Device description:Cell-Dyn has five main modules: The analyzer which aspirates dilutes and analyzes each whole blood specimen. The autoloader which automatically identifies mixes and presents specimens for processing. The pneumatic unit which controls fluid movement in the analyzer and in the autoloader. The data station which controls all system processing and provides the primary operator interface with the system. The color printer which generates reports automatically or on demand.The Cell-Dyn 4000 system uses an Argon-ion laser as the optical light source. The optical bench detects light in the form of scatter from blood cell surfaces and internal structures or fluorescent light from specially stained blood cells.Principles used in Cell-DynThe analyzer counts, sizes and classifies blood cells by the combination of flow cytometry methods: Impedance, Laser light scatter and Fluorescence detection Impedance: the impedance principle is also known as the coulter principle, of counting and sizing cells is based on measurable changes in electrical resistance produced by nonconductive blood cells suspended in an electrolyte solution such as saline are pulled through an aperture (orifice) in a glass tube. In the counting chamber low-frequency electrical current is applied between an external electrode and an internal electrode. Electrical resistance between the two electrodes, or impedance in the current, occurs as the cell pass through the sensing aperture, causing voltage pulses that are measurable. Laser light scatter: Cell counting and fluorescence measurements are made when a hydrodynamically focused stream containing the test cells is passed through a flow cell that is also being intersected by a laser light. As each individual cell passes through the flow cells sensing zone the laser light is simultaneously interrupted and scattered, then excites any endogenous or reagent-dependent fluorescent molecules. The amount and form of light scatter, which is dependent on refractive index, size, and shape of each cell as it passes through the sensing zone, allows their differentiation into different cell types. Fluorescence detection: When fluorescent dyes are added to the cells before their introduction into the analyzer, they will stain certain cell membrane and intracellular structures. As these cells are passed through the sensing zone they emit different wavelengths of fluorescent light, which vary according to the properties of the fluorochrome. Photo detectors collect and measure the light in different wavelength ranges and scatter wavelengths by the use of specific optical filters. Cells are then categorized according to their side-scattered light and fluorescence-intensity characteristics by software analysis of the data file that contains all the measurement made on a cell-by-cell basis.For the WBC parameters and NRBCs, whole blood is diluted with a reagent containing a red fluorescent dye. NRBCs, identified by fluorescence, are excluded automatically from the WBC count. For RBC and platelet parameters, whole blood is diluted with a reagent that prepares the cells for measurement. The dilution is split and measured by both laser optical scatter and focused flow impedance with injection metering. For the hemoglobin parameters whole blood is diluted with cyanide free reagent and measured optically by absorbance. For reticulocyte parameters, an aliquot of RBC/PLT dilution is diluted with a reagent containing a green fluorescence as each cell passes through the laser beam.Parameters of Abbott CELL-DYN 4000Methods for Hemogram and Reticulocyte Count Determination

WBCOptical scatter (primary count), Impedance (secondary count)

RBCImpedance

HbModified cyanmethemoglobin (540nm)

Hct(RBC X MCV) / 10

MCVMean of RBC volume distribution histogram

MCH(Hb X RBC) X 10

MCHC(Hb X Hct) X 100

Platelet countImpedance (approximately 2-30 fL)

RDWRelative value, equivalent to CV

Reticulocyte countProprietary stain (CD4K530), multiangle scatter and fluorescence detection

Hb, hemoglobin; Hct, hematocrit; MCH, mean cell hemoglobin; MCHC, mean cell hemoglobin concentration; MCV, mean cell volume; WBC, white blood cell; RBC, red blood cell; RDW, RBC distribution width

White Blood Cell Differential Determination

NeutrophilsMultiangle Polarized Scatter Separation (MAPPS)

LymphocytesMultiangle Polarized Scatter Separation (MAPSS)

MonocytesMultiangle Polarized Scatter Separation (MAPSS)

EosinophilsMultiangle Polarized Scatter Separation (MAPSS)

BasophilsMultiangle Polarized Scatter Separation (MAPSS)

Multiangle Polarized Scatter Separation technology (MAPSS)Reference/ normal range:

Histogram: PLT and RBC histograms

WBC Histograms

Scatter of all WBC population by MAPSS technology

Sample required: Blood samplesThe evaluation of the instrument was performed by analyzing blood specimens from routine samples after obtaining patients informed consent. Specimens were selected to span the full range of concentrations expected in clinical practice, and at least half the samples were from patients with blood disorders giving results in abnormal low and high ranges. All samples were collected in evacuated 3.5mL tubes containing EDTA K3 and were analyzed within 2 hours after obtaining the blood sample. For the aging study, the samples were stored at room temperature or refrigerated (4 C) and analyzed within 24, 48, and 72 hours.

Limitation and Interferences:

References:Laboratory Hematology Practice edited by Kandice Kottke-Marchant with Bruce H. DavisHematology Clinical Principles and Application fourth edition by Bernadette F. RodakErnesto Grimaldi, MD: Evaluation of the Abbott Cell-Dyn 4000 Hematology Analyzer. Am J Clin Pathol 2000;113:497-505www.accessdata.fda.gov/cdrh_docs/pdf/K971152.pdf