Question

why we have to use   hematology analyzers to dilute separate aliquots of a blood that analyze wbc to separate from rbc and platelet. explain why its done like this.

Answer 1

Hematology analyzers have some common basic components, including hydraulics, pneumatics, and electrical systems. The hydraulics system includes aspirating unit, dispensers, diluters, mixing chambers, aperture baths or flow cells or both, and a hemoglobinometer. The pneumatics system includes vacuums and pressures required for operating the valves and moving the sample through the hydraulics system. The electrical system controls operational sequences of the total system and includes electronic analyzers and computing circuitry for processing the data generated. Some older-model instruments have oscilloscope screens that display the electrical pulses in real time as the cells are counted. A data display unit receives information from the analyzer and prints results, histograms, or cytograms.

Sample handling varies from instrument to instrument based on degree of automation, and systems range from discrete analyzers to walkaway systems with “front-end load” capability. Computer functions also vary, with the larger instruments having extensive microprocessor and data management capabilities. Computer software capabilities include automatic start-up and shutdown, with internal diagnostic self-checks and some maintenance; quality control, with automatic review of quality control data, calculations, graphs, moving averages, and storage of quality control files; patient data storage and retrieval, with δ checks, panic or critical value flagging, and automatic verification of patient results based on user-defined algorithms; host query with the laboratory or hospital information system to allow random access discrete testing capability; analysis of animal specimens; and even analysis of body fluids.

The WBC, RBC, hemoglobin, hematocrit, and platelet counts are considered to be measured directly. Three hydraulic subsystems are used for determining the hemogram: the WBC channel, the RBC/platelet channel, and a separate hemoglobin channel. In the WBC and RBC transducer chambers, diluted WBC and RBC samples are aspirated through the different apertures and counted using the impedance (DC detection) method for counting and sizing cells. Two unique features enhance the impedance technology:

(1) in the RBC/platelet channel, a sheathed stream with hydrodynamic focusing is used to direct cells through the aperture, which reduces coincident passage, particle size distortion, and recirculation of blood cells around the aperture;

(2) in the WBC and RBC/platelet channels, “floating thresholds” are used to discriminate each cell population.