PD ADEQUACY

DOI: 10.1510/icvts.2007.165118
2007;
2008;7:116-120; originally published online Nov 30,Interact CardioVasc Thorac Surg
Giorni, Luca Di Chiara and Sergio Picardo
Zaccaria Ricci, Stefano Morelli, Claudio Ronco, Angelo Polito, Giulia V. Stazi, Chiara
surgery
Inotropic support and peritoneal dialysis adequacy in neonates after cardiac
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ARTICLE IN PRESS
www.icvts.org
doi:10.1510/icvts.2007.165118
Interactive CardioVascular and Thoracic Surgery 7 (2008) 116–120
ᮊ 2008 Published by European Association for Cardio-Thoracic Surgery
Institutional report - Congenital
Inotropic support and peritoneal dialysis adequacy in neonates
after cardiac surgery
Zaccaria Ricci *, Stefano Morelli , Claudio Ronco , Angelo Polito , Giulia V. Stazi , Chiara Giorni ,a, a b a a a
Luca Di Chiara , Sergio Picardoa a
Department of Pediatric Cardiology and Cardiac Surgery, Bambino Gesu` Hospital, Piazza S.Onofrio, 00100, Rome, Italya
Department of Nephrology Dialysis and Transplantation, St Bortolo Hospital, Vicenza, Italyb
Received 15 August 2007; received in revised form 12 November 2007; accepted 14 November 2007
Abstract
We describe the impact of cardiovascular pharmacologic support on peritoneal dialysis adequacy in 20 neonates who required postoperative
renal replacement therapy following cardiopulmonary bypass exposure. Peritoneal dialysis was administered for 2.5 (2) days. Peritoneal
dialysis creatinine clearance was 3.4 (2.1) mlyminy1.73 m and ultrafiltration rate was 9.75 (10) mlyh. Residual creatinine clearance was2
31 (26) mlyminy1.73 m . Peritoneal dialysis creatinine clearance appeared to be a function of dialysate flow up to 100 mlyh. No correlation2
was present between inotropes and vasopressors infusion and peritoneal dialysis creatinine clearanceyultrafiltration rate. LDH clearance
was 0.59 (0.85) mlyminy1.73 m and it did not appear to have a correlation with dialysate flow. Patients in-hospital mortality was 20%,2
significantly higher than overall neonatal population admitted to our ICU (4.8%, Ps0.02). Peritoneal dialysis in neonates allows optimal
ultrafiltration rate and adequate small solute clearance, irrespective of hemodynamic status or vasopressor support.
ᮊ 2008 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.
Keywords: Peritoneal dialysis; Inotropic score; Congenital heart disease; Acute kidney injury
1. Introduction
Renal replacement therapy (RRT) is delivered in up to
10% of children undergoing cardiac surgery for correction
of congenital heart disease and is associated with an
increased mortality rate w1–3x. Cardiopulmonary bypass
(CPB) and low flow states likely contribute to the devel-
opment of acute kidney injury (AKI) w4, 5x. Even in the
absence of evident signs of renal dysfunction, a clinical
condition of fluid retention and generalized edema is
common in neonates after major cardiosurgical interven-
tions w3x. While various therapeutic options are available,
early peritoneal dialysis (PD) administration is the treat-
ment of choice for these patients in many centers w2x.
Optimization of fluid balance is primarily targeted by PD
initiation. Nonetheless, clearance of nitrogenous waste
products and other solutes is also likely to be important in
children who develop AKI. Efficiency of PD in the immediate
postoperative period following CPB, however, may be
affected by several factors: small dialysate exchange vol-
umes are often prescribed and delivered in order to mini-
mize hemodynamic derangements, excessive abdominal
pressure rise and leakage of abdominal catheters w6x. Fur-
thermore, blood flow to the peritoneum may be reduced
secondary to diminished cardiac output, high vasopressors
dose, changes in vascular resistance, or capillary leak w6x.
*Corresponding author. Tel.: q39 06 6859 3333.
E-mail address: zaccaria.ricci@fastwebnet.it (Z. Ricci).
PD is currently accepted as a feasible, safe and effective
therapy but information on clearance and ultrafiltration
patterns during PD in this specific subset of patients are
missing. This study aimed to describe the impact of hemo-
dynamic pharmacologic support on PD adequacy in neonates
who require postoperative PD following CPB exposure.
2. Materials and methods
2.1. Study protocol
We conducted a prospective observational study on a
cohort of 20 consecutive neonates who received postoper-
ative PD after cardiac surgery requiring CPB. Indications to
PD were the presence of oliguria (defined as urine output
-0.5 mlykgyh for more than 4 h) andyor generalized ede-
ma with need for supplementary ultrafiltration. At the time
of enrollment, demographic and clinical data (age, sex,
body surface area, primary diagnosis, surgery, duration of
CPB) were collected (Table 1). Cycling peritoneal dialysis
was performed in all subjects using a cuffed Tenckhoff
catheter. A fixed exchange volume of 10 mlykg was always
infused. Dwell and drainage times varied depending on
patients needs. Hence, final dialysate flow (hourly Qd:
exchange volume=number of exchanges per hour) was
exclusive function of dwell and drainage times and not of
volume infused per cycle. Dialysis fluid glucose concentra-
tion (ATC B05DA, AIC Baxter SpA, Rome, Italy) was 1.35%.

ARTICLE IN PRESS
117Z. Ricci et al. / Interactive CardioVascular and Thoracic Surgery 7 (2008) 116–120
Table 1
Demographic and clinical data of enrolled patients
Age (days) Sex BSA (m )2
Diagnosis CPByX clamp (min) Surgical procedure INM
23 M 0.190 DORVqPValveStqTAPVR 115 S-P shunt No
12 F 0.198 AAI type B 180 Correction Yes
16 F 0.198 TGA 440 Correction No
10 F 0.134 AAI type B 120 Correction No
19 F 0.134 AAI type B 140 Correction No
4 M 0.149 AoCo 120* Coartectomy Yes
30 M 0.198 AoCoqSubAoStqMitralRing 258 Ross-KonnoqMVS No
25 M 0.195 AoCo 18* Coartectomy Yes
2 M 0.198 TAPVRqAoCo 100 Correction No
2 M 0.168 PAqVSD 120 Correction No
26 M 0.226 Tetralogy of Fallot 212 Correction No
8 M 0.204 PAqIAS 60 OPqBT-shunt dx No
24 M 0.198 TGAqIAS 270 ASO No
19 F 0.190 TGAqVSD 330 ASOqclosure of VSD No
30 F 0.184 cAVC type A 230 Correction No
5 F 0.190 HLHS 270 Norwood-Sano Yes
25 M 0.195 AoCo 28* Aortoplasty No
26 M 0.226 Tetralogy of Fallot 212 Correction Yes
BSA, body surface area; CPB, cardiopulmonary bypass; *, cross-clamp time; M, male; F, female; DORV, double outlet right ventricle; PvalveSt, pulmonary valve
stenosis; TAPVR, total anomalous pulmonary venous return; S-P, systemic to pulmonary; AAI, aortic arch interruption; TGA, transposition of the great arteries;
AoCo, aortic coactation; SubAoSt, subaortic stenosis. PA, pulmonary artery; VDS, ventricular septal defect; IAS, intact atrial septum; OPqBT-shunt, outflow
patch and Blalock Taussig shunt; ASO, arterial switch operation; CAVC, common atrioventricular canal; HLHS, hypoplastic left heart syndrome; INM, in-hospital
mortality.
After the institution of PD and every 24 h for a period of
three days a simultaneous sample of blood and 6 h PD
drainage were analyzed locally for creatinine, lactic dehy-
drogenase (LDH), sodium, potassium, glucose and lactates.
These solutes were selected among those routinely avail-
able in our laboratory. Six-hour urine collection was also
analyzed for creatinine clearance in patients with residual
renal function. Mean arterial pressure, heart rate, vaso-
pressors dose, diuretics, ultrafiltration rate, fluid balance
and significant clinical events occurring during the study
period were recorded. Duration of PD, length of intensive
care unit stay and out of hospital mortality were also
documented. The Institutional Review Board of Bambino
Gesu` Hospital approved the protocol and waived the need
for consent from patient parents because of the observa-
tional nature of the study.
2.2. Measurements
Body surface area (BSA) was determined using duBois
formula as follows:
BSA m s0.007184=wt =ht .2 0.425 0.725
PD solute clearance was calculated by multiplying a 6 h
dialysate volume by the ratio between solute concentration
in dialysate and plasma (DyP ). Residual creatinine clear-solute
ance was calculated when present multiplying 6 h urine
volume (simultaneous to dialysate collection) by the ratio
between creatinine concentration in urine and plasma. The
period of 6 h was selected in order to include periods with
constant hemodynamic parameters and drug infusions that
could occur over a broader time. Clearances were always
indexed to 1.73 m .2
Inotropic score (IS) was calculated as previously described
w7x: dopamine mgykgymin=1qdobutamine mgykgymin=1q
milrinone mgykgymin=15qepinephrine mgykgymin=100.
IS is represented by a wide range of values indicating
different inotropic and vasopressor drug regimens. In the
absence of other direct instrumental measures of cardiac
performance, that are not currently available for neonates,
different ISs correlate with different dosages of vasoactive
drugs indirectly indicating different cardiac output states.
In order to compare subgroups subjected to different ISs,
we stratified patients into three pre determined categories:
low IS (value -20), intermediate IS (value between 21 and
30), high IS (value over 31). A further stratification was
obtained dividing patients in low Qd (30–40 mlyh), inter-
mediate Qd (60–75 mlyh) and high Qd (90–120 mlyh).
2.3. Statistical analysis
All data are expressed as mean (S.D.). One-way analysis
of variance was utilized for analysis of hemodynamic par-
ameters among the three IS categories. Two-way analysis
of variance with Qd and IS as sources of variation was
utilized to show the impact of these parameters on solute
clearances and ultrafiltration. Wilcoxon signed rank test
was utilized to compare groups where appropriate. Spear-
man test was used for correlations. A P-value -0.05 was
considered significant.
3. Results
Twenty consecutive neonates who underwent post CPB PD
were considered eligible and no one was excluded from
the protocol. Indication to RRT was oliguria in 13 cases and
generalized edema with need for supplementary ultrafiltra-
tion in seven patients. In all cases AKI developed after

ARTICLE IN PRESS
118 Z. Ricci et al. / Interactive CardioVascular and Thoracic Surgery 7 (2008) 116–120
Fig. 2. Both PD creatinine (a) and LDH (b) dialysate to plasma ratio (DyP)
showed a direct correlation with dwell times duration. In the case of LDH,
longer dwell times allowed a relatively higher increase in DyP ratio with
respect to creatinine. This effect might elucidate the role of allowing longer
dwell times in order to optimize clearance of higher molecular weight
solutes.
Fig. 3. PD creatinine clearance appeared to be a function of Qd.
Fig. 1. Serum creatinine concentration at PD start, day 2 and day 3.
Table 2
Hemodynamic parameters within the three inotropic score (IS) classes
IS 1 IS 2 IS 3 P-value
Lactates (mgydl) 36 (44) 36 (51) 41 (41) 0.88
MAP (mmHg) 48 (7) 53 (9) 48 (10) 0.15
CVP (mmHg) 8 (3) 9 (2) 7 (3) 0.43
HR (bymin) 152 (6) 152 (15) 163 (14) 0.10
MAP, mean arterial pressure; CVP, central venous pressure; HR, heart rate.
surgery. Age at operation was 21 (17) days and weight 2.8
(0.6) kg. Fifty-five dialysate collections were performed.
Five patients out of 20 stopped PD before the third protocol
day. PD was administered for 2.5 (2) days. Heart rate,
systolic arterial pressure, central venous pressure and lac-
tate levels did not show statistical differences between the
three IS categories (P)0.05) (Table 2). Serum creatinine
concentration at PD start was 0.97 mgydl (0.9); it was 0.8
(0.6) at PD stop (P-0.05) (Fig. 1). Mean prescribed Qd
was 60 (45) mlyh. PD creatinine clearance was 3.4 (2.1)
mlyminy1.73 m and ultrafiltration rate was 9.75 (10)2
mlyh. As expected, DyP showed a direct correlationcreatine
with dwell time duration (rs0.37, Ps0.009) (Fig. 2a). PD
creatinine clearance appeared to be correlated Qd up to a
dialysate of 100 mlyh (Ps0.02) (Fig. 3). No correlation was
present between IS and PD creatinine clearance (rs0.178,
Ps0.2). This tendency was maintained when patients were
stratified into three IS classes and three Qd classes (Fig.
4): Qd but not IS was found to affect peritoneal creatinine
clearance (Ps0.0135). Residual renal creatinine clearance
was present in seven patients and was 31 (26) mlyminy1.73
m . Ultrafiltration rate was not correlated to Qd (rsy0.05,2
Ps0.2) nor to IS (rsy0.02, Ps0.18). PD allowed to
achieve a mean negative fluid balance of 160 (228)
mlyday, that corresponded to 10.5 mlyh. LDH clearance
was 0.59 (0.85) mlymin=1.73 m . DyP appeared to have2
LDH
a direct correlation with dwell times (rs0.28, Ps0.048)
(Fig. 2b) but linear regression did not show any correlation
between LDH clearance and Qd. Albumin loss was present
through peritoneal drainage. Mean DyP was 0.05 (0.06)albumin
without significant differences within the three IS classes
(P)0.05). Mean albumin concentration in peritoneal drain-
age was 0.27 gydl (0.46) with a mean albumin loss in the
24 h of 2.2 g (1.3): in particular, daily albumin loss ranged
from 0.01 to 4.3 g.
In-hospital mortality among this cohort of patients was
20%, that was significantly higher than the overall neonatal
population admitted to our ICU (4.8%, Ps0.02). There was
full renal recovey in 19 patients (95%) at PD stop. No major
complications were reported. Catheter site leakage from
catheter insertion was observed in two patients but did not
require any specific intervention. Hemodynamic derange-
ments were never described in correlation with DP cycles.

ARTICLE IN PRESS
119Z. Ricci et al. / Interactive CardioVascular and Thoracic Surgery 7 (2008) 116–120
Fig. 4. Patients were stratified into three IS classes and three Qd classes: Qd
but not IS was found to affect peritoneal creatinine clearance (Ps0.0135).
4. Discussion
PD represents a simple and safe system for fluid removal,
depending on osmolarity, volume and dwell-time of the
dialysis fluid. Prevention and treatment of fluid overload,
main goal of acute renal support, are more likely to be
achieved by application of high dialysate volumes w8–10x.
Unfavorably, modifications of atrial and mean pulmonary
artery and systemic pressure have been observed in chronic
PD and in children after cardiac surgery w11x. For this
reason, a PD prescription of 10 mlykg, previously defined
‘low volume PD’, is commonly prescribed during neonatal
RRT w8x. The aim of our study was to show adequacy of low
flow PD, evaluating if its efficiency at different dwell times
was affected by vasopressor drug administration and
patients hemodynamic conditions. Our cohort of 20 post-
cardiosurgical neonates was very homogeneous about age,
weight and BSA. Interestingly, our patients tended to main-
tain a similar mean arterial pressure and heart rate inde-
pendently from IS, probably due to the fact that in our
center inotropes and vasopressors dose is targeted on these
parameters. In all patients, ultrafiltration needs were ade-
quately fulfilled by PD with an ultrafiltration rate of about
10 mlyh and a negative fluid balance ranging from 50 to
500 mlyday. Net ultrafiltration depends mainly on glucose
concentration of dialysis bags: in our cohort, ultrafiltration
was not influenced by Qd nor by IS. Our PD prescription
determined a relatively low creatinine clearance with a
tendency to increase with Qd: since cycle volumes were
predetermined at 10 mlykg, Qd was augmented only by the
increase of cycles per hour and by the consequent decrease
of dwell times. Creatinine molecular weight is sufficiently
small to cross efficiently the peritoneal membrane (high
DyP ) even when dwell times were very short (Fig. 2a):creatine
for this reason low flow PD is able to progressively increase
creatinine clearance at high Qd with short dwell times.
IS seemed to have no impact on PD efficiency and creat-
inine clearance was never affected by hemodynamic status.
Peritoneal blood flow is generally considered high enough
to avoid any limitations in solute clearance. Nonetheless,
the real impact of effective peritoneal blood flow is still
controversial w12x. In our patients, the absence of corre-
lation between IS and PD creatinine clearance might sug-
gest that during low volume PD mesenteric blood flow
never decreased to a level able to impact PD efficiency. It
remains to be elucidated however, if vasopressor adminis-
tration actually causes mesenteric blood flow reduction,
when hemodynamic parameters are maintained close to
normal levels w13x. The direct correlation between creat-
inine clearance and Qd tended to reach a plateau for flows
above 100 mlyh, that were rarely achieved in our patients.
This threshold might represent the point where mesenteric
blood flow is considered to be a limiting factor to further
clearance rise: it can be speculated that only after reaching
this level of PD dose, IS and hemodynamic status might
impact treatment efficiency. For larger solutes, the low
diffusion coefficients of the molecule may represent the
most important limitation to transport w14, 15x. In our
treatments, analysis of LDH clearance, a 140 kD molecular
weight solute, showed a different clearance pattern from
creatinine: dwell times influenced DyP (Fig. 2b) to theLDH
point that the increase of cycles per hour and the conse-
quent decrease of dwell times did not determine any
clearance rise. Differently from what is described above
about creatinine, higher molecular solutes clearance might
be improved by high exchange volumes with prolonged
dwell times, in order to optimize peritoneal diffusion. We
found a significant albumin loss through peritoneal drain-
age: such amount of proteins is routinely infused in excess
by fresh frozen plasma and human albumin to our patients.
Furthermore, the clinical meaning of such finding is
unclear: particularly, the wide range of albumin loss does
not allow to understand whether the albumin was lost due
to ascites, secondary to heart failure, or to capillary
leakage, secondary either to generalized inflammation and
to chemical peritonitis.
A major limit of this study was its observational nature
and no definitive conclusions can be drawn by these results.
Measured solutes and PD prescriptions were not modified
with respect to the routine of our department. Nonethe-
less, this is the first attempt to monitor PD prescription
and delivery. Further prospective studies should analyze
different PD exchange models and specific mediators clear-
ances to verify our suggestions.
5. Conclusions
Low flow PD in neonates shows optimal ultrafiltration
patterns and adequate small solute clearances, irrespective
of hemodynamic status or vasopressor support.
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DOI: 10.1510/icvts.2007.165118
2007;
2008;7:116-120; originally published online Nov 30,Interact CardioVasc Thorac Surg
Giorni, Luca Di Chiara and Sergio Picardo
Zaccaria Ricci, Stefano Morelli, Claudio Ronco, Angelo Polito, Giulia V. Stazi, Chiara
surgery
Inotropic support and peritoneal dialysis adequacy in neonates after cardiac
This information is current as of August 20, 2008
& Services
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