Study on biological variation of haemostatic parameters in clinically healthy dogs
ABSTRACT Thromboelastography (TEG) may be a valuable supplement to the coagulation assays activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen, antithrombin (AT) and D-Dimer currently used in most clinical pathology laboratories. Allowable imprecision and bias reference limits for analytical tests can be calculated based on measurements of biological variation. No studies to date have examined the effect of biological variation on these haemostasis parameters in the same group of dogs. Plasma samples were collected after a set protocol once weekly for five consecutive weeks from eight healthy dogs (four males and four females) and stored at -80 degrees C until analysis. Randomized duplicate coagulation tests and TEG analyses were performed on all plasma samples within one run. The data were analyzed for outliers and subsequently subjected to nested analysis of variance to obtain the coefficient of analytical, intra-individual and inter-individual variation. From these objective analytical performance standards for imprecision, critical difference, total error and the index of individuality were calculated to assess the utility of conventional population-based reference ranges. All the clotting times (aPTT, PT and TT), fibrinogen, AT and D-Dimer showed a degree of individuality, which may make the use of population-based reference ranges alone an insensitive interpretation criterion, whereas a population-based reference interval seems to be sensitive for interpreting all TEG parameters. Analytical performance standards for imprecision were only met for one of the coagulation assays, whereas all TEG parameters except the alpha angle, alpha achieved this analytical goal.
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- "The plasma coagulation factor activities, PT, aPTT, AT-and PC-activity and fibrinogen concentration were assessed using an automated coagulometric analyser (ACL top 500, Instrumentation Laboratory). Plasma D-dimer concentration was measured using an immunometric flow-through principle (Nycocard Reader II, ILEX) (Wiinberg et al., 2007). The stored citrated plasma samples were transported on dry ice to the Veterinary Clinical Pathology Laboratory, University of Copenhagen, and transit time for the shipment was <24 h. "
ABSTRACT: The inflammatory response to infection can activate the coagulation system via complex interactions. If uncontrolled, this may lead to a consumptive coagulopathy, a major risk factor for a poor clinical outcome. This prospective observational study was conducted to determine whether consumptive coagulopathy in dogs with Babesia rossi infection is related to mortality. Seventy-two client-owned dogs diagnosed with canine babesiosis were included. Diagnosis was confirmed by polymerase chain reaction and reverse line blot and dogs co-infected with Babesia vogeli or Ehrlichia canis were excluded. Blood samples were collected at admission. Coagulation factor-, antithrombin (AT)-, and protein C (PC)-activity, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen and D-dimer concentrations were measured. The mortality rate was 18% (13/72 dogs) and the median activities of all the coagulation factors were significantly lower in the non-survivors compared to the survivors. Median PT and aPTT were significantly longer in the non-survivors compared to the survivors. Median AT activity was not significantly different but median PC activity was significantly decreased in the non-survivors. Median D-dimer concentrations were significantly higher in non-survivors compared to survivors. This study showed that dogs that died from B. rossi infection had a more severe consumptive coagulopathy compared to survivors, characterized by procoagulant activation, inhibitor consumption, and increased fibrinolytic activity.The Veterinary Journal 10/2012; DOI:10.1016/j.tvjl.2012.09.009 · 2.17 Impact Factor
Conference Paper: The effect of sampling and quantization on frequency estimation[Show abstract] [Hide abstract]
ABSTRACT: The effect of sampling and quantization on frequency estimation for a single sinusoid is investigated. The Cramer-Rao bound for 1 bit quantization is derived, and compared with the limit of infinite quantization. It is found that 1 bit quantization gives a slightly worse performance, however, with a dramatic increase of variance at certain frequencies. This can be avoided by using 4 times oversampling. The effect of sampling when using non-ideal antialiasing lowpass filters is therefore investigated. Cramer-Rao lower bounds are derived, and the optimal filters and sampling frequencies are found. Finally, fast estimators for 1 bit sampling, in particular correlation based estimators, are derived. The paper concludes with simulation results for 4 times oversampled 1 bit quantizationAcoustics, Speech and Signal Processing, 1998. Proceedings of the 1998 IEEE International Conference on; 06/1998
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ABSTRACT: Abnormal routine coagulation assay results have been reported to be common in veterinary patients with neoplasia, but the overall hemostatic functional state, including hypercoagulability, has not been described. The overall hemostatic functional state, including hypercoagulability, can be assessed in dogs with neoplasia by tissue factor (TF)-activated thromboelastography (TEG). Thirty-six dogs with malignant neoplasia and 13 dogs with benign neoplasia presented to the Small Animal Veterinary Teaching Hospital, The University of Copenhagen, Frederiksberg, Denmark. Prospective study evaluating the overall hemostatic functional state in dogs with neoplasia by a newly validated TF-activated TEG assay and routine coagulation parameters activated partial thromboplastin time (aPTT), prothrombin time (PT), platelet count, and D-dimer concentration. Hemostatic dysfunction was observed in 28/49 (57%) dogs with neoplasia. Twenty-four were dogs with malignant neoplasia, the majority of which 18/36 (50%) were hypercoagulable, whereas 6/36 (17%) were hypocoagulable. All hypocoagulable dogs had metastatic disease. The proportion of dogs with altered hemostasis was significantly different between dogs with malignant and benign neoplasia. TF-activated TEG detected hypercoagulable and hypocoagulable states in this population of dogs with neoplasia. The most common hemostatic abnormality in dogs with malignant neoplasia was hypercoagulability. These findings suggest that this novel hemostatic function test may be of value as a cage side method for the assessment of overall hemostatic function in dogs with cancer, including the detection of both hyper- and hypocoagulable states as well as mixed disorders.Journal of Veterinary Internal Medicine 01/2008; 22(1):140-7. DOI:10.1111/j.1939-1676.2008.0030.x · 2.22 Impact Factor