Albumin at the start of peritoneal dialysis predicts the development of peritonitis

BACKGROUND

Both peritonitis and serum albumin level are associated with morbidity and mortality in peritoneal dialysis (PD) patients. Severe cases of peritonitis result in hypoalbuminemia. However, it is not clear whether hypoalbuminemia predicts the development of peritonitis.

METHODS

We performed a retrospective analysis of a prospectively collected database from six centers in western Pennsylvania and West Virginia. Incident PD patients with a Charlson Comorbidity Index (CCI) score at the start of PD therapy and serum albumin level measured within 30 days of initiation were selected. Poisson regression was used to analyze predictors of peritonitis.

RESULTS

Three hundred ninety-three patients had a CCI score and serum albumin level measured at the start of PD therapy. Overall peritonitis rate was 0.65 episodes/dialysis-year. Significant univariate predictors were albumin level (rate ratio [RR], 0.79 per 1-g/dL [10-g/L] increase; 95% confidence interval [CI], 0.65 to 0.95; P = 0.015), male sex (P = 0.003), and being dialyzed in the Veterans Administration (RR, 1.97; 95% CI, 1.48 to 2.62; P < 0.001) or other center (RR, 1.68; 95% CI, 1.92 to 5.62; P < 0.001). Although CCI score correlated inversely with albumin level (r = -0.305; P < 0.001), CCI score was only marginally predictive of peritonitis (P = 0.068). In multivariate analysis, predictors were albumin level (RR, 0.74; 95% CI, 0.31 to 1.75; P = 0.002) and race (RR, 1.36; P = 0.024). Patients with an initial serum albumin level less than 2.9 g/dL (29 g/L) had a peritonitis rate of 1.5 episodes/dialysis-year compared with 0.6 episodes/dialysis-year for patients with an initial serum albumin level of 2.9 g/dL or greater (P < 0.001).

CONCLUSION

Hypoalbuminemia at the start of PD therapy is an independent predictor of subsequent peritonitis. Intervention studies to decrease peritonitis risk in this high-risk subset of patients are needed.

Association between residual renal function, inflammation and patient survival in new peritoneal dialysis patients

BACKGROUND

The recent ADEMEX study (Paniagua R, Amato D, Vonesh E et al. J Am Soc Nephrol 2002; 13: 1307-1320) indicates that peritoneal small solute clearance is not as critical for the survival of peritoneal dialysis (PD) patients as thought previously. On the other hand, low residual renal function (RRF), inflammation and an increased peritoneal transport rate (PTR) as evaluated by the peritoneal equilibration test (PET) are reported to be associated with increased mortality in PD patients, but the relationships between these factors and their separate and combined impact on the survival of PD patients are not clear. In this retrospective analysis, we evaluated possible relationships between RRF, inflammation and initial PTR in patients starting PD and the impact of these factors on patient survival.

METHODS

A total of 117 patients with initial assessments for RRF, serum C-reactive protein (CRP) and PET at a mean period of 0.4+/-0.2 months (range 0.1-1.0 months) after start of PD were included in this study. Based on RRF (cut-off point, 4 ml/min/1.73 m(2)), serum CRP (cut-off point, 10 mg/l), and the dialysate to plasma creatinine ratio at 4-h of dwell (mean+1 SD), the patients were divided into different groups: low RRF and high RRF group, high CRP and normal CRP group and high PTR and other PTR group, respectively.

RESULTS

Of 117 patients, 54 patients (46%) were in low RRF (<4 ml/min/1.73 m(2)) group, 36 patients (31%) were in high serum CRP (> or = 10 mg/l) group and 17 patients (15%) were in high PTR group. Forty-nine patients (42%) had one of these characteristics, 26 patients (22%) had two of these characteristics, two patients (2%) had three, and 40 patients (34%) had none of these characteristics. Patients with low RRF were older and had a higher prevalence of high CRP, lower normalized protein equivalent of total nitrogen appearance (nPNA), lower total Kt/V(urea) and lower total creatinine clearance (CCr) whereas patients with high CRP were older and had a higher proportion of men, lower serum albumin, lower nPNA, lower RRF and lower total CCr. Patients with high PTR had lower serum albumin, higher RRF and higher total CCr compared with patients with other PTR. Upon logistic multiple regression analysis, age and RRF were identified as factors affecting inflammation. Overall patient survival was significantly lower in the patients with low RRF, with high CRP, and in patients with more than two of the following: low RRF, high CRP and high PTR. In contrast, in patients with none of the discriminators low RRF, high CRP and high PTR, the 5-year survival was 100%. A high PTR was associated with decreased survival during the initial year on PD, but not thereafter. Patients who died during the follow-up period had a higher prevalence of high CRP and lower serum albumin, lower RRF, lower Kt/V(urea) and lower total CCr. Upon Cox proportional hazards multivariate analysis, age and RRF were predictors of mortality.

CONCLUSIONS

These results indicate that in patients starting PD, low initial RRF is associated with inflammation, and low RRF and inflammation are both associated with high overall mortality. A high PTR was associated with higher mortality, but only during the initial year on PD, whereas Kt/V(urea) did not predict mortality. These results indicate the importance of RRF and inflammation as predictors of mortality in PD patients whereas the predictive power of PTR as such may lose its significance if these two parameters are taken into consideration.

An association between aortic pulse wave velocity, blood pressure and chronic inflammation in ESRD patients on peritoneal dialysis

Increased aortic pulse wave velocity (AoPWV) has been identified as a risk factor for cardiovascular morbidity in the general population and in patients on dialysis. Most of the studies in ESRD patients refer to subjects on hemodialysis. Influence of the inflammatory process on aortic stiffening remains largely unknown. The aim of the present study was to evaluate potential relationships between AoPWV and blood pressure, basic anthropometric parameters, selected growth factors and markers of the inflammatory process in ESRD patients treated with peritoneal dialysis. The study population consisted of 43 patients (19 F, 24 M) with a mean age of 50.6 +/- 13.4 years on PD for a mean period of 21.9 +/- 20.7 months. AoPWV was measured using two pressure transducers placed on the carotid and femoral arteries and connected to an automatic processor (Complion Colson AS, Paris, France). Serum levels of Tumor Necrosis Factor alpha (TNFalpha), interleukin 6 (IL-6) and plasma basic Fibroblast Growth Factor (bFGF) were measured with ELISA; C-reactive protein and fibrinogen with nephelometry. Serum lipid profile was also assessed. Blood pressure was measured in an outpatient department under standardized conditions. Mean aortic pulse wave velocity in the study population was 10.7 +/- 2.1 m/s. No difference in AoPWV was found between men and women. AoPWV correlated significantly with age (R = 0.41; p < 0.01) but not with time on dialysis. Positive relationship between AoPWV and body weight and BMI was shown (R = 0.31; p < 0.05 and R = 0.35; p < 0.05, respectively). AoPWV correlated significantly with systolic blood pressure (SBP), mean arterial pressure (MAP) and pulse pressure (PP) (R = 0.46, p < 0.005, R = 0.46, p < 0.005 and R = 0.43, p < 0.01, respectively). AoPWV correlated with serum IL-6 and plasma bFGF (R = 0.32, p < 0.05 and R = 0.4, p < 0.01; respectively). The correlation with serum CRP was borderline significant (p < 0.53). In multiple regression analysis age (beta 0.38; p < 0.005), plasma bFGF level (beta 0.3; p < 0.05), and systolic blood pressure (beta 0.29; p < 0.05) were independently associated with pulse wave velocity. Our results suggest that AoPWV values in patients on PD are associated with factors similar to those encountered in the general population. We suggest that increased aortic stiffening may also be related to the chronic inflammatory process in PD patients.

Chronic use of sodium ferric gluconate complex in hemodialysis patients: safety of higher-dose (> or =250 mg) administration

BACKGROUND

Almost all hemodialysis (HD) patients require intravenous iron therapy to correct their anemia and maintain their iron stores. Sodium ferric gluconate complex (SFGC) is approved by the Food and Drug Administration (FDA) for treatment of iron deficiency anemia in HD patients at individual doses up to 125 mg over 10 minutes (12.5 mg/min) and has been shown to have a superior safety profile compared with iron-dextran. Higher individual doses of SFGC would permit more rapid repletion of iron stores and greater flexibility in maintenance iron therapy as well as simplify treatment of peritoneal dialysis patients and chronic kidney disease patients.

METHODS

The authors reviewed the safety and tolerability of higher-dose SFGC infusions (> or =250 mg) in 144 HD patients who were previously tolerant to a single 125-mg dose of SFGC. These 144 patients received a total of 590 doses of > or =250 mg of SFGC; 571 doses were 250 mg SFGC, and most of these were infused over 1 hour, an infusion rate of 4.17 mg/min. The other 19 doses were 312.5 mg (n = 1), 375 mg (n = 14), and 500 mg (n = 4). Infusion rates varied from 1.22 mg/min to 25.0 mg/min.

RESULTS

Only one patient was considered intolerant to higher-dosing SFGC after having pruritus after a second 250-mg dose of SFGC. Three patients had nonserious events that did not preclude further dosing of SFGC.

CONCLUSION

Administration of 250 mg SFGC over 1 hour is safe and well tolerated. Individual doses of 375 mg and 500 mg SFGC also were well tolerated, but further research and experience are needed to confirm the safety and tolerance of these doses.

Oral nutritional supplementation increases caloric and protein intake in peritoneal dialysis patients

BACKGROUND

Malnutrition is highly prevalent in peritoneal dialysis (PD) patients and is associated with a poor prognosis. Attempts to improve nutritional status with enteral supplements have yielded poor results.

METHODS

We performed a crossover-design trial on 13 PD patients to investigate whether these patients reduce their food intake after drinking oral nutritional supplements. Patients attended three visits in which they were administered a standard oral nutritional supplement either 2 hours or 30 minutes before lunch or a placebo drink 30 minutes before lunch. Lunch was provided as a self-select buffet-style meal, and food intake was measured. Total intake was calculated by adding the nutritional content of the oral supplement.

RESULTS

Patients showed poor food intake, with mean values equaling only 18% of the recommended daily intake for calories and 34% for protein. Drinking the supplement 2 hours before lunch resulted in a significant increase compared with the placebo visit in total caloric (430 to 843 kcal; P < 0.001) and protein intake (27.6 to 41.3 g; P = 0.006). No significant difference in total intake was detected between drinking the supplement 2 hours versus 30 minutes before lunch.

CONCLUSION

These results indicate that oral nutritional supplements administered before a meal may significantly increase caloric and protein intakes of PD patients.

Peritoneal dialysis in children with acute renal failure after open heart surgery

Acute renal failure is a frequently reported complication after open heart surgery in children and carries a high mortality. Conservative treatment often makes post-operative care difficult and ambiguous. Peritoneal dialysis (PD) or hemofiltration is another therapeutic choice. Hemofiltration has some limitations in pediatric patients. Many aspects of PD are currently under discussion. We retrospectively reviewed 184 children who underwent open heart surgery with cardiopulmonary bypass. Four patients fulfilled the criteria of acute renal failure. PD was performed after conservative treatment failed. All patients successfully survived through the post-operative period. No electrolyte imbalance, fluid overload or acute hemodynamic changes was observed after the initiation of PD. In our limited experience, PD is a safe and effective method for managing patients with acute renal failure after open heart surgery.

[Analysis of renal replacement therapy in patients with renal failure]

The article presents the 10-years experience of renal replacement therapy in a single centre. A total of 158 patients were treated in this period. 77 patients (47 F, 30 M, mean age 18.7 +/- 12 yrs) were treated due to chronic renal failure and 81 (35 F, 46 M, mean age 2.1 +/- 1.5 yrs) due to acute failure. 48 (62%) were treated by haemodialysis, 24 (31%) by peritoneal dialysis and 5 (7%) by both methods. Due to the shortage of dialysis units both children and adults were qualified to the dialysis therapy in our centre. Mean age of haemodialysis patients was 22 yrs and of those treated by peritoneal dialysis 13.5 yrs. 7 patients died (9%) and 30 (39%) were transplanted. 15 (19%) were transferred to other centres. The overall mortality was lower than reported by other authors. 4% of patients were tested HBV positive, 13% HCV positive and 9% both HBV and HCV positive and this rates are lower than the average rate in chronic dialysis patients in Poland. Our experience allows us to conclude that adult patients may be successfully treated in paediatric dialysis centres.

Economic impact of extended time on peritoneal dialysis as a result of using polyglucose: the application of a Markov chain model to forecast changes in the development of the ESRD programme over time

BACKGROUND

The use of polyglucose as a peritoneal dialysis (PD) fluid extends time on PD treatment. It is anticipated, therefore, that the share of patients treated with PD will be positively influenced. The relationship between extension of PD treatment time and an increase of the PD treatment share, however, is complex and needs further investigation. In this paper, a Markov chain model was applied to investigate the impact of extended time on PD treatment for the PD share in all dialysis patients in The Netherlands. Furthermore, the economic impact of the extended time on treatment (ETOT) was explored.

METHODS

Scenarios were forecast over a 10 year period using aggregate data from the End-Stage Renal Registry in The Netherlands (Renine). Three scenarios were simulated in which the median PD technique survival was extended by 8, 10 and 12 months. Two other scenarios explored the impact of the combined effect of ETOT of 10 months together with a 10% and 20% increase of PD inflow shares. Reductions of costs to society due to ETOT were estimated using Dutch cost data on renal replacement therapies.

RESULTS

PD share increases from 30.0% in the null scenario to 34.5% in the scenario with an ETOT of 10 months and an increased PD inflow share of 20%. The reduction in total costs to society of the renal replacement therapies is 0.96%. The average societal costs per discounted patient year for haemodialysis (HD) are 84 100 euros. For PD, these costs are 60 300 euros. A shift from HD to PD results in average cost savings of 28% per patient year.

CONCLUSIONS

In view of high dialysis costs to society, a reduction of 0.96% can be considered to be relevant for healthcare policy makers.

Peritoneal leukocyte survival and respiratory burst responses in patients treated with a low glucose degradation and high pH peritoneal dialysis fluid

The discovery of toxicity related to glucose degradation products (GDP) has initiated the development of new PD fluids with low GDP concentrations and higher, more physiological, pH levels. Cell numbers, differential counts and the respiratory burst responses of peritoneal leukocytes were compared between patients treated with the low GDP, high pH fluid Gambrosol-trio (n=10) and a conventional fluid (n=12). Effluents from over-night dwells were collected and leukocytes were evaluated morphologically and by luminol-amplified chemiluminescence (CL) after stimulation with opsonized zymosan. The frequency of necrosis and early apoptosis was quantified by means of annexin V binding and propidium iodide uptake. The Gambrosol-trio group produced significantly higher (p<5%) macrophage counts and stronger CL responses (p<10%) than did the conventional fluid group. The cell compositions did not differ significantly between the groups. Necrosis was significantly more common among the cells in the conventional fluid group. The occurrence of apoptosis did not differ between the fluids.

Decreased survival among sedentary patients undergoing dialysis: results from the dialysis morbidity and mortality study wave 2

BACKGROUND

Sedentary behavior is associated with an increased risk for death in the general population. However, the association between inactivity and mortality has not been studied in a large cohort of dialysis patients despite the high prevalence of sedentary behavior in this group.

METHODS

We used the Dialysis Morbidity and Mortality Study Wave 2, a prospective study of a national sample of 4,024 incident peritoneal dialysis and hemodialysis patients from 1996 to 1997, to determine whether sedentary behavior is associated with increased mortality during a 1-year period in this group after adjusting for confounding variables.

RESULTS

The study population consisted of the 2,837 patients with accurate survival data who were able to ambulate and transfer. Eleven percent of the sedentary patients died during the study period compared with 5% of nonsedentary patients. In a survival analysis, sedentary behavior (hazard ratio, 1.62; 95% confidence interval, 1.16 to 2.27) was associated with an increased risk for death at 1 year after adjusting for all variables that we postulated might be associated with survival and for differences between sedentary and nonsedentary patients.

CONCLUSION

Sedentary behavior is associated with an increased risk for mortality among dialysis patients similar in magnitude to that of other well-established risk factors, such as a one-point reduction in serum albumin concentration. More attention should be given to exercise behavior in dialysis patients, and controlled clinical trials are needed to further define the association of sedentary behavior with mortality.

Long-term automated peritoneal dialysis in patients with refractory congestive heart failure

Patients with severe congestive heart failure (CHF), mainly class IV on the New York Heart Association (NYHA) scale, became refractory to standard medical therapy. The factor that favored that evolution was renal insufficiency with inadequate renal perfusion. Our objectives in the present study were to make a preliminary assessment of the usefulness of automated peritoneal dialysis (APD) for the treatment of volume overload in those patients. Our study was carried out in the peritoneal dialysis unit of the clinical hospital of Pontificia Universidad Católica de Chile. We studied 3 non uremic patients with refractory CHF secondary to ischemic cardiomyopathy, severe secondary lung hypertension (> 70 mmHg), and associated moderate renal insufficiency. The patients (2 women and 1 man) ranged in age from 55 years to 68 years. A Tenckhoff double-cuff peritoneal catheter was placed in each patient, and peritoneal dialysis was carried out using the nightly intermittent peritoneal dialysis (NIPD) modality. The treatment used was appropriate to obtain a gradual removal of fluids: dialysate dextrose at 1.5% and 2.5%, 4-5 cycles, and total volume of 10-12 L per night. All three patients were able to remain at home, with no signs of hypervolemia. The frequency and length of hospitalizations decreased on average from 59 days pre-APD to 37 days post-APD. No hospitalizations for cardiac problems occurred, and the mean survival was 11 months (range: 6-22 months). This preliminary observation suggests that APD could be offered as an effective treatment for helping to remove fluids in patients with refractory CHF, reducing the number and length of hospitalizations, and improving quality of life.

An association between coronary artery calcification score, lipid profile, and selected markers of chronic inflammation in ESRD patients treated with peritoneal dialysis

BACKGROUND

Chronic uremia is considered a proinflammatory state associated with high cardiovascular morbidity and mortality. The aim of the present study is to evaluate the potential relationship between the prevalence of coronary artery calcification (CAC) and selected factors that may be involved in the process of atherogenesis (lipid profile, acute-phase reactants, growth factors, and cytokines).

METHODS

The study group consisted of 43 patients (19 women, 24 men) with a mean age of 50.6 +/- 13.4 years treated with peritoneal dialysis (PD) for a median period of 15 months (range, 2 to 96 months). Only patients with sinus rhythm were included. CAC score (CaSc) was measured using multirow spiral computed tomography (MSCT). As parameters of lipid profile, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides were assayed. C-reactive protein (CRP) and fibrinogen represented the level of acute-phase activation. Proinflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor-alpha [TNF-alpha]), leptin, and basic fibroblast growth factor (bFGF) also were measured.

RESULTS

Median CaSc equaled 17.9 Agatston units (range, 0 to 5,502 Agatston units). No calcification was detected in 20 subjects (46.5%; CaSc < 10 Agatston units). CaSc correlated with age (R = 0.57; P < 0.0001), body mass index (R = 0.42; P < 0.005), and serum leptin (R = 0.3; P < 0.05) and CRP levels (R = 0.38; P < 0.05). The correlation with PD therapy duration was borderline statistically significant (P = 0.063). Patients with the greatest values for CaSc (> 400 Agatston units) were characterized by significantly greater levels of IL-6, bFGF, and CRP compared with subjects with a CaSc less than 10 Agatston units (P < 0.05 for all). Patients with history of coronary artery disease (CAD) had significantly greater CaSc values (median, 778.6 versus 3.3 Agatston units; P < 0.001) compared with those without CAD. Serum triglyceride levels were significantly greater and HDL cholesterol levels were significantly lower in patients with CAD. The first group also was characterized by significantly greater serum TNF-alpha (P < 0.01) and CRP levels (P < 0.005). In multiple regression analysis, only age was independently associated with CaSc (beta = 0.45; P = 0.002).

CONCLUSION

Our results may suggest an association between CAC and chronic inflammation activity in the mentioned group of patients. To our knowledge, this is the first study reporting the prevalence of CAC in PD patients using the MSCT method. The association between CaSc results and classic, as well as inflammatory, risk factors for CAD found in this study should be interpreted with caution because of its method limitations (cross-sectional design, heterogeneity of study population, and small number of studied patients).

Cost savings from peritoneal dialysis therapy time extension using icodextrin

Previous retrospective studies have reported that icodextrin may prolong peritoneal dialysis (PD) treatment time in patients with refractory fluid overload (RFO). Because the annual cost of PD therapy is lower than that of hemodialysis (HD) therapy in Australia, we prospectively investigated the ability of icodextrin to prolong PD technique survival in patients with RFO. We used a computer model to estimate the savings associated with that therapeutic strategy, based on annual therapy costs determined in a regional PD and HD costing exercise. Patients who met standard criteria for RFO and who were otherwise to be converted immediately to HD, were asked to consent to an open-label assessment of the ability of icodextrin to delay the need to start HD. Time to conversion to HD was measured. The study enrolled 39 patients who were followed for a mean period of 1.1 years. Icodextrin significantly increased peritoneal ultrafiltration by a median value of 368 mL daily. It prolonged technique survival by a mean period of 1.21 years [95% confidence interval (CI): 0.80-1.62 years]. Extension of PD treatment time by icodextrin was particularly marked for patients who had ultrafiltration failure (UFF, n = 20), defined as net daily peritoneal ultrafiltration < 1 L daily (mean extension time: 1.70 years; 95% CI: 1.16-2.25 years). Overall, annualized savings were US$3,683 per patient per year. If just the patients with UFF were considered, the savings increased to US$4,893 per year. Icodextrin prolongs PD technique survival in patients with RFO, permitting them to continue on their preferred therapy. In Australia, that practice is highly cost-effective, particularly in individuals with UFF.

Fivefold reduction in peritonitis using a multifaceted continuous quality initiative program

Despite recent advances in peritoneal dialysis (PD) systems, peritonitis is a significant clinical problem in patients on PD. Risk factors for peritonitis are identifiable and modifiable and require focused intervention. During a baseline period in 1998, we observed consistent differences in peritonitis rates among patients using various PD connection systems. In January 1999, motivated by a need to reduce peritonitis, we initiated a multifaceted continuous quality initiative (CQI) program that included retraining all current patients and all new patients 6 months after initiation and then annually; changing from plastic to titanium adapters between the catheter and the transfer set; and using equipment from a single PD manufacturer for all new patients and for current patients with high peritonitis rates. Furthermore, all patients using HomeChoice cyclers (Baxter Healthcare Corporation, McGaw Park, IL, U.S.A.) were taught to use the Compact Exchange Device II to avoid contamination when spiking solution bags. Peritonitis rates improved from 1 episode per 7.5 patient-months (over 512 patient-months) in 1998 to 1 episode per 36.5 patient-months (over 292 patient-months) as of September 2002. Further analysis also showed a significant difference in peritonitis rates between equipment produced by various manufacturers. There was a statistically significant difference in peritonitis for automated peritoneal dialysis systems. Patients using the Freedom Cycler PD+ (Fresenius Medical Care, Frankfurt, Germany) had an average peritonitis rate of 1 episode per 6.9 patient-months as compared with patients using the HomeChoice cycler (Baxter Healthcare), who experienced 1 episode of peritonitis per 23.9 patient-months on average (p < 0.0001). For continuous ambulatory peritoneal dialysis patients using UltraBag (Baxter Healthcare), the peritonitis rate was 1 episode per 26 patient-months as compared with the Premier Double Bag (Fresenius Medical Care), for which a peritonitis rate of 1 episode per 6.3 patient-months was seen (p < 0.0001). Comparison of the UltraBag (1 episode per 26.0 patient-months) with the Disposable Freedom Set, a single-bag "Y" system (Fresenius Medical Care; 1 episode per 7.5 patient-months) yielded similar results (p < 0.0001). We conclude that ongoing CQI efforts can significantly reduce peritonitis rates. Our efforts included aggressive patient retraining, protocol changes, use of a titanium adapter between the catheter and the transfer set, and careful choice of connectology systems (possible supplier-dependent effect).

Can peritoneal dialysis be used as a long term therapy for end stage renal disease?

Over the last 25 years, since the introduction of CAPD, the use of PD has increased greatly and over this period many advances in technique have been made. As is well known, that home and self-dialysis, such as PD, cost less than in-center HD and can provide excellent survival and a high level of patient rehabilitation. To date however, the demonstration that PD can provide long term dialysis has been limited to a small number of patients. The next few decades will see a marked increase in the worldwide dialysis population, particularly as older and sicker patients are accepted into dialysis. It is likely that worldwide pressures related to cost containment will favour the use of cost effective therapies, such as PD. However, the increased use of PD will continue, only if we continue to improve its efficacy and do not waste the economic benefits gained over HD. We are challenged to improve and develop PD in a way that optimises patient medical and psychosocial outcomes while minimizing costs. This may be achieved by using more biocompatible solutions, hopefully inexpensive, that will maintain the peritoneal membrane intact for long periods, will better preserve the membrane's transport characteristics over time, and thus reduce the main causes of drop out from dialysis.

Prolonged stability of antimicrobial activity in peritoneal dialysis solutions

OBJECTIVE

To evaluate the stability of the antimicrobial chemical and bioactivity of gentamicin, vancomycin, and gentamicin and vancomycin in combination, and the stability of the bioactivity of ceftazidime, admixed in standard peritoneal dialysis solutions and then maintained over a 14-day period at room temperature or under refrigeration.

SETTING

Peritoneal dialysis center and microbiology laboratory at a military, teaching medical center.

MEASUREMENTS

Standard peritoneal dialysate bags admixed with gentamicin, vancomycin, gentamicin and vancomycin in combination, or ceftazidime were stored at either 4 degrees C or 20 degrees C for 14 days. Sequential aliquots were withdrawn and assayed for antibiotic activity by bioassay and, except for ceftazidime, immunoassay for chemical activity. The bioassay was performed using a standardized Kirby-Bauer disc method. Significance was determined by ANOVA and, where the effect size was significant at the p < 0.05 level, the application of the paired t-test or the Wilcoxon signed rank test to the difference in activity between the first and last samples.

RESULTS

Antibiotic concentration by immunoassay did not significantly deteriorate over 14 days for vancomycin or gentamicin when either room temperature or refrigerated samples were studied. By bioassay, gentamicin and ceftazidime, but not vancomycin, lost moderate but significant activity over 14 days when refrigerated bags were assayed (except for an insignificant decrement in gentamicin in the combined vancomycin and gentamicin bags). Bags stored at room temperature, in general, lost significant bioactivity over 14 days, but to levels where clinical efficacy would still be expected. The vancomycin bioassay performed on the combination bags demonstrated a remarkably enhanced bioactivity, presumably reflecting synergy with gentamicin.

CONCLUSION

These data indicate that the study antibiotics admixed with peritoneal dialysis fluids retain stable chemical activity, whether refrigerated or kept at room temperature, for at least 14 days. A moderate decrement in bioactivity occurred for study antibiotics when stored either refrigerated or at room temperature over 14 days, although clinically significant levels were maintained. The clinical significance of a possible synergy between vancomycin and gentamicin is yet to be determined.

Short peritoneal equilibration test: impact of preceding dwell time

In the original peritoneal equilibration test (PET), which established standard values for membrane categorization in 1987, the dwell time of the preceding exchange was approximately 8 hours. Basing the test on an 8-hour prior exchange was convenient when almost all patients were on continuous ambulatory peritoneal dialysis (CAPD); however, many patients are now on some form of automated peritoneal dialysis (PD), and an 8-hour exchange before the PET requires a change in the dialysis schedule. Our goal in the present study was to determine whether the dialysate-to-plasma ratio (D/P) of solutes and the final dialysate to initial dialysate ratio (D/D0) of glucose in the short PET (2-hour equilibration time) are similar whether a 3-hour exchange or an 8-hour exchange precedes the test. The PETs were performed in 9 stable PD patients using 2 L of 2.5% dextrose dialysis solution (Baxter Healthcare, Deerfield, IL, U.S.A.). Before the equilibration exchange, the patients were on a randomly selected long (approximately 8-hour) or short (3-hour) dwell. During the equilibration exchange, dialysate samples were collected at 0.30, and 60 minutes of dwell time and from the drain bag (120-minute sample). Within a week, the PET was repeated in each patient after the alternate-length exchange. The values for D/P creatinine and urea and for D/D0 glucose were almost identical throughout the 2-hour PET after either the long or the short exchange. The D/P protein values tended to be higher in the PET after the long exchange. The short PET can be used for clinical purposes, and the creatinine and glucose results can be used for membrane categorization. Any dwell time between 3 and 12 hours is acceptable for the preceding exchange, and the equilibration test may be performed with either a 2-hour or a 4-hour dwell. The protein values obtained after a 3-hour prior dwell differ from those obtained after a long prior dwell. Protein values must therefore be standardized in a larger number of patients.

Oxidative stress markers and C-reactive protein in end-stage renal failure patients on dialysis

OBJECTIVE

The inflammatory status is a well-documented factor influencing the development of oxidative stress in dialysis patients. This study intends to evaluate the inflammatory activity and the plasma levels of total antioxidant capacity (TAC) and lipid peroxidation products in patients on peritoneal dialysis (PD), by comparison with hemodialysis (HD) patients.

PATIENTS AND METHODS

Plasma concentration of TAC, lipid peroxidation products and C-reactive protein (CRP) were measured in 24 patients on PD, 32 HD patients (pre and post treatment) and 16 normal controls (NC).

RESULTS

All patients had higher levels of TAC and lipid peroxidation products than NC (p < 0.001). Patients on PD, had similar levels to patients before HD but significantly higher (p < 0.001) than those post HD. The CRP concentration was higher in HD than in PD patients (p < 0.05). The percentage of patients with CRP > 10 mg/l was 48% in HD patients and 21% in PD patients. No correlation was observed between CRP and TAC nor CRP and MDA levels.

CONCLUSIONS

We conclude that although PD and HD patients show an equal susceptibility in oxidative stress, CRP levels are higher in HD patients and this is indicative of a higher degree of inflammatory activity in these patients.

Incremental dialysis with automated peritoneal dialysis

Since December 2000, we have proposed incremental dialysis to our patients with a glomerular filtration rate (GFR) of 8-9 mL/min/1.73 m2. The incremental dialysis uses automated peritoneal dialysis (APD) 3-4 days per week ["low frequency APD" (LF-APD)], with or without a full abdomen during the period between the nighttime sessions. From December 1, 2000, to September 30, 2001, LF-APD was selected by 5 patients (2 men, 3 women). Of the 5 patients, 4 worked (age: 53 +/- 12 years; range: 40-69 years), and 1 (age: 78 years) needed assistance from a partner who was available only on certain days of the week. Only 1 patient had diabetic nephropathy. The LF-APD was performed by 4 patients on alternate days ("standard LF-APD"), and by 1 patient 3 times per week (owing to limited availability of the partner). At the beginning of treatment, mean nightly LF-APD was 8.9 +/- 0.9 hours with a volume of 13.4 +/- 3.1 L. In 3 patients, icodextrin was used for the dwell between subsequent APD sessions (1-1.5 L). The other 2 patients kept an empty abdomen (owing to body image). Residual renal function (RRF) was measured every 3 months; adequacy and peritoneal equilibration test (PET), every 6 months. Total nightly APD volume was modified based on the results of the PET. At December 31, 2002, 3 patients with follow-ups of 25, 22, and 15 months were still on LF-APD because their GFR had remained unchanged. In another patient, the frequency of the APD sessions was increased after 5 months to 5 times per week from 3.5 times per week following a clinical assessment of underdialysis; however, that patient had had no significant change in GFR. Following a rapid decline in the diabetic patient's GFR (to 3.6 mL/min/1.73 m2 from 7.9 mL/min/1.73 m2 in 18 months) and refusal by that patient to increase the number of days of APD, the diabetic patient was transferred to hemodialysis. No episodes of peritonitis occurred in a total LF-APD follow-up of 84 patient-months. Compliance, assessed using the HomeChoice Pro system and comparing prescribed and recorded sessions, was total (no missed treatments). In conclusion, LF-APD can be a valid form of incremental dialysis and can help patients to choose PD as their first renal replacement therapy.