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Biomedical subjects

L Uttley

Publications and source records attributed to L Uttley.

17 recordsLinked to original sources
PubMed1995

Limitations of the peritoneal equilibration test in prescribing and monitoring dialysis therapy.

Based on correlation analysis with 24-h dialysis collections the peritoneal equilibration test (PET) has been promoted as an aid to prescribe and monitor dialysis dose. However correlation is an incorrect statistical technique to demonstrate the similarity of one measure to another. The closeness (or limits) of agreement should be measured using the technique of Bland and Altman. One hundred and nineteen patients underwent a 24-h dialysate collection and a PET. D/P ratios for urea and creatinine, dialysate volume, urea and creatinine clearance and KT/V (urea) were calculated using both methods and compared using correlation analysis. In addition the limits of agreement, reflecting the potential margins of difference between the two methods, were determined. When used to calculate a daily dialysate volume required to achieve adequacy targets, the PET was found to result in a prescription error range of -0.6 to +1.51/day for creatinine clearance and -0.9 to +0.61/day for urea clearance. The tendency of the PET to exaggerate clearance resulted in 14% of patients incorrectly achieving a target creatinine clearance of 50 1/week and 17% incorrectly reaching a target KT/V of 1.7. The PET cannot be used in place of 24-h dialysis collections to prescribe or monitor dialysis therapy.

Adult↗
PubMed1994

The normalized protein catabolic rate is a flawed marker of nutrition in CAPD patients.

For both hemodialysis and CAPD patients nutrition has been linked to mortality. Protein calorie malnutrition is present in 20 to 40% of CAPD patients. The normalized protein catabolic rate (NPCR), has been proposed as a useful measure of dietary protein intake and ultimately nutrition. However, the NPCR value has not been consistently predictive of outcome in CAPD patients. We have performed a cross sectional study on 147 clinically stable CAPD patients, who had a mean dialysis duration 22 months, to evaluate the relationship between the NPCR and conventional markers of nutrition. The NPCR was significantly correlated with normalized models of dialysis adequacy including KT/V (urea), total weekly creatinine clearance and the dialysis index. A significant negative correlation was found between individual anthropometric measures and the NPCR. Using a composite nutritional index to nutritionally categorize our population we found a significantly higher NPCR value in the severely malnourished group. The unadjusted protein catabolic rate (PCR) was significantly correlated with individual nutritional measures and was significantly greater in the well-nourished group. The NPCR, obtained by dividing the PCR by body weight (itself a nutritional measure), is lowest in well-nourished or obese patients, and thus as a marker of nutrition may be flawed. The PCR has nutritional relevance, however, adjusting its value to take into account patient size will require prospective evaluation of the influence of small solute removal on body composition.

Adult↗
PubMed1993

Limitations of kinetic models as predictors of nutritional and dialysis adequacy in continuous ambulatory peritoneal dialysis patients.

Nutrition has been shown to predict clinical outcome in continuous ambulatory peritoneal dialysis (CAPD) patients. However, despite the positive relationship between KT/V (urea) and the normalised protein catabolic rate, the ability of urea kinetic modelling to predict clinical outcome or nutrition remains inconclusive. We have evaluated the relationship between nutrition and achieved dialysis in a cross-sectional study of 147 stable CAPD patients on dialysis for a mean period of 22 months. Protein-energy malnutrition was present in 22-32% of the study population. 39 and 41% of the population failed to achieve suggested adequacy targets of 50 liters/week for total creatinine clearance and a weekly KT/V (urea) of 1.7, respectively. Severely malnourished patients had significantly greater normalised clearance and adequacy values than well-nourished patients. Intrinsic actual peritoneal clearance bore no relation to patient size. The subsequent normalisation of this value by a component of patient mass results in a mathematical bias against well-nourished or obese patients. This may explain the failure of such adequacy values to reflect outcome and argues against accepting such values as measures of dialysis well-being.

Body Weight↗
PubMed1992

Imipenem versus netilmicin and vancomycin in the treatment of CAPD peritonitis.

Imipenem/cilastatin is a new thienamycin antibiotic with a broad bactericidal spectrum. We undertook a prospective randomised study to compare the safety and efficacy of intraperitoneal (IP) imipenem/cilastatin (2 gm daily) [group A; 21 patients, mean age 49.2 years] with a combination of IP netilmicin and vancomycin (500 and 60-100 mg daily resp.) [group B; 20 patients, mean age 55.2 years] in CAPD peritonitis. Each patient underwent 4 daily CAPD exchanges with antibiotics in alternate exchanges. The causative organisms were similar in both the groups as was the duration of therapy (gr.A: 6.8 +/- 0.27 days; gr.B: 7.2 +/- 0.51 days; p = NS). Complete cure was marginally better with imipenem/cilastatin (gr.A; 94.1%, gr.B: 83.3%) with less relapses (gr.A: 1 episode; gr.B: 3 episodes). One episode in gr.A (S. aureus) and 2 in gr.B (Yeast & Proteus) failed to resolve and required catheter removal. Two gr. A patients developed generalised convulsions which settled after discontinuation of the drug. Whilst the results show no significant difference in the outcome in the two groups, the use of IP imipenem would offer a possible advantage as a single antibiotic. Larger experience is needed before imipenem can be recommended as a 'blind' first line agent for CAPD peritonitis.

Female↗
PubMed1992

Does catheter immobilization reduce exit-site infections in CAPD patients?

This study was undertaken to ascertain the effectiveness of an immobilization device in reducing exit site infections (ESI) in CAPD patients, and whether immuno-suppressive therapy, diabetes, disconnect system and Staphylococcus aureus nasal carriage had any bearing on the incidence of ESI. Sixty-six patients having a Tenckhoff catheter placement were randomly allocated into one of three groups; immobilizer, tape and non-immobilized group. The groups were monitored for the incidence of ESI over a total period of 347 patient months. The results show no significant difference in infection rates between the three groups, nor do the factors mentioned have any bearing on ESI rate. Whilst immobilization is important, the ineffectiveness of this device was probably related to its design problem.

Bacterial Infections↗
PubMed1989

A collection of problems in CAPD.

Several isolated problems, which in magnitude may appear small, yet can be enormous management problems, are discussed. In most instances experience is limited and literature is sparse. An attempt has been made to collate personal experience with that from the literature in arriving at guidelines for management of these problems.

AIDS-Associated Nephropathy↗
PubMedDate not supplied

Peritoneal dialysate IgG/C3 levels do not predict susceptibility to peritonitis.

OBJECTIVE: To investigate the usefulness of dialysate IgG and C3 concentrations in predicting likelihood of developing peritonitis. DESIGN: Prospective, longitudinal, and comparative study. SETTING: Single university teaching hospital dialysis unit and outpatient clinic. PATIENTS: 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 eleven-hour 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. OUTCOME MEASURES: Dialysate and serum levels of IgG and C3; peritonitis episodes. RESULTS: 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. CONCLUSION: 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.

Adult↗
PubMedDate not supplied

Natural history of Staphylococcus aureus nasal carriage and its relationship to exit-site infection.

OBJECTIVE: To study the natural history of nasal carriage of Staphylococcus aureus (SA) and its impact on exit-site infection (ESI). SETTING: A teaching hospital single-center study. DESIGN: A prospective cohort study in prevalent continuous ambulatory peritoneal dialysis (CAPD) patients. PATIENTS: 153 patients (76 male, 77 female; mean age 46 years) with a mean duration of CAPD of 2.4 years. METHODS: Nasal swabs were taken at approximately 2-month intervals over the mean period of follow-up of 22.6 months and cultured for SA. RESULTS: An average of 69% of patients received systemic antibiotics for therapy of ESI, peritonitis, and other infections during the period of the study, but none received local nasal antibiotics. Four groups of patients were identified according to their nasal carriage history: chronic, intermittent, occasional, and noncarriers. The intermittent and chronic carriers had significantly higher SA ESI than the occasional and noncarrier groups. The intermittent group also had the highest percentage of non-SA ES infections. CONCLUSION: Although this study shows that only half of our CAPD patients with nasal carriage were at risk of developing ESI, we recommend that patients with a positive nasal swab at the start of CAPD therapy should be treated with nasal antibiotics or local antibiotics at the exit site.

Catheters, Indwelling↗