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Laboratory Instrumentation, Reagents, Methods, and Patient Sample as Variables in Coagulation
Published in Harold R. Schumacher, William A. Rock, Sanford A. Stass, Handbook of Hematologic Pathology, 2019
James W. Cook, William A. Rock
During the first half of this century, laboratory assessment of the coagulative properties of blood consisted largely of the evaluation of patient bleeding times, whole-blood clotting time, and later the prothrombin time (PT) as well as the activated partial thromboplastin time (APTT). During this time period, the methods employed were labor intensive and the technicians utilized visual end points of clot formation in an attempt to describe the coagulation process. Needless to say, results varied between laboratories and between technicians. The first breakthrough in standardizing the detection of the coagulation end point came in the 1950s and 1960s, when BBL, a division of the Becton and Dickinson Company automated the manual wire loop method of determining the critical clotting end point with the development of the fibrometer. This instrument, still found in many laboratories today, utilizes an electromechanical technique to detect formation of the first fibrin strand and hence establish an objective end point for clot formation.
Emergencies in dermatosurgery
Published in Biju Vasudevan, Rajesh Verma, Dermatological Emergencies, 2019
B. R. Harish Prasad, C. Madura, M. R. Kusuma
Preoperative evaluation of patients will help in recognizing patients at risk of bleeding. Common drugs that increase the risk of bleeding are aspirin, NSAIDs, warfarin [48], or other newer antiplatelet agents and anticoagulants [49]. Several herbal or over-the-counter (OTC) medications including garlic, ginseng, ginger, feverfew, vitamin E, Ginkgo biloba, and many others can have intended or unintended effects on the coagulation pathway. Hence, investigate the patients for risk of bleeding, which include bleeding and clotting time, prothrombin time, and activated partial thromboplastin time.
Blood
Published in David Sturgeon, Introduction to Anatomy and Physiology for Healthcare Students, 2018
Almost all stages of the coagulation process require the presence of calcium ions (Ca++) and adequate levels of plasma calcium are essential for normal clotting to occur. Clotting factor deficiencies and low levels of other substances, such as vitamin K, can also increase the time it takes for blood to coagulate. For example, most cases (about 80%) of the genetic bleeding disorder haemophilia result because the liver is not able von to produce enough clotting factor VIII (anti-haemophilic factor). Similarly, the most common hereditary clotting disorder, Von Willebrand’s disease, is the result of a deficiency of the plasma protein von Willebrand factor which helps to stabilise the bond between thrombocytes and collagen (see above). Finally, vitamin K is essential for the formation of a number of clotting factors including factor II (prothrombin) and factor X. The anticoagulant drug warfarin inhibits the amount of vitamin K available to the liver and prevents the production of these and other factors. This lengthens clotting time and is useful for the management of those likely to develop blood clots (see Chapter 7). One of the great misconceptions about warfarin is that it somehow ‘thins’ the blood when it actually interferes with the production of clotting factors (e.g. prothrombin). Dietary deficiency of vitamin K can also lead to lengthening of clotting time which is why it is very important to eat delicious green vegetables such as broccoli and spinach.
FlowTriever Retrieval System for the treatment of pulmonary embolism: overview of its safety and efficacy
Published in Expert Review of Medical Devices, 2021
Vivian L. Bishay, Omosalewa Adenikinju, Rachel Todd
AC with heparin is recommended per routine practice to prevent catheter thrombosis. Activated clotting time (ACT) can be checked to maintain appropriate therapeutic goals. The aspiration guide catheter, which is available in 16, 20, and 24 French lumen sizes is advanced over a stiff 0.035” guidewire to the level of the right or left main pulmonary artery just proximal to the thrombus. Initial crossing of the right heart into the pulmonary artery should be done with a balloon-tipped or pigtail-shaped catheter to avoid tracking the guidewire and more importantly the large bore catheter through cordae tendineae. The aspiration guide-catheter should be tracked slowly across the right heart and retracted back to the inferior vena cava if the patient experiences rhythm change or if resistance is felt. The most recent version of the 24 French guide has increased flexibility from the previous generation and is intended to provide superior trackability through the right heart. The aspiration guide-catheter can often be used without the aid of disks for rapid removal of large central clot. A 20 French curved catheter is also available, which has a 260-degree bend at the tip. This catheter can be telescoped through the 24 French allowing for steerability that can improve navigation of left pulmonary artery anatomy as well as the targeting of clot in transit.
“Bad things come in small packages”: predicting venom-induced coagulopathy in Bothrops atrox bites using snake ontogenetic parameters
Published in Clinical Toxicology, 2020
Jorge Carlos Contreras Bernal, Pedro Ferreira Bisneto, João Pedro Tavares Pereira, Hiochelson Najibe dos Santos Ibiapina, Lybia Kássia Santos Sarraff, Cláudio Monteiro-Júnior, Handerson da Silva Pereira, Bruno Santos, Valeria Mourão de Moura, Sâmella Silva de Oliveira, Marcus Lacerda, Vanderson Sampaio, Igor Luis Kaefer, José María Gutiérrez, Paulo Sérgio Bernarde, Hui Wen Fan, Jacqueline Sachett, Ana Maria Moura da Silva, Wuelton Marcelo Monteiro
In this study, one patient died. A 91 year-old male was bitten in the right hand and the right foot. Immediately after the bite the patient reported an intense acute pain in the bitten sites. Eleven hours after the snakebite, patient was hospitalized presenting intense pain in the right foot and edema extending to the whole limb. Eight vials (80 mL) of Bothrops antivenom were administered. He presented with acute renal injury. Patient’s health status deteriorated and 48 hours from admission he was diagnosed with compartment syndrome and was submitted to an extensive fasciotomy in the right leg. Secondary bacterial infection was diagnosed and clindamycin was started. After two days, the patient died of septic shock. Abnormalities in clotting time or platelet counts and bleeding were not observed during hospitalization. The snake brought by the patient was an adult female.
Bothrops snakebites in the Amazon: recovery from hemostatic disorders after Brazilian antivenom therapy
Published in Clinical Toxicology, 2020
Sâmella Silva de Oliveira, Eliane Campos Alves, Alessandra dos Santos Santos, Elizandra Freitas Nascimento, João Pedro Tavares Pereira, Iran Mendonça da Silva, Jacqueline Sachett, Hiochelson Najibe dos Santos Ibiapina, Lybia Kássia Santos Sarraf, Jorge Carlos Contreras Bernal, Luciana Aparecida Freitas de Sousa, Mônica Colombini, Hedylamar Oliveira Marques, Marcus Vinicius Guimarães de Lacerda, Ana Maria Moura-da-Silva, Hui Wen Fan, Luiz Carlos de Lima Ferreira, Ida Sigueko Sano Martins, Wuelton Marcelo Monteiro
Patients’ blood samples were collected at T0, T12, T24, T48 and on discharge. Clotting time was determined by the 20 min whole blood clotting test [23–25]. Blood was defined as unclottable when no clot was formed within 20 min and clottable when a solid or partial clot was formed within 20 min. Platelet counts and mean platelet volume (MPV) were carried out on samples containing potassium EDTA as the anticoagulant. Two percent v/v Bothrops-Lachesis antivenom was added to the samples to neutralize Bothrops venom present in the sample, and counts were determined in an automated cell counter (Sysmex Corp., Kobe, Japan). Thrombocytopenia was defined by a platelet count below 150 × 109/L. Low and high MPV were defined when values were below 7.4 fL and above 10.4 fL, respectively.