Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis

To find an index of adequacy that takes into consideration the effect of the decreasing concentration of urea nitrogen in hemodialysis (HD) and can be used before treatments to quantitate the prescriptions with the same criterion for both HD and continuous ambulatory peritoneal dialysis (CAPD).

The removal index was obtained through mathematical theories and then compared with the urea index (KT/V) values of the sample patients.

Thirty-two HD and 21 CAPD patients were included. All patients were dialyzed with optimal urea index values and had been stable for at least one year.

The removal index in HD (ξHD) for each dialysis was 0.62±0.07, and the normalized removal index in CAPD (ξCAPD) was 0.59±0.11. There was no statistical significance. This result is consistent with the fact that no difference of morbidity or mortality exists between these two modalities.

After mathematical manipulation, the removal index in HD can be presented in the form of the urea reduction ratio, which is a retrospective measure to estimate the performance of hemodialysis. This study implies that the removal index is able to facilitate the prescriptions for adequate dialysis. The removal index can also be used to explain the reason why the urea index values are always larger in HD than in CAPD.

To compare estimates of urea volume (V) and KT/V obtained by the Watson and Hume anthropometric formulas, and to identify the similarities and differences between these estimates.

Theoretical analysis applying wide variations in the determinants of anthropometric V (age, height, weight) in hypothetical women and men. Analysis of urea kinetic studies performed in patients on continuous peritoneal dialysis (CPD).

Four dialysis units in Albuquerque, two in Athens, and two in Thessaloniki.

Three hundred and two CPD patients who had 440 urea kinetic studies.

Standard urea clearance was performed by 24-hour collections of urine and drained dialysate followed by blood sampling. V was estimated by both the Watson and Hume formulas.

Estimates of V and KT/V were compared separately in women and men by Student's t-test, linear regression, and limits of agreement (mean difference±2 SD). The agreement of the KT/V estimates was also tested by the kappa ratio using a value of 1.70 weekly as the lowest acceptable KT/V.

The theoretical analysis indicated important disagreement only in extreme variations from the ordinary in height and, to a lesser extent, weight. Differences due to height variation were pronounced only in hypothetical women. CPD patient findings were as follows: in women, Watson V and weekly KT/V were 30.4±4.4 L and 2.10±0.61, respectively. Corresponding Hume estimates were 30.3±5.4 L and 2.12±0.66, respectively. Corresponding estimates for men were 40.5±5.7 L and 1.92±0.57 (Watson) plus 41.4±5.6 L and 1.88±0.57 (Hume), respectively. By linear regression, KT/VHume = -0.083 + 1.052 (KT/Vw8tson), r = 0.961 (women); and KT/VHume = -0.026 + 0.992 (KT/Vwatson), r = 0.985 (men). Limits of agreement were -1.41 L and 2.10 L for V, and -0.15 and 0.14 weekly for KT/V. In 94.3% of the cases, KT/Vw8tson and KT/VHume agreed (both >1.70 or both <1.70 weekly). Kappa ratio was 0.875 (excellent agreement). The concordant and discordant groups differed in height and degree of obesity, in agreement with the theoretical analysis.

The Watson and Hume formulas provide similar estimates of V and KT/V in CPD patients. Differences may be noted only if women's height or, to a lesser extent, both sexes’ weight is at a great variance with the ordinary values.

To determine the effect a period of “intentional noncompliance” in stable continuous ambulatory peritoneal dialysis (CAPD) patients has on the ratio of measured to predicted creatinine generation.

Prospective study that compares baseline to noncompliant periods in individual CAPD patients.

Nine chronic, stable CAPD patients.

At baseline, measured creatinine production and adequacy parameters (KT/V, creatinine clearance, lean body mass, and protein equivalent of nitrogen appearance) were calculated from 24-hour collections of dialysate and urine while patients were performing their routine dialysis prescriptions. After three days of intentional noncompliance (one less exchange/day) the patients repeated their 24-hour collections, again performing their routine number of exchanges. Measured creatinine production and adequacy parameters were again calculated. Predicted creatinine production for each patient was calculated from standard equations. All parameters at baseline were compared to corresponding parameters after intentional noncompliance.

In all patients, except one where there was no change, there was a statistically significant increase in not only the ratio of measured to predicted creatinine production but also all other parameters.

As suspected by previous investigators, this study suggests that one cause of an elevated ratio of measured to predicted creatinine production may be a recent period of noncompliance with the patient's dialysis prescription. However, these data suggest that an isolated ratio of measured to predicted creatinine generation is not a sensitive predictor of noncompliance with the peritoneal dialysis prescription.

To evaluate the use of the ratio of measured to predicted creatinine excretion as an index of compliance in peritoneal dialysis (PD) patients.

A prospective analysis.

Academic teaching hospital dialysis unit.

Forty-three patients on PD.

Creatinine excretion in daily dialysate and urine collections was measured on one occasion in 10 patients and on two occasions in 33 patients, and, after adding an estimate for extrarenal creatinine degradation, was divided by predicted creatinine excretion to give a creatinine excretion ratio, which has been proposed as an index of compliance with exchanges in PD patients. Values above 1.24 have been suggested to indicate non-compliance. Lean body mass was also estimated from creatinine excretion.

The mean creatinine excretion ratio was 1.12, and 30% of patients had a value above 1.3. Only one patient admitted noncompliance. Studies on four consecutive days of guaranteed compliance in 7 patients with high ratios showed that creatinine excretion remained constant, suggesting that the patients were high creatinine producers rather than noncompliant. Creatinine excretion was stable when measured at intervals of days, but over months it tended to change markedly in many patients. Lean body mass estimations using creatinine excretion were low in most patients.

Comparison of measured and predicted creatinine excretion is not a reliable indicator of noncompliance because many compliant patients consistently excrete more creatinine than predicted. The standard formulas were not validated in dialysis patients and underestimate creatinine excretion significantly in many PD patients. Existing estimates in the literature of non-compliance, using this methodology, may not be accurate. Better methods of detecting this problem are required.

To investigate the usefulness of dialysate IgG and C3 concentrations in predicting likelihood of developing peritonitis.

Prospective, longitudinal, and comparative study.

Single university teaching hospital dialysis unit and outpatient clinic.

Thirty-four uremic patients were studied (20 males, 14 females: mean age 47.2, range 20 73 years). Monthly serum and overnight dialysate (eight to elevenhour dwell) samples were obtained for IgG and C3 estimations over the first six months of the study, and trimonthly samples were obtained thereafter. All patients performed exchanges using standard transfer sets (Baxter system II, Baxter Healthcare Ltd., Thetford, Norfolk, U.K.), used no hypertonic fluid (3.86%) for overnight exchanges, and were followed up for a minimum of 18 months.

Dialysate and serum levels of IgG and C3; peritonitis episodes.

Forty-five episodes of peritonitis occurred in 24 patients during the study period. We examined opsonin levels in the group as a whole, and then in two subgroups of patients: those who remained peritonitis-free throughout the study, and those who did not. There were no significant differences between IgG and C3 levels in the two groups at any time point, and large interpatient and intrapatient variation in levels were seen.

Dialysate levels of IgG and C3 from the overnight dwell are not helpful in predicting the risk of developing continuous ambulatory peritoneal dialysis peritonitis in individual patients. No correlation was found between opsonin levels and onset of clinical peritonitis.

Evaluation of the inflammatory activity in patients on chronic peritoneal dialysis (PD) and patients on chronic hemodialysis (HD) in comparison to patients with chronic renal insufficiency without dialysis treatment and healthy volunteers.

Open, non randomized prospective study.

Nephrology Department, including HD and PD therapy in a university hospital.

Twenty -four patients on chronic PD, 21 patients on chronic HD therapy using a cuprophan dialyzer, 16 patients with chronic renal insufficiency without dialysis treatment, and 33 healthy volunteers; 8 additional patients before and after initiation of chronic HD therapy. All patients and controls were without infection or immunosuppressive therapy.

As a marker of the inflammatory activity in the different patient groups, C-reactive protein (CAP) was measured serially using a sensitive, enzyme-Iinked, immunosorbent assay in order to detect values below the detection limit of standard assays.

All patient groups had CAP levels higher than the normal controls (p < 0.01). Patients on HD had CAP levels significantly higher than PD patients (p < 0.01) whose levels were comparable to patients without dialysis therapy. Accordingly, longitudinal measurements before and after initiation of chronic HD showed a significant increase in CAP levels after the beginning of HD treatment (p < 0.04).

The results suggest that induction of the inflammatory activity is lower during PD compared to HD, since stimulation by the dialyzer membrane, dialysate buffer, or bacterial fragments in the dialysate is avoided. This observation might indicate a possible lower risk of long-term complications in patients with PD.

The purpose of this study was to investigate the effects of acute peritonitis on lymphatic drainage of the peritoneal cavity in conscious sheep

Peritonitis was induced with the addition of 1% casein or 1% albumin to the dialysis solution. Thirty sheep (5 groups of 6) were used in this study. One group received 50 mL/kg intraperitoneal infusions of Dianeal 4.25% (486 mOsm/L); a second group received 1% casein-DianeaI4.25% (493 mOsm/L); a third group received 1% albumin-Dianeal 4.25% (487 mOsm/L). In the fourth and fifth groups (controls and casein-injected) lymph was collected from the caudal mediastinal lymph node and the thoracic duct, both of which are involved in the lymphatic drainage of the peritoneal cavity (peritonitis induced with casein). 1251-human serum albumin (25 μCi) was added to the dialysate as the lymph flow marker. Lymph drainage was estimated from (1) the appearance of the intraperitoneally administered tracer in the blood; (2) the disappearance of the tracer from the peritoneal cavity; and (3) the recovery of tracer in lymph.

In noncannulated animals the cumulative volume removed by lymphatics over 6 hours (based on tracer recovery in blood) was 10.5 ±1.0 mL/kg in control animals versus 5.0 ± 0.6 mL/kg and 8.6 ± 1.2 mL/kg in casein and albumin-infused sheep, respectively. The suggestion of decreased lymph drainage in peritonitis was supported by the cannulation experiments. While the cumulative fluid removed from the peritoneal cavity over 6 hours in caudal lymph was unaffected by peritonitis (3.8 ± 0.4 mL/kg in controls vs 3.6 ± 0.5 mL/kg in casein injected animals), peritonitis reduced flow into the thoracic duct from 3.0 ± 0.3 to 1.1 ± 0.3 mL/kg. The sum of the volume removed in lymph in the cannulated preparations was 6.8 ± 0.4 mL/kg in controls versus 4.7 ± 0.5 mL/kg in the peritonitis group. The total volume removed from the cavity (including an estimate of flow based on the residual recovery of tracer in blood) was reduced from 12.6 ±1.4 in controls to 7.8 ± 0.6 mL/kg in the peritonitis sheep. In contrast, estimates of lymph drainage based on the disappearance of tracer from the peritoneal cavity suggested that lymph drainage increased (from 16.6 ±1.6 mL/kg in controls to 17.8 ±1.5 mL/kg and 25.5 ±1.7 mL/kg in the casein and albumin groups, respectively, in noncannulated animals and from 15.3 ± 1.4 mL/kg in controls to 25.0 ± 1.7 mL/kg in the cannulated group). In both noncannulated and cannulated sheep the total recovery of tracer was less in the peritonitis groups.

These studies demonstrated that lymph drainage of the peritoneal space was decreased in a casein peritonitis model. The decrease in lymph drainage is most obvious in the visceral pathway leading to the thoracic duct; however, diaphragmatic drainage into the right lymph duct may also be inhibited. The disappearance of tracer from the peritoneal cavity was elevated during peritonitis. Tracer disappearance has been used to estimate lymph drainage, but this approach suggested, incorrectly, that lymph flow had increased.