Intra- and inter-rater agreement for the detection of band neutrophils and toxic change in horses.

BACKGROUND: The detection of band neutrophils and toxic change via microscopic blood smear review is vitally important, as their presence indicates systemic inflammation. However, in-clinic evaluation of WBC morphology is often limited. OBJECTIVE: We aimed to determine the agreement between expert raters in the detection of bands and toxic change. METHODS: Three board-certified clinical pathologists each evaluated 109 blood smears from horses with acute disease, and 19 control smears from healthy horses. The pathologists determined if bands were present, and if so, the percentage of bands present. They also determined if toxic change was present, and if so, the grade of toxic change. Intra-rater agreement was evaluated using 12 duplicate blood smears. Agreement on the presence of bands between pathologists and an in-clinic hematology analyzer was evaluated. RESULTS: Intra-rater agreement was substantial to almost perfect. Agreement between pathologists for the detection of bands was moderate, but when pathologists agreed bands were present, there was excellent agreement on the percentage of bands and mature neutrophils. Agreement between pathologists for the detection of high-grade, clinically relevant toxic change was fair. When pathologists agreed high-grade toxic change was present, there was fair agreement on Döhle bodies and cytoplasmic basophilia and poor agreement on cytoplasmic vacuolation. Agreement between individual pathologists and the in-clinic hematology analyzer for the indication of bands was fair to moderate. CONCLUSIONS: Consistent identification of bands and toxic change is challenging, even for highly trained personnel. It is, thus,not surprising that in-clinic blood smear evaluation of WBC morphology by non-experts could be inadequate.

Changes in Student Perceptions and Study Strategies Over Time in a Veterinary Clinical Pathology Course Using Case-Based Instruction.

Veterinary students are challenged to develop new, nonlinear ways of thinking as they learn diagnostic reasoning skills. To support this process, we use real-life cases in our clinical pathology course. Changes in student perceptions regarding the use of cases and changes in study strategies over time have not been previously investigated or compared to student grades. Students participated in three voluntary online surveys that included 4-point Likert scale questions and open-ended questions on the helpfulness of cases for learning and study strategies used during the course. We used Friedman tests to detect any differences in perceptions over time; McNemar's test and Wilcoxon signed-rank tests were used to detect any differences in study strategies over time. Fisher's exact tests were used to examine the association between the Likert scale responses and grades in quartiles. Before beginning the course, 29% of students responded that cases were very helpful to their learning, with similar responses for helpfulness in applying course material and grasping important concepts. There was a significant trend of increasing positivity over the duration of the course, with 74% responding that cases were very helpful at the end of the course. The most-reported study strategy was working individually on cases before the midterm (74% of students), and the most helpful study strategy was attending class regularly (88% reported it as very helpful). Study strategies did not change significantly over time. Overall, perceptions and study strategies did not vary significantly with grades.

Quantifying Novice and Expert Differences in Visual Diagnostic Reasoning in Veterinary Pathology Using Eye-Tracking Technology.

Visual diagnostic reasoning is the cognitive process by which pathologists reach a diagnosis based on visual stimuli (cytologic, histopathologic, or gross imagery). Currently, there is little to no literature examining visual reasoning in veterinary pathology. The objective of the study was to use eye tracking to establish baseline quantitative and qualitative differences between the visual reasoning processes of novice and expert veterinary pathologists viewing cytology specimens. Novice and expert participants were each shown 10 cytology images and asked to formulate a diagnosis while wearing eye-tracking equipment (10 slides) and while concurrently verbalizing their thought processes using the think-aloud protocol (5 slides). Compared to novices, experts demonstrated significantly higher diagnostic accuracy (p <.017), shorter time to diagnosis (p <.017), and a higher percentage of time spent viewing areas of diagnostic interest (p <.017). Experts elicited more key diagnostic features in the think-aloud protocol and had more efficient patterns of eye movement. These findings suggest that experts' fast time to diagnosis, efficient eye-movement patterns, and preference for viewing areas of interest supports system 1 (pattern-recognition) reasoning and script-inductive knowledge structures with system 2 (analytic) reasoning to verify their diagnosis.

Evaluation of coagulation via thromboelastography in healthy horses administered dexamethasone.

Dexamethasone was administered to healthy horses daily for 7 days. Blood samples were collected at 3 time points from both treatment and non-treatment groups, and analyzed via thromboelastography (TEG). There were no significant differences in TEG parameters between treated and untreated horses, or within treatment groups over time.

Évaluation de la coagulation par une thrombo-élastographie chez des chevaux en santé ayant reçu de de la dexaméthasone. La dexaméthasone a été administrée à des chevaux en santé pendant 7 jours. Des échantillons de sang ont été prélevés à trois moments auprès des groupes de traitement et des groupes sans traitement et ensuite analysés par thrombo-élastographie (TEG). Il n'y avait aucune différence significative dans le temps pour les paramètres TEG entre les chevaux traités et non traités ou à l'intérieur des groupes de traitement.(Traduit par Isabelle Vallières).

Educational interventions to improve cytology visual diagnostic reasoning measured by eye tracking.

The teaching of visual diagnostic reasoning skills, to date, has been conducted in a largely unstructured apprenticeship manner. The purpose of this study was to assess if the introduction of two educational interventions improved the visual diagnostic reasoning skills of novices. These were (1) the active use of key diagnostic features and (2) image repetition. A pre-test and post-test research design was used to compare the two teaching interventions to a traditional teaching group and an expert group using eye tracking as an assessment method. The time to diagnosis and the percentage of time spent viewing an area of diagnostic interest (AOI) were compared using independent t-tests, paired t-tests, and analysis of covariance (ANCOVA). Diagnostic accuracy as a dichotomous variable was compared using Chi-square tables. Students taught in an active-learning manner with image repetition behaved most like experts, with no significant difference from experts for percentage of time spent in the AOIs and a significantly faster time to diagnosis than experts (p<.017). Our results from the educational interventions suggest a greater level of improvement in the eye tracking of students that were taught key diagnostic features in an active-learning forum and were shown multiple case examples.

Comparison of arterial and venous whole blood clot initiation, formation, and strength by thromboelastography in anesthetized swine.

Thromboelastography (TEG) analysis was used to determine if differences exist between venous and arterial samples in anesthetized swine, using identical sampling techniques for each of the samples. We hypothesized that TEG parameters would not differ between native whole blood venous and arterial samples. Thirty male Landrace swines were included in the study. Both the femoral artery and vein were catheterized using standard cut-down techniques and with identically sized catheters to rule out any catheter size effects on the results. Standard TEG parameters for native whole venous and arterial blood samples (r, K, α, MA, G, and coagulation index) were measured or calculated, and t-test or Mann-Whitney rank-sum test used for comparison when appropriate. Significant differences were detected for r (venous < arterial), K (venous < arterial), α (venous > arterial), and coagulation index (venous > arterial) TEG parameters. No significant differences were measured for MA or G. These differences are important, especially when temporal changes in TEG are utilized to monitor patient stability and fluid therapy protocols using trends in coagulation properties. Taken together, these results suggest that clots are more likely to form at a faster rate in venous samples compared to arterial samples, but the overall clot strength does not differ. Therefore, if TEG analysis is being used to monitor coagulation profiles in a patient, care should be taken to use the same site and technique if results are to be used for comparative purposes.

Comparison of thromboelastography parameters between different catheter lumen diameters in an uncontrolled haemorrhagic shock model in swine.

Sampling technique is a concern for standardization of thromboelastography (TEG), as it contributes towards preanalytical variation in TEG tracings. The objective of this study was to assess the influence of catheter lumen diameter on TEG parameters with kaolin-activated native blood in a swine haemorrhagic shock model, using standardized sampling techniques. We hypothesized that one or more TEG parameters will differ between venous samples collected from catheters with different diameter lumens. Ten male landrace swine were included in the study. Standard cut-down techniques on both femoral veins were performed and catheterized with a 14-gauge (14G) and a 20-gauge (20G) catheter of the same length. Blood withdrawal times were standardized to 3 s and TEG parameters (R, K, α, maximum amplitude, G and coagulation index) were measured or calculated. Significant differences were detected for R (14G < 20G; P = 0.002), K (14G < 20G; P = 0.026), maximum amplitude (14G > 20G; P = 0.02), G (14G > 20G; P = 0.001) and coagulation index (14G > 20G; P < 0.001). No significant differences were measured for α (P = 0.058). Bias values (method A: 20G; method B: 14G) for R, K, α, maximum amplitude, G and coagulation index were 1.00, 0.14, -1.88, -1.56, -1.39 and -1.07, respectively. Using TEG analysis, kaolin-activated native whole blood samples obtained from 14G catheters are hypercoagulable (clotted faster and stronger clot) compared with samples obtained from 20G catheters. Sampling methodology should be standardized and systematic when comparing TEG parameters.

Thrombelastography in dogs admitted to an intensive care unit.

BACKGROUND: Underlying conditions in dogs admitted to an intensive care unit (ICU) can cause hemostatic dysfunction. Thrombelastography (TEG) may be useful in detecting hemostatic alterations as compared with standard coagulation tests. OBJECTIVES: The purpose of this study was to compare TEG results and those of standard coagulation tests in identifying hemostatic dysfunction in dogs admitted to an ICU and to investigate associations among the variables measured. METHODS: Tissue factor-activated TEG analysis, d-dimer and fibrinogen concentrations, antithrombin (AT) activity, prothrombin time (PT), activated partial thromboplastin time (aPTT), and platelet count were measured using standard techniques on 27 dogs admitted to ICU with a disease known to be associated with hemostatic dysfunction and in 31 clinically healthy control dogs. Results were compared between groups using nonparametric tests and kappa analysis; principal component analysis (PCA) and Spearman rank correlation were used to measure associations among variables. RESULTS: Fourteen of 27 ICU dogs had abnormal TEG tracings, which were used to classify the dogs as hypercoagulable (n=11), hypocoagulable (n=3), or normocoagulable (n=13). Hypercoagulable dogs had significantly increased d-dimer (P=.03) and fibrinogen (P=.01) concentrations compared with normocoagulable dogs. In ICU dogs, positive associations were identified between maximum amplitude (MA), alpha-angle, fibrinogen concentration, and platelet count, and between PT, aPTT, and reaction time (R). Significant correlations were found between MA and fibrinogen (r(s)=.76, P<.001) and between reaction time (R) and PT (r(s)=.51, P=.003). CONCLUSIONS: TEG was useful in detecting hemostatic dysfunction in dogs in an ICU. Positive associations among variables may provide insight as to how overall coagulation status reflects alterations in clot strength and coagulation time. Dogs with TEG tracings indicative of hypercoagulability are likely in procoagulant states. Future studies of the incidence of thrombotic complications in dogs with hypercoagulable TEG tracings are warranted.