Adequacy of peritoneal dialysis: Kt/V revisited

OBJECTIVE

Kt/V urea has been used to assess adequacy of peritoneal dialysis. However, Kt/V urea only reflects the clearance of solute without taking into consideration the effects of dietary protein intake (DPI). The objective of this study is to evaluate the value of Kt/V based on nitrogen balance and to observe if it is the best adequacy index.

METHODS

On the premise that nitrogen balance is obtained, we calculated the minimal adequate dialysate volume and dialysis index (DI), Kt/V and solute removal index (SRI). We compared the values of DI, Kt/V and SRI to evaluate the adequacy of peritoneal dialysis.

RESULTS

Kt/V was changed with DPI and body weight of continuous ambulatory peritoneal dialysis (CAPD) patients. We cannot define adequate dialysis with a single value while DPI and body weight are different since CAPD, SRI and Kt/V are numerically equal. However, dialysis index (DI) can reflect the minimal adequate dialysate volume when DPI and body weight are different and, thus, reflects the adequacy of dialysis.

CONCLUSIONS

DI reflects the balance between DPI and solute clearance; thus, it is more useful to evaluate dialysis adequacy than Kt/V and SRI in clinically stable peritoneal dialysis patients.

Glycosylated hemoglobin and albumin-corrected fructosamine are good indicators for glycemic control in peritoneal dialysis patients

PURPOSE

Diabetes mellitus (DM) is the most common cause of end-stage renal disease and is an important risk factor for morbidity and mortality after dialysis. However, glycemic control among such patients is difficult to assess. The present study examined glycemic control parameters and observed glucose variation after refilling different kinds of fresh dialysate in peritoneal dialysis (PD) patients.

METHODS

A total of 25 DM PD patients were recruited, and continuous glucose monitoring system (CGMS) was applied to measure interstitial fluid (ISF) glucose levels at 5-min intervals for 3 days. Patients filled out diet and PD fluid exchange diaries. The records measured with CGMS were analyzed and correlated with other glycemic control parameters such as fructosamine, albumin-corrected fructosamine (AlbF), glycosylated hemoglobin (HbA1c), and glycated albumin levels.

RESULTS

There were significant correlations between mean ISF glucose and fructosamine (r = 0.45, P<0.05), AlbF (r = 0.54, P<0.01), and HbA1c (r = 0.51, P<0.01). The ISF glucose levels in glucose-containing dialysate increased from approximately 7-8 mg/dL within 1 hour of exchange in contrast to icodextrin dialysate which kept ISF glucose levels unchanged.

CONCLUSION

HbA1c and AlbF significantly correlated with the mean ISF glucose levels, indicating that they are reliable indices of glycemic control in DM PD patients. Icodextrin dialysate seems to have a favorable glycemic control effect when compared to the other glucose-containing dialysates.

The status of, and obstacles to, continuous ambulatory peritoneal dialysis in Thailand

The prevalence of dialysis in Thailand is 282 per million population, and utilization of peritoneal dialysis (PD) is only 4.6% of the utilization of hemodialysis (HD). The causes of low PD utilization include a relatively higher cost of PD care, especially from the patient's perspective; less incentive for PD care on the part of health care providers and hospitals; fewer continuing medical and nursing education programs in PD; unavailability of certified PD nurses; lack of confidence in the quality of PD care; fewer offers of PD as a renal replacement therapy option during pre-dialysis counseling; fear of peritonitis on the part of the patient, and also fear of burdening family members; a less stringent government policy regarding the "PD first" strategy. To increase PD utilization. mandatory strategies are lower PD cost, make all PD equipment reimbursable, launch a stringent "PD first" policy, provide incentives to health care providers and hospitals, and improve the quality of PD care.

Improving outcome of CAPD: twenty-five years' experience in a single Korean center

BACKGROUND

Continuous ambulatory peritoneal dialysis (CAPD) is an established treatment for end-stage renal disease (ESRD). We investigated the outcome of CAPD over a period of 25 years at our institution.

METHODS

CAPD has been performed in 2301 patients in 25 years. After excluding patients with less than 3 months of follow-up and missing data, we evaluated 1656 patients who started peritoneal dialysis between November 1981 and December 2005. Data for sex, age, primary disease, comorbidities, follow-up duration, cause of death, and cause of technique failure were collected. We also examined data for urea kinetic modeling (UKM), beginning in 1990, and peritonitis episodes, including causative organisms, starting in 1992.

RESULTS

Compared to incident patients from 1981-1992, mean age and incidence of ESRD caused by diabetic nephropathy increased in patients from 1993 to 2005. Technique survival after 5 and 10 years was 71.9% and 48.1% respectively. Technique survival was significantly higher in patients who started CAPD after 1992 than in those who started before 1992. Peritonitis was the main reason for technique failure. Overall peritonitis rate was 0.38 episodes per patient-year, with a significant downward trend to 0.29 per patient-year over 10 years, corresponding to a decrease in gram-positive peritonitis. Patient survival after 5 and 10 years was 69.8% and 51.8% respectively. Patient survival improved significantly during 1992-2005 compared to 1981-1992 after adjustment for age, gender, diabetes, and cardiovascular comorbidities [hazard ratio (HR) 0.68, p < 0.01]. Subgroup analysis based on UKM revealed that dialysis adequacy did not affect patient survival. However, diabetes (HR 2.78, p < 0.001), older age (per 1 year: HR 1.06; p < 0.001), serum albumin level (per 1 g/dL: increase, HR 0.52; p < 0.05), and cardiovascular comorbidities (HR 2.32, p < 0.01) were identified as significant risk factors.

CONCLUSION

Technique survival has improved due partly to a decrease in peritonitis, which was attributed to a decrease in gram-positive peritonitis. Patient survival has also improved considering increases in aged patients and ESRD caused by diabetes. The mortality rate of CAPD is still high in older, diabetic, malnourished, and cardiovascular diseased patients. A more careful management of higher risk groups will be needed to improve the outcome of CAPD patients in the future.

An integrative description of dialysis adequacy indices for different treatment modalities and schedules of dialysis

Dialysis adequacy indices that are applied for the evaluation of the efficiency of urea removal include fractional water volume cleared from urea during dialysis (KT T/V), fractional solute removal (FSR), and equivalent urea clearance (EKR). Using a constant-volume, one-compartment urea kinetic model for an anuric patient, the FSR and EKR are shown to depend on only three nondimensional parameters: (i) KT/V, where K is the dialyzer clearance for hemodialysis (HD) or peritoneal mass transport coefficient for peritoneal dialysis (PD), T is the time period of dialysis, and V is urea distribution volume; (ii) T/Tc, where Tc is the length of treatment cycle; and (iii) VD/V, where VD is the volume of dialysis fluid applied. In particular, analytical formulas for FSR and EKR, valid for HD as well as for PD, were derived as functions of these three parameters. Numerical simulations, performed using a two-compartment urea kinetic model, showed that the analytical formulas are valid also for the two-compartment model, except for short, highly effective HD, where the overestimation of FSR and EKR using the analytical formulas is however, not higher than 20 and 16%, respectively. KT T/V is equal to KT/V for HD and FSR for PD. Thus, our formulas provide an integrative description of the relationships between dialysis efficiency indices and operational dialysis parameters that is valid for all modalities and schedules of dialysis. They may be applied not only for standard HD and continuous ambulatory PD, but also for HD with circulating dialysis fluid or intermittent forms of PD.

Establishing a successful home dialysis program

The renewed interest in home dialysis therapies makes it pertinent to address the essentials of establishing and running a successful home dialysis program. The success of a home program depends on a clear understanding of the structure of the home program team, the physical plant, educational tool requirements, reimbursement sources and a business plan. A good command of the technical and economic aspects is important, but the primary drivers for the creation and growth of a home dialysis program are the confidence and commitment of the nephrological team.

Dialysis adequacy indices for peritoneal dialysis and hemodialysis

Dialysis adequacy indices that may be used to evaluate the efficiency of small-solute removal include Kt/V, fractional solute removal (FSR), and equivalent urea clearance (EKR). To analyze possible relationships between those indices, we used the two-compartment variable-volume urea kinetic model to simulate several dialysis modalities: hemodialysis (HD) performed three times or six times weekly, automatic nightly peritoneal dialysis (PD), and continuous ambulatory PD. Instead of targeting a chosen Kt/V value, we selected a weekly FSR of 1.81 as the target adequacy index. We determined hemodialyzer clearances and diffusive mass transport parameters for the peritoneal membrane that yielded the desired value of FSR for a typical patient and dialysis schedule. By theoretic analysis, EKR and FSR are proportional: EKR/FSR = V/Tc, where V = urea distribution volume in the body and Tc = time of the dialysis cycle, usually 1 week. Thus, FSR and EKR have the same meaning and scaling in PD and HD, and may be equivalently applied for assessment of dialysis efficacy.

Ensuring best practice in the treatment of peritonitis and exit site infection

The outcomes and objectives for KB were met by following a case management tool specific to peritonitis and exit site infection. Utilization of the care pathway and protocol ensured best practice in the nursing care provided and the medical treatment administered. Both the peritonitis and the ESI resolved successfully without complications, loss of residual renal function, hospitalization or relapse. KB received retraining on technique and prevention and has had no further episodes of peritonitis or ESI. She continues to do well on PD and maintains her active lifestyle.

Review of combination of peritoneal dialysis and hemodialysis as a modality of treatment for end-stage renal disease

Because the contribution of residual renal function (RRF) to total solute clearance is often significant in continuous ambulatory peritoneal dialysis (CAPD), loss of RRF over time can lead to inadequate dialysis if appropriate prescription management strategies are not pursued. Additionally, declines in ultrafiltration caused by increases in peritoneal permeability may limit continuation of CAPD therapy. Peritoneal dialysis and hemodialysis (PD + HD) combination therapy (complementary dialysis therapy) is an alternative method. This therapy allows the patient to maintain daily activities, as with CAPD, while undergoing once-a-week HD supplements for the insufficient removal of solutes and water. This therapy allows for the continuation of PD without shifting to total HD in PD patients who continue to have uremic symptoms even after individualization of the PD prescription. This treatment option is psychologically more acceptable to patients and may be expected to provide such accompanying beneficial effects as peritoneal resting, improvement of QOL and reduction in medical cost.

Adequacy of dialysis in children: does small solute clearance really matter?

Measurement of dialysis adequacy relies on an assessment of small molecule clearance during the dialysis procedure. However, recent adult studies (HEMO and ADEMEX) that pushed clearance to maximally achievable levels within practical constraints of thrice-weekly hemodialysis or four times daily continuous ambulatory peritoneal dialysis failed to demonstrate improvements in patient outcome above current guidelines. The relatively low incidence of pediatric compared with adult end-stage renal disease limits large-scale study of pediatric dialysis. Several single-center pediatric studies demonstrate a lack of association between small solute clearance alone and patient growth. The aim of the current article is to review the relevant pediatric and adult studies of small solute clearance and put them in the context of optimal dialysis provision. While small solute clearances do indeed matter, clearance is not all that matters. Our quest to provide optimal dialysis requires that we also focus our attention on patient nutritional status, increased dialysis delivery (daily/nocturnal hemodialysis), and adjunctive dialysis modalities (hemofiltration and renal tubular replacement therapy).

Histologic change of peritoneal membrane in relation to adequacy of dialysis in continuous ambulatory peritoneal dialysis patients

BACKGROUND

Long-term exposure of peritoneal membrane to bioincompatible dialysis solutions leads to structural changes and loss of ultrafiltration capability.

OBJECTIVE

We studied the possible relationship between histologic change and the transport characteristics of peritoneal membrane and adequacy of dialysis in continuous ambulatory peritoneal dialysis (CAPD) patients.

PATIENTS AND METHODS

The study included 18 CAPD patients (11 men, 7 women) who underwent a peritoneal biopsy either at initiation of treatment (group A, n = 9) or after a mean of 4 years on CAPD (group B, n = 9). The morphologic changes in the mesothelial cells and the vascular compartment and the thickness of the submesothelial collagenous zone were estimated and compared with observations from 6 patients with normal renal function who underwent biopsy of the parietal peritoneum during abdominal surgery. The relationship of the observed changes in CAPD patients to results from a peritoneal equilibration test (PET) and to adequacy of dialysis [total weekly creatinine clearance (CCr) and Kt/V urea] were also investigated.

RESULTS

The main histologic changes in both groups of patients were loss of mesothelial cells and decrease in the normal mesothelial surface, thickening of the submesothelial collagenous zone, and presence of vascular hyalinosis. The thickness of the submesothelial collagenous zone in both groups of patients was significantly greater than that found in controls (410 mum and 580 mum vs 50 mum, p < 0.05). Although no significant difference was found between morphologic change in the peritoneal membrane of uremic patients starting on CAPD and those who had been on peritoneal dialysis (PD) for a mean period of 4 years, a trend was observed toward more severe lesions in the latter patients. The PET, CCr, and Kt/V urea were not significantly different in the two groups of patients. Those parameters also showed no significant changes when examined at initiation of CAPD and after a mean of 4 years of PD in the same patients (group B). No significant correlations were observed between the histologic changes and the PET, CCr, or Kt/V in both groups of patients.

CONCLUSIONS

Significant structural changes are observed in the peritoneal membrane of uremic patients, and those changes become worse with CAPD treatment. Structural changes are not followed by functional changes during the first 4 years on CAPD.

Dialysis adequacy targets in continuous ambulatory peritoneal dialysis--higher is not necessarily better

Evidence for the recommendations by the Dialysis Outcomes Quality Initiative (DOQI) on peritoneal dialysis targets was obtained largely from observational studies showing improvement of clinical outcome with higher Kt/V. Recently published interventional studies--including the ADEMEX study and several studies from Asia--did not show significant improvement of outcome with increased peritoneal Kt/V or creatinine clearance. The possible reasons for lack of improvement might include the limitations of increased dialysis with regard to middle-molecule clearance and the harmful effects of excessive dialysis. The body of evidence suggests that a total Kt/V below 1.7 is associated with a poorer outcome. A minimal Kt/V target of 1.7 is suggested, with the dialysis prescription also being guided by other clinical parameters.

Peritoneal dialysis adequacy in Asia--is higher better?

Sufficient data are available to support the contention that renal and peritoneal clearances are not equivalent, and that loss of residual renal function (RRF) cannot be completely compensated by an increase in the exchange volume or frequency of peritoneal dialysis. When RRF is minimal (for example, renal Kt/V is 0.1 - 0.3), increasing the peritoneal Kt/V beyond the "conventional" value recommended by the Dialysis Outcomes Quality Initiative yields little additional clinical benefit. The cut-off peritoneal (not total) Kt/V is possibly 1.6 - 1.7. However, delivery of peritoneal small-solute clearance below that cut-off level has a major detrimental effect on clinical outcome in CAPD patients with little RRF. Measures to preserve RRF therefore become an important goal in the treatment of CAPD patients. In short, with regard to RRF (renal Kt/V), higher is always better, and we should always try to preserve it. For peritoneal Kt/V, higher is better only up to a certain limit. The importance of aspects of adequate dialysis other than small-solute removal--especially fluid removal, blood pressure control, nutrition, acid-base balance, mineral metabolism, and anemia and lipid control--cannot be sufficiently emphasized.

[Uremic patients--late referral, early death]

BACKGROUND AND OBJECTIVE

A number of reports from various countries document that patients with renal failure who are referred late to renal units, have more complications e. g. lack of vascular access when dialysis has to be started as well as longer hospitalisation and have also a higher risk of early death. No data on these points are available from Germany.

PATIENTS AND METHODS

In a retrospective analysis the timing of referral to the nephrologists was studied in two Departments of Medicine, e. g. Heidelberg and Vienna, for all patients who started renal replacement therapy. For patients in Heidelberg the relation between timing of referral and survival on dialysis was analysed using the Kaplan-Maier-technique.

RESULTS

In Heidelberg 280 patients were analysed, 174 men, 106 women, age 61.8 +/- 14.5 years; 136 diabetic patients (9 type 1). They had been referred from GPs (n = 131), specialists (diabetologists, cardiologists; n = 20), emergency departments (n = 33), other hospitals (n = 90) or other institutions (n = 16). The measured median creatinine clearance at the time of referral was 14 ml/min (5-34). The median interval between referral and start of dialysis was 17 weeks. 137 patients had been referred < 17 weeks and 143 patients > or = 17 weeks prior to the start of dialysis. 97 of the 111 patients referred < or = 4 weeks prior to dialysis and 59 of the 169 patients referred > 4 weeks had to be dialysed with a central catheter. There were clear differences in patient survival. In patients referred < 17 weeks before the start of dialysis, the actuarial risk of death during the first 12 month was 34.2 % compared to 5.5 % (p < 0.0001) in patients referred > or = 17 weeks. Even the mortality in the interval between 12 and 24 months after the start of dialysis was clearly higher (15.3 %) in patients with late compared to early referral (11.4 %).

CONCLUSION

Late referral of patients with impaired renal function to renal units causes more frequent problems of vascular access, longer hospitalisation, more medical complications, higher costs and higher mortality. Early referral of patients with renal failure is indispensable to improve dialysis outcomes.

The ADEMEX study and its implications for peritoneal dialysis adequacy

In an attempt to improve patient outcomes in peritoneal dialysis (PD), national organizations (such as the National Kidney Foundation Dialysis Outcomes Quality Initiative [NKF-DOQI] process) have formulated clinical practice guidelines based on clinical evidence available at the time of development. For "adequacy" of PD it was acknowledged that there was no prospective randomized interventional clinical trial that evaluated the effect of an increase in peritoneal clearance on outcome. The ADEMEX study is the first such study designed to do this. It was well done and adequately powered for the primary analysis. The study findings indicate that over the range of solute clearances studied, an increase in peritoneal clearance is not associated with an incremental improvement in patient outcome. However, it is noted that the cause of dropout was different between groups, with more dropout for "uremia" in the control group. There are also some limitations in the generalizability of the results. First, the exclusion criteria were likely to exclude patients who were small in body size or were high transporters, patients with the highest relative risk of death. Second, although there was an increase in small solute clearance between control and intervention groups, there was not likely to be an increase in clearance of other potential uremic solutes such as middle molecules. Third, the study did not examine outcomes for patients on cycler therapy. Nevertheless it was a provocative, well-run clinical study which does have implications for clinical practice. It confirms that one prescription does not fit all patients, that many patients below current NKF-DOQI targets for small solute clearance are likely to be adequately dialyzed, and provides evidence-based clinical information for national societies to consider when preparing for the next revision of their guidelines.

Patient and technique survival on CAPD in Turkey

OBJECTIVE

To analyze the status of continuous ambulatory peritoneal dialysis (CAPD) in 12 centers in Turkey.

DESIGN

Retrospective study of CAPD technique and patient outcome.

SETTING

University hospital renal units.

PATIENTS

334 patients [205 males (61%),129 (39%) females; mean age 42.2 +/- 13.8 years; mean follow-up time 23.5 +/- 18.3 months] beginning CAPD between March 1992 and December 1999, and having a minimum follow-up of 3 months.

OUTCOME MEASURE

Patient survival, technique survival, and duration of hospitalization.

RESULTS

Mean weekly Kt/V urea was 1.9 +/- 0.8, weekly creatinine clearance was 62.9 +/- 8.5 L/1.73 m2, and mean serum albumin level was 3.7 +/- 0.6 g/dL. 93 patients (28%) were withdrawn from peritoneal dialysis due to death (12.6%), transplantation (3.9%), transfer to hemodialysis (8.7%), patient failure to adapt (1.5%), and other reasons (1.2%). The major causes of death were cardiovascular disease (60%), infection (19%), malignancy (2%), and others (19%). Cox proportional hazard model analysis indicated age, serum albumin levels, comorbidity, and functional status affected survival and hospitalization (p < 0.05), whereas gender and Kt/V did not (p > 0.05). Estimation of patient survival by Kaplan-Meier analysis showed 94.2%, 88.6%, 84.5%, and 68.9% at 1, 2, 3, and 5 years respectively. Technique survival estimate by Kaplan-Meier analysis was 96.6%, 91.1%, 90.4%, and 77.4% at 1, 2, 3, and 5 years respectively.

CONCLUSION

Peritoneal dialysis is an acceptable method of renal replacement therapy in Turkey. There is controversy regarding the usefulness of Kt/V in predicting mortality and morbidity.

Independent effects of residual renal function and dialysis adequacy on actual dietary protein, calorie, and other nutrient intake in patients on continuous ambulatory peritoneal dialysis

Previous studies have suggested that the cross-sectional relationship observed between total solute clearance (Kt/V) and dietary protein intake (DPI) in patients undergoing dialysis is possibly mathematical in origin. A cross-sectional study on 242 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was performed to determine the differential effects of dialysis adequacy and residual renal function (RRF) on actual dietary intake. All patients underwent a 7-d food frequency questionnaire to quantify daily dietary protein, calorie (DCI), and other nutrient intake, subjective global assessment (SGA), and collection of 24-h dialysate and urine for total (PD and renal) Kt/V and RRF. Patients were categorized into three groups: I (n = 94), total Kt/V >/=1.7 and GFR >0.5 ml/min per 1.73 m(2); II (n = 58), total Kt/V >/=1.7 but GFR <0.5 ml/min per 1.73 m(2); and III (n = 90), total Kt/V <1.7. Sixty-nine percent versus 62% versus 42% of group I versus II versus III patients were well nourished according to SGA (P = 0.004). DPI (1.23 [0.47] versus 1.12 [0.49] versus 0.99 [0.40] g/kg per d; P = 0.002) and DCI (27.3 [8.9] versus 23.8 [8.6] versus 23.0 [8.2] kcal/kg per d; P = 0.002) showed significant decline across the three groups. Intake of other nutrients, including carbohydrate, fat, fatty acids, and cholesterol was higher for group I compared with groups II and III. Adjusting for age, gender, weight, and diabetes, every 1 ml/min per 1.73 m(2) increase in GFR was associated with a 0.838-fold increase in DCI (95% confidence interval to interval, 0.279 to 1.397; P = 0.003) and a 0.041-fold increase in DPI (95% confidence interval, 0.009 to 0.072; P = 0.012), whereas every 0.25-unit increase in total (PD and renal) Kt/V was associated with a 0.570-fold increase in DCI (95% confidence interval, 0.049 to 1.092; P = 0.032) and a 0.052-fold increase in DPI (95% confidence interval, 0.023 to 0.081; P = 0.001). Greater small-solute clearances are associated with better dietary intake and better nutrition. The study confirmed significant and independent effect of RRF, but not PD solute clearance, on actual DPI, DCI, and other nutrient intake in patients on CAPD.

Continuous renal replacement therapy. The real story

Continuous renal replacement therapy (CRRT) is used to treat patients who suffer from acute renal failure. Unlike the more traditional intermittent hemodialysis (IHD), CRRT is administered around the clock, providing patients with nonstop therapy and sparing them the destabilizing hemodynamic and electrolytic changes characteristic of IHD. Many clinicians have reported that CRRT's steady, milder treatment is less traumatic for some of their patients than IHD. For acute renal failure patients who can't tolerate IHD--usually those with very low blood pressure--CRRT is often the only choice of treatment. CRRT can also be used on many patients who can tolerate IHD. But because there is little useful survival data concerning CRRT, and because CRRT is sometimes perceived as significantly more expensive than IHD, some hospital administrators have--groundlessly, we believe--questioned the wisdom of investing in this technology. In this article, we examine CRRT's benefits and take a close look at some of the myths that have impeded its adoption.

An in vitro bacterial touch contamination risk assessment of two CAPD twinbag systems

The objective of this study was to compare, using in vitro quantitative microbiology, the ability of two commercially available peritoneal dialysis solution delivery systems to prevent and remove, via convective fluid flow, intralumenal fluid path bacterial contamination. The two systems (A and B) differed in both the configuration of their flow control, or Y-junction and the method of fluid flow control and also in the design of their Luer tubing connectors. System A had a tubing type Y-junction that requires clamps to control fluid flow and uses a connector with a male Luer that is deeply recessed within a shroud. System B has a dial-type rigid Y-junction with in-line flow control and a connector with a male Luer that is shrouded but not recessed. System A connectors allowed significantly (p<0.0001) fewer bacteria to be transferred into the fluid path than System B after simulated touch contamination. Also, when an equivalent number of bacteria were deliberately placed into the fluid paths of both systems, System A was more effective in removal of the bacterial contamination by convective fluid flow than System B (p<0.0001), resulting in fewer organisms infused into the simulated peritoneum. Specific design features of System A, such as a recessed male Luer, and a Y-junction fluid flow path with low turbulence were likely explanations for its superior results. This study emphasizes the importance of connector and fluid path flow design in the aseptic performance of peritoneal dialysis delivery systems.

Developing a health-related quality-of-life measure for end-stage renal disease: The CHOICE Health Experience Questionnaire

The Choices for Healthy Outcomes in Caring for End-Stage Renal Disease ([ESRD] CHOICE) Study was designed to evaluate the effectiveness of alternative dialysis prescriptions. As part of CHOICE, we developed an instrument for measuring health-related quality of life (HRQOL) for patients with ESRD that would complement the Medical Outcomes Study 36-Item Short-Form Survey (SF-36) and be sensitive to differences in dialysis modality (hemodialysis [HD] and peritoneal dialysis [PD]) and dialysis dose. The selection of HRQOL domains to be included was based on: (1) a structured literature review of 47 articles describing 53 different instruments; (2) content analysis of five focus groups with HD and PD patients, nephrologists, and other providers; (3) a survey of 110 dialysis providers about features of different modalities that affect patient HRQOL; and (4) a semistructured survey of 25 patients with ESRD on the effects of dialysis on functioning and HRQOL. To help prioritize domains and items identified by these methods, a representative sample of 136 dialysis patients rated each item for frequency and bother. A panel of nephrologists provided advice about the salience of items to modality or dose. Items and scales were selected with a preference for existing measures tested in patients with ESRD and were tested for reliability and validity. The first four steps yielded 22 HRQOL domains that included 96 items: 8 generic domains in the SF-36 (health perceptions, physical, social, physical and emotional role function, pain, mental health, and energy); 8 additional generic domains (cognitive functioning, sexual functioning, sleep, work, recreation, travel, finances, and general quality of life); and 6 ESRD-specific domains (diet, freedom, time, body image, dialysis access [catheters and/or vascular], and symptoms). New items were developed or adapted to assess ESRD-specific domains. Scales for these items showed adequate internal consistency (Cronbach's alpha > 0.70, except for time [alpha = 0.57] and quality of life [alpha = 0.68]), as well as convergent and discriminant construct validity in a sample of 928 patients. The final questionnaire included 21 domains (time was deleted) and 83 items. We have designed a patient-centered instrument, the CHOICE Health Experience Questionnaire, that addresses domains that may be sensitive to differences in dialysis modality and dose and shows evidence for reliability and validity as a measure of HRQOL in ESRD.

[The significance of adequacy for success of an automated peritoneal dialysis program]

The dynamic development of APD causes the increasing importance of issues regarding the adequacy of this renal replacement therapy method. Basic parameters of effective dialysis are still Kt/V and weekly creatinine clearance. The lack of steady state of substance concentration in different body compartments is a potential cause of mistakes in calculation of APD adequacy kinetic parameters. The solute removal index (SRI) may be used as an alternative method of dialysis efficacy assessment. However, there is no "ideal" marker of adequacy. Therefore, it should be assessed on the base of analysis including kinetic, clinical and biochemical data. Residual renal function (RRF) is an important factor of successful APD, but there are different opinions concerning the influence of automatic dialysis on RRF preservation presented in literature. The characteristics of peritoneal transport is the basic criterion for the qualification of patients to APD program. Automated techniques are recommended for patients being high-average transporters and particularly high transporters. The evolution of APD creates new perspectives for adequacy assessment and improvement of dialysis efficacy. The performance of multicenter studies and usage of new parameters of adequate dialysis will be very important for the development of APD. The employment of alternative fluids, introduction of modernized catheters and construction of "intelligent cyclers" will create new possibilities for programming and monitoring of dialysis and improvement of patient's life quality.

[Report from the 1st korean-Polish seminar: "Theoretical, technical and clinical aspects of renal replacement therapy (5/18-21/2000)]

This was the first Korean-Polish seminar on renal replacement therapies which provided a survey of current research being carried out in both countries, delivered by leading experts in this field. The topics included malnutrition in uremia, biocompatibility, risk factors and complications in renal replacement therapy, diabetic nephropathy, new solutions for peritoneal dialysis, and peritoneal transport. The organizers strove to select the topics which are currently of interest to researchers from both countries with the purpose to compare results and stimulate discussion concerning possible collaboration in the future.

Unrestricted pore area (A0/Deltax) is a better indicator of peritoneal membrane function than PET

BACKGROUND

How to measure the peritoneal exchange in uremic patients treated with peritoneal dialysis (PD) is still a matter of controversy. Most clinics use the peritoneal equilibration test (PET), but from a theoretical point of view, it would be more appropriate to determine the "area" parameter, A0/Deltax. The latter reflects the total unrestricted pore area per centimeter diffusion distance and can be obtained by three-pore analysis using, for example, the PD capacity test (PDC). To evaluate the different estimates of peritoneal function, PET data and the A0/Deltax parameters were compared with the independently determined uptake of a small diffusible tracer, iohexol (molecular weight of 821 D), from the abdominal cavity to blood.

METHODS

Fourteen patients on routine PD underwent determinations of PET and A0/Deltax using PDC. Within a month, the two-hour uptake of iohexol (6 mg/mL) was also determined from the plasma iohexol concentration following abdominal filling.

RESULTS

A strong correlation was found between the rate of iohexol plasma concentration increase (k30-120) and A0/Deltax (A0/Deltax = 76,300. k30-120 - 1.56; r2 = 0.799; N = 14) for the 2 L dwell, while the PET data were far less related to iohexol uptake (D/DPurea, r2 = 0.409; D/Pcreatinine, r2 = 0.436; and D/D0glucose, r2 = 0.015, respectively).

CONCLUSION

The "area" parameter, A0/Deltax, is superior to the more widely used routine PET as an indicator of peritoneal membrane function. In addition, the concept of A0/Deltax has the virtue of supplying quantitative information about the peritoneal pathophysiology and physiology.

Urea kinetic analysis of automated peritoneal dialysis allows calculation of a CAPD-equivalent Kt/V(urea)

BACKGROUND

Based on evidence of increased mortality with decreasing urea clearance, the Dialysis Outcomes Quality Initiative (DOQI) recommended a weekly Kt/Vurea of 2.0 or higher for patients receiving continuous ambulatory peritoneal dialysis (CAPD). DOQI recommendations for automated peritoneal dialysis (APD) are based on efforts to determine the clearance providing urea mass removal equivalent to CAPD. We have adapted a variable volume direct quantitation urea kinetic model (UKM) in an effort to assess DOQI APD guidelines.

METHODS

The daily urea mass removed with a weekly Kt/Vurea of 2.0 was calculated using standardized CAPD patient profiles. Using this value and defining the pre-APD plasma urea nitrogen (PUN) as C0 and equal to the CAPD steady-state PUN, the UKM reiteratively calculated the urea clearance from an APD treatment that provided a urea mass removal equivalent to CAPD. A total weekly Kt/Vurea was calculated for various levels of continuous urea clearance (defined as Kprt/Vurea) and plotted against Kprt/Vurea (weekly). The impact of dialytic time (t), drain volume of the daytime dwell (delta), and ultrafiltration volume (phi) were assessed, and all profiles were performed with C0 equal to the corresponding blood urea nitrogen of 60, 70, and 80 mg/dL.

RESULTS

The relationship between requisite weekly Kt/Vurea and Kprt/Vurea (weekly) was linear. Weekly Kt/Vurea declined with increasing Kprt/Vurea, t, delta, and phi. The effect of phi on the weekly Kt/Vurea was independent of Kprt/Vurea, and the magnitude of the effect of t and delta on the weekly Kt/Vurea decreased with increasing continuous clearance. Weekly Kt/Vurea values were independent of V and C0. The latter observation allowed extrapolation of CAPD clearance and urea generation relationships to APD: CAPD-equivalent weekly Kt/Vurea = [700 x (UD + Ur)]/(C0 x V), where UD and Ur are the daily urea mass (mg) in dialysate and urine, respectively.

CONCLUSIONS

The APD urea clearance, which provides urea mass removal equivalent to CAPD, varies as a function of a combination of patient and treatment variables. However, a CAPD-equivalent weekly Kt/Vurea can be calculated by collecting appropriate dialysis and urine samples and estimating patient V. The results can be evaluated in the context of evidence-based CAPD guidelines, increasing the precision of adjustment and monitoring of the APD prescription.

Importance of dialysis adequacy in mortality and morbidity of chinese CAPD patients

BACKGROUND

In continuous ambulatory peritoneal dialysis (CAPD), the impact of dialysis adequacy on patient outcome is well established in Caucasian patients but is less clear in Asian patients. Recent evidence suggests that Asian dialysis patients enjoy better overall survival. We hypothesize that dialysis adequacy may be less important in determining outcome for this ethnic group.

METHODS

We performed a single-center prospective observational study. From September 1995, we enrolled 150 existing and 120 new CAPD patients. They were followed for up to three years. We monitored dialysis adequacy and nutritional indices, including Kt/V, weekly creatinine clearance (CCr), residual glomerular filtration rate (GFR), normalized protein catabolic rate (NPCR), percentage of lean body mass (%LBM), and plasma albumin level. Clinical outcomes included mortality, technique failure, and duration of hospitalization.

RESULTS

The duration of study follow-up was 22.1 +/- 12.3 months. In our study population, 136 were male. Seventy were diabetic (25.9%), and 212 were treated with 6 L exchanges per day (78.5%). The body weight was 59.3 +/- 9.4 kg. Baseline total Kt/V was 1.78 +/- 0.41, peritoneal Kt/V 1.48 +/- 0.36, and median residual GFR 0.98 mL/min (range 0 to 7.45). Two-year patient survival was 83.0%, and technique survival was 72.8%. Multivariate analysis showed that the duration of dialysis, diabetes, %LBM, index of dialysis adequacy (Kt/V or CCr), residual GFR, and requirement of a helper for CAPD exchanges were independent factors of patient survival; serum albumin, adequacy index (Kt/V or CCr), and requirement of a helper were independent factors of technique survival. Duration of dialysis, body weight, requirement of helper, cardiovascular disease, HBsAg carrier, serum albumin, and CCr had independent effects on hospitalization. The peritoneal component of Kt/V or CCr had no independent effect on any outcome parameter. When the prevalent and new CAPD cases were analyzed separately, Kt/V predicted survival only for new CAPD cases.

CONCLUSIONS

Our results show that dialysis adequacy has significant impact on outcome of Asian CAPD patients. Although we have excellent medium-term patient and technique survival, this favorable outcome should not prevent health care workers from providing adequate dialysis to Asian patients. The reason of discrepancy in outcome between Asian and Caucasian dialysis patients requires further study.

Peritoneal dialysis adequacy and risk of death

BACKGROUND

The purpose of this study was to evaluate the relationship between dialysis dose, patient characteristics, and medical comorbidities on mortality in chronic peritoneal dialysis patients.

METHODS

This work comprised a study cohort of 1446 patients obtained from a random sample of chronic peritoneal dialysis patients from each dialysis center in three southeastern states. Data collected on a standardized form were used to calculate weekly Kt/V urea and creatinine clearance. Data were linked to Network files containing data on patient demographic and medical comorbidities.

RESULTS

Both weekly Kt/V urea and creatinine clearance were measured at least once in only 60.5% of continuous ambulatory peritoneal dialysis (CAPD) patients and 63.7% of cycler patients. Among the 873 patients who had at least one calculable adequacy measure, the mean (+/-SD) weekly Kt/V urea was 2.13 +/- 0.55, and the normalized mean weekly creatinine clearance was 62.9 +/- 20.4 L/week/m2. During the seven month period of follow-up, there were 140 deaths. In separate logistic regression models that included all of the studied risk factors, using separate variables for the urinary and peritoneal components of dialysis adequacy, each 10 L/week/1.73 m2 increase in the urinary component of weekly creatinine clearance was associated with a 40% decreased risk of death, and each 0.1 unit increase in the urinary component of weekly Kt/V urea was associated with a 12% decreased risk of death. In contrast, the dialysate components of neither weekly creatinine clearance nor weekly Kt/V urea were predictive of death. Other factors that were associated with an increased risk of death included increasing age, diabetes mellitus as the cause of end-stage renal disease (ESRD), and a history of myocardial infarction.

CONCLUSIONS

Residual renal function, as expressed by weekly creatinine clearance or Kt/V urea, is an important predictor of death in chronic peritoneal dialysis patients. The nonsignificant findings regarding peritoneal clearances and mortality may possibly be secondary to the narrow range of peritoneal clearances in this study cohort.

Improving quality of life for dialysis patients through telecare

Home dialysis can improve the care and quality of life for patients with renal failure. We have explored the possibility of extending home care to more patients needing continuous ambulatory peritoneal dialysis (CAPD) using telemedicine. We tested videoconferencing support for five CAPD patients using low-cost ISDN equipment (128 kbit/s). Initial results indicated that it was possible to integrate videocommunication into the daily routine of the clinic and the response from patients was surprisingly positive. Selection of appropriate, affordable technology and the ISDN service support by the telecommunications provider proved to be considerably more difficult than anticipated. The first indications also suggest medical advantages for home teledialysis.

The importance of an extra hour of cycler therapy to obtain better adequacy

As continuous ambulatory peritoneal dialysis (CAPD) patients lose residual renal function, it frequently becomes impossible from them to obtain adequate dialysis unless the dialysis prescription is changed. Increasing the dwell volumes, increasing the frequency of exchanges, and using a night-exchange device or a cycler are the means available to improve adequacy. In an effort to obtain dialysis adequacy, we studied how an extra hour on cycler therapy can contribute to improving dialysis adequacy. Over 18 months, we optimized solute clearance using the PD Adequest program (Baxter Healthcare Corporation, Chicago, Illinois, U.S.A.) in 70 patients. After finding the best total cycler volume, we compared the weekly creatinine clearance and weekly Kt/V from 8-hour cycler therapy to that from 9-hour cycler therapy for the four types of membrane transport. Adding one extra hour on cycler therapy improved weekly creatinine clearance by 3-6.5 L and the weekly Kt/V by 0.16-0.20. When patients are marginally approaching the required weekly Kt/V or creatinine clearance, an extra hour on the cycler may help to achieve the desired adequacy.

Outcome assessment of the Ministry of Health Malaysia dialysis programme

We describe the outcomes on haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) provided by the Ministry of Health (MOH). The assessment was based on data from the Malaysian Dialysis Registry on 2480 HD and 732 CAPD patients who commenced dialysis between 1980 and 1996. Young patients (age < 40) have remarkable long term survival (life expectancies of 16 years on HD, 18 years on CAPD). Adjusting for background mortality, relative survival of older patients was as good as younger ones. Diabetics did poorly. 52% of HD and 26% of CAPD patients were employed in 1996. 71% of HD patients scored 10(normal) on QL index (a measure of quality of life) while 60% of CAPD patients have similar score. Differences in rehabilitation and QL index scores by age, gender and diabetes were also observed. Outcomes of dialysis in the MOH programme are reassuring.

Taking peritoneal dialysis beyond the year 2000

Over the past 25 years, peritoneal dialysis (PD) has steadily improved so that now its outcomes, in the form of patient survival, are equivalent to, and at times better than, those for hemodialysis. We now have a better understanding of the pathophysiology of peritoneal membrane function and damage and the importance of appropriate prescription to meet agreed-upon targets of solute and fluid removal. In the next millennium, greater emphasis will be put on prescription setting and subsequent monitoring. This will entail an increase in automated PD, especially for lifestyle reasons as well as for patients with a hyperpermeable peritoneal membrane. To improve outcomes, dialysis should be started earlier than is currently the case. It is easy to do this with PD, where an incremental approach is made easier by the introduction of icodextrin for long-dwell PD. In the future, solutions will be tailored to be more biocompatible and to provide improved nutrition and better cardiovascular outcomes. Finally, economic considerations favor PD, which is cheaper than in-centre hemodialysis. Thus, for many, PD has become a first-choice therapy, and with further improvements this trend will continue.

[Adequacy of continuous ambulatory peritoneal dialysis in children]

When the use of dialytical therapy is decided after a careful assessment of clinical and laboratory variables, the close supervision of the procedure, that allows a feedback between our indications and its clinical efficacy, is essential. The correct and routine use of validated adequacy tools such as Kt/V and the Peritoneal Equilibration Test (PET) is mandatory. We compare the adequacy figures for adult and pediatric populations, mentioning the Kt/V and PET values obtained in eight patients followed during 12 months in a Nephrology Unit. An initial Kt/V of 2.04 and of 2.14 after 12 months of procedure are values that adjust to the general recommendations discussed in this paper. According to PET results, this group of patients were classified as low average for ultrafiltration and high average for creatinine clearance. Based on the local experience and literature review, some recommendations are made for the management of peritoneal dialysis in children.

High peritoneal residual volume decreases the efficiency of peritoneal dialysis

BACKGROUND

Wide variation in peritoneal residual volume (PRV) is a common clinical observation. High PRV has been used in both continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis to minimize the time of a dry peritoneal cavity and to achieve better dialysis. However, the impact of PRV on peritoneal transport is not well established. In this study, we investigated the effect of PRV on peritoneal transport characteristics.

METHODS

Peritoneal effluents were collected in 32 male Sprague-Dawley rats after a five-hour dwell with 1.36% glucose solution. Forty-eight hours later, a four hour dwell using 25 ml of 3.86% glucose solution and frequent dialysate and blood sampling was done in each rat with 125I-albumin as a volume marker. Before the infusion of the 3.86% glucose solution, 0 (control), 3, 6, or 12 ml (8 rats in each group) of autologous effluent (serving as PRV) was infused to the peritoneal cavity.

RESULTS

After subtracting the PRV, the net ultrafiltration was significantly lower in the PRV groups as compared with the control group: 13.4 +/- 0.5, 12.0 +/- 1.0, 11.7 +/- 1.7, and 8.9 +/- 0.4 ml for 0, 3, 6, and 12 ml PRV groups, respectively (P < 0.001). The lower net ultrafiltration associated with higher PRV was due to (a) a significantly lower transcapillary ultrafiltration rate (Qu) caused by a lower osmotic gradient, and (b) a significantly higher peritoneal fluid absorption rate (KE) caused by an increased intraperitoneal hydrostatic pressure. No significant differences were found in the diffusive mass transport coefficient for small solutes (glucose, urea, sodium, and potassium) and total protein, although the dialysate over plasma concentration ratios values were higher in the high-PRV groups. The sodium removal was significantly lower in the PRV groups as compared with the control group (P < 0.01).

CONCLUSION

Our results suggest that a high PRV may decrease net ultrafiltration through decreasing the Qu, which is caused by a decreased dialysate osmolality, and increasing the KE caused by an increased intraperitoneal hydrostatic pressure. The high volume of PRV also decreased the solute diffusion gradient and decreased peritoneal small solute clearances, particularly for sodium. Therefore, a high PRV may compromise the efficiency of dialysis with a glucose solution.