This study was supported by the Medical Scientific Research Foundation of Guangdong Province, China (A2019224). The funding groups agreed with the study design, data analysis, manuscript preparation, and decision to publish. No other funding was received for this study.

This study and the use of human blood samples were approved by the Ethics Committee of The First Affiliated Hospital of Guangzhou Medical University (GYYY-2016-73). All participants have given their written consent independently or through their parents (in the case of children).
1. Basic information of the study group
NOTE: Venous blood was collected from patients who visited the First Affiliated Hospital of Guangzhou Medical University (Hospital 1) and the Fifth Affiliated (Zhuhai) Hospital of Zunyi Medical University (Hospital 2). The instrument used for blood routine examination in Hospital 1 is Reference system 1, while Hospital 2 uses Reference system 2.
<ol>
	<li>A total of 1066 blood samples were collected from patients who visited Hospital 1 (532) and Hospital 2 (534) and underwent blood routine examinations during January 2021. 
	&#8203;NOTE: Patients were randomly selected, came from multiple departments and suffer from various diseases.</li>
	<li>Exclude patients with incomplete medical records, and those who were not cooperative or refused to give informed consent. Exclude those patients whose blood samples exhibited hemolysis, chyle blood, or cloudiness, or if the blood was inadequate in volume or stored for more than 24 h.</li>
</ol>
2. Study flow and measurements of interest
NOTE: The evaluated system needs 5 &#181;L of the blood sample for determining WBC and the three classification parameters. After collecting blood, the evaluated system and the reference system were used for blood routine examination.
<ol>
	<li>Detect WBC and the three classification parameters of 532 and 534 blood samples using the reference system and the evaluated system, respectively.
	<ol>
		<li>Let a highly trained technician randomly renumber the selected blood samples after completing the clinical test with the reference system. Then, hand over the samples to another highly trained technician for detection of the WBC and classification parameters using the evaluated system.</li>
	</ol>
	</li>
	<li>Reveal the results of the two systems.</li>
	<li>Ask a third technician to analyze the five indicators (namely WBC count, Gran#, Gran%, Lym#, Lym%) shared by both evaluated and reference systems only.</li>
</ol>
3. Procedure for using the evaluated system
NOTE: The evaluated system uses the electrical impedance principle (Coulter principle) to count WBC in the detection element. The testing protocol is divided into six parts: start the analyzer, test preparation, blood collection, reagent mixing, sample analysis, and turn off the analyzer.
<ol>
	<li>Start the analyzer
	<ol>
		<li>Turn the [O/I] power switch on the back of the analyzer to [I]. Check that the indicator light of the analyzer is on.</li>
		<li>Enter the correct username and password in the login dialog box and click on Login. Ensure that the system performs self-check and start-up initialization automatically and then displays the Sample Analysis home page.</li>
	</ol>
	</li>
	<li>Test preparation 
	NOTE: A complete blood sample test requires four consumables: blood lancet, hemolytic reagent, quantitative pipette with a capillary tube inside, and blood cell detection module (Figure 1).
	<ol>
		<li>Click on Next Sample, correctly enter the gender, name, and other clinical information (as required), and select an appropriate reference group. Click on OK to save the information. 
		NOTE: Different age groups have their own reference interval, so choosing the right reference group can get a more suitable alarm prompt. Newborn: 1-28 days old; Children: 29 days to 14 years old; Adult Male/Female/General: more than or equal to 15 years old.</li>
		<li>Tear the thin film of the blood cell detection module, press the Entry/Exit warehouse button, and place the blood cell detection module into the machine warehouse correctly, with its orifice facing outward.</li>
		<li>Puncture the hemolytic reagent sealing film with the tip of a quantitative pipette.</li>
	</ol>
	</li>
	<li>Blood collection
	<ol>
		<li>Capillary blood collection: Disinfect the left ring finger with a cotton swab dipped in alcohol one way and once. After the alcohol naturally dries out, use a blood lancet to puncture the skin of the left ring finger.
		<ol>
			<li>Gently squeeze out the first drop of blood and wipe it with a cotton swab. Squeeze out enough blood to form a full &#34;waterdrop&#34; and collect 5 &#181;L of the blood sample using the capillary tube inside the quantitative pipette.</li>
		</ol>
		</li>
		<li>Venous blood collection: Collect 5 &#181;L of the pre-obtained venous blood sample using the capillary tube inside the quantitative pipette. All tests in this study used venous blood which was collected from each patient (5 mL) using a vacuum vessel containing EDTA-K2 anticoagulant. Complete all tests within 30 min to 24 h.</li>
	</ol>
	</li>
	<li>Reagent mixing
	<ol>
		<li>Insert the quantitative pipette into the hemolytic reagent (2.5 mL) and press it tightly to release the blood sample from the capillary tube.</li>
		<li>Mix the blood in the capillary tube and hemolytic reagent by turning it upside down 15-20 times at a constant speed, until no obvious red blood remains in the capillary tube. In this study, the blood sample is mixed with hemolytic reagent at a ratio of 1:500.</li>
	</ol>
	</li>
	<li>Sample analysis
	<ol>
		<li>Open the lid and squeeze the solution into the blood cell detection module.</li>
		<li>Press&#160;the Entry/Exit warehouse button. After the blood cell detection module enters the warehouse, press the Counting button. 
		NOTE: A flashing green indicator light indicates that the analyzer is counting. The blood cell detection module will automatically exit the warehouse after counting, and it should be removed and disposed of properly. Each test takes only 30 s.</li>
		<li>On the analyzer interface, click on the OK button twice to confirm that the blood cell detection module has been taken out.</li>
		<li>On the analyzer interface, click on the Print button to print the test results.</li>
	</ol>
	</li>
	<li>Turn off the analyzer
	<ol>
		<li>On the analyzer interface, click on the shutdown button, and select Yes in the dialog box that pops up on the interface. Check that the system starts to execute the shutdown sequence.</li>
		<li>Set the [O/I] switch on the back of the mainframe to [O] after the shutdown sequence is completed.</li>
	</ol>
	</li>
</ol>
4. Statistical analysis
<ol>
	<li>Detect the outliers using the generalized extreme studentized deviate (ESD) method and eliminate these outliers for follow-up statistical analysis according to the requirements of the American Association for Clinical Laboratory Standardization (CLSI) EP9-A3 document8.</li>
	<li>Calculate the descriptive parameters such as means and standard deviations (SDs) for normally distributed continuous data; medians and 25%-75% interquartile ranges for nonnormally distributed data; and frequencies and percentages for categorical data.</li>
	<li>Use Pearson &#967;2 test or Fisher&#39;s exact test to determine the degree of relationship between categorical variables. Use the Paired-Sample T-test or Mann-Whitney U test to compare numerical data between groups.</li>
	<li>Show the distribution and linear association of the detected results of the two systems by scatter plots. Apply Spearman&#39;s nonparametric correlation test to access the degree of relationship between the quantitative variables. Use Bland-Altman plots and intraclass correlation coefficient (ICC) to verify the agreement between quantitative values detected by the two systems.</li>
	<li>Analyze the data by statistical software of choice. P-value &#60; 0.05 is considered statistically significant.</li>
</ol>

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The authors have nothing to disclose.

With the advancement of modern laboratory medicine, it is now typical to see several detection technologies utilized in the same or different laboratories to identify the same clinical marker. As a result, more emphasis should be placed on the consistency of test results to assist clinics in making accurate interpretations and judgments of test results. According to the investigation, the total value of laboratory equipment in tertiary hospitals and independent laboratories is substantially higher than that in primary hospitals and other medical institutions4. Although this type of equipment has the advantages of multiple item detection, high accuracy, stability, and large detection flux, it has disadvantages such as being expensive, large and heavy, complex operation, a requirement for many reagents, and high demand for professional quality operators, amongst others, making it unsuitable for primary medical institutions to use. The development of detection instruments and equipment is constantly developing in the direction of automation, intelligence, standardization, personalization, and small portability9. Advantages of POCT testing equipment, such as high timeliness, being lightweight and easy to carry, as well as no maintenance, make up for the shortcomings of large blood analyzers and are more easily accepted by primary medical institutions10. Realizing the comparability of the test results of the same specimen and items by different testing instruments is the core content of laboratory quality management11. However, few studies evaluate the correlation and consistency between POCT hematology analyzer and similar clinical products.
Patients in this study were recruited at random from two centers in Guangzhou (Hospital 1) and Zhuhai (Hospital 2) city, China. There was no significant difference in gender ratios between the two centers. Patients enrolled included those who visited hospitals for physical examination, and outpatients and inpatients from internal medicine, surgery, obstetrics and gynecology, pediatric, critical care departments, etc. The median age of the patients in Hospital 1 is significantly higher than that in Hospital 2 (58 (37, 68) versus 46 (31, 63); P &#60; 0.001). Hospital 1 is a national key specialized hospital for respiratory diseases, with most patients suffering from respiratory diseases which are more likely to affect the elderly12. The scientific study of aging found that the proportion of people over 65 years old in Hospital 1 is higher than that in Hospital 2 (6.67% versus 5.01%)13.
There are some outliers in granulocyte count, accounting for 2.5%, but the outliers of all items are less than 5%, which is within the acceptable range. The linear coefficient R2 of the test results of the evaluated system and the reference system are all greater than 0.75, indicating that the linear regression lines of the two systems have good linear goodness of fit, with white blood cell count and neutrophil count having better linear goodness of fit. The strongest correlation was found between the number of leukocytes and granulocytes (rs = 0.972 and 0.973, respectively) detected by the two systems, followed by granulocyte percentage and lymphocyte percentage (rs = 0.939 and 0.932, respectively), and lymphocyte number (rs = 0.851). Similar to a reported study, the effect of POCT series equipment on white blood cell counting is better than the results of classified indexes14. In addition, the Bland-Altman plot of the difference between the test data of the two systems shows that most of the test points are within the 95% consistency limit, indicating that the test results of the evaluation system and the reference system are in good agreement. Although the results show that the consistency analysis of lymphocytes is slightly lower than that of WBC and granulocytes, the correlation coefficient of lymphocytes is still above 0.85, which means that the two systems also have good consistency when detecting lymphocytes. On the other hand, the Bland-Altman plot shows that the test results of the evaluated system are slightly higher than the test values of the reference system. It is speculated that this may be due to systematic errors in the evaluated system, which makes the overall result high. Firstly, one should carefully check whether the analyzer is placed correctly before the test begins; for example, the surrounding area of the instrument should be kept at a certain distance (&#8805; 20 cm) from the wall or obstacles, and the space where the instrument is placed should be well ventilated. Secondly, the R and D team can also adjust the internal parameters of the system to correct the systematic error.
The novel card-based POCT leukocyte detection system uses the electrical impedance principle to detect leukocytes and their volume distribution15,16. Taking advantage of the difference in electrical conductivity between blood cells and electrolyte solutions, when blood cells with different volume sizes pass through the counting hole, it can cause changes in current or voltage inside and outside the hole, forming a pulse voltage. This pulse voltage is comparable to the number of blood cells and corresponds to the volume size, thus indirectly distinguishing groups of blood cells and counting them separately. Several critical steps in the leukocyte detection using the evaluated analyzer need to be paid attention to, which is closely related to the accuracy of the test results. First, when collecting blood, the first drop of blood should be wiped away with a sterile dry swab, as it may contain excess tissue fluid which may affect the test results. Second, after collecting the second drop of blood with a capillary tube, the blood attached to the outside of the tube should be wiped off to ensure that the collected blood sample volume is exactly 5 &#181;L.In addition, blood samples and hemolytic reagents should be fully mixed. At the same time, ensure that all solutions are fully squeezed into the blood cell detection module.
Because of its outstanding advantages, including low cost, simple operation, being fast, and being free from daily maintenance, this POCT system is very suitable for use in outpatient centers or primary medical units, which is an important supplement to the current clinical application4. The application of this system can cover the blood routine examination in all primary medical institutions in all developing areas of China and has important clinical significance for early screening of diseases, especially infectious diseases and blood diseases17,18. However, an important limitation is that leukocytes can only be divided into three categories (neutrophils, lymphocytes, intermediate cells). In the future, the classification ability of the system should be further improved in order to achieve the purpose of accurate diagnosis.
In conclusion, as a novel leukocyte analysis equipment, POCT leukocyte analyzer has the advantages of being portable, low cost, easy operation, fast and accurate detection; it exhibits good correlation, strong consistency, and reliable comparison with the automatic hematology analyzer widely used in clinics, and is, therefore, suitable for use in primary medical units.

White blood cell (WBC)count or differential is an important indicator to reflect the inflammation of the body, which can distinguish bacterial infection from viral infection. WBC analysis is also helpful to guide the follow-up diagnosis and treatment1. At present, the five-classification fully automatic hematology analyzer has been widely used in large and medium-sized medical units, because it is automatic, has high efficiency, yields accurate and reliable results, and effectively reduces the work intensity of laboratory technicians. It plays an important role in clinical examination2,3. However, most primary medical institutions, such as community healthcare centers and private clinics, have a low adoption rate of a hematology analyzer. According to a nationwide multicenter study on clinical laboratory construction in China, the laboratory construction of primary medical institutions is insufficient, as evidenced by the small size of laboratories, the insufficient talents transmission, and the spread of science and technology to the countryside, amongst other factors4.
Since December 2019, COVID-19 began to spread all over the world and developed into a global pandemic. In the 'post-epidemic era', a series of national policies have been proposed to implement the normalized prevention and control measures of epidemic situations. The laboratory of primary medical institutions plays an important role in grassroots diagnosis and treatment and disease prevention and control. It is the first line of defense and control in epidemic situations, and it is critical to COVID-19 prevention and control5. Some studies have shown that the detection of peripheral blood lymphocytes and neutrophils will contribute to COVID-19 patient screening, diagnosis, and treatment, and that the neutrophil/lymphocyte ratio can also be used as clinical early warning indicators of severe and critical COVID-196,7. Moreover, leukocyte detection has the benefit of providing a quick report. Primary medical and health institutions can extensively carry out leukocyte detection to help detect and screen suspected infections in time.
POCT card-based leukocyte analyzer (evaluated system; see Table of Materials) is a three-classification blood cell analyzer based on the gold standard "Coulter principle". The evaluated system provides quantitative analysis results of one WBC histogram and seven blood parameters including WBC count, number of granulocytes (Gran#), percentage of granulocytes (Gran%), number of lymphocytes (Lym#), percentage of lymphocytes (Lym%), number of intermediate cells (Mid#), and percentage of the intermediate cells (Mid%). It adopts the card-based innovative technology and has advantages such as the availability of single-person detection kit, absence of liquid waste, fast detection in 30 s, being free from routine maintenance, and user-friendly operation. Therefore, it is particularly well-suited to primary medical institutions. This study aims to evaluate the clinical detection performance of POCT card-based leukocyte analyzer by comparing against two fully automatic commercial hematology analyzers (reference system 1 and reference system 2; see Table of Materials) from laboratories of two large-scale public hospitals.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Blood cell detection module</td>
			<td>Chuanghuai Medical Technology Co., Ltd.(Shenzhen, China)</td>
			<td></td>
			<td>consumables for evaluated system</td>
		</tr>
		<tr>
			<td>Blood lancet</td>
			<td>Chuanghuai Medical Technology Co., Ltd.(Shenzhen, China)</td>
			<td></td>
			<td>consumables for evaluated system</td>
		</tr>
		<tr>
			<td>Hemolytic reagent</td>
			<td>Chuanghuai Medical Technology Co., Ltd.(Shenzhen, China)</td>
			<td></td>
			<td>consumables for evaluated system</td>
		</tr>
		<tr>
			<td>IBM SPSS Statistics 25</td>
			<td>International Business Machines Corp., Armonk, NY</td>
			<td></td>
			<td>Software for data analysis</td>
		</tr>
		<tr>
			<td>MedCalc 11.4.2.0</td>
			<td>2021 MedCalc Software Ltd</td>
			<td></td>
			<td>Software for data analysis</td>
		</tr>
		<tr>
			<td>Microsoft Excel 2019</td>
			<td>Microsoft</td>
			<td></td>
			<td>Software for data analysis</td>
		</tr>
		<tr>
			<td>Point-of-care testing (POCT) card-based leukocyte analyzer</td>
			<td>Chuanghuai Medical Technology Co., Ltd.(Shenzhen, China)</td>
			<td>CX-2000</td>
			<td>Evaluated system</td>
		</tr>
		<tr>
			<td>Quantitative pipette with capillary tube inside</td>
			<td>Chuanghuai Medical Technology Co., Ltd.(Shenzhen, China)</td>
			<td></td>
			<td>consumables for evaluated system</td>
		</tr>
		<tr>
			<td>Siemens fully automatic hematology analyzer and its related reagents and consumables</td>
			<td>Siemens Healthcare Diagnostics Inc.</td>
			<td>ADVIA 2120i</td>
			<td>Reference system 2</td>
		</tr>
		<tr>
			<td>UniCel DxH 800 Coulter Cellular Analysis System and its related reagents and consumables</td>
			<td>Beckman Coulter, Inc.</td>
			<td>DxH 800</td>
			<td>Reference system 1</td>
		</tr>
	</tbody>
</table>

evaluation of a point-of-care testing analyzer for measuring peripheral blood leukocytes

White blood cell (WBC) is an important indicator of inflammation in the body, and it can help distinguish between bacterial and viral infections. At present, most primary medical institutions in China have a poor percentage of adoption of blood-testing technology, and a hematology detection system with a high price to performance ratio and easy operation is urgently needed in primary healthcare centers. This paper introduces the principle and operation procedures of a point-of-care testing (POCT) card-based leukocyte analyzer (evaluated system), which was used to detect WBC indexes such as neutrophils, lymphocytes, and intermediate group cells (including eosinophils, basophils, and monocytes) in whole blood. The results from the evaluated system were compared to those from two commercial automatic hematology analyzers (reference system). The correlation and consistency between the evaluated system and the commercial reference systems were analyzed. The results showed that WBC count and number of granulocytes detected by the evaluated and reference systems showed a strong positive correlation (rs = 0.972 and 0.973, respectively), while the number of lymphocytes showed a relatively low correlation (rs = 0.851). A Bland-Altman plot showed that the major difference between the values detected by the evaluated system and the reference systems is within 95% limits of agreement (LoA), indicating that the two systems are in good agreement. In conclusion, the evaluated system has an excellent correlation, robust consistency, and a reliable comparison with the results of the widely used automatic hematology analyzers. It is ideal for WBC detection in primary medical institutions where a full-automatic five-category hematology analyzer is unavailable, especially during the COVID-19 normalized prevention and control period.

Sample data 
A total of 1066 patients were enrolled in two research centers, including Hospital 1 (n = 532) and Hospital 2 (n = 534). The patient characteristics are shown in Table 1. The percentage of males is 49.9% and the median age is 52 (32, 66) years. Patients enrolled in the study were comprised of inpatients (51.1%), outpatients (39.0%), and physical examination patients (8.4%). The samples tested were from patients who visited the internal medicine departments (30.6%), surgery departments (19.1%), obstetrics and gynecology departments (9.0%), pediatric departments (3.9%), etc.
Detecting aberrant results (outliers) 
Taking the reference system results as the horizontal axis and the evaluated system results as the vertical axis, a scatter plot of five leukocyte indexes of 1066 samples was obtained (results are not shown). Suspicious abnormal points are obvious in the scatter plot of five leukocyte indexes. According to the results of the ESD method, among the 1066 samples, there were 16 outliers in WBC count, 27 outliers in Gran#, 8 outliers in Gran%, 15 outliers in Lym#, and 9 outliers in Lym%. The data was analyzed after eliminating the outliers, which account for less than 5% in total.
Correlation analysis in the evaluated system and reference systems 
Figure 2 shows the scatter plot and Spearman correlation analysis of the test results. The results show that WBC count, Gran#, Gran%, Lym#, and Lym% have good linearity and correlation between the two systems; the linear coefficient R2 is between 0.7759 and 0.9676, and the correlation coefficient rspearman is between 0.851 and 0.973 (all P-values &#60; 0.001). WBC and Gran# exhibit the strongest correlation between the two systems (R2 = 0.9608 and 0.9676, respectively; rspearman = 0.972 and 0.973, respectively), whereas Lym# exhibit the weakest correlation between the systems (R2 = 0.7759; rspearman = 0.851). However, we could not evaluate the correlation and consistency of intermediate cells (Mid#/%), because they are separated into smaller divisions (i.e., eosinophils, basophils, and monocytes) in the reference system.
Consistency Analysis 
A Bland-Altman plot has been obtained to visualize the consistency analysis and the &#177;2 SD has been marked as limits of agreement (LoA). The results are shown in Figure 3. For the WBC, the mean value of the difference is 0.9 x 109/L between the evaluated and reference systems, and the 95% confidence interval (CI) of the difference is -0.7 x 109 ~ 2.5 &#215; 109/L.There are 94.48% (992/1050) samples within the 95% CI, which means that the WBC results detected by the evaluated system are in good agreement with the reference system. For Gran# and Gran%, the mean value of the difference between the evaluated and reference systems is 0.8 x 109/L and 2.0%, respectively, while the 95% CI of the difference is 0.7 x 109 ~ 2.2 x 109/L and -7.7% ~ 11.7%, respectively. There are 94.23% (979/1039) and 94.99% (1005/1058) samples within the 95% CI, respectively. For Lym# and Lym%, there are 93.82% (986/1051) and 93.76% (991/1057) samples within the 95% CI, and the average difference value is 0.33 x 109/L and 1.8%, respectively. The average values of the differences in the leukocyte indexes are all above 0, indicating that the test results of the evaluated system are slightly higher than those of the reference system.
Correlation Analysis in different patient groups 
The WBC count results for the samples from patients of different ages and genders and those from different departments were compared and analyzed for correlations. The results showed that the WBC level of the evaluated system is higher than that of the reference system. There is no significant difference in consistency and correlation between male and female patients (ICC: 0.97 versus 0.98; rspearman: 0.98 versus 0.97). The consistency and correlation are better for the inpatients than for the outpatients (ICC: 0.98 versus 0.96; rspearman: 0.98 versus 0.96), as shown in Table 2.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63364/63364fig01.jpg" /> 
Figure 1: Representative photographs of the evaluated system and its supporting reagents and consumables. (A) The analyzer uses the Coulter principle to detect leukocytes in blood by three classifications. Its small size (242 mm x 397 mm x 321 mm) makes it easy to transport. (B) Limited supporting reagents and consumables are combined in a suit as a single-person detection kit, which can be stored and used at room temperature. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63364/63364fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/63364/63364fig02.jpg" /> 
Figure 2: Scatter plots of five leukocyte indexes detected by the evaluated system and reference system. R2 = linearity coefficient, rs = Spearman correlation coefficient (95% CI), and n = sample size. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63364/63364fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/63364/63364fig03.jpg" /> 
Figure 3: Bland-Altman plot of the five leukocyte indexes detected by the evaluated system and reference system. The Y-axis depicts the difference of measured values between the evaluated and reference systems while the X-axis depicts the mean value of leukocyte indexes measured by the evaluated and reference systems. The continuous black line represents the average difference value for the entire pool of samples and the dashed black lines represent 95% upper and lower limits of agreement (mean limits of agreement &#177; 1.96 SD). ESi denotes values measured by the evaluated system and RSi denotes values measured by the reference system. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63364/63364fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Table 1: General data of the study population. n = sample size, IQR = interquartile range. The P-value corresponds to the comparison of the sample data from Hospital 1 and Hospital 2. Chi-square test (&#967;2) was used to compare the differences between categorical variables in groups (when the theoretical frequency was less than 5, the Fisher exact probability method was used to calibrate), and t-test or Mann-Whitney U test was used to compare numerical data between groups. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63364/Table 1.xlsx" target="_blank">Please click here to download this Table.</a>
Table 2: Correlation analysis of the WBC results detected by the evaluated system and reference system in different patient groups. n = sample size; IQR = interquartile range; and ICC = intraclass correlation coefficient (a value &#62; 0.75 indicates good reliability). rs = Spearman&#39;s correlation coefficient; rs of 0.90-1.00, 0.70-0.90, 0.50-0.70, 0.30-0.50 and 0-0.30 indicate, respectively, very high, high, moderate, low, and negligible positive correlation. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63364/Table 2.xlsx" target="_blank">Please click here to download this Table.</a>

Watch this Scientific Journal Video about Evaluation of a Point-of-Care Testing Analyzer for Measuring Peripheral Blood Leukocytes at JoVE.com

Evaluation of a Point-of-Care Testing Analyzer for Measuring Peripheral Blood Leukocytes

A protocol to measure peripheral blood leukocytes using a POCT card-based leukocyte analyzer is presented here. Same blood samples were tested by two automated hematology analyzers to evaluate the consistency and accuracy of the results. The results showed that the evaluated analyzer had a good correlation with the reference system.

White blood cell (WBC) is an important indicator of inflammation in the body, and it can help distinguish between bacterial and viral infections. At ...

evaluation-point-care-testing-analyzer-for-measuring-peripheral-blood

Nanyang Technological University

Research

JoVE Journal

Medicine

3.9K Views.  First Affiliated Hospital of Guangzhou Medical University. A protocol to measure peripheral blood leukocytes using a POCT card-based leukocyte analyzer is presented here. Same blood samples were tested by two automated hematology analyzers to evaluate the consistency and accuracy of the results. The results showed that the evaluated analyzer had a good correlation with the reference system.

Video: Evaluation of a Point-of-Care Testing Analyzer for Measuring Peripheral Blood Leukocytes

Rapid Point-of-Care Assay of Enoxaparin Anticoagulant Efficacy in Whole Blood

There is the need for a clinical assay to determine the extent to which a patient's blood is effectively anticoagulated by the low-molecular-weight-heparin (LMWH), enoxaparin. There are also urgent clinical situations where it would be important if this could be determined rapidly. The present assay is designed to accomplish this. We only assayed human blood samples that were spiked with known concentrations of enoxaparin. The essential feature of the present assay is the quantification of the efficacy of enoxaparin in a patient's blood sample by degrading it to complete inactivity with heparinase. Two blood samples were drawn into Vacutainer tubes (Becton-Dickenson; Franklin Lakes, NJ) that were spiked with enoxaparin; one sample was digested with heparinase for 5 min at 37 &deg;C, the other sample represented the patient's baseline anticoagulated status. The percent shortening of clotting time in the heparinase-treated sample, as compared to the baseline state, yielded the anticoagulant contribution of enoxaparin. We used the portable, battery operated Hemochron 801 apparatus for measurements of clotting times (International Technidyne Corp., Edison, NJ). The apparatus has 2 thermostatically controlled (37 &deg;C) assay tube wells. We conducted the assays in two types of assay cartridges that are available from the manufacturer of the instrument. One cartridge was modified to increase its sensitivity. We removed the kaolin from the FTK-ACT cartridge by extensive rinsing with distilled water, leaving only the glass surface of the tube, and perhaps the detection magnet, as activators. We called this our minimally activated assay (MAA). The use of a minimally activated assay has been studied by us and others. 2-4 The second cartridge that was studied was an activated partial thromboplastin time (aPTT) assay (A104). This was used as supplied from the manufacturer. The thermostated wells of the instrument were used for both the heparinase digestion and coagulation assays. The assay can be completed within 10 min. The MAA assay showed robust changes in clotting time after heparinase digestion of enoxaparin over a typical clinical concentration range. At 0.2 anti-Xa I.U. of enoxaparin per ml of blood sample, heparinase digestion caused an average decrease of 9.8% (20.4 sec) in clotting time; at 1.0 I.U. per ml of enoxaparin there was a 41.4% decrease (148.8 sec). This report only presents the experimental application of the assay; its value in a clinical setting must still be established.

Demonstration of a rapid quantitative assay of the inhibition of blood coagulation by the low-molecular-weight-heparin, enoxaparin. The contribution of enoxaparin is assessed by removing its influence through digestion with heparinase. A fuller description of the assay is detailed in our published paper.1 The assay still requires clinical confirmation.

There is the need for a clinical assay to determine the extent to which a patient's blood is effectively anticoagulated by the ...

Repetitive Blood Sampling from the Subclavian Vein of Conscious Rat

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to detect drug exposure. The rat blood sampling method determines the quality of the plasma and further affects the precision of the test results. The subclavian vein blood collection method described in this protocol collects blood samples repeatedly in the conscious state of animals to meet the needs of PK and TK tests. The skills of restraint handling and appropriate procedure of needle incision ensure the success rate of blood collection. It is easy to operate while ensuring the quality of plasma and at the same time catering to animal welfare. However, this method requires skilled operation, and an improper one may cause animal weakness, pain, lameness, and even mortality. The current method has been used in the testing facility for a 4-week oral toxicity study in Sprague Dawley (SD) rats with TK. The maximum amount of blood collected within 24 h did not exceed 20% of the animal's total blood. The animals' body weight was more than 200 g for males and females. The data showed that the animals' bodyweight increased steadily every week, and the clinical observation was normal after repetitive sample collection.

The present protocol describes a simple and efficient method for collecting blood from the subclavian vein in rats. It enables rapid, timely, and easily identifiable sampling without anesthesia and obtains high-quality blood through repetitive sample collection.

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to ...

Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening sequelae. While whole leg compression ultrasound with color and spectral Doppler is commonly performed in radiology and vascular labs, point-of-care ultrasound (POCUS) is becoming more common in the acute care setting. Providers appropriately trained in focused POCUS can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. This paper describes a simplified yet validated approach to POCUS by describing a three-zone protocol for lower extremity DVT POCUS image acquisition. The protocol explains the steps in obtaining vascular images at six compression points in the lower extremity. Beginning at the level of the proximal thigh and moving distally to the popliteal space, the protocol guides the user through each of the compression points in a stepwise manner: from the common femoral vein to the femoral and deep femoral vein bifurcation, and, finally, to the popliteal vein. Further, a visual aid is provided that may assist providers during real-time image acquisition. The goal in presenting this protocol is to help make proximal lower extremity DVT exams more accessible and efficient for POCUS users at the patient&#39;s bedside.

Traditionally, lower extremity deep venous thrombosis (DVT) is diagnosed by radiology-performed venous duplex ultrasound. Providers appropriately trained in focused point-of-care ultrasound (POCUS) can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. We describe the scanning technique for focused POCUS DVT lower extremity examination.

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening ...

Point-of-Care Lung Ultrasound in Adults: Image Acquisition

Consultative ultrasound performed by radiologists has traditionally not been used for imaging the lungs, as the lungs&#39; air-filled nature normally prevents direct visualization of the lung parenchyma. When showing the lung parenchyma, ultrasound typically generates a number of non-anatomic artifacts. However, over the past several decades, these artifacts have been studied by diagnostic point-of-care ultrasound (POCUS) practitioners, who have identified findings that have value in narrowing the differential diagnoses of cardiopulmonary dysfunction. For instance, in patients presenting with dyspnea, lung POCUS is superior to chest radiography (CXR) for the diagnosis of pneumothorax, pulmonary edema, lung consolidations, and pleural effusions. Despite its known diagnostic value, the utilization of lung POCUS in clinical medicine remains variable, in part because training in this modality across hospitals remains inconsistent. To address this educational gap, this narrative review describes lung POCUS image acquisition in adults, including patient positioning, transducer selection, probe placement, acquisition sequence, and image optimization.

Point-of-care ultrasound (POCUS) of the lungs provides quick answers in rapidly changing clinical scenarios. We present an efficient and informative protocol for image acquisition for use in acute care settings.

Consultative ultrasound performed by radiologists has traditionally not been used for imaging the lungs, as the lungs&#39; air-filled nature normally ...

Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways

Airway management remains a crucial part of perioperative care. The conventional approach to assessing potentially difficult airways emphasizes the LEMON method, which looks for and evaluates the Mallampati classification, signs of obstruction, and neck mobility. Clinical findings help predict a higher likelihood of difficult tracheal intubation, but no clinical result reliably excludes difficult intubation. Ultrasound as an adjunct to clinical examination can provide the clinician with a dynamic anatomical airway assessment, which is impossible with clinical examination alone. In the hands of anesthesiologists, ultrasound is becoming more popular in the perioperative period. This method is particularly applicable for identifying proper endotracheal tube positioning in specific patient populations, such as those who are morbidly obese and patients with head and neck cancer or trauma. The focus is on identifying the normal anatomy, correctly positioning the endotracheal tube, and refining the parameters that predict difficult intubation. Several ultrasound measurements are clinical indicators of difficult direct laryngoscopy in the literature. A meta-analysis revealed that the distance from the skin to the epiglottis (DSE) is most associated with a difficult laryngoscopy. An ultrasound of the airway could be applied in routine practice as an adjunct to the clinical examination. A full stomach, rapid sequence intubation, gross visual anatomical abnormalities, and restricted neck flexibility prevent using ultrasound to assess the airway. The airway evaluation is performed with a linear array transducer of 12-4 MHz, with the patient in the supine position, with no pillow, and with the head and neck in a neutral position. The central axis of the neck is where the ultrasound parameters are measured. These image acquisitions guide the standard ultrasound examination of the airway.

A point-of-care ultrasound (POCUS) is a simple, non-invasive, and portable tool that enables dynamic airway assessment. Several studies have attempted to determine the role of ultrasound parameters as an adjunct to clinical examination in predicting difficult laryngoscopies.

Airway management remains a crucial part of perioperative care. The conventional approach to assessing potentially difficult airways emphasizes the LEMON ...

Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition

The goal of this protocol is to develop a standardized method for acquiring images of the optic nerve sheath and measuring the optic nerve sheath diameter (ONSD). Diagnostic ultrasound of the ONSD to detect intracranial hypertension has traditionally faced many problems because of methodologic discrepancies. Due to inconsistencies in the measuring techniques, the potential for ONSD to become a non-invasive bedside monitoring tool for ICP has been hampered. However, establishing a transparent, consistent methodology for measuring the ONSD would support its use as a valid and reliable method of identifying intracranial hypertension. This is important as it has both high sensitivity and specificity in acute care settings. This narrative review describes ONSD POCUS image acquisition, including patient positioning, transducer selection, probe placement, the acquisition sequence, and image optimization. Further, visual aids are provided to assist in real-time during image acquisition. This method should be considered for patients for whom there are concerns regarding intracranial hypertension but who do not have an intracranial monitor in place.

Point-of-care ultrasound (POCUS) of the optic nerve sheath diameter (ONSD) has been shown to be useful in identifying patients with increased intracranial pressure (ICP). However, the non-standardized technique for this POCUS has hampered its use. We present a standardized image acquisition protocol for use in the acute care setting.

The goal of this protocol is to develop a standardized method for acquiring images of the optic nerve sheath and measuring the optic nerve sheath diameter ...

Imaging the Abdominal Aorta with Point-of-Care Ultrasound

An Approach to Point-Of-Care Ultrasound Evaluation of the Abdominal Aorta

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography (CT) is the current gold standard to image the abdominal aorta, the process of obtaining a CT may be time-consuming, requires the use of intravenous contrast dye, and involves exposure to ionizing radiation. Point-of-care Ultrasound (POCUS) can be performed at the bedside and has excellent sensitivity and specificity for the diagnosis of abdominal aortic aneurysm and excellent specificity for the diagnosis of abdominal aortic dissection. Additionally, POCUS is non-invasive, cost-effective, lacks ionizing radiation, requires no intravenous contrast dye, and can be performed without taking the patient from a critical care area. Screening for abdominal aortic aneurysm (AAA) can be done in primary care settings as well. 
This article will review the approach to POCUS of the abdominal aorta to evaluate such critical pathology. In this paper, we will review the sonographic anatomy of the abdominal aorta as well as the choice of the ultrasound probe, description of POCUS image acquisition, and some pearls and pitfalls of using POCUS to aid in the diagnosis of potentially life-threatening abdominal aortic pathology.

Author Spotlight: Using Point-of-Care Ultrasound for Comprehensive Evaluation of the Abdominal Aorta

This protocol reviews the steps to image the abdominal aorta with point-of-care ultrasound. We discuss image acquisition, troubleshooting imaging pitfalls and artifacts, and the recognition of life-threatening abdominal aortic pathology.

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography ...

Gastric Ultrasound Technique for Mitigating Peri-Procedural Aspiration Risk

Gastric Point of Care Ultrasound in Adults: Image Acquisition and Interpretation

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical inquiries related to gastric content. One emerging concern pertains to patients about to undergo sedation and/or endotracheal intubation: the elevated risk of aspiration from the patient&#39;s stomach contents. Aspiration of gastric contents into the lungs poses a serious and potentially life-threatening complication. This occurs more frequently when the stomach is considered &#34;full&#34; and can be affected by the techniques employed for airway management, making it potentially preventable. To mitigate the risk of peri-procedural aspiration, two distinct medical specialties (anesthesiology and critical care medicine) have independently developed techniques to utilize ultrasonography for identifying patients requiring &#34;full stomach&#34; precautions. Due to these separate specialties, the work of each group remains relatively unfamiliar outside its respective field. This article presents descriptions of both techniques for gastric ultrasound. Furthermore, it explains how these approaches can complement each other when one of them falls short. Regarding image acquisition, the article covers the following topics: indications and contraindications, selection of the appropriate probe, patient positioning, and troubleshooting. The article also delves into image interpretation, complete with example images. Additionally, it demonstrates how one of the two techniques can be employed to estimate gastric fluid volume. Lastly, the article briefly discusses medical decision-making based on the findings of this examination.

Author Spotlight: Point-of-Care Ultrasound for Gastric Content Assessment and Risk Stratification in Perioperative Care 

This protocol introduces two methods for image acquisition in gastric ultrasonography. Additionally, tips are provided for interpreting this information to assist in medical decision-making.

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical ...

Ultrasound in Evaluating Diaphragm Dysfunction and Monitoring Treatment

Measuring Diaphragm Thickness and Function Using Point-of-Care Ultrasound

The diaphragm is the main component of the respiratory muscle pump. Diaphragm dysfunction can cause dyspnea and exercise intolerance, and predisposes affected individuals to respiratory failure. In mechanically ventilated patients, the diaphragm is susceptible to atrophy and dysfunction through disuse and other mechanisms. This contributes to failure to wean and poor long-term clinical outcomes. Point-of-care ultrasound provides a valid and reproducible method for evaluating diaphragm thickness and contractile activity (thickening fraction during inspiration) that can be readily employed by clinicians and researchers alike. This article presents best practices for measuring diaphragm thickness and quantifying diaphragm thickening during tidal breathing or maximal inspiration. Once mastered, this technique can be used to diagnose and prognosticate diaphragm dysfunction, and guide and monitor response to treatment over time in both healthy individuals and acute or chronically ill patients.

Author Spotlight: Unraveling the Impact of Mechanical Ventilation on Diaphragm Function and Patient Outcomes 

Diaphragm thickness and function can be assessed in healthy individuals and critically ill patients using point-of-care ultrasound. This technique offers an accurate, reproducible, feasible, and well-tolerated method for evaluating diaphragm structure and function.

The diaphragm is the main component of the respiratory muscle pump. Diaphragm dysfunction can cause dyspnea and exercise intolerance, and predisposes ...

Advancing Bedside Care: A Multidisciplinary Guide to Kidney-Genitourinary POCUS

Point-of-Care Kidney and Genitourinary Ultrasound in Adults: Image Acquisition

A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with diagnostic imaging. Common imaging modalities include either computed tomography or diagnostic ultrasound. Traditionally, ultrasound of the kidney-genitourinary system has required consultative teams consisting of a sonographer performing image acquisition and a radiologist performing image interpretation. However, diagnostic point-of-care ultrasound (POCUS) has recently emerged as a useful tool to troubleshoot acute kidney injury at the bedside. Studies have shown that non-radiologists can be trained to perform diagnostic POCUS of the kidneys and bladder with high accuracy for a set number of important conditions. Currently, diagnostic POCUS of the kidney-genitourinary system remains underused in actual clinical practice. This is likely because image acquisition for this organ system is unfamiliar to most clinicians in specialties that encounter acute kidney injury, including primary care, emergency medicine, intensive care, anesthesiology, nephrology, and urology. To address this multi-specialty educational gap, this narrative review was developed by a multi-disciplinary group to provide a specialty-agnostic framework for kidney-genitourinary POCUS image acquisition: indications/contraindications, patient positioning, transducer selection, acquisition sequence, and exam limitations. Finally, we describe foundational concepts in kidney-genitourinary ultrasound image interpretation, including key abnormal findings that every bedside clinician performing this modality should know.

Author Spotlight: Developing a Bedside Protocol for Kidney and Genitourinary Ultrasonography

Point-of-care ultrasound (POCUS) of the renal and genitourinary (renal-GU) system can help to screen for certain causes of kidney dysfunction. However, despite its clinical utility, renal-GU POCUS remains underutilized due to a lack of training among clinicians. To address this gap, this article describes renal-GU image acquisition and interpretation.

A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with ...