Coulter principle that : the particles suspended in the electrolyte with the electrolytic solution through the orifice tube,the constant current circuit design leads to holes between the inner and outer tubes an instantaneous change in the resistance between two electrodes,a potential pulse.Size and number and size of the particle is proportional to the number of pulse signals.This is mainly based on the blood cells compared to diluent,poor blood cells are made by the characteristics of the conductor.Initially,only the original calculation and measurement Coulter counter erythrocytes.Later,with the continuous improvement of technology continues to evolve and devices,clinicians can also use it to calculate and measure the white blood cells.To the 1970s,the further development of technology allows technicians to separate platelets.
Evolution of automated cell counters
Cytometer in the traditional sense is by studying the peripheral blood smear,using blood cells and white blood cell count and instrument done manually(also known as 100 smear classification,manual leukocyte count or manual counters).According to Kurt principle led to the invention of the Coulter counter,and subsequently developed a technologically advanced automated hemotology analyzer.Since then,the instrument's technical level has been rising.Due to advances in technology,a single instrument can be analyzed more parameters,thus greatly improving the efficiency of the blood test,the reduction of a multiple sample analysis instrument case.Modern cell analyzer capable of measuring white blood cell (wbc),leukocyte(five categories),red blood cells (rbc),hemoglobin (hgb),platelets (plt),mean corpuscular volume (mcv),mean platelet volume,and can automatically calculate blood cells hematocrit (hct),mean corpuscular hemoglobin (mch),mean corpuscular hemoglobin concentration (mchc),red blood cell distribution width,platelet volume and platelet distribution width.
Other important factors include automatic blood analyzer speed and they run the number of samples that can be processed per batch (large processing capacity can reduce the turnaround time).
Instant test (poct)
Instant test (poct) is becoming an important adjunct to the blood lab practice.WBC count can be a blood cell analyzer has been in the intensive care unit and other areas have been practical use.
Contrast manual cell counting and automatic cell count
Although the peripheral blood smear examination of the information provided is automatic cell count can not be obtained,but it still has some limitations and some special requirements.
Manual cell count limitations
Need to have some experience in order to make smears technically maintain adequate standardization and consistency in the operation.
-Is subjective,labor-intensive and statistically unreliable(calculated only 100-200 cells).
-Coefficient of variation reported (cv) from 30% to 110 %,and is inaccurate.
-Counting the cells manually recognition error : This is generally lymphocytes and monocytes want with cell division and abnormal forms of variation(lymphocytes and blasts) separate.Monocytes are often underestimated,and lymphocytes are often overestimated.
Advantage of the automatic analyzer
Using an automatic biochemistry analyzer for sale cell count is a fast,objective,statistically significant(calculated above 8000 cells),and will not be counted manually due to various biases affected.Compared with manual methods,automated analyzer more efficient,more cost-effective.Some automatic analyzer can handle 120-150 samples per hour.Further,to ensure accurate automatic classification of white blood cell count absolute reliability and reproducibility.
Inadequacies automatic analyzer
Automatic blood cell analyzer may also cause cell count too much or too little of the phenomenon.Some analyzers especially impedance type counter only checks the size and number of particles,may not correctly distinguish tiny platelet aggregation and nucleated red blood cells.Platelet aggregation may be incorrectly classified as white blood cells or red blood cells,and nucleated red blood cells may also be wrongly classified as white blood cells,lymphocytes are classified as particularly vulnerable.In addition,large or illegible atypical cells,immature neutrophils and toxic reactive lymphocytes are also likely to be incorrectly classified.