Pre-analytical specimen labelling and processing errors in the ICU

Introduction: Specimen rejections have been associated with increased in-hospital stay and cost. The majority of errors occur in the pre-analytic phase. Specimen rejection can lead to high rate of recollection, delay in result availability, and high rate of test abandonment. These factors affect patient care and safety. Methods: This study conducted a retrospective review of Patient Safety Learning System (PSLS) reports for the intensive care unit (ICU) at The Ottawa Hospital General Campus (TOH) between 2010 and 2018, and a prospective review using interviews, surveys, and process mapping. Results: From 2098 PSLS reports, 52.6% were related to laboratory specimen collection and processing (pre-analytic phase). Specimen mislabelling with the wrong patient identifier accounted for 9.8% of pre-analytical error reports, while 16.4% of errors were due to non-sufficient quantity (NSQ) of specimen. 12.2 % of pre-analytical error reports involved cytology specimens. Conclusions: Pre-analytical errors are not only costly and resource draining, but may also place a burden on patients. Areas where errors were found include labels and requisitions stored in bedside cabinets, inconsistencies between specimen labels and requisitions, out-dated and difficult to access laboratory manuals, and non-sufficient quantity specimen collection. In the future we hope to start new initiatives to tackle these issues to improve patient safety and hospital efficiencies. This includes the development of a website for the laboratory manual, so that it is more easily accessible and user-friendly. With a new electronic medical record (EMR) system at TOH in 2019, we will explore the affects of pre-analytical processing of specimens.

Character correlation and its use for identification

A method is presented for correlating phylogenetic characters through cladistic analysis. It extends the use of phylogenetic datasets for diagnostic purposes. It improves matrix-based identification tools by predicting novel character-state combinations that were not observed when the key was constructed. By interpreting homoplasy as analytical error, hypothetical character-state combinations are tested for the homoplasy that they would add to the shortest tree(s). The correlation is equal to the homoplasy summed across all state combinations, divided by a maximum possible value. The results depend on uncertainty about the sequence of state transitions and their overlap among characters. A correlation index r is proposed for sets of non-additive characters; it is a kind of multiple-regression value, and its ensemble value R is a statistic of a whole matrix. This approach can be used to select sets of the best "proxy" characters to substitute for unobservable characters of interest. The concept can be extended to continuous characters. Worked examples are given with datasets of various insect orders.

Technical note: apatite and zircon (U-Th)/He analysis using quadrupole and magnetic sector mass spectrometry

Apatite and zircon (U-Th)/He thermochronological data are obtained through a combination of crystal selection, He content measurement by extraction from crystal and analysis using noble gas mass spectrometry, and measurement of U, Th and Sm contents by dissolution and solution analysis using inductively coupled plasma mass spectrometry (ICP-MS). In this contribution, we detail the complete protocols developed for over more than a decade that allow apatite and zircon (U-Th)/He data to be obtained with precision. More specifically, we show that the He content can be determined with a high precision using a calibration of the He sensibility based on the Durango apatite and its use also appears crucial to check for He, U-Th-Sm analytical problems. The Durango apatite used as a standard is therefore a suitable mineral to perform precise He calibration and yield (U-Th)/He ages of 31.1 ± 1.4 Ma with an analytical error of less than 5 %. The (U-Th)/He ages for the FCT zircon standard yields a dispersion of about 9 %, with mean age of 27.0 ± 2.6 Ma comparable to other laboratories. For the long-term quality control of the (U-Th)/He data, attention has been paid to evaluate the drift of He sensibility, blanks through time and those of (U-Th)/He ages and Th/U ratios (with Sm/Th when possible), all associated with the use of Durango apatite and Fish Canyon Tuff zircon as standards.

Analytical validation of eight methods of thyroglobulin measurement in fine-needle aspiration washouts

Background Thyroglobulin (Tg) assay in washout fluids of fine needles, after cervical lymph nodes aspiration, is used for detecting metastases from differentiated thyroid carcinomas. Assay methods are the same as for Tg in serum. However, with non-serum samples, methods require extensive validation to notably check for the absence of matrix effect. This study fits this context. Our objectives were to assess analytic performances, in washout fluid, of eight different Tg assay methods and to compare them to validated data in serum. Methods Eleven medical laboratories participated in this study. The matrix tested was phosphate-buffer saline containing 1% bovine serum albumin (PBS-1% BSA). Samples used were dilutions, in this buffer, of Certified Reference Material (CRM 457). We verified, for all methods, the limit of detection, precision, linearity, trueness and accuracy. Results In PBS-1% BSA, the functional sensitivities (FS) were comparable to those expected for serum. All the methods were linear. The relative biases of trueness were between –24.5 and 10.2% around 1 µg/L. Total analytical error was ≤40% near the functional sensitivity values. Conclusion No quantitatively important matrix effect was observed. All the methods showed their ability to measure Tg in PBS-1% BSA, over the concentration range of interest, with acceptable total analytical error. We validated the functional sensitivity value as a decision threshold in thyroidectomized patients after treatment and with low concentrations of serum Tg.

The Ultramicrochemical Analyses (UMCA) of Fluid Inclusions in Halite and Experimental Research to Improve the Accuracy of Measurement

Fluid inclusions in halite are widely used in research to determine the conditions of sedimentation in salt basins and reconstruct the chemical composition of seawater during a specific geological period. However, previous preliminary studies of the genetic types of inclusions, considered in the present research project, have not received due attention. Consequently, we decided to take into account the main distinguishing features of fluid inclusions in halite, belonging to various genetic types. The ultramicrochemical analysis (UMCA) method is one of the several methods that are used for the quantitative determination of the chemical composition of the primary fluid inclusions in halite. We have upgraded that technique, and that allowed us to reduce the analytical error rates of each component determination. The error rates were calculated in the study of Ca-rich and SO4-rich types of natural sedimentary brines.