The freckle plot (daily turnaround time chart): a technique for timely and effective quality improvement of test turnaround times.

Test turnaround times are often monitored on a monthly basis. However, such an interval usually means that not all causes for delay in test reporting can be unequivocally identified for institution of remedial action. We have devised a daily chart--the freckle plot--that graphically displays the test turnaround times by laboratory receipt time. Different symbols are used to designate specimens reported within the test's turnaround time limit, those within 10 min beyond that limit, and those well outside the limit. These categories are adjustable to suit different limits of stringency. Freckle plots are produced on a daily basis and can be used to track down causes for test delays. Using the 1-h turnaround time "stat" potassium test as a model, we found 16 causes for test delay, of which 9 were potentially remediable. By applying these remedies, we were able to increase test compliance, in the day shift, from 91.5% (95% confidence interval 88.8%-93.7%) to 97.6% (95% confidence interval 96.4-98.55%), which is significant at P < 10(-7). This daily plot is a useful quality assurance tool, supplementing the more conventional tests used to ensure laboratory quality improvement.

A clinical evaluation of the Cobas Fara clinical chemistry analyzer for some routine serum enzymes and glucose.

The authors evaluated the Cobas FARA centrifugal analyzer with respect to pipetting precision and accuracy, instrument temperature, spectrophotometric response, and analytic performance for the assay of five serum enzymes and glucose. Spectrophotometric response, temperature response, pipetting precision, and accuracy were satisfactory. However, sufficient time must be allowed for cuvet contents to reach a stable temperature before measurements are made. Total day-to-day imprecision (within plus between run) was less than 5% (coefficient of variation) for aspartate and alanine aminotransferases (AST; Enzyme Commission classification number [EC] EC 2.6.1.1; and ALT; EC 2.6.1.2); alkaline phosphatase (AP; EC 3.1.3.1); gamma-glutamyltransferase (GGT; EC 2.3.1.2); lactate dehydrogenase (LD; EC 1.1.1.17); creatine kinase (CK; EC 2.7.3.1); and glucose assays. Results compare well with those obtained with other current clinical chemistry analyzers; correlation coefficients were greater than 0.993. Sample-to-sample carryover was negligible, and method linearity was satisfactory for all tests.

Mailbox: program designed to improve communication in clinical laboratories.

A MUMPS program called MAILBOX allows information to be more efficiently disseminated in a hospital department of clinical biochemistry. Readily accessible to all staff as the department is equipped with video display units in every laboratory and office, MAILBOX allows laboratory staff to send and read departmental messages; send, read, and save personal messages; sign in to and out of the department; and locate all other staff. Departmental messages containing information of general interest are automatically displayed on signing on to MAILBOX. Personal messages are directed to specific people, who are so informed when signing on; they can only be read by the sender and intended recipient(s).

The organization of a 24-hour blood alcohols (volatiles) screening service in a hospital laboratory.

We describe the organization that evolved in the Clinical Biochemistry Department of a tertiary-care hospital for handling blood (serum) alcohol (volatiles) determinations. We use a microprocessor-controlled capillary gas chromatography system which will detect and quantitate methanol, ethanol, isopropanol and acetone. Minimal operator intervention is required, allowing operation of the system 24 hours each day, thus permitting timely detection of these volatiles. A Specimen Trace Card has been devised to document continuity of sample handling from the time of blood collection until completion of the analysis. This has proved of value when laboratory records are used for legal purposes.

Biological variance of cholinesterase and 5'-nucleotidase in serum of healthy persons.

We measured cholinesterase (EC 3.1.1.8) and 5'-nucleotidase (EC 3.1.3.5) activities in serum of 24 healthy laboratory staff during 12 months. Overall mean activities ranged from 5.3 to 13.4 kU/L for cholinesterase and 5.4 to 9.8 U/L for 5'-nucleotidase. Cholinesterase activity was significantly (p less than 0.01) higher for men than for women. 5'-Nucleotidase activity was significantly (p = 0.01) higher for subjects 40 years or older than for those younger than 40, but was not different with respect to sex or time of year. Average intra- and interindividual variances (SD2) were 0.38 and 2.69 for cholinesterase and 1.41 and 0.97 for 5'-nucleotidase, respectively. Intra- to interindividual standard deviation ratios were 0.38 for cholinesterase and 1.21 for 5'-nucleotidase. Average within-run analytical variances were 0.13 and 0.3 (4% and 13% of total variance) for cholinesterase and 5'-nucleotidase, respectively. The importance of these findings in regards to diagnostic interpretation of serum cholinesterase and 5'-nucleotidase results is discussed.

The EPOS Automated Selective Chemistry Analyzer evaluated.

We evaluated the analytical performance of the EPOS (Eppendorf Patient Oriented System) Automated Selective Chemistry Analyzer, using the following tests for serum analytes: alanine and aspartate aminotransferases, lactate dehydrogenase, creatine kinase, gamma-glutamyltransferase, alkaline phosphatase, and glucose. Results from the EPOS correlated well with those from comparison instruments (r greater than or equal to 0.990). Precision and linearity limits were excellent for all tests; linearity of the optical and pipetting systems was satisfactory. Reagent carryover was negligible. Sample-to-sample carryover was less than 1% for all tests, but only lactate dehydrogenase was less than the manufacturer's specified 0.5%. Volumes aspirated and dispensed by the sample and reagent II pipetting systems differed significantly from preset values, especially at lower settings; the reagent I system was satisfactory at all volumes tested. Minimal daily maintenance and an external data-reduction system make the EPOS a practical alternative to other bench-top chemistry analyzers.

The clinical biochemistry laboratory computer system and result entry: validation of analytical results.

We describe an array of checking routines that can aid laboratory staff in detecting possible errors in results being entered into a laboratory computer. A single result is checked at the worksheet stage for its numeric format and for its numeric status by comparison with appropriate reference ranges, and action and hazard limits. If a previous result exists then the present result can be compared with it (delta checking). Laboratory documentation of abnormal results is important and we describe three types; worksheet, exception report(s) and histograms of results. The clinical reports leaving the laboratory should flag abnormal results so that the clinician is prompted to examine, and question if necessary, results which are extreme or have changed significantly since the last analysis. Effective error detection requires cooperation between the laboratory and clinical units.

Digitisers: their use in the entry of orders, urinalysis results, and isoenzyme interpretation in a clinical biochemistry computer system.

The processes of order entry, urinalysis result, and isoenzyme interpretation entry into a laboratory computer system is a time consuming activity. We have designed a series of forms for use with a digitising pad that allow us rapidly to enter orders, urinalysis results, and isoenzyme interpretative comments into our laboratory computer system. We have shown that digitiser entry is always significantly faster than manual entry. Although there are many devices available to facilitate computer entry, we believe that the digitiser technique is an attractive option because of its ease of use, speed, reliability, and low cost.

A BASIC program for serum cholinesterase phenotyping using a microcomputer.

We have modified a BASIC program for serum cholinesterase phenotyping using a microcomputer. This program accepts the reaction-rate result of total and inhibitor assays of activity, allows the patient to be identified and prints out a full account of the fitting process thus allowing adequate documentation. We believe that this modification enhances the usefulness of the program to laboratories engaged in the routine determination of serum cholinesterase phenotyping.

Elevation of serum lactate dehydrogenase-5 following methylglucamine iodipamide (Cholografin/Biligrafin) infusion for intravenous cholangiography.

Methylglucamine iodipamide (Cholografin-North America; Biligrafin-Europe, Squibb) is the only contrast medium in clinical usage for opacification of the biliary tree in intravenous cholangiography. We report two cases of elevation of serum lactate dehydrogenase-5 activity following infusion of 40 ml of Cholografin. This occurred without overt clinical signs of adverse reaction to contrast medium. This elevation was 65% of serum LD-5 activity in case one, 91% in case two. The elevation peaked at 12 h after administration of contrast medium in both cases and persisted for at least 24 h. These findings suggest that methylglucamine iodipamide causes transient hepatocellular toxicity, the mechanism of which is not known.