Influence of peritoneal residual volume on the results of the peritoneal equilibration test. Prospective study

BACKGROUND

Categorization of the capacity of ultrafiltration during a peritoneal equilibration test (PET) is a usual step during the monitoring of peritoneal transport characteristics of Peritoneal Dialysis (PD) patients. Quantifying the peritoneal residual volume (Vr) after the dwell preceding the PET (Vrpre) and at the end of the test (Vrpost) could help to improve the accuracy of the estimation of this variable.

METHOD

Following a prospective design, we calculated Vrpre and Vrpost in 116 patients, incident or prevalent on DP, who underwent one or two (n = 27) PET with 3,86/4,25% glucose-based PD solutions and complete drainage at 60 min. We evaluated the consistency of Vr by comparing Vrpre and Vrpost, as also these two parameters in repeated tests. We scrutinized potential associations between demographic and clinical factors, on one side, and the amount of Vr on the other, as also the impact of correcting ultrafiltration during PET for Vr on the categorization of the capacity of ultrafiltration.

RESULTS

As a mean, Vrpost was larger than Vrpre. Consequently, correction of ultrafiltration for Vr resulted in significantly higher values than those obtained according to the standard procedure (494 vs. 449 mL, p < 0,0005). We disclosed marked inconsistencies for different estimations of Vr in the same patients (Vrpre vs Vrpost and repeated PET studies). Moreover, no demographic or clinical variable was able to predict the amount of Vr. We observed a significant deviation (>200 mL) between both methods of estimation of the capacity of utrafiltration in only 12,9% of the patients. However, 21,1% of the patients categorized as cases of ultrafiltration failure according to the standard procedure did not maintain this condition after correction for Vr.

CONCLUSIONS

Correction for Vr of the capacity of ultrafiltration during a PET carries, as a mean, a minor impact on the categorization of this parameter. However, the results of the test can be significantly affected in 12,9% of the cases. We have been unable to detect demographic or clinical predictors of Vr, which suggests a random component for the mechanics of single peritoneal exchanges. We suggest that Vr should be estimated at the time of categorizing the capacity of ultrafiltration, whenever inconsistencies during serial PET studies are detected.

Long-term trends in the incidence of peritoneal dialysis-related peritonitis disclose an increasing relevance of streptococcal infections: A longitudinal study

Background

The selective impact of strategies for prevention of PD-related peritonitis (PDrP) may have modified, in the long term, the causal spectrum, clinical presentation and outcomes of these infections.

Objectives

To compare trends in the incidence of PDrP by different microorganisms during a 30-year period, with a particular focus on streptococcal infections. To analyze the clinical presentation and outcomes of these infections. Secondarily, to investigate how the isolation of different species of streptococci can influence the clinical course of PDrP by this genus of bacteria.

Method

Following a retrospective, observational design we investigated 1061 PDrP (1990–2019). We used joinpoint regression analysis to explore trends in the incidence of PDrP by different microorganisms, and compared the risk profile (Cox), clinical presentation and outcomes (logistic regression) of these infections.

Main results

Our data showed a progressive decline in the incidence of PDrP by staphylococci and Gram negative bacteria, while the absolute rates of streptococcal (average annual percent change +1.6%, 95% CI -0.1/+3.2) and polymicrobial (+1.8%, +0.1/+3.5) infections tended to increase, during the same period. Remarkably, streptococci were isolated in 58.6% of polymicrobial infections, and patients who suffered a streptococcal PDrP had a 35.8% chance of presenting at least one other infection by the same genus. The risk profile for streptococcal infections was comparable to that observed for PDrP overall. Streptococcal PDrP were associated with a severe initial inflammatory response, but their clinical course was generally nonaggressive thereafter. We did not observe a differential effect of different groups of streptococci on the clinical presentation or outcome of PDrP.

Conclusions

Time trends in the incidence of PDrP by different microorganisms have granted streptococci an increasing relevance as causative agents of these infections, during the last three decades. This behaviour suggests that current measures of prevention of PDrP may not be sufficiently effective, in the case of this genus of microorganisms.

Does Prior Abdominal Surgery Influence Peritoneal Transport Characteristics or Technique Survival of Peritoneal Dialysis Patients?

INTRODUCTION

Prior abdominal surgery may result in peritoneal membrane adhesions and fibrosis, compromising the success of peritoneal dialysis (PD). The impact of this factor on peritoneal membrane function and PD technique survival has not been adequately investigated.

METHODS

Following an observational, retrospective design, we studied 171 incident PD patients, with the main objective of analyzing the influence of prior abdominal surgical procedures (main study variable) on baseline and evolutionary peritoneal transport characteristics (main outcome) and PD patient and technique survival (secondary outcomes). Abdominal surgeries were categorized according to the degree of presumed injury to the peritoneal membrane. We also considered the additive effect of aggressions to the membrane during the first year on PD therapy.

RESULTS

All patients had a baseline peritoneal equilibration test with complete drainage at 60', and 113 patients had a second study at the end of the first year. Sixty-one patients (35.7%) had a record of prior abdominal surgery, including 29 patients with at least one major intraperitoneal surgery, 22 having undergone minor intraperitoneal procedures, and 21 with a background of major abdominopelvic extraperitoneal surgery. We did not observe differences, at baseline or after 1 year, among patients with or without previous abdominal procedures regarding small solute transport, overall capacity of ultrafiltration, free water transport, small pore ultrafiltration, or peritoneal protein excretion. Stratified analysis, considering prior and first-year-on-PD peritoneal aggressions, did not reveal any differences, although in this case our analysis was hampered by a limited statistical power. Abdominal surgical events did not influence patient or PD technique survival.

CONCLUSION

Prior abdominal surgical procedures do not appear to compromise peritoneal membrane function or technique survival in patients successfully started on PD.

[SARS-CoV-2 infection in patients on renal replacement therapy. Report of the COVID-19 Registry of the Spanish Society of Nephrology (SEN)]

Introducción

La reciente aparición de la pandemia por el coronavirus SARS-CoV-2 ha impactado de forma muy importante en la población general. Los pacientes en tratamiento renal sustitutivo (TRS) no han sido ajenos a esta situación y por sus características resultan especialmente vulnerables. Presentamos los resultados del análisis del Registro COVID-19 de la Sociedad Española de Nefrología.

Material y métodos

EL Registro comenzó a funcionar el 18 de marzo de 2020. Recoge variables epidemiológicas, datos del contagio y diagnóstico, clínica acompañante, tratamientos y desenlace. Se trata de un registro on line. Los pacientes fueron diagnosticados de infección por SARS-CoV-2 en base a los resultados de la PCR del virus, realizada tanto en pacientes que habían manifestado clínica compatible o tenían signos sospechosos como en aquellos a los que se había hecho como cribado tras algún contacto conocido con otro enfermo.

Resultados

A fecha 11 de abril el Registro disponía de datos de 868 pacientes, procedentes de todas las comunidades autónomas. La modalidad de TRS más representada es la hemodiálisis en centro (HDC) seguida de los pacientes trasplantados. La clínica de presentación es similar a la población general. Un porcentaje muy elevado (85%) requirió ingreso hospitalario, un 8% en unidades de cuidados intensivos. Los tratamientos más utilizados fueron hidroxicloroquina, lopinavir-ritonavir y esteroides. La mortalidad es elevada y alcanza el 23%: los pacientes fallecidos estaban con más frecuencia en HDC, desarrollaban más frecuentemente neumonía y recibían en menos ocasiones lopinavir-ritonavir y esteroides. La edad y la neumonía se asociaban de forma independiente al riesgo de fallecer.

Conclusiones

La infección por SARS-CoV-2 afecta ya a un número importante de pacientes españoles en TRS, fundamentalmente aquellos que están en HDC, las tasas de hospitalización son muy elevadas y la mortalidad es elevada; la edad y el desarrollo de neumonía son factores asociados a mortalidad.

A Comparative Analysis on the Incidence of Peritonitis and Exit-Site Infection in Capd and Automated Peritoneal Dialysis

Objective

To compare the incidence of peritonitis and exit-site infection in an ample group of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis in a single center during a 10-year period.

Design

Nonrandomized, prospective study.

Setting

Public, tertiary care hospital providing peritoneal dialysis care to a population of (approximately) 750 000 people.

Patients

We studied 213 patients on CAPD and 115 on automated peritoneal dialysis (APD) starting therapy between January 1989 and August 1998, with a minimum follow-up of 3 months.

Main Outcome Measures

Using a multivariate approach, we compared the incidence, clinical course, and outcome of peritonitis and exit-site infections in both groups, controlling for other risk factors for the complications studied.

Results

The incidence of peritonitis was higher in CAPD than in APD (adjusted difference 0.20 episodes/ patient/year, 95% confidence interval 0.08 – 0.32). There was a trend for CAPD patients to present earlier with peritonitis than APD patients, yet the incidence of and survival to the first exit-site infection were similar in both groups. The etiologic spectrum of infections displayed minor differences between groups. Automated PD patients were more frequently hospitalized for peritonitis, but otherwise, the complications and outcome of peritonitis and exit-site infections did not differ significantly between patients on CAPD and those on APD.

Conclusions

Automated PD is associated with a lower incidence of peritonitis than is CAPD, while exit-site infection is similarly incident under both modes of therapy. The etiologic spectrum, complications, and outcome of peritonitis and exit-site infection do not differ markedly between CAPD and APD. Prevention of peritonitis should be included among the generic advantages of APD over CAPD.

Sodium Removal in Patients Undergoing CAPD and Automated Peritoneal Dialysis

Objectives

To compare sodium removal in continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) patients, and to identify the main factors that modify Na removal in clinical practice in these patients.

Design

Study in three steps. Cross-sectional observational (Study A), and longitudinal interventional (Studies B and C).

Patients and Methods

First (Study A) we carried out a cross-sectional survey of Na removal in 63 patients on CAPD and 78 patients on APD. Second (Study B), we studied Na removal in 32 patients before and after changing from CAPD to APD therapy. Finally (Study C), we analyzed the impact on Na removal of introducing icodextrin for the long dwell in 16 patients undergoing CAPD or APD.

Results

In Study A, total Na removal averaged 210 mmol/day for CAPD patients and 91 mmol/day for APD patients ( p < 0.001); Na removal was < 100 mmol/day in 7.1% of CAPD patients and 56.4% of APD patients. Multivariate analysis identified ultrafiltration [B = 125 mmol/day, 95% confidence interval (CI) 110, 140], CAPD therapy (B = 60 mmol/day, 95%CI 37, 83), and residual diuresis (B = 51 mmol/L, 95%CI 34, 69) as independent predictors of Na removal (adjusted r2 = 0.76). For APD patients, longer nocturnal dwell times and performing a supplementary diurnal exchange were also independently associated with higher Na removal rates. In Study B, Na removal decreased from 192 to 92 mmol/day (median) after the change to APD ( p = 0.02). In Study C, peritoneal Na removal increased from 98 to 148 mmol/day (median) ( p = 0.04) after introducing icodextrin.

Conclusions

Standard APD schedules are frequently associated with poor Na removal rates. For any degree of ultrafiltration, Na removal is better in CAPD than in APD. Icodextrin, supplementary diurnal exchanges, and longer nocturnal dwell times improve Na removal in APD. Sodium removal can be estimated from ultrafiltration in patients on CAPD, but must be specifically monitored in patients on APD.

Peritonitis-Related Mortality in Patients Undergoing Chronic Peritoneal Dialysis

Peritonitis is a well-known cause of mortality in peritoneal dialysis (PD) patients. We carried out a retrospective study to disclose the clinical spectrum and risk profile of peritonitis-related mortality. We analyzed 693 episodes of infectious peritonitis suffered by 565 patients (follow-up 1149 patient-years). Death was the final outcome in 41 cases (5.9% of episodes), peritonitis being directly implicated in 15.2% of the global mortality and 68.5% of the infectious mortality observed. In 41.5% of patients with peritonitis-related mortality, the immediate cause of death was a cardiovascular event. Highest mortality rates corresponded to fungal (27.5%), enteric (19.3%), and Staphylococcus aureus (15.2%) peritonitis. Multivariate analysis disclosed that the baseline risk of peritonitis-related mortality was significantly higher in female [relative risk (RR) 2.13, 95% confidence interval (CI) 1.24 – 4.09, p = 0.02], older (RR 1.10/year, CI 1.06 – 1.14, p < 0.0005), and malnourished patients (RR 2.51, CI 1.21 – 5.23, p = 0.01) with high serum C-reactive protein (s-CRP) levels (RR 4.04, CI 1.45 – 11.32, p = 0.008) and a low glomerular filtration rate (RR 0.75 per mL/minute, CI 0.64 – 0.87, p < 0.0005). Analysis of risk after a single episode of peritonitis and/or subanalysis restricted to peritonitis caused by more aggressive micro-organisms disclosed that overall comorbidity [odds ratio (OR) 1.21, CI 1.05 – 1.71, p = 0.005], depression (OR 2.35, CI 1.14 – 4.84, p = 0.02), and time on PD at the time of the event (OR 1.02/month, CI 1.00 – 1.03, p = 0.02) were other predictors of mortality.

In summary, the etiologic agent is a definite marker of peritonitis-related mortality but gender, age, residual renal function, inflammation (s-CRP), malnutrition, and depression are other significant correlates of this outcome. Most of these risk factors are common to cardiovascular and peritonitis-related mortality, which may explain the high incidence of cardiovascular event as the immediate cause of death in patients with peritonitis-related mortality.

Incidence and Significance of Peritoneal Eosinophilia during Peritoneal Dialysis-Related Peritonitis

Objective

To determine the incidence and significance of peritoneal eosinophilia (PEo) during peritoneal dialysis (PD)-related peritonitis.

Design

Retrospective observational study.

Setting

Tertiary-care public hospital.

Patients and Method

We performed a cytological study of dialysate at the start of 465 cases of peritonitis diagnosed between January 1987 and May 2002. Cases associated with PEo (> 10% eosinophils) were classified according to their infectious or seemingly noninfectious origin. We compared the two groups, trying to disclose differentiating patterns of presentation.

Results

We found PEo in 42 cases. Infectious peritonitis was the final diagnosis in 22 of the 42 cases; a diagnosis of idiopathic eosinophilic peritonitis was finally established in 20 cases. The etiologic spectrum of infectious peritonitis with PEo did not differ markedly from the global spectrum of peritonitis in our unit. Infectious peritonitis with PEo tended to appear later in the course of PD therapy, presented with more severe clinical symptoms, displayed higher total peritoneal leukocyte and neutrophil counts, and showed lower degrees of PEo than idiopathic eosinophilic peritonitis, but overlap between the groups was significant.

Conclusions

Peritoneal eosinophilia is infrequent but not rare during infectious PD-related peritonitis. Our findings agree with established concepts on idiopathic eosinophilic peritonitis, but overlap in presentation with infectious eosinophilic peritonitis is significant, which should be taken into consideration at the time of planning therapy for this condition.

Use of Icodextrin during Nocturnal Automated Peritoneal Dialysis Allows Sustained Ultrafiltration While Reducing the Peritoneal Glucose Load: A Randomized Crossover Study

Background

Optimization of ultrafiltration and preservation of the peritoneal membrane are desirable objectives in peritoneal dialysis (PD) patients. Mixtures of glucose-and non-glucose-based solutions may help to meet both targets simultaneously.

Aim

To analyze the effects, in terms of ultrafiltration and peritoneal glucose load, of including icodextrin-based dialysate in the nocturnal schedule of patients undergoing automated PD (APD).

Method

Following a randomized crossover design, 17 APD patients underwent two 10-day study periods under identical prescription (including amino acid-based solution for the night schedule), except for the substitution of 2 L glucose-based dialysate in the nocturnal mixture (control) by a similar amount of icodextrin-based dialysate (icodextrin phase) in one period. Dependent variables included ultra-filtration, sodium removal, peritoneal glucose load, and residual renal function. We measured serum and urine levels of icodextrin metabolites at the end of each phase.

Results

Ultrafiltration was marginally higher during the icodextrin phase (median 815 vs 763 mL/day, p = 0.07), while peritoneal sodium removal was similar in both phases (74 vs 71 mmol/L/day). Peritoneal glucose load (median 67.5 vs 104.0 g/day, p < 0.005) and absorption (14.0 vs 35.6 g/day, p < 0.005) were lower during the icodextrin phase. Diuresis was also modestly lower during the icodextrin phase (500 vs 600 mL/day, p < 0.05). Serum levels of icodextrin metabolites were moderately higher in the icodextrin phase ( p < 0.005) in patients both on and off diurnal icodextrin.

Conclusion

Inclusion of amino acid- and icodextrin-based solutions in the nocturnal schedule of APD patients may allow sustained ultrafiltration and sodium removal while significantly reducing the peritoneal glucose load in these patients.

Status of SARS-CoV-2 infection in patients on renal replacement therapy. Report of the COVID-19 Registry of the Spanish Society of Nephrology (SEN)☆

Introduction

The recent appearance of the SARS-CoV-2 coronavirus pandemic has had a significant impact on the general population. Patients on renal replacement therapy (RRT) have not been unaware of this situation and due to their characteristics they are especially vulnerable. We present the results of the analysis of the COVID-19 Registry of the Spanish Society of Nephrology.

Material and methods

The Registry began operating on March 18th, 2020. It collects epidemiological variables, contagion and diagnosis data, signs and symptoms, treatments and outcomes. It is an online registry. Patients were diagnosed with SARS-CoV-2 infection based on the results of the PCR of the virus, carried out both in patients who had manifested compatible symptoms or had suspicious signs, as well as in those who had undergone screening after some contact acquainted with another patient.

Results

As of April 11, the Registry had data on 868 patients, from all the Autonomous Communities. The most represented form of RRT is in-center hemodialysis (ICH) followed by transplant patients. Symptoms are similar to the general population. A very high percentage (85%) required hospital admission, 8% in intensive care units. The most used treatments were hydroxychloroquine, lopinavir–ritonavir, and steroids. Mortality is high and reaches 23%; deceased patients were more frequently on ICH, developed pneumonia more frequently, and received less frequently lopinavir–ritonavir and steroids. Age and pneumonia were independently associated with the risk of death.

Conclusions

SARS-CoV-2 infection already affects a significant number of Spanish patients on RRT, mainly those on ICH, hospitalization rates are very high and mortality is high; age and the development of pneumonia are factors associated with mortality.

Analysis of Factors Influencing the Prognostic Significance of Hyponatremia in Peritoneal Dialysis Patients

BACKGROUND

The evidence linking low serum sodium levels with the risk of mortality in peritoneal dialysis (PD) patients is controversial. Considering the different mechanisms contributing to hyponatremia in these patients, it is conceivable that the prognostic significance of this factor may vary, according to the clinical setting.

METHODS

Following a retrospective, observational design, we analyzed the association between hyponatremia and mortality in 748 patients incident on PD. We applied multivariate strategies of analysis, with the main objective of identifying subgroups of patients in whom hyponatremia could sustain different degrees of association with mortality (main outcome variable). For this purpose, we performed preliminary analyses to: (1) disclose predictors of serum sodium levels before and after (mean of first 3 months) initiation of PD (main study variable) and (2) investigate the overall prognostic significance of hyponatremia, in our patients.

RESULTS

Comorbidity, hypoalbuminemia, and lower glomerular filtration rate (GFR) were main predictors of hyponatremia. Use of icodextrin was another inverse correlate of serum sodium, and the only consistent predictor of a decline of natremia, once PD was started. Multivariate analysis confirmed early hyponatremia as an independent marker of survival. However, stratified analyses showed that this association was most apparent in specific subsets, namely, hypoalbuminemic, more anemic patients with higher baseline levels of GFR and C-reactive protein and faster peritoneal solute transport rates. Other factors potentially reinforcing the prognostic significance of hyponatremia included lower lean body mass levels, nonprescription of renin-angiotensin-aldosterone system antagonists, and use of icodextrin-based PD solution. On the contrary, baseline overhydration or categorization by classic predictors of mortality (age, comorbidity, diabetes) did not appear to influence the risk pattern associated with lower serum sodium levels.

CONCLUSIONS

Our results suggest that hyponatremia performs as a consistent correlate of the risk of mortality mainly in PD patients manifesting direct or indirect signs of inflammation and wasting, while this association is not apparently linked to the presence of overhydration or nominal, preexisting comorbid conditions.

High rates of protein intake are associated with an accelerated rate of decline of residual kidney function in incident peritoneal dialysis patients

BACKGROUND

Preservation of residual kidney function (RKF) is a relevant objective in peritoneal dialysis (PD) patients. The influence of dietary protein intake (PI) on this variable has not been adequately investigated.

METHODS

Following an observational design, we studied 336 patients incident on PD, with a minimum follow-up of 6 months. The main study variable was the mean PI [normalized rate of protein nitrogen appearance (nPNA)] during the first 4 months on PD. The main outcome variables were the absolute rate of decline of RKF and the proportion of patients presenting a >50% decay of their RKF during the first year of follow-up. We applied univariate and multivariate strategies of analysis, taking into consideration the main control variables bearing a correlation with nPNA and/or RKF.

RESULTS

Mean nPNA (first 4 months) was 1.23 ± 0.33 g/kg/day, while the overall rate of decline of RKF was -0.13 ± 0.29 mL/min/month; 69 patients (25.1%) had lost >50% of their initial RKF by the end of the first year. Univariate analysis disclosed consistent associations between the main study variable on one hand and baseline RKF (r = 0.32, P < 0.0005) and its rate of decline (r = -0.23, P < 0.0005) on the other. The latter two variables were also significantly correlated (r = -0.36, P < 0.0005). Multivariate analysis identified mean nPNA as an independent predictor of the rate of decline of RKF [odds ratio 1.09 per 0.10 g/kg/day, 95% confidence interval (CI) 0.99-1.19, P = 0.058] and, in particular, of the probability of losing >50% of the baseline RKF during the first year of treatment (odds ratio 1.15 per 0.10 g/kg/day, 95% CI 1.04-1.27, P = 0.006).

CONCLUSION

Higher rates of PI during the first months of therapy are associated with a faster decline of RKF among patients incident on PD. Our results underline the convenience of keeping an adequate balance between sufficient protein ingestion, to prevent malnutrition and wasting, and sensible restriction in stable, adequately nourished individuals with rates of intake in the higher range or above-recommended allowances.

Peritoneal Water Transport Characteristics of Diabetic Patients Undergoing Peritoneal Dialysis: A Longitudinal Study

BACKGROUND

Volume overload is frequent in diabetics undergoing peritoneal dialysis (PD), and may play a significant role in the excess mortality observed in these patients. The characteristics of peritoneal water transport in this population have not been studied sufficiently.

METHOD

Following a prospective, single-center design we made cross-sectional and longitudinal comparisons of peritoneal water transport in 2 relatively large samples of diabetic and nondiabetic PD patients. We used 3.86/4.25% glucose-based peritoneal equilibration tests (PET) with complete drainage at 60 min, for these purposes.

MAIN RESULTS

We scrutinized 59 diabetic and 120 nondiabetic PD patients. Both samples showed relatively similar characteristics, although diabetics were significantly more overhydrated than nondiabetics. The baseline PET disclosed lower ultrafiltration (mean 439 mL diabetics vs. 532 mL nondiabetics, p = 0.033) and sodium removal (41 vs. 53 mM, p = 0.014) rates in diabetics. One hundred and nine patients (36 diabetics) underwent a second PET after 12 months, and 45 (14 diabetics) underwent a third one after 24 months. Longitudinal analyses disclosed an essential stability of water transport in both groups, although nondiabetic patients showed a trend where an increase in free water transport (p = 0.033) was observed, which was not the case in diabetics.

CONCLUSIONS

Diabetic patients undergoing PD present lower capacities of ultrafiltration and sodium removal than their nondiabetic counterparts. Longitudinal analyses disclose an essential stability of water transport capacities, both in diabetics and nondiabetics. The clinical significance of these differences deserves further analysis.

Baseline Residual Kidney Function and Its Ensuing Rate of Decline Interact to Predict Mortality of Peritoneal Dialysis Patients

Background

Baseline residual kidney function (RKF) and its rate of decline during follow-up are purported to be reliable outcome predictors of patients undergoing Peritoneal Dialysis (PD). The independent contribution of each of these factors has not been elucidated.

Method

We report a multicenter, longitudinal study of 493 patients incident on PD and satisfying two conditions: a glomerular filtration rate (GFR) ≥1 mL/minute and a daily diuresis ≥300 mL. The main variables were the GFR (mean of urea and creatinine clearances) at PD inception and the GFR rate of decline during follow-up. The main outcome variable was patient mortality. The secondary outcome variables were: PD technique failure and risk of peritoneal infection. The statistical analysis was based on a multivariate approach, placing an emphasis on the interactions between the two main study variables.

Main Results

Baseline GFR and its rate of decline performed well as independent predictors of both patient mortality and risk of peritoneal infection. These two main study variables maintained a moderate correlation with each other (r² = 0.12, p<0.0005), and interacted clearly, as predictors of patient mortality. A low baseline GFR followed by a fast decline portended the worst survival outcome (adjusted HR 3.84, 95%CI 1.81–8.14, p<0.0005)(Ref. baseline GFR above median plus rate of decline below median). In general, the rate of decline of RKF had a greater effect on mortality than baseline GFR, which had no detectable effect on survival when the decline of RKF was slow (HR 1.17, 95% CI 0.81–2.22, p = 0.22). Conversely, a relatively high GFR at the start of PD still carried a significant risk of mortality, when RKF declined rapidly (HR 1.89, 95% CI 1.05–3.72, p = 0.028).

Conclusion

The risk-benefit balance of an early versus late start of PD cannot be evaluated without taking into consideration the rate of decline of RKF. This circumstance may contribute to explain the controversial results observed at the time of evaluating the potential benefits of an early initiation of PD.

Analysis of Ultrafiltration Failure Diagnosed at the Initiation of Peritoneal Dialysis with the Help of Peritoneal Equilibration Tests with Complete Drainage at Sixty Minutes. A Longitudinal Study

♦

BACKGROUND

Ultrafiltration failure (UFF) diagnosed at the initiation of peritoneal dialysis (PD) has been insufficiently characterized. In particular, few longitudinal studies have analyzed the time course of water transport in patients with this complication. ♦

OBJECTIVE

To investigate the time course of peritoneal water transport during the first year on PD in patients presenting UFF since the initiation of this therapy (study group). ♦

METHOD

Prospective, observational, single-center design. We analyzed, at baseline and after 1 year of follow-up, peritoneal water transport in 19 patients incident on PD with UFF. We used incident patients without UFF as a control group. Water transport was characterized with the help of 3.86/4.25% dextrose-based peritoneal equilibration tests (PETs) with complete drainage at 60 minutes. ♦

RESULTS

The study group revealed a disorder of water transport affecting both small-pore ultrafiltration (SPUF) (p = 0.054 vs incident without UFF) and free water transport (FWT) (p = 0.001). After 1 year of follow-up, FWT displayed a general increasing trend in the study group (mean variation 48.9 mL, 95% confidence interval [CI] 15.5, 82.2, p = 0.012), while the behavior of SPUF was less predictable (-4.8 mL, 95% CI -61.4, 71.1, p = 0.85). These changes were not observed in incident patients without UFF. Neither initial clinical characteristics, baseline PET-derived parameters, or suffering peritoneal infections during the first year predicted the time course of the capacity of UF in the study group. Recovery from incident UFF was apparently linked to improvement of SPUF. ♦

CONCLUSIONS

Patients with UFF at the start of PD suffer a disorder of peritoneal water transport affecting both FWT and SPUF. Free water transport increases systematically in these patients after 1 year of follow-up. The evolution of SPUF is less predictable, and improvement of this parameter marks reversibility of this complication.

Compared decline of residual kidney function in patients treated with automated peritoneal dialysis and continuous ambulatory peritoneal dialysis: a multicenter study

BACKGROUND

There is controversy concerning the compared rates of decline of residual kidney function (RKF) in patients treated with continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD).

OBJECTIVES AND METHOD

Following an observational, multicenter design, we studied 493 patients initiating peritoneal dialysis (PD) in four different Spanish units. We explored the effect of the PD modality on the rate of decline of RKF and the probability of anuria during follow-up. We applied logistic regression for intention-to-treat analyses, and linear mixed models to explore time-dependent variables, excluding those affected by indication bias.

MAIN RESULTS

Patients started on APD were younger and less comorbid than those initiated on CAPD. Baseline RKF was similar in both groups (p = 0.50). Eighty-seven patients changed their PD modality during follow-up. The following variables predicted a faster decline of RKF: higher (rate of decline) or lower (anuria) baseline RKF, younger age, proteinuria, nonprimary PD, use of PD solutions rich in glucose degradation products, higher blood pressure, and suffering peritonitis or cardiovascular events during follow-up. Overall, APD was not associated with a fast decline of RKF, but stratified analysis disclosed that patients with lower baseline RKF had an increased risk for this outcome when treated with this technique (HR: 2.26, 95% CI: 1.09-4.82, p = 0.023). Moreover, the probability of anuria during follow-up was overtly higher in APD patients (HR: 3.22, 95% CI: 1.25-6.69, p = 0.002).

CONCLUSIONS

Starting PD patients directly on APD is associated with a faster decline of RKF and a higher risk of developing anuria than doing so on CAPD. This detrimental effect is more marked in patients initiating PD with lower levels of RKF.

Treatment of Peritoneal Dialysis-Related Peritonitis with Ciprofloxacin Monotherapy: Clinical Outcomes and Bacterial Susceptibility over Two Decades

Background

There is controversy about the preferred initial antibiotic therapy for peritoneal dialysis (PD)-related peritonitis. Quinolones have been used extensively in this setting, yet their long-term effectiveness is unknown.

Aim

To analyze the results of a protocol of treatment of PD-related peritonitis with ciprofloxacin, maintained over two decades.

Method

We analyzed the clinical outcome of 682 episodes of bacterial peritonitis treated with intraperitoneal ciprofloxacin monotherapy, and the time course of bacterial susceptibility to this antimicrobial, in a historical cohort of 641 PD patients (1988-2007). Main outcome variables included changes to initial therapy and rates of hospital admission, catheter removal, relapse, reinfection, PD dropout, and mortality. For comparisons we divided the study period into phases A (1988-1994), B (1995-2000), and C (2001-2007).

Results

The incidence of Staphylococcus aureus peritonitis decreased, while the incidences of polymicrobial and negative-culture peritonitis increased after phase A. In vitro susceptibility to ciprofloxacin decreased significantly only among coagulase-negative staphylococci (87.0% susceptible strains in phase A vs 70.0% in B and 70.1% in C, p = 0.006). Overall success rates (catheter not removed and ongoing PD after the episode) remained stable, at over 85%. However, the proportion of patients treated solely with ciprofloxacin declined from 75.7% (A) to 47.3% (B) to 32.4% (C) ( p < 0.0005) and admission rates increased from 12.7% to 16.8% to 24.9% respectively ( p = 0.001). These changes affected all the etiologic groups except culture-negative peritonitis. In vitro resistance to ciprofloxacin was a marker of multiresistance and correlated strongly with clinical outcome of peritonitis. Among isolates susceptible to ciprofloxacin, changing initial therapy for any reason also predicted a poor outcome.

Conclusions

Following satisfactory early results, the effectiveness of ciprofloxacin as monotherapy for PD-related peritonitis has declined markedly in the long term. This decline cannot be explained solely by a decrease of in vitro susceptibility to this antimicrobial, which was significant only among coagulase-negative staphylococci. Resistance to ciprofloxacin is a strong marker of in vitro multiresistance and poor clinical outcome of peritonitis.

Treatment of peritoneal dialysis-related peritonitis with ciprofloxacin monotherapy: clinical outcomes and bacterial susceptibility over two decades

BACKGROUND

There is controversy about the preferred initial antibiotic therapy for peritoneal dialysis (PD)-related peritonitis. Quinolones have been used extensively in this setting, yet their long-term effectiveness is unknown.

AIM

To analyze the results of a protocol of treatment of PD-related peritonitis with ciprofloxacin, maintained over two decades.

METHOD

We analyzed the clinical outcome of 682 episodes of bacterial peritonitis treated with intraperitoneal ciprofloxacin monotherapy, and the time course of bacterial susceptibility to this antimicrobial, in a historical cohort of 641 PD patients (1988-2007). Main outcome variables included changes to initial therapy and rates of hospital admission, catheter removal, relapse, reinfection, PD dropout, and mortality. For comparisons we divided the study period into phases A (1988-1994), B (1995-2000), and C (2001-2007).

RESULTS

The incidence of Staphylococcus aureus peritonitis decreased, while the incidences of polymicrobial and negative-culture peritonitis increased after phase A. In vitro susceptibility to ciprofloxacin decreased significantly only among coagulase-negative staphylococci (87.0% susceptible strains in phase A vs 70.0% in B and 70.1% in C, p = 0.006). Overall success rates (catheter not removed and ongoing PD after the episode) remained stable, at over 85%. However, the proportion of patients treated solely with ciprofloxacin declined from 75.7% (A) to 47.3% (B) to 32.4% (C) (p < 0.0005) and admission rates increased from 12.7% to 16.8% to 24.9% respectively (p = 0.001). These changes affected all the etiologic groups except culture-negative peritonitis. In vitro resistance to ciprofloxacin was a marker of multiresistance and correlated strongly with clinical outcome of peritonitis. Among isolates susceptible to ciprofloxacin, changing initial therapy for any reason also predicted a poor outcome.

CONCLUSIONS

Following satisfactory early results, the effectiveness of ciprofloxacin as monotherapy for PD-related peritonitis has declined markedly in the long term. This decline cannot be explained solely by a decrease of in vitro susceptibility to this antimicrobial, which was significant only among coagulase-negative staphylococci. Resistance to ciprofloxacin is a strong marker of in vitro multiresistance and poor clinical outcome of peritonitis.

Use of icodextrin during nocturnal automated peritoneal dialysis allows sustained ultrafiltration while reducing the peritoneal glucose load: a randomized crossover study

BACKGROUND

Optimization of ultrafiltration and preservation of the peritoneal membrane are desirable objectives in peritoneal dialysis (PD) patients. Mixtures of glucose- and non-glucose-based solutions may help to meet both targets simultaneously.

AIM

To analyze the effects, in terms of ultrafiltration and peritoneal glucose load, of including icodextrin-based dialysate in the nocturnal schedule of patients undergoing automated PD (APD).

METHOD

Following a randomized crossover design, 17 APD patients underwent two 10-day study periods under identical prescription (including amino acid-based solution for the night schedule), except for the substitution of 2 L glucose-based dialysate in the nocturnal mixture (control) by a similar amount of icodextrin-based dialysate (icodextrin phase) in one period. Dependent variables included ultrafiltration, sodium removal, peritoneal glucose load, and residual renal function. We measured serum and urine levels of icodextrin metabolites at the end of each phase.

RESULTS

Ultrafiltration was marginally higher during the icodextrin phase (median 815 vs 763 mL/day, p = 0.07), while peritoneal sodium removal was similar in both phases (74 vs 71 mmol/L/day). Peritoneal glucose load (median 67.5 vs 104.0 g/day, p < 0.005) and absorption (14.0 vs 35.6 g/day, p < 0.005) were lower during the icodextrin phase. Diuresis was also modestly lower during the icodextrin phase (500 vs 600 mL/day, p < 0.05). Serum levels of icodextrin metabolites were moderately higher in the icodextrin phase (p < 0.005) in patients both on and off diurnal icodextrin.

CONCLUSION

Inclusion of amino acid- and icodextrin-based solutions in the nocturnal schedule of APD patients may allow sustained ultrafiltration and sodium removal while significantly reducing the peritoneal glucose load in these patients.

Serum levels of anti-alphaGalactosyl antibodies predict survival and peritoneal dialysis-related enteric peritonitis rates in patients undergoing renal replacement therapy

BACKGROUND

Anti-Galalpha1-3Gal antibodies (anti-alphaGal) represent a significant fraction of natural antibodies and were implicated in several disease states, yet their origin and physiological significance remain largely undisclosed.

METHODS

Under a prospective observational design, we estimated anti-alphaGal immunoglobulin G (IgG)/IgM and antipig hemolytic antibody (APA) levels in 133 patients starting dialysis therapy and again after a 1-year follow-up. We used baseline data to show correlations with demographic, nutritional, inflammatory, and anemia markers and analyzed their correlation with outcomes by using univariate and multivariate strategies of survival analysis.

RESULTS

Serum anti-alphaGal and APA levels showed wide baseline variability, but remained relatively stable in time. Both were measurable in dialysate of peritoneal dialysis (PD) patients, showing close correlation to serum levels. We observed no association between levels of anti-alphaGal/APA and nutritional markers, but showed direct correlations of anti-alphaGal IgM (P = 0.005) and APA levels (P = 0.001) with tumor necrosis factor alpha (TNF-alpha) levels. High APA levels also were associated with severe anemia (P = 0.006). High baseline anti-alphaGal IgM (P = 0.03) and APA levels (P = 0.045) predicted later risk for enteric peritonitis in PD patients. Finally, univariate and multivariate analyses showed a consistent association between high baseline anti-alphaGal IgM (P = 0.014) and APA (P = 0.021) levels and global risk for mortality during follow-up.

CONCLUSION

Anti-alphaGal IgM and APA levels at the start of dialysis therapy are significant predictors of later risk for mortality and, in PD patients, enteric peritonitis. Both correlate directly with TNF-alpha levels and, in the case of APA, severity of anemia in these patients.

Incidence and significance of peritoneal eosinophilia during peritoneal dialysis-related peritonitis

OBJECTIVE

To determine the incidence and significance of peritoneal eosinophilia (PEo) during peritoneal dialysis (PD)-related peritonitis.

DESIGN

Retrospective observational study.

SETTING

Tertiary-care public hospital.

PATIENTS AND METHOD

We performed a cytological study of dialysate at the start of 465 cases of peritonitis diagnosed between January 1987 and May 2002. Cases associated with PEo (> 10% eosinophils) were classified according to their infectious or seemingly noninfectious origin. We compared the two groups, trying to disclose differentiating patterns of presentation.

RESULTS

We found PEo in 42 cases. Infectious peritonitis was the final diagnosis in 22 of the 42 cases; a diagnosis of idiopathic eosinophilic peritonitis was finally established in 20 cases. The etiologic spectrum of infectious peritonitis with PEo did not differ markedly from the global spectrum of peritonitis in our unit. Infectious peritonitis with PEo tended to appear later in the course of PD therapy, presented with more severe clinical symptoms, displayed higher total peritoneal leukocyte and neutrophil counts, and showed lower degrees of PEo than idiopathic eosinophilic peritonitis, but overlap between the groups was significant.

CONCLUSIONS

Peritoneal eosinophilia is infrequent but not rare during infectious PD-related peritonitis. Our findings agree with established concepts on idiopathic eosinophilic peritonitis, but overlap in presentation with infectious eosinophilic peritonitis is significant, which should be taken into consideration at the time of planning therapy for this condition.

Sodium removal in patients undergoing CAPD and automated peritoneal dialysis

OBJECTIVES

To compare sodium removal in continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD) patients, and to identify the main factors that modify Na removal in clinical practice in these patients.

DESIGN

Study in three steps. Cross-sectional observational (Study A), and longitudinal interventional (Studies B and C).

PATIENTS AND METHODS

First (Study A) we carried out a cross-sectional survey of Na removal in 63 patients on CAPD and 78 patients on APD. Second (Study B), we studied Na removal in 32 patients before and after changing from CAPD to APD therapy. Finally (Study C), we analyzed the impact on Na removal of introducing icodextrin for the long dwell in 16 patients undergoing CAPD or APD.

RESULTS

In Study A, total Na removal averaged 210 mmol/day for CAPD patients and 91 mmol/day for APD patients (p < 0.001); Na removal was < 100 mmol/day in 7.1% of CAPD patients and 56.4% of APD patients. Multivariate analysis identified ultrafiltration [B = 125 mmol/day, 95% confidence interval (CI) 110,140], CAPD therapy (B = 60 mmol/day, 95%CI 37, 83), and residual diuresis (B = 51 mmol/L, 95%CI 34, 69) as independent predictors of Na removal (adjusted r2 = 0.76). For APD patients, longer nocturnal dwell times and performing a supplementary diurnal exchange were also independently associated with higher Na removal rates. In Study B, Na removal decreased from 192 to 92 mmol/day (median) after the change to APD (p = 0.02). In Study C, peritoneal Na removal increased from 98 to 148 mmol/day (median) (p = 0.04) after introducing icodextrin.

CONCLUSIONS

Standard APD schedules are frequently associated with poor Na removal rates. For any degree of ultrafiltration, Na removal is better in CAPD than in APD. Icodextrin, supplementary diurnal exchanges, and longer nocturnal dwell times improve Na removal in APD. Sodium removal can be estimated from ultrafiltration in patients on CAPD, but must be specifically monitored in patients on APD.

Hyperleptinemia in uremic patients undergoing conservative management, peritoneal dialysis, and hemodialysis: A comparative analysis

We performed a cross-sectional study in a wide sample of patients with chronic renal failure undergoing conservative therapy (CTh) (n = 79), peritoneal dialysis (PD) (n = 75), and hemodialysis (HD) (n = 51), with the aim of analyzing the impact of the different modes of therapy on serum leptin levels. We used a multivariate approach, taking into consideration the potential effects of other epidemiological, dialysis-related, nutritional, and hormonal factors on serum leptin. Leptin levels were higher in patients treated with PD (median, 36 ng/mL) than in those undergoing CTh (10.8 ng/mL) or HD (5.4 ng/mL) (P < 0.0005). This difference persisted after controlling for gender, body mass index, and fasting insulin levels, suggesting that imbalances in these factors may only partially explain the differences found between the three modes of therapy. Leptin levels showed a significant negative correlation with peritoneal protein losses in PD patients but were poorly associated with factors such as proteinuria, daily peritoneal glucose absorption (PD), renal function, or adequacy of dialysis. Leptin and insulin-like growth factor-I (IGF-I) were significantly correlated in PD patients, but the study design did not allow for establishing a meaning for this correlation. In conclusion, serum leptin levels are increased in PD patients when compared with CTh or HD patients. Differences in gender distribution, fat mass, and insulin levels may partially explain these findings, but other undefined factors also may have a role in producing these results.