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Biomedical subjects

C Mion

Publications and source records attributed to C Mion.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Protein catabolic rate determination from a single measurement of dialyzed urea.

Protein catabolic rate (PCR, in g protein/kg/day) for anuric patients can be accurately determined without blood sampling by equating urea generation over 7 days to the urea dialyzed in the three dialyses of this period as measured by partial dialysate collection (PDC) or with a urea monitor. The feasibility of determining the week's dialyzed urea from measurement of urea dialyzed in a single session, obviating the need to monitor three consecutive dialyses, was examined in a steady-state simulation of 540 anuric patients spanning the full range of dialysis parameters. It was found that the first, midweek, and last dialyses account for nearly constant fractions (37.9, 32.1, and 30.0%, respectively) of the week's urea removal, leading to equations of the form: PCR = CU/BW + 0.17 where U is the grams of urea dialyzed in the first, midweek, or final dialysis of the week, C = 2.45, 2.89, or 3.10, respectively, and BW is the patient's dry weight in kilograms. These equations were tested on 1312 weeks of PDC data gathered in 42 dialysis patients. Using the midweek U resulted in a mean absolute error in PCR < 0.05 g/kg/day when compared to PCR determined using all three of the week's U values.

Aged↗
PubMedDate not supplied

On-line dialysis quantification in acutely ill patients: preliminary clinical experience with a multipurpose urea sensor monitoring device.

Direct dialysis quantification offers several advantages compared with conventional blood urea kinetic modeling, and monitoring urea concentration in the effluent dialysate with an on-line urea sensor is a practical approach. Such a monitoring device seems desirable in the short-term dialysis setting to optimize and personalize both renal replacement therapy and nutritional support of acutely ill patients. We designed a urea monitoring device consisting of a urea sensor, a multichannel hydraulic circuit, and a PC microcomputer. The sensor determines urea from catalysis of its hydrolysis by urease in liquid solution during neutral conditions. Hydrolysis of urea produces NH4+, and creates an electrical potential difference between two electrodes. Each concentration determination of urea is the average value of 10 measurements; samples are diverted and measured every 7 min. Laboratory calibration of the urea sensor has demonstrated linearity over the range 2-35 mmol/L. Urea monitoring was performed throughout the treatment course, either on the effluent dialysate or ultrafiltrate in seven acutely ill patients treated by either hemofiltration (n=5) or hemodiafiltration (n=2). The slope of the concentration of urea in the effluent over time was used to calculate an index of the dialysis dose delivered (Kt/V), urea mass removal, and protein catabolic rate. In addition, samples of the effluent were drawn every 21 min, and sent to the central laboratory for measurement of urea concentrations using an autoanalyzer. Kt/V values also were calculated with Garred's equation using pre and post session concentrations of urea in blood. Concentrations of urea in the effluent determined by the urea sensor were found to be very close to those obtained from the central laboratory over a wide range of values (3 to 42 mmol/L). In addition, Kt/V values for both hemofiltration and hemodiafiltration, when calculated with concentrations of urea in the effluent obtained by the urea sensor, did not significantly differ from Kt/V values obtained from the laboratory concentrations of urea in the effluent. On-line urea sensor monitoring of the effluent suppresses the cumbersome task of total effluent collection, and the complexity of urea kinetic analysis. The multipurpose prototype described here represents a new, simple, and direct assessment of dialysis dose and protein nutritional status of acutely ill patients, and is suitable for various modalities.

Acute Kidney Injury↗
PubMedDate not supplied

Reuse of "highly permeable" dialyzers with peroxyacetic acid as sole cleansing and disinfecting agent.

In the past few years, dialyzer reuse has gained increased clinical acceptance. This has been due both to the availability of automated reconditioning machines and powerful chemical cleaning and disinfecting agents. In this study the authors evaluated the effectiveness of a newly available peroxyacetic acid solution (PAS) (Dialox) as the dual cleaning and disinfecting agent in the reuse of highly permeable dialyzers. An in vivo study was conducted with ten patients already involved in our center's reuse program using the Renatron reprocessing machine and PAS at various dilutions. One hundred forty dialyzers of three different brands and membrane types (HF80 used for hemodiafiltration [HDF], Filtral 16 used for hemodialysis [HD], and FH88 used for hemofiltration [HF]) were employed for a total of 1182 treatments, giving an average 8.4 uses per module. Significantly more uses were obtained with the HF80 and Filtral 16 dialyzers (9.7 and 9.4, respectively) than for the FH88 modules used by the HF patients (6.7 uses per module). Compromised cleaning by backfiltration due to the lack of a second dialysate port on the FH88 may be a possible explanation. Greater membrane plugging due to higher ultrafiltration rates in HF may be another factor. Patient variability was found to be another factor in dialyzer reuse. The cleaning effectiveness of various dilutions of PAS was also tested in this study. The number of uses achieved was not found to vary significantly with PAS strength; however, a greater frequency of second or third reprocessing was required with more dilute cleaning solution. The authors found the dilution achieved on the Renatron reprocessing machine using the currently marketed PAS concentrate to be the most cost effective.

Disinfection↗
PubMedDate not supplied

Beta-2 microglobulin serum levels in maintenance dialysis. What does it mean?

beta-2 Microglobulin levels (beta-2M) were analyzed at four month intervals in sera of 237 patients on various forms of dialysis over a 2 year period; twelve patients volunteered to participate in short-term kinetics studies. Duplicate beta-2M measurements in biologic fluids were performed using an RIA kit. The data presented confirm elevated serum beta-2M in dialyzed patients whatever the dialysis method used and give an overview on various factors affecting circulating serum beta-2M. Intraindividual beta-2M variations were 13% in stable ESRD patients. Unusually high values (greater than 2 SE) were observed in patients presenting with severe intercurrent disease (e.g., cancer). The only significant difference observed between groups of patients, HD (46 +/- 1 mg/L) and PD (IPD: 33 +/- 3, CAPD: 37 +/- 2 mg/L), was due to the residual renal function preserved in a higher percentage of PD patients. No significant difference was noted in HF (40 +/- 2 mg/L) and HDF (38 +/- 5 mg/L) patients, despite a higher beta-2M removal rate. beta-2M membrane permeability differs greatly among filters. It is high for AN69 and Polysulfone, intermediate for Polyamide, low for Polyacrylonitrile and none for Cuprophane. Peritoneal membrane is highly permeable to beta-2M with beta-2M dialysate/serum levels of 0.20 at the end of a 6 hr exchange. In conclusion, beta-2M determination in uremic patients is useful in assessing material permeability and biocompatibility. However, it is too early to determine the impact or the beneficial effects of using highly permeable membrane to prevent beta-2M-amyloidosis related nonarticular complications.

Adult↗