Discussion on the determination of hematocrit time and speed by micro centrifuge and the use of the instrument

Zhang Shuqiong's hematocrit is an important index of hemorheology The increase of its result is not only closely related to cerebral infarction, but also seen in polycythemia The decrease of it means anemia or blood loss, so it is very important to determine the accuracy of the result Micro high speed centrifugation has long been introduced by the International Committee for hematology standards (ICSH) But up to now, there are few domestic manufacturers of micro high-speed centrifuge, and some products have quality problems One of the TGL-12B micro high-speed centrifuges purchased by our lab has a centrifugal speed of less than 12000r / min, which means that the sealant is thrown off or the capillary is broken For this reason, we have taken measures to reduce the rotating speed and extend the centrifugal time through many tests and comparisons, which has overcome the disadvantages of the instrument and achieved satisfactory results Here is the introduction 1 Materials and methods 1.1 samples were collected from heparin anticoagulant samples which were examined by hemorheology in outpatients and inpatients 1.2 apparatus (1) apparatus: tcl-12b micro high speed capillary centrifuge of Shanghai "Flying Pigeon Brand" (one digital display type and one common type respectively), Zui high speed 12000r / min, centrifugal radius 8.5cm, Zui large relative centrifugal force 13600g, adjustable speed, horizontal rotary table type, 24 capillary tubes can be set, timing range 0-30min (2) Glass capillary: it is produced by instrument factory of West China Medical University The inner diameter is 0.9-1.1mm, the wall thickness is 0.10-1.15mm, the tube length is 120mm, and the time is 55-60mm (3) Others: soap, sheet rubber mud, calculator, ruler 1.3 methods the blood samples were evenly mixed, the blood on the outer wall of the capillary tube filled with blood samples was wiped off, one end of the tube mouth was sealed with glue and soap, and placed symmetrically in the flat plate groove of the micro centrifuge in sequence The sealing end is in contact with the inner wall of the flat plate, the cover plate is covered, screwed, and centrifuged at a fixed time and speed Results 2.1 comparison of hematocrit measured at different time and rotating speed 24 samples were randomly centrifuged on two centrifuges at different time and rotating speed, and then taken out for measurement in turn (hematocrit = RBC volume / total blood volume × 100%) Calculate the mean ± standard deviation of each group, take 12000r / min 5min group as the control, calculate the variance, 2.2 compare the hematocrit values of 12 samples with the same centrifugation time, rotating speed and capillary length On the same centrifuge, compare the results with the same centrifugation time, rotating speed and capillary length The results are shown in Table 2 The centrifuge is a tool for the determination of hematocrit The international recommended method for hematocrit detection is micro high-speed centrifugation, which has the advantages of low blood volume, high speed (12000r / min, 5min), good repeatability and so on At present, there are few matching or qualified micro high-speed centrifuges in the domestic manufacturers of Hemorheology inspection instruments Manufacturer of micro centrifuge Shanghai Feige centrifuge is a well-known manufacturer specializing in the production of various centrifuges for many years The parameters and air test of two TGL-12B micro high-speed centrifuges purchased by our lab successively meet the setting requirements However, in practical application, we have encountered a common type of capillary, when the rotating speed is above 8000r / rain, the micro capillary is almost powdery broken, and the results can not be measured The digital display type is better than the ordinary type, but if the continuous operation time is too long, the phenomenon of cement peeling off or capillary fracture will occur The reason may be the rapid temperature rise in the machine, the defects of the heat dissipation and shock absorption device, and the quality of the centrifugal disk, which need to be discussed with the manufacturer In order to overcome the above shortcomings, we take the hematocrit value of digital display 12000r / min centrifugation for 5min as a reference, take the measures of reducing the rotating speed and prolonging the centrifugation time, and carry out the tests in different time and speed segments It can be seen from table 1 that the mean values of each group of hematocrit values of digital display 7000r / min for 8min, 10000r / min for 7min and 12000r / min for 5min are the same, and occasionally there are the phenomena of cement peeling off and capillary fracture The average value of each group of 5000r / min 13min, 600 (O / min 10min, 7080r / min 8min) of the common type was equal to that of the digital display type 12000r / min 5mln After 6 min of 800oF / min, the capillary was almost broken and the results could not be measured The test results show that it is very important to select qualified centrifuges The newly purchased centrifuges can only be found quality problems after several tests with reference to the real objects When the centrifugal speed is less than 12000r / min (13600g), the centrifugal time can be prolonged by reducing the rotating speed, so that the hematocrit will not sink Each laboratory should establish its own reference range (normal reference value range of our department: 37% 47% for men and 35% 43% for women) we chose digital display type 10000r / min 7min and common type 600 (O / min 10rain or 7080r / mln 7min) The two instruments were used in rotation, which not only did not delay the time, but also could overcome the phenomenon that the capillary sealing cement was thrown off or the capillary was broken due to the high rotational speed and the rapid temperature rise in the machine The results were accurate and reliable Author unit: scientific research laboratory, Chengdu Third People's Hospital, 610031 L ~ JLL