Analysis of the phenomenon of blood cell plugging in the blood cell analyzer

The phenomenon of clogged blood cells in a hematology cell analyzer is usually due to obstruction of the internal pipes or channels of the instrument, causing the blood sample to be unable to pass smoothly or to be trapped in certain locations. This phenomenon can negatively impact result accuracy and instrument performance. The following is an analysis of some common causes that may cause blood cells to clog:
1. The occurrence of hole blockage is related to whether the blood collection technique is performed correctly. Carrying a large amount of epithelial cell tissue or cotton fibers can easily block the hole, and it is difficult to eliminate it. Sometimes cotton wool and other substances can be seen in large-diameter holes, regardless of The question of whether to be fully automatic or semi-automatic mostly occurs in pre-diluted samples, and almost never in whole blood samples.

2. There are problems with anticoagulation. The wrong anticoagulation ratio and too short placement time are also one of the reasons. This is also an important reason why the test classification is not good and the platelets are unstable within 25 minutes. The combination of EDTA anticoagulant and platelet coagulation factor reaction requires time, this time shortens as the temperature rises, which is why problems tend to occur when the weather gets cold.

3. Coagulation and mixing, blood coagulation, poor mixing, and incorrect use of anticoagulant.

Everyone knows the above common sense things. If these situations are not grasped or handled well at one time, it will not cause the hole to be blocked immediately or after the specimen is completed. Instead, it will only happen if the above situations occur multiple times over time. There are several mechanisms below:

4. Blocking mechanism of WBC channel:
Regarding the problem of hemolytic agent, insufficient hemolysis is the main reason. It should be noted that obvious insufficient hemolysis will show an increase in HGB and WBC, which can easily give people a warning. What we are talking about here is slight insufficient hemolysis, which cannot be seen on WBC and HGB. The change in value may be very slight, and there will be an irregular rising curve before the lymphatic peak on the WBC graph, which should arouse enough vigilance. Generally, if this happens, serious hole plugging will occur within 30 days. The main reason is that the hemolytic agent destroys the red blood cells incompletely or the red blood cell fragments adhere and aggregate. If this situation continues for a long time, they will adhere to the small holes. The attachment of these cell fragments and protein deposition on the small holes will be like cement for building a house. , the layer after layer accumulates thicker and thicker, and it will be difficult to remove it by concentrating and cleaning when it is suspected that the hole may be blocked.
Diluent problem. The physical and chemical indicators of the diluent are unqualified, causing the cells to be unable to be diluted at correct intervals. Poor dissociation will cause cell aggregation, which is obvious on the histogram. However, if there is a hole blocking problem, the problem cannot be seen on the histogram. The reason is that when replacing reagents, corresponding sensitivity and gain adjustments are made, and the calibration coefficient is also adjusted accordingly. In this way, the problem cannot be seen on the histogram. Replacing the diluent with slightly better physical and chemical indicators will solve the problem. Notice the obvious changes in the histogram.

5. RBC channel blocking mechanism: After the blood sample is diluted thousands of times, it is counted by resistance method in the red blood cell counting cell. During the dilution process, there is no other reagent intervention except the diluent. The white blood cell pool can somewhat eliminate the interference of some proteins and debris through the action of hemolyzing agent, and the distribution and dilution in the red blood cell pool is often started after the white blood cell specimen is distributed and mixed with hemolyzing agent, bubbles, etc., while white blood cells and red blood cells The pools are counted at the same time, so the suspension mobility of protein fragments in the red blood cell pool is higher than that in the white blood cell pool, and proportionally speaking, the ratio of these proteins and debris is also higher than that in the white blood cell pool. This is one of the main reasons why red blood cells block the holes.

6. Insufficient negative pressure. On a blood analyzer, insufficient negative pressure will provide favorable conditions for proteins and debris to adhere to the small holes. Therefore, the monitoring and adjustment of counting negative pressure and emptying negative pressure is generally better at the upper limit, which leaves more room.

7. The problem of cleaning agents. The function of cleaning agents is to remove proteins and debris attached to small holes and pipes. If the cleaning agent is not effective, it will not play its due role and will inevitably cause the holes to be blocked in the long run. These cleaning agents are often used every time. It must be used after specimen testing. If the physical and chemical indicators are too high, the cleaning agent will foam or other components cannot be cleaned, which will affect the count. If the physical and chemical indicators are too low, it will not be effective. This means that the cleaning agent is second only to the diluent. Due to the complexity, some instruments do not have ordinary cleaning agents, but only concentrated cleaning agents. This cleaning agent is often replaced by sodium hypochlorite. Poor filtration or even no filtration at all will cause large particles to block the holes and prevent flushing. Cleanliness affects counts and can corrode pipes and associated pools, valves, pumps, and other components.

8. On instruments with many hole blocking monitoring levels/small hole high-pressure burning designs, the probability of hole blocking is also very high.

9. There are problems with operation settings, but there are two problems.
First, if the quality of the cleaning agent is not good, the effect will not be achieved, and leakage anywhere in the pipeline will cause air to enter, which means that a mixture of air and cleaning agent will be sucked in, especially when the cleaning agent is used up and replaced. The reagent was not filled after the reagent, and there was a long section of the pipeline filled with air. Also, the cleaning agent caused by air leakage could not remain in the No. 4 valve port for a long time. Over time, it would slowly fall back into the cleaning agent bottle, forming an air lock. In this way, due to the quantitative time when absorbing the cleaning agent, the predetermined absorption volume is not reached within the specified time. When injecting the counting pool, it will not be able to inject enough cleaning agent into the counting pool, which will also form during forward and backflush. The air is recoiling instead of the cleaning agent. This situation will also cause the cleaning agent to be injected into the counting pool and splash, causing corrosion to the components, especially the key LCD panel above.

Second, there is the problem of program setting, that is, how many tests are automatically cleaned once. The default of the instrument is to automatically clean once every 50 tests. This is no problem for units with a daily sample volume of more than 100. It can be done more than 2 times a day. Rinse, but for units with less than 50 specimens a day, this means that there will never be automatic cleaning. Therefore, set this interval according to the specific situation of the user, and set it arbitrarily between 10 and 50 times. There is only one premise, which is to ensure that there are 2-4 times of positive and backwash automatic cleaning every day, which will greatly reduce the probability of hole clogging.

10. If there is a slight blockage, in addition to the small holes in the concentrated soaking pool, check the negative pressure and valves. Note that if HGB and WBC share a pool structure, try not to soak the entire pool with concentrated solution or sodium hypochlorite to avoid doing so for a long time. To damage the pool and affect the HGB, you can use a syringe to absorb the sodium hypochlorite solution, replace it with a suction tip, and backwash the small hole through the pipe in the rear pool, and then empty the pool as quickly as possible, so that the damage to the pool will be minimal. For severe blockage, you can first use a syringe to backflush with air from the rear pool to completely open the small hole passage, and then use sodium hypochlorite or concentrated liquid to backflush. If it is really serious, it must be disassembled and treated with an ultrasonic oscillator.

11. Instruments without automatic cleaning must master one principle, which is to divide the daily sample volume into 2-4 parts on average, and add concentrated cleaning in the middle. Generally, 50 times is the unified requirement of each manufacturer. Each instrument has a cleaning function to achieve Just perform this amount manually once. Don't wait for a problem to occur before you get busy, otherwise it will be too late. Such cleaning only costs a few dollars and a few minutes. There is no need to save this, otherwise the repair will cost dozens of times that amount. There is also the follow-up of quality control. In addition to the quality control after starting up every day, during the specimen testing process, every certain specimen must be followed by a quality control test to monitor the status of the instrument at all times. Such minor problems such as insufficient negative pressure for hole plugging It can be discovered in time. Many large hospitals conduct every 50 tests and a quality control. Each hospital decides according to its own situation. When the maintenance engineer is finished or looking for problems, he can choose a larger test interval. It is also a good idea to set up quality control monitoring separately to determine where the problem lies.

In view of the phenomenon of clogged blood cells, it is recommended to perform instrument maintenance to ensure that the inside of the instrument is clean and the pipes are unobstructed. At the same time, operators must strictly follow the instructions in the operation manual to ensure good blood sample quality and avoid excessive dilution or coagulation. If the blood cell blockage persists, it is recommended to contact the manufacturer or professional technicians for further investigation and repair.