Page 655 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 30 ■ Instrumentation in Hematology 639

In 2000, CellaVision (Lund, Sweden) launched the

Di Master Octavia. T e system consists o an automated BOX 30.3

microscope with a 100× objective, a stepper motor and light

control unit, and a progressive three-chip CCD color cam-

era connected to a computer with so ware or localization, Fibrinolytic Hemostasis Panel Assays

segmentation, and classi cation o white and RBCs. T e sys- α-2-Antiplasmin

tem processes eight slides per batch, utilizing a slide holder. Plasminogen

It allows or remote review o a smear and storage o up to Plasminogen activator inhibitor

20,000 slides with images in a database. issue plasminogen activator

In comparison with earlier attempts by other manu actur-

ers, the Di Master Octavia handles wedged smears stained Solution Container No. Time

according to the Wright, Wright-Giemsa, or May-Grünwald-

Giemsa staining protocols and uses ANNs trained on a large Fixative 2 30 s

database o cells. It was the rst image analysis system to Wright stain 3 3 min

locate and preclassi y cells into 15 di erent categories and Stain buffer 4 6 min

automatically precharacterize six RBC morphologic charac- Deionized water 5 1.5 min

teristics. T e platelet estimates and erythrocyte precharacter-

ization are per ormed in an overview image corresponding Drying stage 6 3 min

to eight high-power elds (100×). Review and release o

results can be done remotely.

Electromechanical Methods

NOTE: This is a good time to complete Review Questions T e earliest instruments to detect blood clotting were devel-

related to preceding content. oped between 1920 and 1940. T ese instruments were based

primarily on detection o the ormation o a brin clot and

replaced visual observation o the ormation o a brin clot
INSTRUMENTS IN COAGULATION in a test tube. By the mid-1960s, electromechanical instru-

STUDIES ments were in widespread use. In the 1970s, photo-optical

methods replaced electromechanical devices in most labora-
Many di erent manu acturers produced laboratory-based

coagulation analyzers, many o which are capable o per orm- tories, except student laboratories or as a backup method in

ing clottable, immunoassay, and chromogenic assays. T e di - routine laboratories.

culty with some instruments is that many o them are unable T e principle o electromechanical methodology is the

to transmit an industry-standard test identi er (LOINC code) measurement o conduction or impedance o an electri-

to the host laboratory in ormation system (LIS). cal current by the ormation o brin. An example o such

Various models are available in a wide range o prices a semiautomated instrument is the brometer. T is system

designed or di erent size laboratories. Each instrument consists o a 37°C heat block, an automatic pipette, and a

o ers unique advantages (e.g., high throughput, reduced mechanical mixer and timer block.

reagent volume, integral bar-code reader, cap piercing, or A er the appropriate containers are lled and plasma

automatic sample predilution). Many instruments o er user- samples and thromboplastin substrate are incubated, plasma

programmable methods and preprogrammed methods. is added to the substrate to initiate the timing mechanism.

Suggested screening panels include thrombotic hemo- T is timing mechanism triggers a digital readout time and

stasis panel (Box 30.2) and a brinolytic hemostasis panel the probe unit. T e probe arm holds two electrodes. When

(Box 30.3). in operation, it drops down and allows the electrodes to all
into place within the reaction well containing the plasma-

thromboplastin mixture. T e stationary probe does not move

when the instrument is in operation but unctions in con-
BOX 30.2 junction with the moving electrode. T is stationary electrode

is responsible or creating an electrical potential between it

Thrombotic Hemostasis Panel Assays and the moving electrode. T e moving electrode is located in
ront o the stationary electrode in the probe arm. When a test

Antithrombin is being per ormed, this electrode cycles through the plasma-

Factor VIII:C thromboplastin mixture every hal second until a clot orms.

Heparin A detection circuit is activated when a brin strand is ormed

Lupus anticoagulant between the two electrodes, thus completing the circuit. Circuit

Protein C activation stops the timer and prevents urther movement o

Protein S and ree protein S the moving electrode. Electromechanical methods, such as

the brometer, can be used or various coagulation assays.