Weight loss and weight gains in patients starting peritoneal dialysis; the effect of peritonitis

AIM

Earlier studies reported that peritoneal dialysis (PD) patients gained fat mass after initiating dialysis. Clinical practice and demographics have changed over time with earlier initiation of dialysis and increasing numbers of elderly, co-morbid patients. As such, we wished to review changes in body composition with dialysis.

METHODS

Changes in body composition were compared by dual x-ray absorptiometry (DXA) in 151 adult PD patients, 81 males (54.6%), 50 diabetic (30.1%), mean age 60.5 ± 16.7 years, shortly after starting PD and then a median of 24 months later, to allow for the initial impact of dialysis.

RESULTS

Overall, weight appeared stable (71.7 ± 15.4 vs. 71.9 ± 15.3 kg). On follow-up, total weekly urea clearance fell from 2.29 (1.85-3.0) to 1.93 (1.63-2.4) whereas peritoneal glucose absorption increased from 119 (46-217) to 321 (187-805) mmol/day, p < .001, and estimated dietary protein (nPNA) fell from 0.92 ± 0.23 to 0.86 ± 0.23 g/kg/day, p = .006. However, 69 (45.7%) patients gained weight, with greater change in both lean and fat mass index versus those with weight loss (0.8 [-0.5 to 2.0] vs. -0.7 [-2.1 to 0.2] and 0.9 [-0.1 to 2.3] vs. 0 [-2.6 to 0.8] kg/m² , p < .001), respectively. Although there were no differences in hospital admissions, patients who gained weight experienced fewer episodes of PD peritonitis (0 [0-1] vs. 1[0-2], p = .019).

CONCLUSION

Dietary protein intake declined over time, and more PD patients lost weight. The major difference between those who gained and lost weight was episodes of peritonitis. Greater attention to nutritional support may potentially reduce loss of lean body mass.

Increase of Intra-Abdominal Fat in Patients Treated with Continuous Ambulatory Peritoneal Dialysis

Objective

To evaluate changes in amount and distribution of body fat in patients treated with continuous ambulatory peritoneal dialysis (CAPD).

Design

Prospective study. Computed tomography (CT) and dual energy x-ray absorptiometry (DEXA) were used for determination of body composition at commencement of CAPD, and after a mean of 7.2 months of dialysis treatment.

Setting

CAPD unit at an academic teaching hospital.

Patients

The study included 19 consecutive patients who started CAPD during a 15-month time frame. Of these 19 patients, 12 (8 males) with a mean initial age of 60 years completed the study.

Main Outcome Measures

Siemens Somatom HiQ (Erlangen, Germany) was used for CT of the abdomen and of the right thigh. Fat and muscle areas were expressed as square centimeters. The proportion of total fat mass was determined by body composition analysis using DEXA (DPX-L densitometer) (Lunar, Madison, WI, U.S.A.) and expressed as percentage of total body weight (FAT%).

Results

Body weight changed from 67.1 to 68.4 kg (p = 0.20), and the intra-abdominal fat area increased 22.8% (p = 0.02). This increase was predominantly seen in male patients (p = 0.007). The FAT% changed from 27.8% to 30.9% (p = 0.25), without difference between sexes.

Conclusion

The increase of intra-abdominal fat found in this study may suggest a mechanism by which the established risk for CAPD patients to develop cardiovascular morbidity and mortality may be at least partially explained.

Cardiovascular Disease and Risk Factors in Patients Treated by Continuous Ambulatory Peritoneal Dialysis

The opinions and assertions contained herein are private and are not to be construed as official or representing those of the Uniformed Services University of the Health Sciences or the Department of Defense, U.S.A.

Evaluation of Short-Chain Polypeptides as An Osmotic Agent in Continuous Ambulatory Peritoneal Dialysis Patients

Objectives

To assess whether dialysate containing short-chain polypeptides is well tolerated in continuous ambulatory peritoneal dialysis (CAPD) patients and to determine its effect on fluid and solute transport, plasma amino acid levels, and biochemical parameters.

Design

Two -treatment, two-period cross -over design.

Setting

Renal Unit, Academic Medical Center, Amsterdam and Renal Unit, University Hospital, Gent.

Patients

Two groups of 10 stable CAPD patients.

Intervention

All patients received a trial solution (1.36% glucose and 1% peptides, 381 mOsm/kg) and a control solution (2.27% glucose, 404 mOsm/kg) in randomized order. The patients were examined on four consecutive days in which two dwell periods on days 1 and 3 of either 4 (Group I) or 8 hours (Group II) were performed.

Results

The peptide solution was well tolerated in all patients. In addition, no differences were found in the parameters for the effective peritoneal surface area and the intrinsic permeability, implying that no irritating effect of the peptide solution was present. Net ultrafiltration was not different in Group I: -43±125 versus 86±125 mL (mean±SEM) and marginally lower in Group II: -94±64 versus 51±64 mL, despite the lower osmolality of the trial solution compared to the control solution. Glucose absorption was higher than the peptide absorption in all patients: Group I: 66±10% versus 57±13% (p = 0.0003); Group II: 80±5% versus 72±11% (p = 0.006). No differences in plasma amino acid profiles could be detected.

Conclusion

Short-chain polypeptides are absorbed less than glucose and can be used as an osmotic agent in CAPD patients. However, longer-term studies are needed to evaluate possible additional effects of peptides on the nutritional status of CAPD patients.

The Effect of Body Weight on CAPD Related Infections and Catheter Loss

CAPD related infections an d catheter loss continue to be the major problems facing the peritoneal dialysis patient. Few risk factors for infections and catheter loss have been identified. We hypothesized that overweight and underweight patients may be at increased risk for infections and catheter related problems. We examined the effect of the patient's weight at the start of peritoneal dialysis on the subsequent peritonitis and catheter infection rates, as well as catheter loss. Weight was expressed as a percentage of ideal body weight (IBW). Those patients who were more than 110% of IBW were considered to be overweight, 90 to 110% of IBW normal and less than 90%, underweight. An equivalent percentage of patients were overweight and underweight at the initiation of peritoneal dialysis (55/228, 24% for both groups). Overweight, normal, and underweight patients had peritonitis rates of 1.0, 0.9, and 0.8 episodes/y and catheter infection rates of 1.1, 1.2, and 0.8 episodes/y, respectively. Despite these similar rates, catheter loss due to infectious complications was greatest in the overweight group and least in the underweight group (p<0.05). No obvious explanation for the difference in catheter loss rate was found. Neither S. aureus nor P. aeruginosa infections occurred more frequently in the overweight patients. However, S. aureus infections more often led to catheter loss in the overweight patients. Catheter loss due to catheter leaks and failure to drain was similar in the three groups of patients. We conclude that deviation from ideal body weight at the initiation of dialysis is not a risk factor for CAPD related infections. However, for unclear reasons, increasing weight is associated with increasing risk of catheter loss secondary to infections. Further research in this area is warranted.

Long Peritoneal Dialysis Dwells With Icodextrin: Kinetics of Transperitoneal Fluid and Polyglucose Transport

Background and objective: During peritoneal dialysis (PD), the period of effective net peritoneal ultrafiltration during long dwells can be extended by using the colloidal osmotic agent icodextrin but there are few detailed studies on ultrafiltration with icodextrin solution exceeding 12 h. We analyzed kinetics of peritoneal ultrafiltration in relation to icodextrin and its metabolites for 16-h dwells with icodextrin.

Design, setting, participants, and measurements: In 20 clinically stable patients (mean age 54 years; 8 women; mean preceding time on PD 26 months), intraperitoneal dialysate volume (V_D) was estimated from dilution of ¹²⁵I-human serum albumin during 16-h dwell studies with icodextrin 7.5% solution. Sodium was measured in dialysate and plasma. In 11 patients, fractional absorption of icodextrin from dialysate, dialysate, and plasma amylase and high and low (Mw <2 kDa) Mw icodextrin fractions were analyzed.

Results: Average V_D increased linearly with no difference between transport types. At 16 h, the cumulative net ultrafiltration was 729 ± 337 ml (range −18 to 1,360 ml) and negative in only one patient. Average transcapillary ultrafiltration rate was 1.40 ± 0.36 ml/min, and peritoneal fluid absorption rate was 0.68 ± 0.38 ml/min. During 16 h, 41% of the initial mass of icodextrin was absorbed. Plasma sodium decreased from 138.7 ± 2.4 to 136.5 ± 3.0 mmol/L (p < 0.05). Dialysate glucose G2–G7 oligomers increased due to increase of G2–G4 metabolites while G6–G7 metabolites and higher Mw icodextrin fractions decreased. In plasma maltose and maltotriose (G2–G3 metabolites) increased while higher Mw icodextrin oligomers were almost undetectable. Dialysate amylase increased while plasma amylase decreased.

Conclusions: Icodextrin resulted in linear increase of V_D with sustained net UF lasting 16 h and with no significant difference between peritoneal transport types. In plasma, sodium and amylase declined, G2–G3 increased whereas larger icodextrin fractions were not detectable. In dialysate, icodextrin mass declined due to decrease of high Mw icodextrin fractions while low Mw metabolites, especially G2–G3, increased. The ability of icodextrin to provide sustained UF during very long dwells – which is usually not possible with glucose-based solutions – is especially important in anuric patients and in patients with fast peritoneal transport.

Superiority of icodextrin compared with 4.25% dextrose for peritoneal ultrafiltration

Several clinical observations suggest the superiority of icodextrin compared with 4.25% dextrose in optimizing peritoneal ultrafiltration (UF), but no rigorous controlled evaluation has hitherto been performed. For comparing icodextrin and 4.25% dextrose during the long dwell of automated peritoneal dialysis, a multicenter, randomized, double-blind trial was conducted in 92 patients (control, 45; icodextrin, 47) with 4-h dialysate to plasma ratio creatinine >0.70 and D/D(0) glucose <0.34. Long-dwell net UF and the UF efficiency ratio (net UF volume per gram of dialysate carbohydrate absorbed) were determined at baseline, week 1, and week 2. The control and treatment groups were comparable at baseline (all patients using 4.25% dextrose for the long dwell) with regard to mean (+/-SEM) net UF (201.7 +/- 103.1 versus 141.6 +/- 75.4 ml, respectively; P = 0.637) and the percentage of patients with negative net UF (control, 37.8%; treatment, 42.6%; P = 0.641). During the study period, net UF was unchanged from baseline in the control group but increased significantly (P < 0.001) in the icodextrin group from 141.6 +/- 75.4 to 505.8 +/- 46.8 ml at week 1 and 540.2 +/- 46.8 ml at week 2. In the icodextrin group, the incidence of negative net UF was significantly lower (P < 0.0001) than in the control group. Findings were similar for UF efficiency ratio. Rash was reported significantly more often in the icodextrin group. This study showed that in high-average and high transporters, icodextrin is superior to 4.25% dextrose for long-dwell fluid and solute removal.

A randomized controlled trial to evaluate the efficacy and safety of icodextrin in peritoneal dialysis

BACKGROUND

This article presents the results of two randomized, double-blind, controlled studies conducted to compare the efficacy and long-term safety of icodextrin and 2.5% dextrose for the once-daily long dwell in continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD).

METHODS

Both studies were active-control comparisons of 7.5% icodextrin and 2.5% dextrose for the once-daily long dwell. The efficacy study was a 4-week evaluation of net ultrafiltration and peritoneal clearances of creatinine and urea nitrogen in 175 CAPD patients. The 52-week study in CAPD and APD patients examined the long-term safety of icodextrin and longer term effects, such as body weight and quality of life.

RESULTS

Mean net ultrafiltration (587.2 versus 346.2 mL, P < 0.001) and clearances of urea nitrogen (4.5 versus 4.1 mL/min, P < 0.001) and creatinine (4.0 versus 3.5 mL/min, P < 0.001) were increased significantly with icodextrin. Patients receiving icodextrin had no increase in weight after 52 weeks, in contrast to a weight gain of almost 2 kg in the dextrose group (P < 0.05). There were significantly fewer patients reporting edema in the icodextrin group compared with the dextrose group (6.3% versus 17.9%, P < 0.01). There were no statistically significant differences between groups for the incidence and severity of adverse events. There were small decreases in sodium and chloride and increases in alkaline phosphatase with icodextrin.

CONCLUSION

Icodextrin provides patients with greater fluid removal and small solute clearance, no weight gain over 52 weeks, and a decreased risk of edema.

Pharmacokinetics of icodextrin in peritoneal dialysis patients

Pharmacokinetics of icodextrin in peritoneal dialysis patients.

BACKGROUND

Icodextrin is a glucose polymer osmotic agent used to provide sustained ultrafiltration during long peritoneal dialysis (PD) dwells. A number of studies have evaluated the steady-state blood concentrations of icodextrin during repeated use; however, to date the pharmacokinetics of icodextrin have not been well studied. The current study was conducted to determine the absorption, plasma kinetics and elimination of icodextrin and metabolites following a single icodextrin exchange.

METHODS

Thirteen PD patients were administered 2.0 L of solution containing 7.5% icodextrin for a 12-hour dwell. Icodextrin (total of all glucose polymers) and specific polymers with degrees of polymerization ranging from two to seven (DP2 to DP7) were measured in blood, urine and dialysate during the dwell and after draining the solution from the peritoneal cavity.

RESULTS

A median of 40.1% (60.24 g) of the total administered dose (150 g) was absorbed during the 12-hour dwell. Plasma levels of icodextrin and metabolites rose during the dwell and declined after drain, closely corresponding to the one-compartment pharmacokinetic model assuming zero-order absorption and first-order elimination. Peak plasma concentrations (median C peak = 2.23 g/L) were observed at the end of the dwell (median Tmax = 12.7 h) and were significantly correlated with patients' body weight (R2 = 0.805, P < 0.001). Plasma levels of icodextrin and metabolites returned to baseline within 3 to 7 days. Icodextrin had a plasma half-life of 14.73 hours and a median clearance of 1.09 L/h. Urinary excretion of icodextrin and metabolites was directly related to residual renal function (R2 = 0.679 vs. creatinine clearance, P < 0.01). In the nine patients with residual renal function, the average daily urinary excretion of icodextrin was 473 +/- 77 mg per mL of endogenous renal creatinine clearance. Icodextrin metabolites DP2 to DP4 were found in the dialysate of subsequent dextrose exchanges, contributing to their elimination from blood. Changes in intraperitoneal concentrations of icodextrin metabolites during the dwell revealed a dual pattern, with a progressive rise in the dialysate concentration of smaller polymers (DP2 to DP4) and a progressive decline in the dialysate concentrations of the larger polymers (DP5 to DP7), suggesting some intraperitoneal metabolism of the glucose polymers. This increase in dialysate metabolite levels, however, did not contribute significantly to dialysate osmolality. In addition, some diffusion of maltose (DP2) from blood to dialysate may have occurred. There were no changes in serum insulin or glucose levels during icodextrin administration, indicating that icodextrin does not result in hyperglycemia or hyperinsulinemia as occurs during dextrose-based dialysis. Serum sodium and chloride declined in parallel with the rise in plasma levels of icodextrin, supporting the hypothesis that these electrolyte changes are the result of the increased plasma osmolality due to the presence of icodextrin metabolites.

CONCLUSIONS

The pharmacokinetics of icodextrin in blood following intraperitoneal administration conforms to a simple, single-compartment model that can be approximated by zero-order absorption and first-order elimination. A small amount of intraperitoneal metabolism of icodextrin occurs but does not contribute significantly to dialysate osmolality. The metabolism of absorbed icodextrin and the resultant rise in plasma levels of small glucose polymers (DP2 to DP4) do not result in hyperglycemia or hyperinsulinemia, but may result in a small decrease in serum sodium and chloride.

Effects of icodextrin in automated peritoneal dialysis on blood pressure and bioelectrical impedance analysis

BACKGROUND

Glucose absorption from glucose-based dialysis fluids limits ultrafiltration from the daytime dwell in automated peritoneal dialysis (APD). Icodextrin may allow greater ultrafiltration during the daytime period in APD, enhancing fluid control.

METHODS

A 7.5% icodextrin dialysate was compared with a 2. 27% glucose dialysate for the daytime dwell in 14 subjects on APD. Blood pressure, weight and body water compartments estimated by multifrequency bioelectrical impedance (MFBIA) were determined in subjects using 2.27% glucose as the daytime dwell and then repeated 1 month after switching to icodextrin.

RESULTS

Icodextrin resulted in symptomatic hypotension requiring reduction of antihypertensive medication in six of the 14 patients. Despite this reduction in treatment, systolic blood pressure fell from 142.4 (23.9) mmHg to 122.9 (17.7) mmHg, P<0.005, and diastolic blood pressure tended to fall from 82.8 (9.8) mmHg to 76.8 (10.1) mmHg, P=0.075. Change in systolic blood pressure significantly correlated with changes in weight (r=0.62, P<0.05) and MFBIA estimates of total body water (TBW) (r=0.56, P<0.05), extracellular water (ECW) (r=0.79, P<0.002), extra/intracellular water ratio (ECW/ICW) (r=0.72, P<0.01) and derived resistances R(ecf) of ECW (r=-0.69, P<0.01) and R(inf) of TBW (r=-0.66, P<0.02). Changes in diastolic blood pressure significantly correlated with changes in ECW (r=0.64, P<0.02) and ECW/ICW ratio (r=0.58, P<0.05), and almost significantly with R(ecf) (r=-0.51, P=0.08) and R(inf) (r=-0.52, P=0.07) estimated by MFBIA, but not with changes in weight or TBW.

CONCLUSIONS

Use of icodextrin for the daytime dwell in APD results in improved fluid balance and blood pressure control compared with 2.27% glucose. MFBIA detected clinically important changes in fluid content in these patients.

Effect of simvastatin treatment on the dyslipoproteinemia in CAPD patients

HMG-CoA reductase inhibitors have been proven effective in decreasing the plasma cholesterol levels in patients affected with various forms of hypercholesterolemia, familial dysbetalipoproteinemia, familial combined hyperlipidemia and in nephrotic and diabetic dyslipidemia. The purpose of this study was to monitor and evaluate the efficiency and safety of the therapy with simvastatin, an HMG-CoA reductase inhibitor, in a group of patients treated by continuous ambulatory peritoneal dialysis (CAPD) with severe hypercholesterolemia. Monitoring of the changes occurring in the various lipids and apolipoproteins in these patients included the measurements of the plasma lipids and apolipoproteins A-I, A-II, B, C-II, A-IV and Lp(a). Lipoproteins were separated by gel filtration, on a Superose 6HR column, before and after 24 weeks of treatment. The patterns were compared to those observed in a group of primary hyperlipidemic patients treated with Lovastatin, a compound of the same class. The drug was well tolerated by the CAPD patients and no adverse reaction was observed. In addition to the decrease of the total and LDL cholesterol, similar to that reported in other groups of patients, we further observed a decrease of the apo E concentration in both the CAPD and the hyperlipidemic patients. This decrease was especially pronounced in the HDLE fraction and could involve an upregulation of the apo B-E and/or apo E receptor. These results should provide information about the mechanism of action of this drug in patients with end-stage renal disease.

Kinetics of peritoneal protein loss during CAPD: II. Lipoprotein leakage and its impact on plasma lipid levels

We quantified the plasma levels and peritoneal loss of lipids and lipoproteins, and studied the composition of plasma and effluent lipoproteins in 16 patients on CAPD (5 females and 11 males, 18 to 76 years old). Five patients were studied prospectively (at 0, 1, 3 and 6 months) and 11 patients at 6 to 58 months on CAPD (N = 30). Elevated levels of plasma VLDL and reduced levels of plasma HDL were maintained in these patients throughout 58 months of CAPD, whereas the initially increased LDL levels showed a tendency towards normalization. All plasma lipoproteins (VLDL, IDL, LDL and HDL) were present in the peritoneal effluent. The lipoproteins isolated from plasma and peritoneal fluid shared a similar lipid and apolipoprotein composition. The peritoneal transport characteristics of plasma lipoproteins were similar to other plasma macromolecules. Their clearance correlated with their molecular mass, plasma concentration and dwell time, but was not affected by duration of CAPD treatment. The plasma lipid and lipoprotein levels were unaffected by the rate of glucose absorption. The peritoneal protein clearance correlated positively with plasma levels of triglyceride and LDL, and negatively with plasma HDL. An inverse correlation was observed also between plasma levels of HDL and its peritoneal clearance (r = -0.393, P less than 0.025, N = 30). The continuous peritoneal loss of HDL and the hypertriglyceridemia were found to contribute most to the persistent low plasma levels of HDL in CAPD patients, and thus may lead to the accelerated atherosclerosis observed in these patients.