Validation and impact of a new technique for assessment of glomerular filtration rate in patients with liver disease.

OBJECTIVES: Previously we have proposed a technique for the measurement of plasma clearance in patients with ascites. The impact of using the technique was assessed and the results compared with those from a reference technique in 111 patients having glomerular filtration rate measurements as part of their workup for liver transplantation. METHODS: Results of calculations using the new technique were compared with plasma clearance measurements obtained using a conventional slope-intercept technique and with clearance measurements based on urine collection. Discrepancies between the results of plasma clearance and urinary clearance assessments were investigated by using an uncollimated gamma camera to measure the total retention of the tracer. RESULTS: Conventional slope-intercept calculations overestimated clearance compared with the new technique by more than 20% in 21% of the patients. Significant differences between the results of the two methods were more likely in patients with more severe ascites. Results of urine collection-based measurements of Cr-51 EDTA clearance were frequently significantly lower than measurements using the new technique, whereas measurements of urinary clearance of creatinine were higher. Gamma camera measurements suggest that discrepancies between total and urinary clearance of Cr-51 EDTA are due to incomplete urine collection. CONCLUSION: The new technique is a practical method for assessment of kidney function and should be used in patients with liver disease who have or may have ascites.

Development of a modified sampling and calculation method for isotope plasma clearance assessment of the glomerular filtration rate in patients with cirrhosis and ascites.

AIM: The aim of this study was to identify a practical sampling regimen and calculation method that could be used to measure the glomerular filtration rate in patients with ascites using plasma sampling. PATIENTS AND METHODS: Thirteen potential liver transplant patients with cirrhosis and ascites were injected with Cr-51 ethylenediaminetetraacetic acid, and plasma samples were obtained at up to 16 time points for each patient. Reference clearance values were calculated using the area under the plasma clearance curve, which was calculated using all the available data points. Clearance calculations were then performed using three and four data points from each patient and three different calculation methods to identify a sampling regimen and calculation method that yielded good agreement with the reference values. RESULTS: The reference clearances ranged from 6 to 80 ml/min. Sampling at 2, 4, 8 and 24 h and calculation of the area under the plasma clearance curve using a log-linear trapezoidal rule with extrapolation to zero and infinity yielded a relative root mean square difference from the reference of less than 7%. CONCLUSION: This method for measuring glomerular filtration rate in patients with cirrhosis and ascites was found to be more accurate than the slope-intercept technique and is a practical alternative to urine collection.

Clinical governance improves the quality of nuclear medicine reporting.

OBJECTIVE: To assess the quality of nuclear medicine reporting, within a private UK hospital, of five physicians from four different National Health Service trusts and compare it with a similar previous clinical governance exercise. METHODS: Reports (n=140) were shown anonymously to all five physicians, including the one who produced the report. Each physician ranked them on a scale of 1-5, with 1 and 5 corresponding to complete disagreement and complete agreement, respectively. All reports with at least one score of <4 were subjected to consensus review by all five physicians and subsequently given a consensus score. RESULTS: Six hundred and ninety-one audit opinions were present out of a possible 700 (98.7%). Forty-three reports were reviewed, of which 11 received a consensus score of <4 (7.9%). This is not significantly different from the proportion of nontrivial errors in our earlier study (10.2%). Only three reports were present, however, with a score of <3 (2.1%), significantly fewer (P<0.02) than the proportion of nontrivial errors in our earlier study. No scores of 1 were recorded. No reporter attracted significantly more scores of <4 compared with the overall proportion of such scores. A score given by an auditing physician which was 2 or more points different from the consensus score was defined as a suboptimal audit. Forty-four of 691 suboptimal audits (6.4%) were present, significantly fewer than the proportion of suboptimal audits in our earlier study (9.7%; P<0.03). CONCLUSION: Studies such as these provide a useful framework for monitoring performance. This improved significantly in this study as compared with our previous audit.