significant decreasein the mean creatinine dialysate to plasma ratio (D/

P creatinine) in the HI transporters and an increase

in the LA and LO transporters. The mean dialysate toinstilled glucose ratio (D/Do) significantly increased

in the HI transporters. The change in both the D/P

creatinine and the D/Do of an individual strongly and

inversely correlated to their respective initial values.

The change in D/P creatinine and D/Do were signifi-cantly and inversely correlated to each other, mdi-

cating an actual transport change. No correlation

was found between the change in transport withperitonitis episodes or frequencies. The centrifugal

change of transport toward average described heremay explain why low clearances or low ultrafiltrationrates due to rapid transport are infrequent causes of

peritoneal dialysis technique failure, and why pa-tients who have been dialyzed for a long period areusually HA transporters.

I Receivea May 3, 1993. Accepted August 16, 1993.

2 Correspondence to Dr. K.D. Nolph, Division of Nephrology, Department of

internal Medicine. MA436. Health Sciences center. One Hospital Drive, colum-

bla, MO 65212.

1046-6673/0407.1466$03.OO/OJournal of the American society of NephrologyCopyright C 1994 by the Amr$can Society of Nephroiogy

Key Words: Transport, peritonealmembrane, peritonealequil-

ibration test, membrane durabiilty. membrane stability

S ince the peritoneal equilibration test (PET) wasintroduced by Twardowski et al. in 1987 (1), the

abridged (standard (PET) has been widely acceptedas a useful means with which to identify the perito-neal solute transport rate and thereby tailor an mdi-vidual’s peritoneal dialysis prescription (2-4). Thetest consists of measuring the dialysate to plasma

ratio (D/P) of creatinine at 0.5, 1 , 2, and 4 h anddialysate dextrose to baseline dialysate concentrationratio (D/Do). Dialysate drainage volume (DV) at 4 h isdetermined by completely draining the dialysate. A

simplified fast PET, with only the ratios and drainagevolume at 4 h measured, was later developed and

accepted as a useful alternative to the originalPET. (5).

According to the 4-h DIP creatinine result, patientscan be categorized into high, high-average, low-aye-rage. and low transporters (3, 6). Similarly, the

D/Do ratio can be used in such a way. The hightransporters usually have good dialysis clearances

but poor ultrafiltration. Intermittent dialysis, partic-ularly nocturnal automated, is the preferable ther-apy. The low transporters usually have good ultrafil-

tration but low small solute clearances with standardcontinuous ambulatory peritoneal dialysis (CAPD) (3,7). The high-average and low-average transporters,particularly the former, usually have adequate di-

alysis clearances and ultrafiltration, and typicalCAPD or continuous cyclic peritoneab dialysis is usu-ally the suitable treatment mode.

The result of PET repeated within a short periodwas demonstrated to be very consistent (1 , 8). Thereproducibility of the test is important for its value

in predicting the best treatment modality for pa-tients. However, changes in the result of the test on

a long-term basis are not well delineated. If the trans-port rate changes with time, it means that the bestmode of therapy for a patient may also change.

Since the PET was first used in our center in 1983,we have accumulated a long observation interval to

evaluate change in the peritoneal transport rate asindicated by the PET. In this article, we report ourdata from the analysis of repeated PET in our pa-

tients. It is important to stress that this study wasnot a prospective routine follow-up of our total pop-

Lo et al

Journal of the American Society of Nephrology 1467

ulation; the repeated PET was done in cases where

change was suspected. Thus, the incidence of changecould be different from a prospective study of a total

population.

PATIENTS AND METHODS

All chronic peritoneal dialysis patients in our di-

alysis center with two or more standard PET per-formed with 2 L of 2.5% dextrose dialysis solutionmore than 1 week apart were included in this retro-

spective analysis. No PET included in the analysiswas done within 1 mo of the completion of the peri-

tonitis antibiotic treatment. No PET was performedfewer than 10 days after catheter insertion. The 4-hD/P glucose corrected creatinine ratio (5), the D/Do

ratio, and the DV were used as the parameters for

study.Patients were categorized into the four different

groups of transporters (high, high average, low aye-rage and low) according to the DIP creatinine ratio ofthe initial PET, as described by Twardowski (dividing

ratios, >0.81. >0.65 to 0.81, >0.50 to 0.65, and 0.50or less, respectively (3). A change in DIP creatinine

in one individual that was more than 1 SD of theinitial DIP creatinmne of this study population wasregarded as significant.

Statistical differences between groups were ana-lyzed by t test, x2 test, and Fisher’s exact test whereappropriate. A paired t test was used to analyzechanges within the same group.

RESULTS

In an unpublished prior control study, we assessedthe reproducibility of 4 1 paired PET repeated over

short intervals (fewer than 2 days); the mean coeffi-dent of variation was 1 .75 ± 1 .35% (SD), and the

absolute mean difference in DIP creatinine betweentests was 0.024 ± 0.0 17.

From 1 983 to November 1 992, there were 55 pa-

tients who had two or more PET performed morethan 1 wk apart. They represented nearly 25% of allchronic peritoneal dialysis patients over the sameretrospective period. The number of PET performed

on each patient ranged from two to seven (mean,2.85). According to the initial PET, 16 patients werehigh transporters, 1 7 were high-average transport-cr5, 1 5 were bow-average transporters, and 7 werelow transporters. The mean initial DIP creatinine

was 0.687 ± 0. 1 53. The initial mode of dialysis ther-apy was CAPD, except for two patients on nocturnalintermittent peritoneal dialysis (Table 1). The initialPET were performed at a mean of 5.46 ± 1 1 .8 (SD)mo (range, 0. 1 to 47. 1) from the start of peritoneal

dialysis. and the final PET were performed at 27.3 ±28. 1 mo (range, 1 .3 to 1 32.7). The interval was 21.9

± 22.7 mo (range, 0.4 to 102.2). The demographicdata, the results of the initial and final PET, and theaveraged daily dialysate concentration used at thetime of initial and final PET of different transportersare shown in Table 1.

The mean DIP creatinine decreased and the meanD/Do increased in the initial high and high-averagetransporters, but they moved in opposite directions,

respectively, in the low-average and low transporters.

Statistically significant changes were seen in thehigh. low-average, and low transporters for DIP cre-atinine (P < 0.001) and in the high transporters for

D/Do (P < 0.001). The final mean DIP creatinine wasstill significantly higher in the initial high transport-ers than the final value in the initial low transporters

(P < 0.00 1 ); final means for low transporters werealso significantly different from finah means for high-average transporters (P < 0.02) and low-averagetransporters (P < 0.01). The final mean D/Do of the

high transporters remained the lowest and that ofthe low transporters the highest, with P < 0.001

between the high and low transporters and P < 0.03

between the high-average and bow transporters.There was also an increase in the DV in the hightransporters and a decrease in the DV in the lowtransporters, but the changes were not statisticallysignificant (Table 1 ). The average dialysate daily con-centration used at the time of the initial PET was

significantly higher in the high than in the low trans-porters (P < 0.01). Although there was a decrease inthe diabysate concentration used in the high trans-porters and an increase in that used in the low-average and low transporters. the changes were notstatistically significant.

The change in DIP creatinine was found to bestrongly and inversely correlated with the initial D/Pcreatinine value (r = -0.746; P < 0.001; Figure 1).Patients with a high initial DIP creatinine had a

negative change, whereas those with a low DIP cre-atinine had a positive change. A similar relationshipwas found between the change in D/Do and the initial

D/Do (r = -0416; P < 0.001 ; Figure 2) and betweenthe change in liv and the initial DV (r = -0.844; P <

0.001; Figure 3). The change in D/Do correlated withthe change in DIP creatinine significantly (r =

-0.709; P < 0.001 ; Figure 4). No correlation wasfound between the change in DV and the change inD/P creatinine or the change in D/Do. The high trans-porters were found to have a significantly older age

than the low transporters (P < 0.00 1 ; Table 1 ). A

significant correlation between the DIP creatinineand the age of patient was found with the initial

transporter (r = 0.37 1 ; P < 0.0 1 ; Figure 5a) but notwith the final PET (Figure 5b). Similarly, the initialD/Do correlated with age in an inverse manner (r =

-0.353; P < 0.01 ; Figure 6a), but not the final D/Do(Figure 6b).

ALL PATIENTS

#{149}#{149}

ALL PATIENTS0.3 -

0.2

0.1

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-0.1

-0.2

-0.3

-0.4 -

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

INITIAL D/P Creatinine

Figure 1 . The correlation between the change in DIP cre-atinine in individual patients and their corresponding initialD/P creatinine value (r= -0.746; P< 0.00 1).

r- -0.746p<0.001

0.4

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0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8INITIAL D/Do

Figure 2. The correlation between the change in D/Do inindividual patients and their corresponding initial D/Dovalue (r= -0.816; P< 0.001).

Peritoneal Transport in Repeated PET

1468 Volume 4 - Number 7 ‘ 1994

TABLE I . Results of different rates of transporters according to the D/P creatinine ratio of initial PET#{176}

Parameter Hign High Avg Low Avg Low P

N 16 17 15 7Initial PD mode I NTPD I IPDAge, mean 57.6b 52.0 52.6 42.5b <0.00 lbSD 8.1 14.2 12.9 9.1PD months, mean 3.3 7.9 7.2 0.7 NSSD 8.7 13.9 13.7 1.4Interval, mean 21.9 25.8 16.4 24.3 NSSD 20.2 25.4 24.7 12.2Initial DIP, mean 0.873 0.713 0.579 0.435SD 0.04 0.04 0.036 0.063Final DIP, meanc 0.74ld 0.698 0.698d 0.559d <0.00 IdSD 0.081 0.115 0.086 0.110

Initial D/Do, mean 0.215 0.389 0.424 0.527SD 0.063 0.097 0.052 0.072

FinalD/Do,mean 0.358’s 0.373 0.396 0.463 <0.OOld

SD 0.063 0.082 0.074 0.076

InitialDV(mL),mean 2171 2169 2297 2534

SD 216 683 358 168

FinalDV(mL),mean 2296 2184 2250 2415 NSd

SD 242 607 236 154

Initial concn, mean 2.84b 2.43 2.28 f95b <0.0 lb

SD 0.58 0.55 0.66 0.65Final concn, mean 2.75 2.41 2.42 2.16 NSd

SD 0.81 0.50 0.68 0.42

a Age and duration of peritoneal dialysis (PD) referred to the initial PET. concn. average daily dialysate concentration (% dextrose). PD mode; allare cAPD/continuous cyclic PD (CCPD) unless specified. NS. not significant; NTPD, nightly tidal PD; IPD. intermittent PD.b p compared between high and low transporters.C p value between low and high transporters. <0.001; low and high-average transporters, <0.02; low and low-average transporters. <0.01.

0 p compared between initial and final value.. p value between low and high transporters, <0.001; low and high-average transporters. <0.03.

a)C

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500 1000 1500 2000 2500 3000 3500

INITIAL DRAINAGE VOLUME

Figure 3. The correlation between the change in DV inindividual patients and their corresponding initial DV (r =

-0.844; P< 0.00 1).

0

0

0

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CHANGE IN

0.0 0.1 0.2 0.3

D/P Creatinine

0.4

Figure 4. The correlation between the change in D/Do inindividual patients and their corresponding change in D/Pcreatinine (r= -0.709; P< 0.00 1).

ALL INITIAL PETs ALL FINAL PETs

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AGE AGE

Figure 5. (a) The correlation between the initial D/P creatinine and the age of the patients (r = 0.371; P < 0.01). (b) Nocorrelation was found between the final D/P creatinine and the age of the patients. NS, not significant.

30 40 50 60 70 80 90

Lo et al


Figure 7 shows the change in DIP creatinine ofdifferent individual patients over time. For those whohad a decrease in DIP creatinine, the decrease took

place in the first 1 8 mo; the DIP creatinine wouldusually rise again after 24 mo of peritoneal dialysis.Thirty-eight patients had their PET repeated within

the first 1 8 mo of peritoneal dialysis. Among these38 patients, a significant drop of DIP creatinine wasfound in the high transporters (P < 0.001) and asigni�cant rise was found in the low-average (P <

0.01) and low transporters (P < 0.001 ; Figure 8).Fourtees�i patients, none of whom were low trans-

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porters, had at least one PET performed after 1 8 moof peritoneal dialysis and another PET repeated after24 mo of dialysis. The DIP creatinine increased inthese three groups of transporters (Figure 9). Al-though the numbers in each group are too small for

statistical analysis, the overall change in all 1 4 pa-tients was significant. The DIP creatinine increasedfrom 0.663 ± 0.086 to 0.725 ± 0.089 (P < 0.01).

Changes in transport were not rebated to peritonitisepisodes or their frequency. All PET studies wereperformed at least 1 mo after any peritonitis episodes

resolved. Changes in transport in each group were in

ALL INITIAL PETs FINAL PETs0.8

0.7

0.6

0.5

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DURATION OF PERITONEAL DIALYSIS (months)

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1470 Volume 4 ‘ Number 7 . 1994

Perltoneal Transport in Repeated PET

AGE AGE

Figure 6. (a) The correlatior� between the initial D/Do and the age of the patients (r= 0-0.353; P< 0.01). (b) No correlationwas found between the final D/Do and the age of the patients. NS. not significant.

0.9

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Figure 7. D/P creatinine values of individuals in the four transport groups over time.

the same direction in patients without any peritonitishistory. There were 28 patients in the study who

never had peritonitis.The change in DIP creatinine in the first 1 8 mo

was significantly correlated with the initial DIP cre-atinine (r = -0.705; P < 0.001 ; Figure 10), but thechange in DIP creatinine after 24 mo of peritoneal

dialysis was not correlated with either the initial

D/P or the first DIP creatinine after 1 8 mo of perito-

neal dialysis.The final transport rate status of the different

initial transporters is shown in Table 2. There was a

significant increase in the proportion of high-averagetransporters (P < 0.03). Only three initial hightransporters. eight high-average transporters, fourlow-average transporters, and 1 low transporter re-

P<0.o01

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0 3 6 9 12 15 18

MEAN DURATION OF PERITONEAL DIALYSIS (months)

Figure 8. The change in D/P creatinine in 38 patients with their PET repeated within the first 18 mo of peritoneal dialysis. Astatistically significant difference was reached in the high transporters (P < 0.00 1), the low-average transporters (P < 0.01),

and the low transporters (P< 0.001). NS, not significant.

1 .0

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36 48 60 72 84MEAN DURATION OF PERITONEAL DIALYSIS

Figure 9. The change in D/P creatinine in 14 patients with at least one PET performed after 18 mo and another performedafter 24 mo of peritoneal dialysis. No low transporters was found by this criterion. Overall mean D/P creatinine increased from0.663 ± 0.086 to 0.725 ± 0.089 (P< 0.01).

Lo ef al


0.3

0.2 -

24

mained in their initial categories. Most high trans-porters became high-average (1 0 of 1 6) or low-

average (3 of 1 6) transporters, most low-averagetransporters became high-average (9 of 1 5) trans-porters, and most low transporters became low-av-erage (4 of 7) or high-average (2 of 7) transporters.However, most high-average transporters remainedin the same category (8 of 1 7). whereas some became

high transporters and some became low-averagetransporters. There were 1 5 patients with a change

of DIP creatinine of more than 1 SD (0. 1 53) (Table2). This significant decrease in DIP creatinine was

found in four high transporters and two high-averagetransporters; a significant increase was found in fourlow transporters, four low-average transporters. and

one high-average transporter. Statistical significancewas reached between the high and low transportersfor significant increase in DIP creatinine (P < 0.01)

and low-average transporters for significant decrease(P < 0.03).

0.3

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1472 Volume 4 . Number 7 - 1994

-0.4 ‘ ‘ ‘I’ll

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0INITIAL D/P Creatinine

Figure 10. The correlation between the change in D/P cre-atinine in the first 18 mo of peritoneal dialysis and thecorresponding initial D/P creatinine (1= -0.705; P< 0.00 1).

There were no statistical differences in the clinical

outcome of the four groups of transporters in terms

of death and transfer to other modes of replacementtherapy. However, more low transporters were trans-planted (P < 0.01 versus high transporters and P <

0.02 versus low-average transporters) and more low-average transporters stayed on peritoneal dialysis (P

< 0.04 versus low transporters). There was no death

directly related to inadequate dialysis. Ultrafiltrationfailure was the reason of transfer to hemodialysis in

two patients. but high lymphatic absorption was dockumented to be the reason of ultrafiltration failure inone of them. The other patient with type I ultrafiltra-

tion failure was an initial high-average transporterwith a final DIP creatinine of 0.822. Inadequate di-

alysis was the cause of transfer to hemodialysis inan initial low transporter, even though his final DIPcreatinine increased to 0.538.

DISCUSSION

Our study describes a selected population of pa-tients who stayed on chronic peritoneal dialysis forat least 2 yr on average and had repeated PET. Trans-port changes in early dropouts are thus not included.Repeated PET studies, rather than routine studies,were done to assess possible changes in transport.

Thus, this retrospective analysis of our clinical prac-tice looks for transport changes in patients morelikely to have had suspected changes. Further eval-

uations involving unselected chronic peritoneal di-alysis patients are needed. Nevertheless, the patternof change observed in different transport groups inour study is of interest.

Our data showed that the peritoneal transport rates

TABLE 2. The change in transport status in different initial transporters according to D/P creatinine#{176}

TransportersAccording to

Initial PET

Final PET Tran sport Status Chang e > I SD

High High Avg Low Avg Low Increase Decrease

HighN= 16 3 10 3 0 0(0%) 4(25%)High avg N = I 7 3 8 5 1 1 (6%) 2 (12%)Low avg N= 15 2 9 4 0 4 (27%) 0 (0%)

Low N = 7 0 2 4 1 4 (57%) 0 (0%)

TotalN=55 8 29 17 2 9 6

0 p < 0.03 for the change in the number of high-average transporters. by x2 test; P < 0.01 for the number of patients with an increase >1 SD

between high and low transporters; and P< 0.03 for the number of patients with a decrease >1 SD between high and low-average transporters.by two-sided Fisher’s exact test.

TABLE 3. Clinical outcome of different groups of transporters

High High Avg Low Avg Low I�

Total,N 16 17 15 7

Death, N 7 (44%) 6 (35%) 5 (33%) 1 (14%) NS

Change to HD, N 4 (25%) 5 (29%) 1 (7%) 2 (28%) NSChange to IPD, N 8 (50%) 4 (24%) 4 (27%) 3 (43%) NSTransplanted, N 0 (0%) 2 (12%) 0 (0%) 3 (43%)

Still on PD 5 (31%) 3 (18%) 9 (60%) I (14%)

0 NS. not significant.b Between low and high transporters. P< 0.01; between low and low-average transporters. P< 0.02.C Between low and low-average transporters, P < 0.04 by two-tailed Fisher’s exact test.

Lo et al


of chronic peritoneal dialysis patients as indicatedby PET are not static. They change in a fashion thathas never been described before: the direction andthe amplitude of change are dependent on their initial

transport rate. The initial high transporters tend tohave the transport rate decrease, and the low trans-porters tend to have the transport rate increase with

time. Such migration toward the mean may help toexplain why low clearances or low ultrafiltration withrapid transport are infrequent causes of CAPD tech-

nique failure (9). However, this centrifugal directionof change only occurred in the first 1 8 mo, and thetransport rates tended to slowly increase thereafter,regardless of the initial transport status. On the otherhand, despite changes in transport rates from initial

extremes, the high transporters still have a highertransport rate than the others, and the low trans-

porters have a lower transport rate. A simple meth-odobogic migration toward a mean seems unlikelybecause DIP creatinine and D/Do glucose changeswere inversely correlated to a high degree, suggesting

that actual transport changes and the mean changeof DIP creatinine in the high. bow-average, and bow

transporters were much higher than the coefficientof variation we analyzed previously.

In a previous study, we have already noted that

patients with a longer duration of peritoneal dialysiswere mostly high-average transporters. Our previous

hypothesis was that this was because of a naturalselection process: those with high-average transportstay on peritoneab dialysis. whereas those at either

extreme drop out (1). In this study, we demonstratethat this phenomenon is also the result of changestoward average transport during the course of long-

term peritoneal dialysis in the outlying groups.Increases in peritoneal transport rates with time

have been observed by others (10, 1 1), but no changewas found by some (8, 1 2). In all of the reportedseries, the change in DIP creatinine was not analyzedaccording to the initial value. The high and low trans-

porters were mixed together and studied as a group.The opposite directional changes of the transport ratein the first 1 8 mo of peritoneal dialysis in the outlyinggroups discovered in our analysis may explain the

absence of overall changes in average values.Changes in different directions in some individualshave been noted, despite the lack of changes in a

group (1 , 8, 1 2), but no factors related to the change,such as age or number of peritonitis episodes, couldbe identified. Unfortunately, the initial DIP creati-nine value was not included as one of the factors

studied.Increases in transport rates were mainly reported

in those series with a long follow-up (1 0. 1 1 . 1 3). Wealso found that the DIP creatinine increases after thefirst 1 8 mo of peritoneal dialysis. regardless of theinitial transport rate status or the initial direction of

change. There have been some mechanisms pro-

posed for this phenomenon, including an increase in

peritoneal surface area and/or peritoneal permeabil-ity. Although it is unlikely that the peritoneal surface

area will increase with dialysis. increases in perito-neal permeability may be explained by structuralchanges in the peritoneum and its vasculature (14,1 5). The causes of the initial centrifugal changes intransport rate reported herein are also unknown.Could the initial high transport rates in some of thepatients represent a transient reaction to catheterinsertion and/or dialysate solution enhancing trans-port? Many initial tests were performed in the earlymonths of peritoneal dialysis, but none fewer than1 0 days after catheter insertion. Obviously, many of

these patients were genuine high transporters tostart with because most of their transport rates stillstayed higher than the others after some time onperitoneal dialysis. The use of higher concentrations

of glucose in the high transporters may play a part,but it is difficult to prove whether change relates tomore hyperosmolar dialysate exposure.

No correlation of the transport rate with age in

adult peritoneal dialysis patients has been previouslyreported. However, it has been generally acceptedthat the transport rate is higher in children than in

adults (16). Young children are often high or high-average transporters (1 7). An age-related D/P creati-

nine level was described by Schroeder et a!. ( 1 8). TheD/P creatinine ratio decreased with age but did notreach a significant difference between those younger

and older than 3. In this report, we found a correla-tion of the Initial transport rate with age, whetherthe D/P creatinine or the D/Do is used to indicate the

transport rate. However, the correlation with agedisappeared with the final PET. This means that theage factor may be only applicable in the original,untouched peritoneum. As the duration of peritoneal

dialysis increases, other factors may appear and theage factor no longer predominates. This may explain

why our previous reports. and many other reports.did not find any age/transport rate relationship inthe cross-sectional analyses with PET done at differ-ent durations of peritoneal dialysis.

Similar to findings in other reports (1 0), the changein transport rate did not correlate with the numberof peritonitis episodes or the peritonitis rate. This

does not mean that peritonitis would not affect thetransport rate. It is well established that peritonitisreduces the ultrafiltration acutely by increasing the

permeability of the peritoneum (1 9. 20). In most

cases, recovery occurred within a few weeks (2 1).The long-term effect is not known. but peritonitismay bead to a reduction in peritoneal surface area,resulting in a reduction in transport rate or sclerosing

peritonitis with a marked decrease, or sometimesmarked increase, in transport rate (22, 23). Because


1474 Volume 4 . Number 7 . 1994

death or transfer to hemodialysis might result froma severe episode of peritonitis, the change in trans-port rate that might have occurred in these patientswould never have a chance to be documented.

In conclusion, the peritoneal transport of perito-neal dialysis patients as indicated by repeated PETis not always static. In our select group of patients

with clinically suspected changes in transport, thetransport rate tended to decrease in the high trans-porters and increase in the low transporters. This

phenomenon may be beneficial to high and and lowtransporters by increasing ultrafiltration and in-creasing solute clearances, respectively.

ACKNOWLEDGMENTS

Dr. W. K. La was sponsored by the Ho Hung-Chiu Medical Education

Foundation Fellowship to the Division of Nephrology. University of

Missouri-Columbia. as a Research Fellow.

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Changes in the Peritoneal Equilibration Test in Selected Chronic Peritoneal Dialysis Patients1

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