Karl D. Nolph
eritoneal dialysis is a technique whereby infusion of dialysis solu-
tion into the peritoneal cavity is followed by a variable dwell
time and subsequent drainage. Continuous ambulatory peri-
toneal dialysis (CAPD) is a continuous treatment consisting of four to
five 2-L dialysis exchanges per day (Fig. 4-1A). Diurnal exchanges last
4 to 6 hours, and the nocturnal exchange remains in the peritoneal
cavity for 6 to 8 hours. Continuous cyclic peritoneal dialysis, in real-
ity, is a continuous treatment carried out with an automated cycler
machine (Fig. 4-1B). Multiple short-dwell exchanges are performed at
night with the aid of an automated cycler machine. Other peritoneal
dialysis treatments consist of intermittent regimens (Fig. 4-2A-C).
During peritoneal dialysis, solutes and fluids are exchanged between
the capillary blood and the intraperitoneal fluid through a biologic
membrane, the peritoneum. The three-layered peritoneal membrane
consists of 1) the mesothelium, a continuous monolayer of flat cells,
and their basement membranes; 2) a very compliant interstitium; and
3) the capillary wall, consisting of a continuous layer of mainly non-
fenestrated endothelial cells, supported by a basement membrane. The
mesothelial layer is considered to be less of a transport barrier to fluid
and solutes, including macromolecules, than is the endothelial layer
. The capillary endothelial cell membrane is permeable to water
through aquaporins (radius of approximately 0.2 to 0.4 nm) . In
addition, small solutes and water are transported through ubiquitous
small pores (radius of approximately 0.4 to 0.55 nm). Sparsely popu-
lated large pores (radius of approximately 0.25 nm, perhaps mainly
venular) transport macromolecules passively. Diffusion and convection CHAPTER
move small molecules through the interstitium with its gel and sol
phases, which are restrictive owing to the phenomenon of exclusion
[3,4]. The splanchnic blood flow in the normal adult ranges from 1.0
to 2.4 L/min, arising from celiac and mesenteric arteries . The lym-
phatic vessels located primarily in the subdiaphragmatic region drain
fluid and solutes from the peritoneal cavity through bulk transport.
4.2 Dialysis as Treatment of End-Stage Renal Disease
The extent of lymph drainage from the peritoneal cavity is a sub- fraction of glucose absorbed from the dialysate at specific times can
ject of controversy owing to the lack of a direct method to mea- be determined by the ratio of dialysate glucose concentrations
sure lymph flow. at specific times to the initial level in the dialysis solution. Tests
Dialysis solution contains electrolytes in physiologic con- are standardized for the following: duration of the preceding
centrations to facilitate correction of acid-base and electrolyte exchange before the test; inflow volume; positions during
abnormalities. High concentrations of glucose in the dialysis inflow, drain, and dwell; durations of inflow and drain; sam-
solution generate ultrafiltration in proportion to the overall pling methods and processing; and laboratory assays .
osmotic gradient, the reflection coefficients of small solutes Creatinine and urea clearance rates are the most commonly used
relative to the peritoneum, and the peritoneal membrane indices of dialysis adequacy in clinical settings. Contributions
hydraulic permeability. Removal of solutes such as urea, creati- of residual renal clearances are significant in determining the
nine, phosphate, and other metabolic end products from the body adequacy of dialysis. The mass-transfer area coefficient (MTAC)
depends on the development of concentration gradients between represents the clearance rate by diffusion in the absence of ultrafil-
blood and intraperitoneal fluid, and the transport is driven by the tration and when the rate of solute accumulation in the dialysis
process of diffusion. The amount of solute removal is a function solution is zero. Peritoneal clearance is influenced by both blood
of the degree of its concentration gradient, the molecular size, and dialysate flow rates and by the MTAC . Therefore, the
membrane permeability and surface area, duration of dialysis, and maximum clearance rate can never be higher than any of these
charge. Ultrafiltration adds a convective component proportion- parameters. At infinite blood and dialysate flow rates, the clearance
ately more important as the molecular size of the solute increases. rate is equal to the MTAC and is mass-transfer–limited. Large mol-
The peritoneal equilibration test is a clinical tool used to charac- ecular weight solutes are mass-transfer–limited; therefore, their
terize the peritoneal membrane transport properties . Solute clearance rates do not increase significantly with high dialysate flow
transport rates are assessed by the rates of their equilibration rates . In CAPD, blood flow and MTAC rates are higher than is
between the peritoneal capillary blood and dialysate (see Fig. 4-8). the maximum achievable urea clearance rate. However, the urea
The ratio of solute concentrations in dialysate and plasma at specif- clearance rate approximately matches the dialysate flow rate, sug-
ic times during the dwell signifies the extent of solute transport. The gesting that the dialysate flow rate limits CAPD clearances.
Peritoneal Dialysis Regimens
Continuous peritoneal dialysis regimens.
Day Night Day Night
A, Continuous ambulatory peritoneal dialy-
sis (CAPD); B, continuous cyclic peritoneal
2.0 dialysis (CCPD) is shown. Multiple sequen-
tial exchanges are performed during the day
1.0 and night so that dialysis occurs 24 hours a
day, 7 days a week.
Day Night Day Night
B Exchanges, n
Principles of Peritoneal Dialysis 4.3
Day Night Day Night Intermittent peritoneal dialysis regimens.
Left Peritoneal dialysis is performed every day
but only during certain hours. A, In daytime
ambulatory peritoneal dialysis (DAPD),
1.0 multiple manual exchanges are performed
during the waking hours. B, Nightly peri-
0.0 toneal dialysis (NPD) is also performed
while patients are asleep using an automated
cycler machine. One or two additional day-
time manual exchanges are added to
enhance solute clearances.
Left Day Night Day Night
Blood urea nitrogen, mg/dL
Blood 4 Dialysate
0 80 160 240 320 400 480 560 0
0 40 80 120 160 200 240 280 320 360
A Time, min B Time, min
Solute removal. Solute concentration gradients are at maximum at rate by either increasing the intraperitoneal dialysate volume per
the beginning of dialysis and diminish gradually as dialysis progress- exchange or increasing the frequency of exchange. By convection
es. As the gradients diminish, the solute removal rates decrease. or enhanced diffusion, solutes are able to accompany the bulk flow
Solute removal can be enhanced by increasing the dialysate flow of water. (From Nolph and coworkers ; with permission.)
4.4 Dialysis as Treatment of End-Stage Renal Disease
Dialysate to plasma ratio
Dialysate to plasma ratio
0.4 Urea 0.4 Urea
0.3 Creatinine 0.3 Creatinine
Uric acid Uric acid
0.2 Phosphorus 0.2 Phosphorus
0.1 Inulin 0.1 Inulin
0 100 200 300 400 500 0 100 200 300 400 500
A Dwell time, min B Dwell time, min
Solute removal. The rates of change of solute concentrations are is near 1.0. Smaller size solutes (ie, urea and creatinine) diffuse
similar for 1.5% dextrose dialysis solutions (panel A) and 4.25% across the membrane faster, equilibrate sooner, and are influenced
dextrose dialysis solutions (panel B). Hypertonic exchanges enhance more by exchange frequency as compared with larger size solutes
solute removal owing to larger drain volumes. Net solute diffusion (ie, uric acid, phosphates, inulin, and proteins). (From Nolph and
ceases at equilibration when the dialysate to plasma solute ratio (D/P) coworkers ; with permission.)
Total dialysate volume (V)
per exchange (Ccr)
Creatnine dialysate to
plasma ratio (D/P)
1.0 2600 Ccr=V
NIPD DAPD CAPD Ccr=V × D/P
1700 NTPD CCPD CCPD
0 (NE) (DE) 0
1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
1 2 3 4 5 6 7
A Dwell time, h B Dwell time, h C Dwell time, h
Solute removal. In a highly permeable membrane, smaller molecules Consequently, intraperitoneal volume peaks later. Ultrafiltration in
(ie, urea and creatinine) are transported at a faster rate from the a low transporter peaks late during dwell time. Therefore, a low
blood to dialysate than are larger molecules, enhancing solute removal. transporter continues to generate ultrafiltration even after 8 to 10
Similarly, glucose (a small solute used in the peritoneal dialysis solution hours of dwell. The solute creatinine dialysate to plasma ratio
to generate osmotic force for ultrafiltration across the peritoneal mem- (D/P) increases linearly during the dwell time. Patients with average
brane) is also transported faster, but in the opposite direction. This solute transfer rates have ultrafiltration and mass transfer patterns
high transporter dissipates the osmotic force more rapidly than does between those of high and low transporters. NIPD—nightly inter-
the low transporter. Both osmotic and glucose equilibriums are mittent peritoneal dialysis; NTPD—nighttime tidal peritoneal dialy-
attained eventually in both groups, but sooner in the high trans- sis; DAPD—daytime ambulatory peritoneal dialysis; CAPD—con-
porter group. Intraperitoneal volume peaks and begins to diminish tinuous ambulatory peritoneal dialysis; CCPD (NE)—continuous
earlier in the high transporter group. When the membrane is less cyclic peritoneal dialysis (night exchange); CCPD (DE)—continu-
permeable, solute removal is lower, ultrafiltration volume is larger ous cyclic peritoneal dialysis (day exchange). (From Twardowski
at 2 hours or more, and glucose equilibriums are attained later. ; with permission.)
Principles of Peritoneal Dialysis 4.5
150 Solute sieving. A, Dialysate sodium concentration is initially reduced and tends to return
Serum and dialysate to baseline later during a long dwell exchange of 6 to 8 hours. B, Dialysate sodium con-
130 centration decreases, particularly when using 4.25% dextrose dialysis solution, because of
120 1.5% dextrose
dialysis solutions the sieving phenomenon. Removal of water during ultrafiltration unaccompanied by sodium,
110 in proportion to its extracellular concentration, is called sodium sieving [7,12]. The peri-
100 toneum offers greater resistance to the movement of solutes than does water. This probably
relates to approximately half the ultrafiltrate being generated by solute-free water movement
0 100 200 300 400 500
through aquaporins channels. Therefore, ultrafiltrate is hypotonic compared with plasma.
A Dwell time, min Dialysate chloride is also reduced below simple Gibbs-Donnan equilibrium, particularly
during hypertonic exchanges. Patients with a low peritoneal membrane transport type tend
to reduce dialysate sodium concentration more than do other patients. Therefore, during a
short dwell exchange of 2 to 4 hours, net electrolyte removal per liter of ultrafiltrate is
well below the extracelluar fluid concentration. As a result, severe hypernatremia, excessive
150 thirst, and hypertension may develop. This hindrance can be overcome by lowering the
140 dialysate dialysate sodium concentration to 132 mEq/L. In patients who use cyclers with short dwell
4.25% dextrose exchanges and who generate large ultrafiltration volumes, lower sodium concentrations
dialysis solutions may need to be used (such as 118 mEq/L for 2.5% glucose solutions or 109 mEq/L for
100 4.25% solutions). In continuous ambulatory peritoneal dialysis with long dwell exchanges
90 of 6 to 8 hours, significant sieving usually does not occur, whereas in automated peritoneal
Inflow dialysis with short dwell exchanges, sieving may occur. Sieving predisposes patients to
0 100 200 300 400 500 thirst and less than optimum blood pressure control, especially in those who have low-nor-
B Dwell time, min mal serum sodium levels, those with low peritoneal membrane transporter rates, or both.
(From Nolph and coworkers ; with permission.)
Transcapillary ultrafiltration Fluid removal by ultrafiltration. During peritoneal dialysis, hyperosmolar glucose solution
600 generates ultrafiltration by the process of osmosis. Water movement across the peritoneal
membrane is proportional to the transmembrane pressure, membrane area, and membrane
hydraulic permeability. The transmembrane pressure is the sum of hydrostatic and osmotic
500 pressure differences between the blood in the peritoneal capillary and dialysis solution in
the peritoneal cavity. Net transcapillary ultrafiltration defines net fluid movement from the
peritoneal microcirculation into the peritoneal cavity primarily in response to osmotic
400 pressure. Net ultrafiltration would equal the resulting increment in intraperitoneal fluid
volume if it were not for peritoneal reabsorption, mostly through the peritoneal lymphatics.
Peritoneal reabsorption is continuous and reduces the intraperitoneal volume throughout
300 the dwell. A, The net transcapillary ultrafiltration rate decreases exponentially during the
dwell time, owing to dissipation of the glucose osmotic gradient secondary to peritoneal
volume glucose absorption and dilution of the solution glucose by the ultrafiltration. Later in the
200 exchange net, ultrafiltration ceases when the transcapillary ultrafiltration is reduced to a
rate equal to the peritoneal reabsorption. B, When the transcapillary ultrafiltration rate
decreases below that of the peritoneal reabsorption rate, the net ultrafiltration rate becomes
negative. Consequently, the intraperitoneal volume begins to diminish. Thus, peak ultrafiltra-
tion and intraperitoneal volumes are observed before osmotic equilibrium during an exchange.
(Continued on next page)
0 1 2 3
A Dwell time, h
Peak intraperitoneal volume Dialysate
0 1 2 3 4
B Dwell time, h
4.6 Dialysis as Treatment of End-Stage Renal Disease
FIGURE 4-7 (Continued)
Serum C, Osmotic equilibrium most likely precedes glucose equilibrium
because of both solute sieving and the higher peritoneal reflection
340 coefficient of glucose compared with other dialysate solutes, allow-
Osmotic ing net transcapillary ultrafiltration to continue at a low rate even
320 equilibrium after osmotic equilibrium. D, Ultrafiltration can be maximized by
measures that delay osmotic equilibrium, which can be accom-
plished by using hypertonic glucose solutions, larger volumes, or
both, during an exchange. More frequent exchanges shorten dwell
0 1 2 3 4 times and increase the dialysate flow rate and thus avert attaining
C Dwell time, h osmotic equilibrium. Additionally, potential exists for enhancing
ultrafiltration by measures that reduce the peritoneal reabsorption
rate. (From Mactier and coworkers ; with permission.)
0 1 2 3 4
D Dwell time, h
STANDARDIZED 4-HOUR PERITONEAL EQUILIBRATION TEST Standardized 4-hour peritoneal equilibra-
tion test. Dt/D0 glucose—final to initial
dialysate glucose ratio.
1. Perform an overnight 8- to 12-h preexchange.
2. Drain the overnight exchange (drain time not to exceed 25 min) with patient in the upright position.
3. Infuse 2 L of dialysis solution over 10 min with patient in the supine position. Roll the patient from side to side after
every 400-mL infusion.
4. After the completion of infusion (0 time) and at 120 min, drain 200 mL of dialysate. Take a 10-mL sample, and
reinfuse the remaining 190 mL into the peritoneal cavity.
5. Position the patient upright, and allow patient ambulation if able.
6. Obtain a serum sample at 120 min.
7. At the end of study (240 min), drain the dialysate with the patient in the upright position
(drain time not to exceed 20 min).
8. Measure the drained volume, and take a 10-mL sample from the drained volume after a good mixing.
9. Analyze the blood and dialysate samples for creatinine and glucose concentrations.
10. Correct the serum and dialysate creatinine concentrations for high glucose level (correction factor 0.000531415).
11. Calculate the dialysate to plasma ratios for creatinine, and so on, and calculate the Dt/D0 glucose.
Correction of creatinine levels
Equation to correct the creatinine levels in dialysate and serum.
Corrected creatinine (mg/dL) The creatinine levels in dialysate and serum need to be corrected
= Observed creatinine (mg/dL) – (glucose [mg/dL] x 0.000531415) for high glucose levels, which contribute to formation of noncreatinine
chromogens during the creatinine assay. The correction factor may
vary from one laboratory to another. In our laboratory at the University
of Missouri–Columbia, the correction factor is 0.000531415.
Accordingly, the corrected creatinine is calculated as in the equation.
The correction in the serum is minimal due to low blood sugar levels;
however, it is significant in dialysate, especially during the early
phase of dwell (0- and 2-hour dialysate samples).
Principles of Peritoneal Dialysis 4.7
Intraperitoneal residual volume Equation to calculate the intraperitoneal residual volume. Residual volume is the volume
Vin(S3 – S2) of dialysate remaining in the peritoneal cavity after drainage over 20 minutes. The residual
(S1 – S3) volume can be determined by knowing the dilution factor for solutes such as potassium, urea,
and creatinine during the next instillation. The calculation of residual volumes is based on
the assumption that the mixing of fluid in the peritoneal cavity is instantaneous and com-
plete. This equation is used for the calculation, where Vin is instillation volume; S1 is solute
concentration in pretest exchange dialysate; S2 is solute concentration in instilled dialysis
solution; and S3 is solute concentration immediately after instillation (0 dwell time). The
residual volumes by urea, creatinine, glucose, potassium, and protein are calculated and
averaged for accuracy. The measurement of residual volumes is of limited clinical useful-
ness; however, it is of great value in a research setting in which accurate determination of
intraperitoneal volume is required.
Urea Creatinine Classification of peritoneal transport func-
tion. Based on the peritoneal equilibrium
0.9 0.9 test results, peritoneal transport function
Dialysis to plasma ratio
Dialysis to plasma ratio
may be classified into average, high (H),
0.7 and low (L) transport types. The average
transport group is further subdivided into
high-average (HA) and low-average (LA)
0.5 0.5 types. For the population studied by
Twardowski and coworkers , the trans-
0.3 port classification is based on means; stan-
dard deviations (SDs); and minimum and
maximum dialysate to plasma ratio (D/P)
0.1 0.1 values over 4 hours for urea, creatinine,
glucose, protein, potassium, sodium, and
0 1/ 1 2 3 4 0 1/
2 1 2 3 4 corrected creatinine (panels A–G).
A Hours B Hours (Continued on next page)
Final to initial dialysate glucose ratio
Dialysate to plasma ratio × 1000
0 1/ 1 2 3 4
2 1 2 3 4 2
C Hours D Hours
4.8 Dialysis as Treatment of End-Stage Renal Disease
FIGURE 4-11 (Continued)
1.1 1.00 The volume of drainage correlates positively
with dialysate glucose and negatively with
D/P creatinine values at 4-hour dwell times
(panel H). (From Twardowski and cowork-
Dialysate to plasma ratio
Dialysate to plasma ratio
ers ; with permission.)
0.1 –SD LA
1/ 0 1/ 1 2 3 4
0 2 1 2 3 4 2
E Hours F Hours
ADK vol05 ch p04 fig11F
Corrected creatinine Max
Dialysate to plasma ratio
0 Drain Residual Volume
2 1 2 3 4 volume pre-eq post-eq
G Hours H
CLINICAL APPLICATIONS OF THE In clinical practice it is customary to perform the baseline standard-
PERITONEAL EQUILIBRATION TEST ized peritoneal equilibrium test (PET) approximately 3 to 4 weeks
after catheter insertion. The PET is repeated when complications
occur. The standardized test for clinical use measures dialysate
Peritoneal membrane transport classification creatinine and glucose levels at 0, 2, and 4 hours of dwell time
1. Choose peritoneal dialysis regimen. and serum levels of creatinine and glucose at any time during
2. Monitor peritoneal membrane function.
the test. The extensive unabridged test, as originally proposed
by Twardowski and coworkers , has become a very important
3. Diagnose acute membrane injury.
4. Diagnose causes of inadequate ultrafiltration.
5. Diagnose causes of inadequate solute clearance.
6. Estimate dialysate to plasma ratio of a solute at time t.
7. Diagnose early ultrafiltration failure.
8. Predict dialysis dose.
9. Assess influence of systemic disease on peritoneal membrane function.
Principles of Peritoneal Dialysis 4.9
Baseline peritoneal equilibrium test Population distribution of peritoneal membrane transport types.
Baseline peritoneal equilibrium test results of patients on long-term
peritoneal dialysis in the United States suggest that approximately
High High average Low average Low
transporter transporter transporter transporter 68% have average transport rates, 16% have high transport rates,
D/P creatinine D/P creatinine D/P creatinine D/P creatinine and another 16% have low transport rates . Similar distributions
of transport types have been documented worldwide [14–16].
D/P—dialysate to plasma ratio.
16% 68% 16%
Baseline peritoneal equilibrium test Using transport type to select a peritoneal dialysis regimen. Because
clearance rates continue to increase with time, patients with low
High High average Low average Low transport rates are treated with long dwell exchanges, ie, continu-
ous cyclic peritoneal dialysis (CCPD). Owing to the low rate of
NIPD NIPD High-dose CAPD increase in the dialysate to plasma ratio (D/P), the clearance rate
DAPD CAPD High-dose CCPD only when significant per unit of time is augmented relatively little by rapid exchange
residual renal techniques such as nightly intermittent peritoneal dialysis (NIPD).
function is present On the contrary, the clearance per exchange rate over long dwell
exchanges would be less in patients with high transport rates.
During the short dwell time, patients with high transport rates
capture maximum ultrafiltration and small solutes are completely
equilibrated. Therefore, these patients are best treated with tech-
niques using short dwell exchanges, ie, NIPD or daytime ambulato-
ry peritoneal dialysis (DAPD). Patients with average transport rates
can be effectively treated with either short or long dwell exchange
techniques. CAPD—continuous ambulatory peritoneal dialysis.
0.97 Diagnosis of early ultrafiltration failure. The dialysate to plasma ratio (D/P) curve of sodi-
um, during the unabridged peritoneal equilibrium test (2.5% dextrose dialysis solution),
typically shows an initial decrease owing to the high ultrafiltration rate. Because of sodium
Dialysate to plasma ratio
0.92 sieving, the ultrafiltrate is low in sodium. Consequently, the dialysate sodium is lowered,
0.9 resulting in a lower D/P ratio of sodium. Later, during the dwell when ultrafiltration ceas-
es, dialysate sodium tends to equilibrate with that of capillary blood, returning the D/P
ratio of sodium to baseline. Absence of the initial decrease of the D/P of sodium is an indi-
cation of ultrafiltration failure and is typically seen in the early phase of sclerosing encap-
sulating peritonitis. (From Dobbie and coworkers ; with permission.)
0.0 1.0 2.0 3.0 4.0
4.10 Dialysis as Treatment of End-Stage Renal Disease
C= Creatinine and urea clearances rates. These rates are estimated by dividing the amount of
where C = clearance in mL/min: solute removed per unit of time by the plasma solute concentration. Alternatively, clearance
DxV = dialysate solute removed per minute; also can be estimated by multiplying the solute equilibration rate per unit of time by the
D = dialysate solute concentration; volume of dialysate into which equilibration occurred over the same unit of time. By con-
V = volume of dialysate in mL/min; and vention, the creatinine clearance rate is normalized to body surface area.
P = plasma solute concentration
The urea clearance is normalized to total body water (volume of urea distribution in the
or body) and is expressed as Kt/V. The Kt/Vvalue is a number without a unit ([mL/min min]/
C=(D/P) x V
mL). During intermittent dialysis, with a dialysate flow rate of 30 mL/min, the typical urea
where C = clearance in mL/exchange at time t; clearance is about 18 to 20 mL/min . Increasing the dialysate flow rates to 3.5 to 12
D/P = solute equilibrium rate at time t; and
V = volume of dialysate at time t L/h by rapid exchanges increases the urea clearance rate to a maximum of 30 to 40 mL/min.
A Beyond this maximum rate, the clearance rate begins to decrease owing to the loss of mem-
brane-fluid contact time with infusion and drainage; inadequate mixing may also occur
Kt/V [19–22]. Clearance could be enhanced by increasing the membrane-solution contact .
where K = urea clearance in mL/min; Continuous dialysate flow techniques using either two catheters or double-lumen catheters
t = minutes of therapy; and also have enhanced the urea clearance rate to a maximum of 40 mL/min. At these high flow
V = volume of urea distribution or total
body water rates, poor mixing, channeling, abdominal pain, and poor drainage limit successful applica-
B tion. Maintaining a fluid reservoir in the peritoneal cavity (called tidal peritoneal dialysis)
and then replacing only a fraction of the intraperitoneal volume rapidly, increases clearance
rates by about 30% compared with the standard technique using the same doses owing to
maintaining fluid-membrane contact at higher dialysis-solution flow rates [24–29]. During
continuous ambulatory peritoneal dialysis (CAPD) in adults, the optimum volume that
ensures complete membrane-solution contact is about 2 L [30,32]. Successful use of 2.5-
and 3.0-L volumes has been reported in adult patients undergoing CAPD; however, hernial
complications are increased [32,33].
Mass-transfer area coefficient
The mass-transfer area coefficient (MTAC). The MTAC represents the clearance rate by
The diffusive mass transfer is estimated by
diffusion in the absence of ultrafiltration and when the solute accumulation in the dialysis
solution is zero [34–39]. MTAC is equal to the product of peritoneal membrane perme-
A ability (P) and effective peritoneal membrane surface area (S). Thus, when both capillary
M=I (C – C )
R P D
blood and dialysate flows are infinite, the clearance rate is directly proportional to the
where M = diffusive mass transfer: effective peritoneal surface area and inversely proportional to the overall membrane resis-
A = effective membrane surface area;
tance. However, infinite blood and dialysate flows cannot be achieved, and the maximum
I = coefficient of proportionality;
R = sum of all resistances; clearance rate is unattainable. The closest measurable value, the MTAC, was introduced.
Cp = solute concentration in the potential The MTAC represents an instantaneous clearance without being influenced by ultrafiltra-
capillary blood; and tion and solute accumulation in the dialysate. The MTAC is measured over a test exchange
CD = solute concentration in the dialysate during which at least two blood and dialysate samples are obtained at different dwell
times. The precision of the measurement is enhanced with more data points. The MTAC
is seldom used clinically; however, it is a very useful research tool.
Dividing both sides of the equation by solute
concentration in peripheral blood (CB) will
yield instantaneous clearance or the MTAC;
M A CP CD
R CB CB (
If the peritoneal capillary blood flow is infinite,
Cp will equal Cb and
R ( (
If the dialysate flow is also infinite,
then Co will equal 0, and
Principles of Peritoneal Dialysis 4.11
1. Clough G, Michel CC: Quantitative comparisons of hydraulic perme- 22. Tenckhoff H, Ward G, Boen ST: The influence of dialysate volume
ability and endothelial intercellular cleft dimensions in single form and flow rate on peritoneal clearance. Proc Eur Dial Transplant Assoc
capillaries. J Physiol 1988, 405:563–576. 1965, 2:113–117.
2. Pannekeet MM, Mulder JB, Weening JJ, et al.: Demonstration of 23. Trivedi HS, Twardowski ZJ: Long-term successful nocturnal intermittent
aquaporin-CHIP in peritoneal tissue of uremic and CAPD patients. peritoneal dialysis: a ten-year case study. In Advances in Peritoneal
Peritoneal Dial Int 1996, 16(suppl 1):S54. Dialysis. Edited by Khanna R. Toronto, Canada: Peritoneal Dialysis
3. Flessner MF, Dedrick RL, Schultz JS: Exchange of macromolecules Publications; 1994:81–84.
between peritoneal cavity and plasma. Am J Physiol 1985, 248:H15. 24. Di Paolo N: Semicontinuous peritoneal dialysis. Dial Transplant
4. Flessner MF, Fenstermacher JD, Blasberg RG, Dedrick RL: Peritoneal 1978, 7:839–842.
absorption of macromolecules studied by quantitative autoradiography. 25. Finkelstein FO, Kliger AS: Enhanced efficiency of peritoneal dialysis
Am J Physiol 1985, 248:H26. using rapid, small-volume exchanges. ASAIO J 1979, 2:103–106.
5. Wade OL, Combes B, Childs AW, et al.: The effect of exercise on the 26. Twardowski ZJ, Nolph KD, Khanna R, et al.: Tidal peritoneal dialysis.
splanchnic blood flood and splanchnic blood volume in normal man. In Ambulatory Peritoneal Dialysis: Proceedings of the IVth Congress
Clin Sci 1956, 15:457. of the International Society for Peritoneal Dialysis, Venice, Italy, June
6. Twardowski ZJ, Nolph KD, Khanna R, et al.: Peritoneal equilibration 1987. Edited by Avram MM, Giordano C. New York: Plenum;
test. Peritoneal Dial Bull 1987, 7:138–147. 1990:145–149.
7. Ahearn DJ, Nolph KD: Controlled sodium removal with peritoneal 27. Twardowski ZJ, Prowant BF, Nolph KD, et al.: Chronic nightly tidal
dialysis. Trans Am Soc Artif Intern Organs 1972, 28:423. peritoneal dialysis (NTPD). ASAIO Trans 1990, 36:M584–M588.
8. Popovich RP, Moncrief JW: Kinetic modeling of peritoneal transport: 28. Twardowski ZJ: Tidal peritoneal dialysis: acute and chronic studies.
In Today’s Art of Peritoneal Dialysis. Edited by Trevino-Bacerra A, Eur Dial Transplant Nurses Assoc Eur Renal Care Assoc September
Boen FST. Basel, Switzerland: Karger; 1979:59–72. [Contributions to 1990, 15:4–9.
Nephrology, 1.] 29. Twardowski ZJ: Tidal peritoneal dialysis. In Dialysis Therapy. Edited
9. Twardowski ZJ: Physiology of peritoneal dialysis. In Clinical Dialysis. by Nissenson AR, Fine RN. Philadelphia: Hanley & Belfus;
Edited by Nissenson AR, Fine RN, Gentile DE, edn 3. Norwalk, CT: 1993:153–156.
Appleton & Lange; 1995:322. 30. Twardowski ZJ, Nolph KD, Prowant BF, et al.: Efficiency of high vol-
10. Nolph KD, Twardowski ZJ, Popovich RP, et al.: Equilibration of peri- ume low frequency continuous ambulatory peritoneal dialysis
toneal dialysis solutions during long dwell exchanges. J Lab Clin Med (CAPD). ASAIO Trans 1983, 29:53–57.
1979, 93:246–256. 31. Krediet RT, Boeschoten EW, Zuyderhoudt FMJ, et al.: Differences in
11. Twardowski ZJ: Nightly peritoneal dialysis (why? who? how? and the peritoneal transport of water, solutes and proteins between dialy-
when?). Trans Am Soc Artif Intern Organs 1990, 36:8–16. sis with two- and with three-litre exchanges [thesis]. In Peritoneal
Permeability in Continuous Ambulatory Peritoneal Dialysis Patients.
12. Nolph KD, Hano JE, Teschan PE: Peritoneal sodium transport during Edited by Krediet RT. Amsterdam, Holland: University of Amsterdam;
hypertonic peritoneal dialysis: physiologic mechanisms and clinical 1986:129–146.
implications. Ann Intern Med 1969; 70:931.
32. Twardowski Z, Janicka L: Three exchanges with a 2.5 liter volume
13. Mactier RA, Khanna R, Twardowski ZJ, et al.: Contribution of lym- for continuous ambulatory peritoneal dialysis. Kidney Int 1981,
phatic absorption to loss of ultrafiltration and solute clearances in 20:281–284.
continuous ambulatory peritoneal dialysis. J Clin Invest 1987,
80:1311–1316. 33. Twardowski ZJ, Prowant BF, Nolph KD, et al.: High volume, low fre-
quency continuous ambulatory peritoneal dialysis. Kidney Int 1983,
14. Zabetakis PM, Krapf R, DeVita MV, et al.: Determining peritoneal 23:64–70.
dialysis prescriptions by employing a patient-specific protocol.
Peritoneal Dial Int 1993, 13:189–193. 34. Randerson DH: Continuous ambulatory peritoneal dialysis-a critical
appraisal [thesis]. Sydney, Australia: University of New South Wales;
15. Wolf CJ, Polsky J, Ntoso KA, et al.: Adequacy of dialysis in CAPD and 1980.
cycler PD; the PET is enough. Peritoneal Dial Bull 1992, 8:208–211.
35. Pyle WK: Mass transfer in peritoneal dialysis [thesis]. Austin: University
16. Struijk DG, Krediet RT, Koomen GCM, et al.: A prospective study of of Texas; 1981.
peritoneal transport in CAPD. Kidney Int 1994, 1739–1744.
36. Farrell PC, Randerson DH: Mass transfer kinetics in continuous ambu-
17. Dobbie JW, Krediet RT, Twardowski ZJ, et al.: A 39-year-old man latory peritoneal dialysis. In Proceedings of the First International
with loss of ultrafiltration. Peritoneal Dial Int 1994, 14:384–394. Symposium on Continuous Ambulatory Peritoneal Dialysis. Edited by
18. Nolph KD, Popovich RP, Ghods AJ, et al.: Determinants of low Legrain M. Amsterdam, Holland: Excerpta Medica; 1980:34–41.
clearances of small solutes during peritoneal dialysis. Kidney Int 37. Pyle WK, Moncrief JW, Popovich RP: Peritoneal transport evaluation
1978, 13:117–123. in CAPD. In CAPD Update. Edited by Moncrief JW, Popovich RP.
19. Boen ST: Kinetics of Peritoneal Dialysis. Baltimore, MD: Medicine; New York: Masson; 1981:35–52.
1961:243–287. 38. Pyle WK, Popovich RP, Moncrief JW: Mass transfer in peritoneal dial-
20. Penzotti SC, Mattocks AM: Effects of dwell time, volume of dialysis ysis. In Advances in Peritoneal Dialysis. Edited by Gahl GM, Kessel
fluid, and added accelerators on peritoneal dialysis of urea. J Pharm M, Nolph KD. Amsterdam, Holland: Excerpta Medica; 1981:41–46.
Sci 1971, 60:1520–1522. 39. Garred LF, Canaud B, Farrell PC: A simple kinetic model for assessing
21. Pirpasopoulos M, Lindsay RM, Rahman M, et al.: A cost-effectiveness peritoneal mass transfer in continuous ambulatory peritoneal dialysis.
study of dwell time in peritoneal dialysis. Lancet 1972, 2:1135–1136. ASAIO J 1983, 6:131–137.