Haemodialysis leucopenia: the role of membrane type and re-use

Adsorption of ß2-Microglobulin on Dialysis Membranes: Comparison of Different Dialyzers and Effects of Reuse Procedures

In order to measure ß2-microglobulin adsorption on dialysis membranes, uremic plasma was passed through different dialyzers in a simulated hemodialysis circuit in which both plasma and dialysate compartments were organized as closed loops, the ultrafiltration pressure being adjusted to minimize water shifts. Under these conditions, comparison of the amounts of ß2-m in the plasma and dialysate compartments allowed us to calculate the binding of ß2-m to the membrane at different times of the procedure. Whereas cuprophane membrane (Gambro gf 180m, 1.8m2) did not bind ß2-m, AN69 (Filtral, 1.1 m2), high flux polysulfone (F60, 1.2m2) and modified polyamide (Polyflux 130, Gambro, 1.3m2) were found to adsorb 49 ± 8 mg (mean ± SEM), 17 ± 5 mg and 38 ± 4 mg of 82-m, respectively. These data were confirmed in trace labeling experiments with 125I-ß2-m. Adsorption was a saturable phenomenon occurring during the first 90 min of in vitro dialysis. After reuse with peracetic acid, the adsorption capacity of AN69 membrane was lowered to 20 ± 4 mg of ß2-m, contrasting with the unchanged adsorption after reuse with sodium hypochlorite. These data indicate that adsorption significantly contributes to ß2-m removal during hemodialysis with certain dialyzers and that reuse procedures may affect the propensity of dialysis membranes to bind 82-m.

Description and predictive factors of infection in patients with chronic kidney disease admitted to the critical care unit

OBJECTIVES

To describe the spectrum of infection and multidrug-resistant bacterial colonization, and to identify early predictors of infection in patients with chronic kidney disease (CKD) admitted to the critical care unit (CCU).

METHODS

A 7-month observational prospective single-centre study in a French university hospital.

RESULTS

791 patients were admitted to the CCU, 135 of whom (17%) had severe CKD. Among these, 41 (30%) were infected on admission. Infection was microbiologically documented in 32 patients (78%), of which 7 (22%) were related to Pseudomonas aeruginosa. There was no infection related to extended-spectrum β-lactamase-producing enterobacteriaceae despite a 12% carriage rate on admission. A temperature ≥37.6 °C and a leukocyte count >12.000/mm³ were specific but poorly sensitive of infection (91% and 80%, and 45% and 39%, respectively). Using the threshold of 0.85 ng/ml, procalcitonin was a strong independent predictor of infection on admission (OR 12.8, 95% CI 4.4-37.3). Age (≥60 years) and the cause of CKD were two other predictors.

CONCLUSIONS

Infection accounts for one-third of CCU admissions in CKD patients, with a high prevalence of P. aeruginosa. The usual diagnostic criteria are inaccurate for diagnosing infection in this population. A procalcitonin ≥0.85 ng/ml might be helpful for early identifying CKD patients with infection.

Procalcitonin serum levels in children undergoing chronic haemodialysis

Infections account for considerable morbidity and mortality in patients requiring haemodialysis (HD). Procalcitonin (PCT)-a low molecular weight protein of 13 kDa-helps one to distinguish viral from bacterial infections and to evaluate the severity of bacterial infections. We investigated (1) PCT baseline levels in eight children undergoing chronic HD with high-flux membranes and (2) changes in the serum levels of PCT, C-reactive protein (CRP) and beta-2-microglobulin (beta2-MG)-a peptide with biochemical characteristics similar to those of PCT-before and after haemodialysis sessions. Blood sampling was performed three times in the mid-week session. Serum PCT of the seven uninfected children before HD sessions was increased (0.75+/-0.07 ng/ml), whereas CRP levels were normal. PCT after dialysis decreased significantly by 40% (P<0.0001) compared with initial values, whereas CRP levels before and after HD were not different. beta2-MG decreased by 70%, probably due to different biochemical properties of both proteins. PCT serum levels 15 min and 60 min after the HD session remained unchanged in comparison with those at the end of the HD session, suggesting accumulation of PCT between HD sessions rather than HD-induced production to be responsible for the increased baseline PCT serum levels. We concluded that CRP serum levels were not affected by HD in our group. Moderately elevated baseline PCT serum levels that are presumably due to reduced renal clearance and uraemia and dialysis-ability of PCT should be taken into consideration. However, increase of serum PCT in patients with severe bacterial infections is generally massive (10-fold to 1,000-fold), suggesting a low risk for false negative results in such cases.

Procalcitonin for accurate detection of infection in haemodialysis

BACKGROUND

Infection results in considerable morbidity and mortality in haemodialysis patients. Diagnosis of infection can be difficult because currently applied laboratory parameters may be non-specifically altered due to uraemia or haemodialysis (HD). This study investigated the diagnostic value and kinetics of serum procalcitonin (PCT), a low-molecular-weight protein, in patients receiving intermittent HD.

METHODS

Sixty-eight patients receiving intermittent HD for end-stage renal disease (n=48) or acute renal failure (n=20) were prospectively studied, 47 treated with high-flux and 21 with low-flux membranes. Of 36 patients with severe infections or sepsis, 27 were treated with high-flux and nine with low-flux membranes. WBC, serum PCT and C-reactive protein (CRP) concentrations were measured immediately before HD, and PCT repeatedly during the following 48 h.

RESULTS

When determined immediately before HD, PCT demonstrated a sensitivity of 89%, a specificity of 81%, and positive and negative predictive values of 84 and 87%, indicating severe infection or sepsis. These levels were higher than the respective values for CRP (89, 48, 68 and 78%) and WBC (58, 75, 71 and 59%). After 4 h of HD with high-flux membranes, PCT decreased significantly to 83+/-25% and did not return to predialysis concentrations before 48 h. This decrease in serum PCT resulted in markedly reduced sensitivity (65%) and negative predictive value (54%). In contrast, no marked change in PCT concentration occurred during or after HD with low-flux membranes.

CONCLUSION

Serum PCT is an accurate indicator of severe infection and sepsis in patients receiving intermittent HD. High-flux membranes substantially decrease PCT. When utilizing high flux membranes, serum PCT concentrations should be determined prior to the start of HD.