Biomedical subjects

Robert A Mactier

Publications and source records attributed to Robert A Mactier.

3 recordsLinked to original sources

PubMed2004

Peritoneal dialysis-associated peritonitis in Scotland (1999-2002).

BACKGROUND: Peritonitis is a major complication of peritoneal dialysis (PD). We have performed a national study of all patients on PD in Scotland over a 3.5 year period examining the causes of technique failure, rates of peritonitis, causative organisms, clinical outcomes and differences between automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD). METHODS: All 10 adult renal units in Scotland participated in the study and the data include all 1205 patients who were on PD in Scotland from January 1999 to June 2002. The data were collected prospectively by the PD nurses and reported to the Scottish Renal Registry every 6 months. RESULTS: Refractory or recurrent peritonitis was the cause of technique failure in 167 patients (42.6% of all cases of technique failure). There were 928 cases of peritonitis in 1487 patient-years, which equates to an overall peritonitis rate of one episode every 19.2 months. The peritonitis rates for APD and CAPD were similar at one episode every 20.3 months and one episode every 18.6 months, respectively. These results include 88 cases of peritonitis due to relapse or re-infection. There was a statistically significant difference (P = 0.012) in peritonitis rates between units using nasal mupiricin (one episode every 21.9 months) and those that did not (one episode every 18.3 months). Coagulase-negative Staphylococcus was the most common cause of peritonitis (29%), although this rate is lower than in historic studies. The overall initial cure rate was 75%. The initial cure rate for APD was 77.2% and for CAPD was 73.7%. No causative organism was isolated in 17% of cases. CONCLUSION: PD-associated peritonitis is the leading cause of technique failure in Scotland. We validate previous studies showing a decrease in the proportion of peritonitis episodes that are caused by coagulase-negative staphylococci. APD peritonitis rates are not significantly better than CAPD peritonitis rates in Scotland, and the initial cure rates for APD and CAPD are similar.

Coagulase↗

PubMed2002

Predicting 30-minute postdialysis blood urea concentrations using the stop dialysate flow method.

The stop dialysate flow (SDF) method has been the recommended method of postdialysis urea sampling by the Scottish Renal Association since November 1998. However, this method does not lend itself to calculation of Kt/V using currently favored formulas, which require either a 30-minute postdialysis sample or a 20-second "slow flow" sample. We, therefore, derived a formula that uses a 5-minute postdialysis urea sample using the SDF method to estimate the urea concentration at 30 minutes. Blood samples were obtained from 70 hemodialysis patients immediately before dialysis and at 0, 5, and 30 minutes postdialysis. Half of the patients from each unit were randomly selected to form the linear regression equation: Estimated 30-minute urea concentration = 1.06 x (5-minute urea concentration) + 0.22. This equation was validated using the data from the remaining 35 patients. This showed a very close correlation between measured and estimated urea concentration at 30 minutes (R2 = 0.97), and a Bland-Altman plot confirmed this close relationship. The sensitivity, specificity, positive, and negative predictive values of this equation were high when used to estimate 30-minute urea reduction ratio (URR) greater than 65% (100%, 85.7%, 97%, and 100%, respectively) and 30-minute Kt/V greater than 1. 2 (96.7%, 100%, 100%, and 80%, respectively). The coupling of the SDF method with the above formula combines the advantages of simple and reproducible postdialysis blood sampling with an accurate estimation of the 30-minute postdialysis blood urea concentration, URR, and Kt/V. This method should be a useful tool for comparative audit of hemodialysis adequacy.

Adult↗

PubMed2002

Derived equations are not precise enough to predict the adequacy of creatinine clearance in peritoneal dialysis patients.

BACKGROUND: Most renal units assess dialysis adequacy in peritoneal dialysis (PD) patients by formal 24-hour collections of urine and effluent dialysate. We sought a reliable method of predicting dialysis adequacy that allows a decrease in the frequency of these formal and cumbersome measurements. METHODS: We created a formula for estimating total creatinine clearances, then assessed the clinical utility of this formula and other published formulae in predicting adequate and inadequate dialysis in PD patients. We collected data over a 6-month period in 2001 from 288 PD patients from 9 centers in Scotland. Four out of every 5 patients were selected at random to create a formula for estimating total creatinine clearance per week, and the fifth patient was used to form a validation group. We plotted creatinine excretion against age, and the resultant linear regression equation was transformed to produce a formula for predicting total creatinine clearance per week, based on patient sex, weight, and serum creatinine. We used the data from the validation subgroup to calculate predictive values for our derived formula and data from all of the patients to calculate predictive values for the Cockcroft and Gault, Jones, and Modification of Diet in Renal Disease Study formulae. RESULTS: Neither our derived formula nor the three published formulae were sufficiently powerful to predict accurately either adequate or inadequate PD clearance. Receiver operator characteristic curves showed that no significant improvement in these predictive values could be achieved by altering either the sensitivity or the specificity. CONCLUSION: Prediction formulae are not accurate enough to detect underdialysis in PD patients.

Adolescent↗