Simplified Method for Removing Direct Oral Anticoagulant Interference in Mechanical Coagulation Test Systems-A Proof of Concept.

BACKGROUND: Direct oral anticoagulants (DOACs) cause unwanted interference in various hemostasis assays, including lupus anticoagulant (LA) testing, where false positive and false negative identification may occur. DOAC Stop (DS) is an activated charcoal (AC) product used to specifically and effectively adsorb DOACs from test plasma. This process normally requires plasma treatment, centrifugation and plasma separation prior to tests, but inexperienced operators may also inadvertently transfer residual AC particles, thereby potentially adversely affecting clot detection. METHODS: We hypothesized that residual DS might not be problematic for mechanical clot detection. We therefore investigated the potential impact of DS and a new DS liquid (DS-L) product on clotting tests using a mechanical clot detection system. Varying concentrations of DS were added to normal and abnormal plasmas with and without DOAC presence. Clotting tests including PT, APTT and dRVVT were performed directly in the analyzer without plasma/DS centrifugation. RESULTS: DS up to double the recommended treatment level had only minor effects on all test results, despite completely obscuring visibility in the plasma/reagent mix. This confirms that the centrifugation step may be able to be omitted when using mechanical detection systems. CONCLUSIONS: Should DS carryover into treated plasmas occur, this should not cause issues with testing performed on mechanical clot-sensing devices. Moreover, we hypothesize that DS can be used directly in these systems, without the need for centrifugation, thereby simplifying its many potential applications.

Early Blood Clot Detection Using Forward Scattering Light Measurements Is Not Superior to Delta Pressure Measurements.

The occurrence of thrombus formation within an extracorporeal membrane oxygenator is a common complication during extracorporeal membrane oxygenation therapy and can rapidly result in a life-threatening situation due to arterial thromboembolism, causing stroke, pulmonary embolism, and limb ischemia in the patient. The standard clinical practice is to monitor the pressure at the inlet and outlet of oxygenators, indicating fulminant, obstructive clot formation indicated by an increasing pressure difference (ΔP). However, smaller blood clots at early stages are not detectable. Therefore, there is an unmet need for sensors that can detect blood clots at an early stage to minimize the associated thromboembolic risks for patients. This study aimed to evaluate if forward scattered light (FSL) measurements can be used for early blood clot detection and if it is superior to the current clinical gold standard (pressure measurements). A miniaturized in vitro test circuit, including a custom-made test chamber, was used. Heparinized human whole blood was circulated through the test circuit until clot formation occurred. Four LEDs and four photodiodes were placed along the sidewall of the test chamber in different positions for FSL measurements. The pressure monitor was connected to the inlet and the outlet to detect changes in ΔP across the test chamber. Despite several modifications in the LED positions on the test chamber, the FSL measurements could not reliably detect a blood clot within the in vitro test circuit, although the pressure measurements used as the current clinical gold standard detected fulminant clot formation in 11 independent experiments.

Automated occlusion detection for the diagnosis of acute ischemic stroke: A detailed performance review.

INTRODUCTION: Stroke is a leading cause of adult disability and death worldwide. Automated detection of stroke on brain imaging has promise in a time critical environment. We present a method for the automated detection of intracranial occlusions on dynamic CT Angiography (CTA) causing acute ischemic stroke. METHODS: We derived dynamic CTA images from CT Perfusion (CTP) data and utilised advanced image processing to enhance and display major cerebral blood vessels for symmetry analysis. We reviewed the performance of the algorithm on a cohort of 207 patients from the International Stroke Perfusion Imaging Registry (INSPIRE), with Large Vessel Occlusion (LVO) and non-LVO strokes. Included in the data were images with chronic stroke, various artefacts, incomplete vessel occlusions, and images of poorer quality. All images were annotated by stroke experts. In addition, each image was graded in terms of the difficulty of the task of occlusion detection. Performance was evaluated on the overall cohort, and with respect to occlusion location, collateral grade, and task difficulty. We also evaluated the impact of including additional perfusion data. RESULTS: Images with a rating of lower difficulty achieved a sensitivity and specificity of 96% and 90%, respectively, while images with a moderate difficulty rating achieved 88% and 50%, respectively. For cases of high difficulty, where more than two experts or additional data were required to reach consensus, sensitivity and specificity was 53% and 11%. The addition of perfusion data to the dCTA images increased the specificity by 38%. CONCLUSION: We have provided an unbiased interpretation of algorithm performance. Further developments include generalising to conventional CTA and employing the algorithm in a clinical setting for prospective studies.

Bioimpedance Analysis as Early Predictor for Clot Formation Inside a Blood-Perfused Test Chamber: Proof of Concept Using an In Vitro Test-Circuit.

Clot formation inside a membrane oxygenator (MO) due to blood-to-foreign surface interaction represents a frequent complication during extracorporeal membrane oxygenation. Since current standard monitoring methods of coagulation status inside the MO fail to detect clot formation at an early stage, reliable sensors for early clot detection are in demand to reduce associated complications and adverse events. Bioimpedance analysis offers a monitoring concept by integrating sensor fibers into the MO. Herein, the feasibility of clot detection via bioimpedance analysis is evaluated. A custom-made test chamber with integrated titanium fibers acting as sensors was perfused with heparinized human whole blood in an in vitro test circuit until clot formation occurred. The clot detection capability of bioimpedance analysis was directly compared to the pressure difference across the test chamber (ΔP-TC), analogous to the measurement across MOs (ΔP-MO), the clinical gold standard for clot detection. We found that bioimpedance measurement increased significantly 8 min prior to a significant increase in ΔP-TC, indicating fulminant clot formation. Experiments without clot formation resulted in a lack of increase in bioimpedance or ΔP-TC. This study shows that clot detection via bioimpedance analysis under flow conditions in a blood-perfused test chamber is generally feasible, thus paving the way for further investigation.

Benchmark dataset for clot detection in ischemic stroke vessel-based imaging: CODEC-IV.

We present an annotated dataset for the purposes of creating a benchmark in Artificial Intelligence for automated clot detection. While there are commercial tools available for automated clot detection on computed tomographic (CT) angiographs, they have not been compared in a standardized manner whereby accuracy is reported on a publicly available benchmark dataset. Furthermore, there are known difficulties in automated clot detection - namely, cases where there is robust collateral flow, or residual flow and occlusions of the smaller vessels - and it is necessary to drive an initiative to overcome these challenges. Our dataset contains 159 multiphase CTA patient datasets, derived from CTP and annotated by expert stroke neurologists. In addition to images where the clot is marked, the expert neurologists have provided information about clot location, hemisphere and the degree of collateral flow. The data is available on request by researchers via an online form, and we will host a leaderboard where the results of clot detection algorithms on the dataset will be displayed. Participants are invited to submit an algorithm to us for evaluation using the evaluation tool, which is made available at together with the form at https://github.com/MBC-Neuroimaging/ClotDetectEval.

Evaluation of the Analytical Performances of the Biolabo SOLEA 100 Optical Coagulometer and Comparison with the Stago STA-R MAX Analyser in the Determination of PT, APTT, and Fibrinogen.

INTRODUCTION: The Biolabo Solea 100 is a fully automated coagulation analyser using an optical system to detect coagulation designed to meet the needs of small- and medium-sized laboratories. This study aimed to evaluate the analytical performance in terms of bias, precision, and interference of the Biolabo Solea 100 coagulometer under routine laboratory conditions. In addition, a comparison was made with Stago STA-R MAX. MATERIALS AND METHODS: Imprecision and bias were evaluated for activated partial thromboplastin time (APTT), fibrinogen (FIB), and prothrombin time (PT) at the medical decision levels. The results of 200, 181, and 206 plasma samples for APTT, FIB, and PT, respectively, were compared with those obtained by Stago STA-R MAX. In addition, the interference level of bilirubin, haemoglobin, triglycerides, and fractionated heparin was evaluated. RESULTS: Repeatability, intermediate imprecision, bias, and total error are overall below the defined limits of acceptability. Of interest is the high degree of agreement between Solea 100 and STA-R MAX with respect to PT (s), which fits perfectly with the theoretical line of identity (y = 0 + 1.00x). No interferences were found within the limits stated by the manufacturer, with some exceptions for APTT with heparin and APTT and PT for higher bilirubin concentrations. CONCLUSIONS: In conclusion, the performance of the Solea 100 optical analyser is satisfactory and adequate for the determination of routine coagulation tests. Moreover, they are perfectly comparable to mechanical systems, such as STA-R MAX and other upper-level analysers, even considering the low interference levels under routine conditions.

Detection of Thrombosis in the Extracorporeal Membrane Oxygenation Circuit by Infrasound: Proof of Concept.

As of today, there exist no reliable, objective methods for early detection of thrombi in the extracorporeal membrane oxygenators (ECMO) system. Within the ECMO system, thrombi are not always fixed to a certain component or location in the circuit. Thus, clot fragments of different shapes and consistencies may circulate and give rise to vibrations and sound generation. By bedside sound measurements and additional laboratory experiments (although not detailed herein), we found that the presence of particles (clots or aggregates and fragments of clots) can be detected by analyzing the strength of infra-sound (< 20 Hz) modes of the spectrum near the inlet and outlet of the centrifugal pump in the ECMO circuit. For the few patients that were considered in this study, no clear false positive or negative examples were found when comparing the spectral approach with clinical observations. A laboratory setup provided insight to the flow in and out of the pump, confirming that in the presence of particles a low-amplitude low-frequency signal is strongly amplified, enabling the identification of a clot.

Comparación de la detección foto óptica vs. electromecánica del coágulo / Comparison of mechanical vs. optical clot detection / Comparação da detecção foto-óptica vs. eletromecânica do coágulo

El objetivo de este estudio fue determinar si la detección foto óptica del coágulo es equivalente a la detección electromecánica al realizar el tiempo de protrombina (TP), el tiempo de tromboplastina parcial activado (APTT) y el dosaje de fibrinógeno (FBG). Se estudiaron 258 pacientes consecutivos que concurrieron al laboratorio para realizar estudios de hemostasia. Se utilizaron tres coagulómetros: ACL TOP (foto-óptico) y STArt y Destiny plus como detección electro mecánica. EL TP, APTT y FBG fueron realizados en todos los equipos antes de transcurridas tres horas de la toma de la muestra. Se obtuvo una buena correlación entre los resultados obtenidos con ambos métodos de detección TP (%): (ACL TOP vs. STArt R=0,989; ACL TOP vs. Destiny plus R=0,988), APTT: (ACL TOP vs. STArt R=0,938; ACL TOP vs. Destiny Plus R=0,989), y FBG (ACL TOP vs. STArt R=0,97; ACL TOP vs. Destiny Plus R=0,984). La diferencia de los resultados entre plataformas son menores al error total permitido establecido por los criterios de CLIA (ETa TP y APTT =15% y FBG 20%) en el 95% de las muestras. En los tres coagulómetros evaluados, correctamente mantenidos y calibrados, la detección foto-óptica arrojó resultados equivalentes a la detección electromecánica.

The aim of this study was to determine whether two distinct methodologies based on optical or mechanical clot detection are comparable. Prothrombin time (PT), activated partial thromboplastine time (APTT) and fibrinogen results obtained with mechanical method using two different coagulometers are compared with those obtained by photo optical method within three hours of blood collection. The statistical analysis demonstrated an excellent correlation between optical or mechanical platform for TP, APTT and FBG. TP (%) showed (ACL TOP vs. STArt R=0.989; ACL TOP vs. Destiny Plus R=0.988), APTT: (ACL TOP vs. STArt R=0.938; ACL TOP vs. Destiny Plus R=0.989) y FBG (ACL TOP vs. STArt R=0.97; ACL TOP vs. Destiny Plus 0.984). The differences between optical or mechanical clot detection results are lower than the total error allowable in 95% of the studied samples. To conclude with, the three coagulometers evaluated have maintenance performed and are calibrated according to the international guidelines, and the results obtained with an optical or mechanical clot detection method are equivalent.

O objetivo deste estudo foi determinar se a detecção foto-óptica do coágulo é equivalente à detecção eletromecânica ao realizar o tempo de protrombina (TP), o tempo de tromboplastina parcial ativado (APTT) e a dosagem de fibrinogênio (FBG). Foram estudados 258 pacientes consecutivos que concorreram ao laboratório para realizar estudos de hemostasia. Foram utilizados três coagulómetros: ACL TOP (foto-óptico) e STArt e Destiny plus como detecção eletromecânica. O TP, APTT e FBG foram realizados em todos os equipamentos antes de decorridas três horas da tomada da amostra. Uma boa correlação foi conseguida entre os resultados obtidos com ambos os métodos de detecção TP (%): (ACL TOP vs. STArt R=0,989; ACL TOP vs. Destiny plus R =0,988), APTT: (ACL TOP vs.STArt R=0,938; ACL TOP vs. Destiny Plus R=0,989), e FBG (ACL TOP vs. STArt R=0,97; ACL TOP vs. Destiny Plus R=0,984). A diferença dos resultados entre plataformas é menor ao erro total permitido estabelecido pelos critérios de CLIA (ETa TP e APTT =15% e FBG 20%) em 95% das amostras. Nos três coagulómetros avaliados, corretamente mantidos e calibrados a detecção foto-óptica lança resultados equivalentes à detecção eletromecânica.