Search PubMed⌕ Search

Biomedical subjects

B Canaud

Publications and source records attributed to B Canaud.

At least 73 records · Page 4Linked to original sources
PubMed1997

Equations for the calculation of the protein catabolic rate from predialysis and postdialysis urea concentrations and residual renal clearance in stable hemodialysis patients.

Several simple equations exist for the calculation of K1/V from predialysis (Cpre) and postdialysis (Cpost) measurements of urea concentration. Analogous equations are needed for precise determination of patients protein catabolic rate (nPCR) from Cpre and Cpost. In this study we develop three simple nPCR equations from urea mass balance theory. The equations, which include a term for residual function, may be applied to any session of the week for patient dialyzed three times weekly who are in steady state with respect to dialysis dose and protein catabolism. The precision of each equation was tested with Cpre Cpost data obtained from steady state simulations of 540 patients without residual renal clearance (KR) and 972 simulated patients with significant residual KR. The simplest equation has the form: [formula: see text] where V is urea distribution volume and a and d are constants varying with session of the week. When compared to nPCR values calculated from formal urea kinetic modeling, the error determined with this formula never exceeded 5% for the midweek or final session. A more complicated equation of the form: [formula: see text] provided nPCR estimates with a maximum error < 1.3% for any dialysis session of the week and for KR up to 4 ml/min for a 70-kg patient. The only data required for the latter equation are Cpre, Cpost, length of dialysis session, volume ultrafiltered (delta BW), and an approximate value of the patient's urea distribution volume. The proposed equations permit nPCR to be calculated simply and accurately for stable patients dialyzed three times a week.

Algorithms↗
PubMed1997

[Oxidative stress and chronic renal insufficiency: what can be a prophylactic approach?].

Cardiovascular diseases represent the first cause of mortality in chronic renal failure patients treated by hemodialysis. Alterations in lipid metabolism and oxidative stress are recognized as vascular risk factors. Their corrections could be of interest for atherosclerosis prevention. In order to evaluate interest of an therapeutic intervention, we have analyzed oxidative metabolism in hemodialysis patients by determining the production of oxygen reactive species (ROS), the level of defense mechanisms, and the balance between nitric oxide (NO) and ROS, responsible for anti- or proxidant effects of NO. During dialysis sessions performed with cellulosic membrane (Cuprophan) an increase in hydroperoxide production by platelets was noted (12 HETE) (5.62 +/- 0.94 pg); similarly, superoxide anion (O2(0)-) production by monocytes (fluorescence index: 115 +/- 24) and by polynuclear cells (fluorescence index: 115 +/- 24) was enhanced. On the other hand, anti-oxidant defenses were significantly reduced with a decrease in RBC SOC activity (0.92 +/- 0.06 U/mg Hg) and in RBC vitamin E (0.7 +/- 0.07 mg/l) concentration. We have demonstrated a profound alteration in the L-arginine/NO pathway consequently to an accumulation of NO synthases inhibitors or activators. The necessity to reduce the production of ROS during dialysis sessions justifies the use of more biocompatible membranes, such as modified cellulosic or synthetic membranes, decreasing leucocyte activation. In addition, NO synthetase inhibitors can be preferentially eliminated by convection. Finally, a supplementation with an exogenous anti-oxidant, such as oral vitamin E (500 mg/day for 6 months) normalizes RBC vitamin E levels and concomitantly allows a decrease in MDA concentrations In conclusion, oxidative metabolism alterations observed in hemodialysis are multifactorial: preventive measures include the use of a more biocompatible material, the reequilibrium of the NO/ROS balance, and supplementation with exogenous anti-oxidants.

Antioxidants↗
PubMed1996

Extensive necrotizing livedo reticularis in a patient with chronic renal failure, hyperparathyroidism and coagulation disorder: regression after subtotal parathyroidectomy.

Necrotizing livedo reticularis is an infrequent, life-threatening complication of chronic renal failure. Since Selye's studies in 1962, calciphylaxis, i.e. acute calcium deposition in tissue, is considered the main pathomechanism, especially because hyperparathyroidism are very frequently present. However, other etiological and/or triggering factors, such as coagulation disorders, direct cellular toxicity of parathormone or calcium on endothelium, might be involved, acting perhaps in a cumulative way. We report a case with a circulating anticoagulant which supports this hypothesis.

Adult↗
PubMed1996

Nephrotic syndrome associated with chronic lymphocytic leukemia resistant to immunosuppressive drugs: remission obtained by splenectomy.

Chronic lymphocytic leukemia is a common disease in the elderly but is rarely associated with a nephrotic syndrome. The rarity of this association suggests that leukemic cells may have certain properties or features that may lead to the development of glomerulonephritis. Effective medical treatment of the leukemia may not necessarily allow regression of the nephrotic syndrome; however, the effects of splenectomy on nephrotic proteinuria when associated to chronic lymphocytic leukemia have never been evaluated. We report the case of a 50-year-old male with stage C CD5+ chronic lymphocytic leukemia associated with a nephrotic syndrome due to Type I membranoproliferative glomerulonephritis. Chlorambucil and prednisone were unable to control the leukemia and the nephrotic range proteinuria, and were discontinued because of poor hematologic tolerance. A splenectomy immediately resulted in a spectacular remission of both chronic lymphocytic leukemia and the nephrotic syndrome. Spleen lymphocytes were collected and tested in quantitative flow cytometry for the expression of the main B cell associated markers. They did not exhibit any particular immunophenotypic pattern. This report of a remission of a glomerulonephritis associated with chronic leukemia following splenectomy is evidence of a possible relationship between the two diseases.

Glomerulonephritis, Membranoproliferative↗
PubMed1996

Removal of constitutive and inducible nitric oxide synthase-active compounds in a modified hemodiafiltration with on-line production of substitution fluid: the contribution of convection and diffusion.

Chronic renal failure and the uremic state lead to accumulation of various endogenous inhibitors of nitric oxide synthase. Previous studies on end-stage uremic patients nitric oxide synthase activity in murine vascular endothelium and cytokine-induced macrophage cell lines was shown to be modulated during treatment (Nephrol Dial Transplant 1995; 10: 1386-96). Paired filtration dialysis, a modified hemodiafiltration technique, physically separates convection from diffusion. Plasmas, ultrafiltrates and dialysates from seven uremic patients undergoing paired filtration dialysis performed using ultrapure apyrogen substitution fluid in the absence (first 120 min) or presence (last 120 min) of extracellular fluid reduction were tested for their inhibitory/stimulatory effect on ecNOS, constitutively expressed on t.End 1 cell line, a murine vascular endothelium, or for their inducing effect on iNOS, inducible on J774 cells, a macrophage cell line. On ecNOS, Group 1 (stimulatory, 3/7 patients) markedly enhanced the ecNOS activity as compared to control plasma, whereas group 2 plasma (inhibitory, 4/7 patients) inhibited ecNOS plasma. Post-dialysis plasma samples from all Group 1 and 2 patients showed a marked decrease of the predialysis stimulatory and inhibitory activity, respectively. On iNOS: all patient plasmas stimulated iNOS activity. The UF and particularly the dialysate had a remarkable iNOS inducing effect (Group 1). The substitution fluid obtained at 120 min during treatment in Group 1 and 2 had no effect on NOS activity. No correlation was found between predialysis ecNOS or iNOS activity values with mean systolic or diastolic pressures. These studies suggest a complex balance of ecNOS inhibitors/stimulators and iNOS inducers in uremia. Dialysis may remove ecNOS inhibitors and stimulators by convection and, in the latter case, by diffusion. iNOS inducers are removed during dialysis, suggesting the biocompatibility of the dialysis system with the on-line production of ultrapure substitution fluid.

Adult↗
PubMed1995

[Treatment of acute kidney failure].

The appropriate treatment of acute renal failure (ARF) is a function of its type and of its underlying causes. Functional ARF requires medical treatment directed towards the correction of kidney hemodynamic disequilibrium and the restoration of adequate glomerular filtration rate (suppression of drugs, correction of hypovolemia, hypotension or shock by vascular refilling and inotropic drug therapy). Obstructive ARF requires restoration of urinary tract patency by urological intervention (internal or external urinary catheter shunt) and treatment of factors underlying the obstruction (lithotomy, steroids, radio and (or) chemotherapy). Organic ARF commonly necessitates referral to a nephrology unit for renal replacement therapy, the choice of treatment modality (hemodialysis, hemofiltration, peritoneal dialysis) depending upon availability and staff expertise as well as patient clinical condition, associated comorbidity and gravity of ARF.

Acute Kidney Injury↗
PubMed1995

Prognosis of acute renal failure in the elderly.

UNLABELLED: Life expectancy is uncertain in the elderly with ARF. In order to determine whether a costly supportive management is worthwhile, we have studied a group of 68 elderly patients (over 65 years of age) admitted to the ICU with ARF. PATIENTS: 47 male; 21 female; 72 +/- 6 years old. Types of ARF include prerenal 24; obstructive 9; intrinsic 35 (acute tubular necrosis 30; glomerulonephritis 4; vascular 1). The mean simplified acute physiology score (SAPS) was 14 +/- 4; 39 patients (57.3%) had more than two underlying diseases; 42 patients (61.7%) were on mechanical ventilation; 40 patients (60%) underwent haemodialysis. The overall survival rate was 36.7%. Among the parameters studied, organic systemic failure index (OSF), diuresis, blood lactate, systolic blood pressure, urea appearance rate (UAR), differed significantly in survivors and deceased. From these results we conclude that the elderly with non-oliguric ARF, normal blood lactate, low catabolic state, and no more than two organ failures have a fair chance of recovering and should therefore be treated aggressively. In other cases, decisions to proceed with intensive supportive measures should be made according to individual characteristics.

Acute Kidney Injury↗
PubMed1995

[Role of continuous ambulatory peritoneal dialysis (CAPD) in a program for the treatment of chronic renal insufficiency. Problems posed by transfer of CAPD to transplantation or hemodialysis].

Continuous ambulatory peritoneal dialysis (CPAD) is a fully recognized method for treating end stage renal disease patients. However, literature data in agreement indicating that CAPD is a treatment modality for short to mid-term period. Largest series show that technical survival for CAPD averaged 50% at 3 years. Transplantation, curing temporarily ESRD patients, represents a success exit for CAPD in only 25 to 30% of patients. CAPD does not impair long term success of renal graft. Post-operative morbidity related to peritoneal catheter (exit skin infection and peritonitis) and abdominal problems represents a significant risk that should be prevented by appropriate measures. Hemodialysis transfer, failure of the method, represents an exit modality in 50 to 60% of patients. Whatever causes of CAPD failure, psycho-social difficulties, inadequacy of dialysis, edema due to fluid excess, malnutrition, severe peritonitis, transfer to hemodialysis must be considered as soon as possible to prevent deleterious effects on patient survival. Such facts indicate that CAPD program must be associated with large and appropriate withdrawal hemodialysis facilities. CAPD may be also a waiting modality for hemodialysis patients faced with temporary or repeated vascular access problems. In this last case it must be emphasized that hemodialysis to CAPD transfer will reduce "dialysis dose" efficiency (e.g., urea Kt/V) by 50%. We conclude that rationale use of CAPD would provide an excellent treatment modality for end stage renal disease patients for a short or mid-term period of time.

Humans↗
PubMed1995

[Necrotic angiodermatitis revealing a secondary hyperparathyroidism due to chronic renal insufficiency: healing after subtotal parathyroidectomy].

Severe skin necrosis of poor prognosis have been rarely reported among chronic renal failure patients. Their clinical outbreak must rapidly lead to search for a secondary hyperparathyroidism. Early parathyroidectomy seems is the only treatment able to stop the progression of the skin lesions. From an original clinical observation we discuss the different mechanisms involved.

Adult↗
PubMed1995

Creatinine kinetic modelling: a simple and reliable tool for the assessment of protein nutritional status in haemodialysis patients.

While the mathematical modelling of urea kinetics is in wide use for evaluating treatment adequacy and protein nutrition in dialysis patients, the kinetics of creatinine generation in dialysis patients has been relatively unexplored. In this study creatinine kinetic modelling as a clinical tool was investigated in a group of 90 patients treated by haemodialysis (n = 20), haemodiafiltration (60), haemofiltration (7), or biofiltration (3) over a 6-36-month period. A single pool model of creatinine kinetics was employed to obtain monthly values of creatinine distribution space and creatinine appearance rate. Extrarenal creatinine degradation rate, estimated using a clearance of 0.038 l/kg/24 h as suggested by Mitch and co-workers, was added to creatinine appearance rate in urine and dialysate to calculate a corrected creatinine index (CI). Extrarenal degradation accounted for 12 +/- 2% of CI. CI was higher in males (22.4 +/- 4.5 mg/kg/24 h) than females (19.8 +/- 4.8) and decreased with age, falling off more sharply for the female group (CI = 29.9-0.185.age, R = 0.72) than the males (CI = 24.1-0.030.age, R = 0.31). CI was found to correlate strongly with protein catabolic rate determined by urea kinetic modelling (CI = 8.84 +/- 10.91.PCR). Low or reduced CI was associated in this study group with severe malnutrition status and high mortality rate. CI is suggested as a strong predictor of patient morbidity and mortality.

Creatinine↗
PubMed1994

[Amanita proxima poisoning: a new cause of acute renal insufficiency].

To our knowledge Amanita proxima poisoning has never been reported. Amanita proxima is a mushroom seldomy encountered, similar to a common and edible species: Amanita ovoïdae. During October 1992, we had the opportunity to care for five cases of intoxications with Amanita proxima. In all cases early digestive disorders, cytolytic hepatitis and acute renal failure were noted. Outcome was favourable for all patients within three weeks with total recovery of both renal and hepatic functions with symptomatic treatment. Temporary dialysis was required in four patients.

Acute Kidney Injury↗
PubMed1994

[Central venous catheters: a temporary access, sometimes temporarily prolonged or even permanent].

Out of the 427 patients regularly attended to at the Centre d'Hémodialyse du Languedoc Méditerranéen, 144 have required at one stage the use of internal jugular vein for hemodialysis. Subclavian or femoral cathethers have been resorted to temporarily pending the re-establishment of a pre-existing vascular access. Jugular catheters have been reserved for lasting utilizations thanks to Carnaud's technique using two catheters. Gradually the use of such catheters has become imperative to offer vascular access for the treatment of hemodialysis or to create truly "permanent" accesses. This second solution only concerns a limited number of patients either for their private convenience, or when the establishment of an internal access would require a heavy and uncertain operation.

Actuarial Analysis↗