Ahmed Alayoud

A model to predict optimal dialysate flow.

Diffusive clearance depends on blood (Qb) and dialysate flow (Qd) rates and the overall mass transfer area coefficient (KoA) of the dialyzer. In this article we describe a model to predict an appropriated AutoFlow (AF) factor (AF factor = Ratio Qd/Qb), that is able to provide adequate Kt/V for hemodialysis patients (HDP), while consuming lower amounts of dialysate, water and energy during the treatment. We studied in vivo the effects of three various Qd on the delivered dose of dialysis in 33 stable HDP. Hemodialysis was performed at Qd of 700 mL/mn, 500 mL/mn, and with AF, whereas specific dialysis prescriptions (treatment time, blood flow rate [Qb], and type and size of dialyzer) were kept constant. The results showed that increasing the dialysate flow rate more than the model of AF predicted had a small effect on the delivered dose of dialysis. The Kt/V (mean ± SD) was 1.52 ± 0.16 at Qd 700, 1.50 ± 0.16 at Qd 500, and 1.49 ± 0.15 with AF. The use of the AF function leads to a significant saving of dialysate fluid. The model predicts the appropriate AF factor that automatically adjusts the dialysate flow rate according to the effective blood flow rate of the patient to achieve an appreciable increase in dialysis dose at the lowest additional cost.

Quantification of hemodialysis dose: what Kt/V to choose?

Background Quantification of hemodialysis became more accurate and easier after the advent of ionic dialysance and the use of methods for estimating urea distribution volume (V). The aim of this study was to compare different methods of hemodialysis dose assessment: Kt/VDau (Daugirdas 2nd generation), Kt/VOCM (Kt by OCM (Online Clearance Monitor) and V by Watson), and Kt/VBCM (Kt by OCM and V by bio-impedance); and to assess the dialysis adequacy, defined by a Kt/V≥1.4. Design Prospective, observational study. Methods 35 hemodialysis sessions were evaluated in 35 chronic hemodialysis patients. During each session, we measured simultaneously, Kt/VOCM, Kt/VBCM and calculated Kt/VDau by performing blood samples before and after each session. Results 35 patients, gender (M/F: 19/16), mean age of 50.49 years, were evaluated. We noted a difference between the three methods of evaluating Kt/V index: Kt/VDau, Kt/VOCM and Kt/VBCM (1.82 ± 0.29; 1.45 ± 0.23; 1.8 ± 0.33, p<0.001). Comparison of Kt/VOCM with Kt/VDau and Kt/VBCM leads to a significant systematic underestimate of Kt/V by 22% and 20.5% respectively. Better agreement between Kt/VDau and Kt/VBCM was observed. The adequate hemodialysis was achieved, according to three methods: Kt/VDau, Kt/VOCM and Kt/VBCM respectively in 100%, 57,1% and 88.6% of the cases. Conclusions The Kt/V index is different depending on the method used for its evaluation. The three methods can be used for quantification of hemodialysis with a better agreement between Kt/VDau and Kt/VBCM. In this study, Kt/VOCM results underestimate hemodialysis efficiency. This difference has to be considered when applying quantification of hemodialysis to clinical practice.

The Kt/V by ionic dialysance: Interpretation limits.

The availability of hemodialysis machines equipped with online clearance monitoring (OCM) allows frequent assessment of dialysis efficiency and adequacy without the need for blood samples. Accurate estimation of the urea distribution volume (V) is required for Kt/V calculated from OCM to be consistent with conventional blood sample-based methods. A total of 35 patients were studied. Ionic dialysance was measured by conductivity monitoring. The second-generation Daugirdas formula was used to calculate the Kt/V single-pool (Kt/VD). Values of V to allow comparison between OCM and blood-based Kt/V were determined using Watson formula (VWa), bioimpedance spectroscopy (Vimp), and blood-based kinetic data (Vukm). Comparison of Kt/Vw ocm calculated by the ionic dialysance and Vw (Kt/Vw ocm) with Kt/VD shows that using VW leads to significant systematic underestimation of dialysis dose by 24%. Better agreement between Kt/V ocm and Kt/VD was observed when using Vimp and Vukm. Bio-impedancemetry and the indirect method using the second-generation Daugirdas equation are two methods of clinical interest for estimating V to ensure greater agreement between OCM and blood-based Kt/V.

[Predilution online hemodiafiltration: which dose of anticoagulation?].

INTRODUCTION Patients in end stage renal disease on hemodialysis are in higher risk of bleeding related to the anticoagulation used during a session, so only the lowest effective dose of anticoagulation must be used. The aim of this study was to evaluate the efficacy of predilution in hemodiafiltration with reduced dose of anticoagulation compared to hemodialysis in preventing coagulation of circuits. PATIENTS AND METHODS This study was conducted in stable hemodialysis patients without high bleeding risk. All patients were treated by two different treatments: (A) conventional hemodialysis, (B) predilution hemodiafiltration with the half dose of anticoagulation used during treatment (A). Other confounding parameters were kept constant during the study. The primary endpoint was the incidence of major thrombotic events judged on a subjective visual score. RESULTS Twenty-one patients were included (105 sessions for each treatment). Major incidents are occurring more frequently in predilution hemodiafiltration with reduced dose of anticoagulation (P=0.03). The premature discontinuation of sessions was more frequent in predilution hemodiafiltration, this difference was not significant (P=0.07). Duration of sessions was significantly shorter in predilution hemodiafiltration (P=0.03). The higher frequency of thrombotic events in predilution hemodiafiltration has no effect on net ultrafiltration volume achieved in both treatments. CONCLUSION Predilution hemodiafiltration with a lower dose of anticoagulation did not prevent major clotting of extracorporeal circuit manner at least equivalent to a reference method.

Insuffisance rénale aiguë révélant une hypothyroïdie auto-immune

Although the clinic picture is often indicative of muscle manifestations in patients with hypothyroidism, signs and symptoms of this condition are variable from simple elevation of serum muscle enzymes with myalgia, muscle weakness, cramps to rhabdomyolysis with acute renal failure which remains a rare event. Thyroid hormones affect the function of almost every body organ, and thyroid dysfunction produces a wide range of metabolic disturbances. Hypothyroidism is associated with significant effects on the kidney which the pathophysiology seems to be multifactorial, but the exact mechanisms remain poorly understood. Hypothyroidism as a cause of renal impairment is usually overlooked, leading to unnecessary diagnostic procedures. The main objective of our observation is to report a case of acute renal failure revealing an autoimmune hypothyroidism in which thyroid hormone substitution led to a significant improvement in muscular, thyroid and renal disorders.

Bisalbuminemia during remission of nephrotic syndrome.

The bisalbuminemia acquired outside of the long-term antibiotic treatment is an exceptional event. It is a rare condition characterised by the presence of two distinct fractions of serum albumin on electrophoresis. This anomaly reflects the presence, at the same time, of a normal albumin and a modified albumin. These changes of albumin may be related to various causes. Their association with nephrotic syndrome is exceptional. We report a case of bisalbuminemia during a period of remission of nephrotic syndrome.

A model to calculate cardiac output in hemodialysis patients by thermodilution.

The Blood Temperature Monitor module (BTM) is used to measure recirculation by thermodilution in dialysis. Numerous studies have confirmed its interest in the measuring of the vascular access flow. In this letter we describe a model to calculate cardiac output in dialysis by the BTM.