PEPconnect

PFA-100® Analyzer Instrument Overview

Identify key components and functions. Identify role of platelets in clotting process. Identify how test cartridges simulate in vivo hemostasis to measure platelet function.

NOTE:  This course is provided for informational purposes only and does not contain an assessment.

Welcome to the PFA-100® System Instrument Overview online training course. Platelet dysfunction can be acquired, inherited, or induced by platelet inhibiting agents, such as Aspirin®. It’s clinically important to assess platelet function as a potential cause of a bleeding disorder, especially in critically ill patients who may develop life-threatening hemorrhages. Unlike other traditional screening tests for platelet dysfunction that are expensive and lack standardization, reproducibility, and sensitivity, new advances in technology now allow laboratories to measure platelet function more precisely and efficiently. The PFA-100® system is a new technology that has been clinically proven to satisfy most needs for assessment of platelet dysfunction. The PFA-100® instrument uses disposable test cartridges containing a biochemically active membrane coated with collagen and either epinephrine or adenosine diphosphate to simulate in vivo platelet function in an in vitro environment. NOTE: This course does not include audio. Upon successful completion of this course, you will be able to: Identify features and benefits of the PFA-100® System Describe key components of the PFA-100® System and describe their functions Describe the important role of platelets in the clotting process Describe how PFA-100® test cartridges simulate in vivo hemostasis to measure platelet function Congratulations. You have completed the PFA-100® System Instrument Overview Online Training course. Listed below are the key points that have been presented. Identify features and benefits of the PFA-100®. The PFA-100® System is the first in vitro system specifically designed for routine, rapid, and cost-effective detection of platelet function abnormalities. The PFA-100®’s dual test cartridges allow a physician to differentiate between the platelet inhibiting effects of Aspirin® versus platelet dysfunctions due to other causes. PFA-100® tests yield abnormal results in essentially all patients with von Willebrand syndrome, whereas other screening tests will be normal in approximately 35% of patients with von Willebrand syndrome. Identify key components of the PFA-100® and describe their functions. Key components at the front of the instrument include the control panel with LCD and keypad, a compartment that holds trigger solution, a carousel that holds the test or priming cartridges, and a printer. The carousel includes a cassette that holds two kinds of disposable test cartridges: Collagen/ Epinephrine (COL/EPI) and Collagen/ADP (COL/ADP). The carousel also houses incubation wells to warm the sample in the test cartridges before testing begins. Key components at the rear of the instrument include a software upgrade slot, an LCD contrast adjustment button, an external PC port, and a bar code reader port. The rear of the instrument also includes the ON/OFF power switch, power supply, and fuse holder. Describe the important role of platelets in the clotting process. When a blood vessel is damaged, platelets undergo the following changes to stop bleeding in the damaged area. Platelets come in contact with exposed collagen in the wall of damaged cells to initiate platelet adhesion at the site of injury. Platelet adhesion activates platelets, which change shape, release ADP, and begin to stick together. Activated platelets initiate platelet aggregation in the damaged area, and release platelet factor 3 and Ca++. Platelet aggregation causes the formation of a platelet plug to stop bleeding in the damaged area.  Describe how PFA-100® test cartridges simulate in vivo hemostasis to measure platelet function. Inside the test cartridge, the system aspirates whole blood through a capillary and through a microscopic aperture cut into the membrane. This activity exposes platelets to high shear flow conditions. As platelets come in contact with the membrane, they are exposed to the Collagen/Epinephrine or Collagen/ADP coating on the membrane surface. Just as in a vascular injury, when platelets come in contact with collagen, platelet adhesion starts to occur, followed by platelet activation, aggregation, and finally the formation of a platelet plug at the aperture. The number of seconds required for a platelet plug to occlude the aperture is called the closure time or CT.    The PFA-100® System allows laboratories to measure most defects of platelet function more precisely and efficiently as compared to other traditional screening test which lack standardization and reproducibility. The PFA-100® System is the first in vitro system specifically designed for routine, rapid and cost-effective detection of platelet function abnormalities. Other features and benefits include the following: Simple to use and requires no specialized knowledge or training Meets requirements of each laboratory's quality control system Yields abnormal results in essentially all patients with von Willebrand disease Dual test cartridges allow a physician to differentiate between the platelet inhibiting effects Aspirin® versus platelet dysfunctions due to other causes Exterior components (front) include: Control panel with LCD and keypad Compartment containing trigger solutions Test cartridge carousel Printer Exterior components (rear) include: Software upgrade slot LCC adjustment button External PC and bar code reader ports Power switch, supply and fuse holder   Exterior Front Components Learn about exterior front components. Checklist TitleChecklist TypeChecklist ContentFront Key ComponentsHTML Key components include the control panel with LCD and keypad, a compartment that holds trigger solution, a carousel that holds the test or priming cartridges, and a printer. Control PanelHTML The control panel area consists of an LCD and a keypad. The LCD displays software commands for running samples and controls, performing maintenance, setting up the system, and printing data. Use softkeys in conjunction with numeric keys to navigate through the system software, select a system operation to perform, set instrument settings, enter patient order information, or print data. Trigger Solution CompartmentHTML Trigger solution is a reagent used to prime the instrument when powered on. Pull the lever up to open the access door, load the trigger solution vial, close the access door, and then push the lever down to spike the trigger solution vial.  Carousel CassetteHTML The carousel includes a cassette, which holds disposable Collagen/Epinephrine or Collagen/ADP test cartridges for running samples and reusable blue priming cartridges. The carousel also includes incubation wells to warm the sample in the test cartridge before testing begins.  CarouselHTML The carousel rotates the cartridge clockwise to start sample processing. The system identifies the number and type of test cartridges, dispenses trigger solution, incubates the samples, then performs analysis. When testing is complete, the carousel rotates to the outside for test cartridge removal.  PrinterHTML The printer is located at the top of the instrument. To thread the printer paper, open the printer door and gently pull the paper up through the slot in the door.  Exterior Back Components Learn about exterior back components. Checklist TitleChecklist TypeChecklist ContentRear Key ComponentsHTML The rear of the instrument includes a software upgrade slot, an LCD contrast adjustment button, an external PC port, and bar code reader port. Use the software upgrade slot to update the system software by inserting a software card into the slot. Use the external computer port to download data to an external computer. Use the bar code reader port to connect the instrument to a bar code reader to identify barcoded samples to the system during analysis.  PowerHTML The rear of the instrument also includes the ON/OFF power switch, power supply, and fuse holder.  Fuse HolderHTML To install the fuse, pry open the fuse compartment. The door swings out to allow you to remove the fuse holder. Install the appropriate fuse in the fuse holder, and then reinsert into the fuse compartment.  Hemostasis is the process of maintaining blood in its fluid state so that it flows freely through arteries, veins and capillaries. Hemostasis also involves stopping bleeding in cases of trauma or disease. During normal hemostasis, if a blood vessel is injured, the following interdependent systems are called to action: Vascular system Platelets Blood coagulation factors Fibrinolysis Vascular System Learn about the role of the vascular system. When a blood vessel is damaged, the following vascular reactions can occur:  Vasoconstriction: blood vessels narrow to reduce blood flow to a damaged area Collagen exposure: platelets and clotting factors of the intrinsic pathway activate when they come in contact with collagen (layer which is part of the sub-endothelium of blood vessels) exposed from damaged blood vessels Platelets as well as the clotting factors of the intrinsic pathway are directly affected by exposure to the collagen layer in a damaged blood vessel. The intrinsic pathway is initiated when contact is made between blood and exposed endothelial cell surfaces. The exposure of collagen to a vessel surface is the primary stimulus of the intrinsic pathway.   ​Collagen exposed in vessel lining Blood vessel Vasoconstriction Endothelium Blood components (platelets and clotting factors) Platelets Learn about the role of platelets. When a blood vessel is damage, platelets undergo the following changes: Platelets come in contact with exposed collagen in the wall of damaged cells to initiate platelet adhesion at the site of injury. Platelet adhesion activates platelets, which change shape, release ADP, and begin to stick together. Activated platelets initiate platelet aggregation in the damaged area, and release platelet factor 3 and Ca++. ​Platelet aggregation causes the formation of a platelet plug to stop bleeding in the damaged area.  Although platelets are not complete cells, they are active chemically. Over 40 substances are secreted from platelets during the release reaction that accompanies aggregation, including ADP. With one minute, fibrin strands appear, trapping RBCs and WBC into the clot to make it stronger.   Platelet Disorders Learn about platelet disorders. Tab TitleTextASA Ingestion of acetyl salicylic acid (ASA), such as Aspirin®, affects platelet aggregation for up to eight days¹ by inhibiting the formation of Thromboxane A2, a potent platelet agonist, and release of ADP, which can lead to prolonged bleeding in some patients. ¹ Wintrobe's Clinical Hematology, 10th Edition, (G.R. Lee, J. Foerster, J. Lukens, F. Paraskevas, J.P. Greer and G.M. Rodgers, eds), Williams & Wilkins, Baltimore, Chapter 70: 1807. BSS Bernard-Soulier syndrome is an inherited hemostasis disorder in which the platelet count is normal or decreased but the platelet morphology is abnormal: platelets are larger than normal and lack a surface membrane receptor that mediates platelet adhesion: glycoprotein Ib. Deficiency in this adhesive receptor impairs platelet adhesion, which can lead to prolonged bleeding in the patient ITP Idiopathic thrombocytopenic purpura (ITP) is an acquired platelet disorder that occurs when the immune system makes antibodies against the patient’s own platelets, reducing the number of circulating platelets needed to stop bleeding.  von Willebrand Disease von Willebrand disease is the most common inherited bleeding disorder caused by a deficiency or functional abnormality in von Willebrand factor molecule. This defect interferes with platelet adhesion and aggregation, which can lead to prolonged bleeding in the patient Thrombocytopenia Thrombocytopenia is a platelet deficiency and can result from many causes, such as when the spleen enlarges from disease and traps platelets inside the spleen, reducing the number of circulating platelets needed to stop bleeding.  Certain viral infections can cause decreased production of megakaryocytes in the bone marrow, reducing the number of circulating platelets needed to stop bleeding. Glanzmann Thrombasthenia Glanzmann thrombasthenia is an inherited disorder in which the platelet count, platelet morphology, and platelet adhesion functionality are usually normal, but platelets lack a surface membrane receptor that mediates platelet aggregation, glycoprotein IIb/IIIa. Abnormal platelet aggregation results, which can lead to prolonged bleeding in the patient. If a smear is made from the patient’s capillary or venous blood without an anticoagulant, the platelets do not form characteristic clumps. Now that you can identify PFA®-100 key components and have reviewed the role of platelets in the clotting process, let’s take a closer look at a test cartridge so you understand how the PFA-100® simulates in vivo hemostasis in an in vitro setting. Test Cartridges Learn about test cartridges. Checklist TitleChecklist TypeChecklist ContentPrepare CarouselHTML The carousel includes a cassette that holds two kinds of disposable test cartridges: Collagen/Epinephrine or COL/EPI and Collagen/ADP or COL/ADP. Pipette Patient SampleHTML To begin processing, the technologist pipettes 800 μL of anticoagulated whole blood from a patient or control sample into the sample reservoir opening in the test cartridge. Load CassetteHTML The technologist then loads the cassette into the carousel. The carousel rotates to the instrument interior, where the sample is warmed to 37° C in incubation wells.  AspirationHTML Inside the test cartridge, the system aspirates whole blood through a capillary and through a microscopic aperture cut into the membrane. This activity exposes platelets to high shear flow conditions. AdhesionHTML As platelets come in contact with the membrane, they are exposed to the Collagen/Epinephrine or Collagen/ADP coating on the membrane surface. Just as in a vascular injury, when platelets come in contact with collagen, platelet adhesion starts to occur. Platelet adhesion activates platelets, which change shape and begin to stick together around the aperture. AggregationHTML Activated platelets initiate platelet aggregation. Platelet aggregation causes the formation of a platelet plug at the aperture. Platelet PlugHTML The number of seconds required for a platelet plug to occlude the aperture is called the closure time—or CT.  Prolonged CT results indicate a platelet dysfunction due to drugs, decreased von Willebrand factor, or other thrombocytopathy. The PFA-100®’s dual test cartridges allow physicians to differentiate between antiplatelet drug effects, such as Aspirin®, and platelet dysfunctions due to other causes.

  • platelet
  • clotting
  • hemostasis