Potassium but Not Lactate Dehydrogenase Elevation Due To In Vitro Hemolysis Is Higher in Capillary Than in Venous Blood Samples

Context.—Elevated potassium concentrations due to in vitro hemolysis can lead to errors in diagnoses and treatment. Recently, we observed that potassium elevation in capillary samples appeared higher than expected, based on hemolytic index (H-index). Objective.—To investigate the relation between potassium increase and H-index for capillary samples. As a control, the same analysis was performed for lactate dehydrogenase (LDH). Design.—Potassium results of 332 760 venous and 2620 capillary samples were selected. For LDH, 135 974 venous and 999 capillary samples were included. Venous and capillary samples were differentiated by using patient age, as we perform mostly capillary blood sampling in children and venous sampling in adults. Results were obtained with Beckman-Coulter DxC800 analyzers. Results.—The increase in potassium with increasing H-index was considerably higher for capillary samples than venous samples. Linear regression revealed a potassium increase of 0.38 mEq/L per increment in H-index for capillary samples, whereas a 0.17 mEq/L increase was found for venous samples. For LDH, no differences were found between venous and capillary samples. Conclusions.—At identical H-index, capillary samples showed higher potassium elevations than venous samples. A possible explanation is that capillary sampling causes increased leakage of ions, such as potassium, from erythrocytes, compared with proteins such as hemoglobin and LDH. These results are especially important considering the increasing use of whole blood point-of-care analyzers, where the H-index is often not determined. Potassium results should therefore be interpreted with caution to avoid severe misdiagnosis of hypokalemia and hyperkalemia.

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Point-of-care measurement of clozapine concentration using a finger-stick blood sample

Journal of Psychopharmacology ◽

10.1177/0269881121991567 ◽

2021 ◽

pp. 026988112199156

Author(s):

David Taylor ◽

Matthew Atkins ◽

Robert Harland ◽

Irina Baburina ◽

James H MacCabe ◽

...

Keyword(s):

Blood Sample ◽

Point Of Care ◽

Venous Blood ◽

Laboratory Method ◽

Capillary Blood ◽

Strong Positive Correlation ◽

Blood Samples ◽

Clozapine Concentration ◽

Capillary Sample ◽

Finger Stick

Background: The use of clozapine demands regular monitoring of clozapine plasma concentrations and of white blood cell parameters. The delay between sending blood samples for analysis and receiving the results hinders clinical care. Point-of-care testing (POCT) can provide drug assay results within a few minutes. Aim: This study aimed to investigate the utility of a novel point-of-care device that can measure clozapine concentrations using capillary blood samples collected via a finger stick. Method: During a five-week period starting in June 2019 eligible patients were asked to provide a finger-stick capillary sample in addition to their usual venous blood sample. Samples were analysed by the novel point-of-care device and by the standard laboratory method. Capillary blood samples were tested by the MyCare™ Insite POCT analyser, and a quantitative measurement of clozapine concentration was provided within six minutes. Results: A total of 309 patients agreed to measurements by the two methods. Analysis revealed clozapine concentrations in venous blood as determined by the laboratory method ranged from 20 to 1310 ng/mL and by POCT from 7 to 1425 ng/mL. There was a strong positive correlation ( R = 0.89) between the results from the venous and the capillary sample methods. The slope of the association between standard assay and MyCare™ Insite was 1.0 with an intercept of –21 ng/mL, indicating minimal bias. Conclusion: Clozapine concentrations can be accurately measured at the point of care using capillary blood samples collected via a finger stick. This approach may be more acceptable than venous sampling to patients and, with almost instant results available, more useful to clinicians.

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A Comparison of Venous versus Capillary Blood Samples when Measuring Blood Glucose Using a Point-of-Care, Capillary-Based Glucometer

Prehospital and Disaster Medicine ◽

10.1017/s1049023x19004850 ◽

2019 ◽

Vol 34 (05) ◽

pp. 506-509

Author(s):

Jessica Topping ◽

Matthew Reardon ◽

Jake Coleman ◽

Brian Hunter ◽

Haruka Shojima-Perera ◽

...

Keyword(s):

Blood Glucose ◽

Point Of Care ◽

Research Question ◽

Venous Blood ◽

Hospital Setting ◽

Capillary Blood ◽

Needle Stick Injury ◽

Blood Samples ◽

Significant Difference ◽

Venous Sample

AbstractBackground:Blood glucose level (BGL) is routinely assessed by paramedics in the out-of-hospital setting. Most commonly, BGL is measured using a blood sample of capillary origin analyzed by a hand-held, point-of-care glucometer. In some clinical circumstances, the capillary sample may be replaced by blood of venous origin. Given most point-of-care glucometers are engineered to analyze capillary blood samples, the use of venous blood instead of capillary may lead to inaccurate or misleading measurements.Hypothesis/Problem:The aim of this prospective study was to compare mean difference in BGL between venous and capillary blood from healthy volunteers when measured using a capillary-based, hand-held, point-of-care glucometer.Methods:Using a prospective observational comparison design, 36 healthy participants provided paired samples of blood, one venous and the other capillary, taken near simultaneously. The BGL values were similar between the two groups. The capillary group had a range of 4.3mmol/l, with the lowest value being 4.4mmol/l and 8.7mmol/l the highest. The venous group had a range of 2.7mmol/l, with the lowest value being 4.1mmol/l and 7.0mmol/l the highest.For the primary research question, the mean BGL for the venous sample group was 5.3mmol/l (SD = 0.6), compared to 5.6mmol/l (SD = 0.8) for the capillary group. This represented a statistically significant difference of 0.3mmol/l (P = .04), but it did not reach the a priori established point of clinical significance (1.0mmol/l). Pearson’s correlation coefficient for capillary versus venous indicated moderate correlation (r = 0.42).Conclusion:In healthy, non-fasted people in a non-clinical setting, a statistically significant, but not clinically significant, difference was found between venous- and capillary-derived BGL when measured using a point-of-care, capillary-based glucometer. Correlation between the two was moderate. In this context, using venous samples in a capillary-based glucometer is reasonable providing the venous sample can be gathered without exposure of the clinician to risk of needle-stick injury. In clinical settings where physiological derangement or acute illness is present, capillary sampling would remain the optimal approach.

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Comparison of capillary, venous and buffy coat blood samples in detecting Plasmodium species among malaria suspected patients attending at Hamusite health center. A cross-sectional study

BMC Infectious Diseases ◽

10.1186/s12879-021-06290-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Getu Abeje ◽

Woyneshet Gelaye ◽

Getaneh Alemu

Keyword(s):

Health Center ◽

Detection Rate ◽

Venous Blood ◽

Cross Sectional Study ◽

Buffy Coat ◽

Blood Film ◽

Capillary Blood ◽

Sectional Study ◽

Cross Sectional ◽

Blood Samples

Abstract Background Both capillary and venous blood samples have been interchangeably used for the diagnosis of malaria in Ethiopia. However, Plasmodium parasites are thought to be more concentrated in capillary than in venous blood. Hence, selecting a sample source where parasites are more concentrated is indispensable approach in order to maximize the accuracy of blood film microscopy. Therefore, the present study aimed to compare the detection rate and the parasitemia level of Plasmodium species from conventional capillary and venous blood films, and buffy coat preparations. Methods A facility based cross-sectional study was conducted from Feburary to March 2020 among 210 febrile patients attending Hamusite health center, northwest Ethiopia. Capillary and venous blood samples were collected and buffy coat was prepared from each sample. Thin and thick blood films were prepared, stained, and examined microscopically following standard protocol. Data were analysed using Statistical Package for Social Sciences Software version 20 and Med-Calc software version 19.3. Results Capillary blood buffy coat (61/210, 29.0%) had significantly higher detection rate as compared to capillary (48/210, 22.9%) and venous (42/210, 20.0%) blood films (p < 0.001). However, no significant difference was observed between capillary and venous blood films (p = 0.070) in detecting Plasmodium species. The highest and the lowest mean asexual stage parasite counts were found in capillary blood buffy coat (4692.88) and venous blood (631.43) films, respectively showing significant variations (p < 0.001). Mean gametocyte count was also highest in capillary blood buffy coat (3958.44). As compared to capillary blood buffy coat, the sensitivity of venous blood buffy coat, capillary blood film and venous blood film were 73.8, 78.7, 68.9%, respectively. Conclusion Capillary blood buffy coat samples showed the highest sensitivity in detecting and quantitating malaria parasites that its use should be promoted in clinical settings. However, conventional capillary and venous blood films could be used interchangeably.

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Effects of Different Methods Used to Take Blood Samples on Blood Glucose Measurements

Clinical Nursing Research ◽

10.1177/10547738211024782 ◽

2021 ◽

pp. 105477382110247

Author(s):

Eda Ergin ◽

Ayten Zaybak

Keyword(s):

Blood Glucose ◽

Glucose Tolerance Test ◽

Venous Blood ◽

Tolerance Test ◽

Capillary Blood ◽

Oral Glucose ◽

Blood Samples ◽

Significant Difference ◽

Measurement Results ◽

Quasi Experimental

The purpose of this study is to compare whether or not there is a difference between venous and capillary blood samples in blood glucose measurements and investigate the effects of different aseptic methods used in skin cleaning before collecting blood samples on measurement results. This quasi-experimental study was conducted with 109 patients. The capillary first and second blood drop values taken from the patients after fasting and at 2 hours following 75 g oral glucose tolerance test (OGTT) and capillary and venous blood glucose values were compared. There was no significant difference between the median venous blood glucose value and the capillary second blood drop value taken after wiping the finger with alcohol. There was no significant difference between the first and second blood drop values of capillary blood glucose 2 hours after OGTT.

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Blood Glucose Assay Using Dextrostix and a Reflectance Meter

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/000456327200900144 ◽

1972 ◽

Vol 9 (1-6) ◽

pp. 91-94 ◽

Cited By ~ 6

Author(s):

I. W. Percy-Robb ◽

R. S. McMaster ◽

A. D. B. Harrower ◽

L. J. P. Duncan

Keyword(s):

Blood Glucose ◽

Venous Blood ◽

Reference Method ◽

Capillary Blood ◽

Blood Samples ◽

Laboratory Staff ◽

Glucose Assay ◽

Reflectance Meter ◽

High Degree ◽

Blood Glucose Concentrations

The ‘Dextrostix’-reflectance meter system for blood glucose analysis has been evaluated using a blood glucose reference method. A high degree of concordance between the two methods was obtained when analyses were performed by skilled laboratory staff on venous blood samples containing fluoride, with a 75 s contact time. Skilled laboratory staff performed significantly better than unskilled staff. Capillary blood glucose concentrations correlated poorly with concentrations in venous blood samples taken at the same time as the capillary blood.

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Platelet Phenotyping and Function Testing in Thrombocytopenia

Journal of Clinical Medicine ◽

10.3390/jcm10051114 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1114

Author(s):

Kerstin Jurk ◽

Yavar Shiravand

Keyword(s):

Function Analysis ◽

Point Of Care ◽

Bleeding Complications ◽

Diagnostic Significance ◽

Blood Samples ◽

Skilled Personnel ◽

Life Threatening ◽

And Function ◽

Function Testing

Patients who suffer from inherited or acquired thrombocytopenia can be also affected by platelet function defects, which potentially increase the risk of severe and life-threatening bleeding complications. A plethora of tests and assays for platelet phenotyping and function analysis are available, which are, in part, feasible in clinical practice due to adequate point-of-care qualities. However, most of them are time-consuming, require experienced and skilled personnel for platelet handling and processing, and are therefore well-established only in specialized laboratories. This review summarizes major indications, methods/assays for platelet phenotyping, and in vitro function testing in blood samples with reduced platelet count in relation to their clinical practicability. In addition, the diagnostic significance, difficulties, and challenges of selected tests to evaluate the hemostatic capacity and specific defects of platelets with reduced number are addressed.

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Comparative study of i-SENS glucometers in neonates using capillary blood samples

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2020-1367 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ha Nui Kim ◽

Soo-Young Yoon

Keyword(s):

Reference Values ◽

Point Of Care ◽

Evaluation Process ◽

Capillary Blood ◽

Performance Criteria ◽

Accuracy Evaluation ◽

Blood Samples ◽

Average Reference ◽

Error Grid ◽

Accuracy Performance

Abstract Objectives The accuracy of point-of-care blood glucometers in the detection and evaluation of neonatal hypoglycemia is a concern. This study compared the performance of three i-SENS glucometers with that of the YSI 2300 STAT Plus Analyzer, which was used as a reference. Methods The leftover neonatal capillary blood samples of 319 patients were used in this study. The evaluation process and accuracy performance criteria were based on the International Organization for Standardization 15197:2013 guidelines. The evaluation involved three i-SENS glucometers (BAROzen H Expert plus, CareSens PRO, and CareSens H Beat) and the ACCU-CHEK® Inform II glucometer. Results The accuracy evaluation yielded acceptable results as follows: a) 100 and 100% for BAROzen H Expert plus; 99.8 and 100% for CareSens PRO; 98.7%, and 97.2% for CareSens H Beat glucometers were within the range of ±0.8 mmol/L (15 mg/dL) and ±15% of the average reference values at glucose concentrations <5.55 mmol/L (100 mg/dL) and ≥5.55 mmol/L (100 mg/dL), respectively, and b) all estimated glucose values (100%) were within the zones A and B of Consensus Error Grid for all three i-SENS glucometers. There was good correlation between the glucose values estimated by the glucometers and the reference values (R>0.990). Conclusions This study demonstrated that i-SENS glucometers exhibit acceptable performance and can be used as effective point-of-care devices in neonates.

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Point-of-care microvolume cytometer measures platelet counts with high accuracy from capillary blood

PLoS ONE ◽

10.1371/journal.pone.0256423 ◽

2021 ◽

Vol 16 (8) ◽

pp. e0256423

Author(s):

William M. Dickerson ◽

Rebecca Yu ◽

Helena U. Westergren ◽

Jonathan Paraskos ◽

Philipp Schatz ◽

...

Keyword(s):

Point Of Care ◽

Venous Blood ◽

Reference Method ◽

Time Data ◽

Platelet Recovery ◽

Blood Samples ◽

Impedance Analyzer ◽

Platelet Counts ◽

Platelet Antibodies ◽

Care Assessment

Background Point-of-care (PoC) testing of platelet count (PLT) provides real-time data for rapid decision making. The goal of this study is to evaluate the accuracy and precision of platelet counting using a new microvolume (8 μL), absolute counting, 1.5 kg cytometry-based blood analyzer, the rHEALTH ONE (rHEALTH) in comparison with the International Society of Laboratory Hematology (ISLH) platelet method, which uses a cytometer and an impedance analyzer. Methods Inclusion eligibility were healthy adults (M/F) ages 18–80 for donation of fingerprick and venous blood samples. Samples were from a random N = 31 volunteers from a single U.S. site. Samples were serially diluted to test thrombocytopenic ranges. Interfering substances and conditions were tested, including RBC fragments, platelet fragments, cholesterol, triglycerides, lipids, anti-platelet antibodies, and temperature. Results The concordance between the rHEALTH and ISLH methods had a slope = 1.030 and R2 = 0.9684. The rHEALTH method showed a correlation between capillary and venous blood samples (slope = 0.9514 and R2 = 0.9684). Certain interferents changed platelet recovery: RBC fragments and anti-platelet antibodies with the ISLH method; platelet fragments and anti-platelet antibodies on the rHEALTH; and RBC fragments, platelets fragments, triglycerides and LDL on the clinical impedance analyzer. The rHEALTH’s precision ranged from 3.1–8.0%, and the ISLH from 1.0–10.5%. Conclusions The rHEALTH method provides similar results with the reference method and good correlation between adult capillary and venous blood samples. This demonstrates the ability of the rHEALTH to provide point-of-care assessment of normal and thrombocytopenic platelet counts from fingerprick blood with high precision and limited interferences.

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