Evaluation of the i-STAT point-of-care capillary whole blood hematocrit and hemoglobin: Comparison to the Siemens RAPIDLab 1200, Sysmex XE5000, and manual spun hematocrit

A New Hematocrit Measurement Method Using a Chemiluminescence Biosensor and Its Application in a Chemiluminescence Immunoassay Platform for Myocardial Markers Detection with Whole Blood Samples

The accuracy and precision of analyte concentrations measured in whole blood by chemiluminescence immunoassay (CLIA) have been significantly affected by erythrocytes, which leads to poor application of whole blood CLIA in clinical practice. In this work, a chemiluminescence biosensing optical platform for blood hematocrit (HCT) analysis using MAGICL 6000 (Getein Biotechnology, Nanjing, China) was designed, implemented, and fully characterized. The developed method was successfully applied to determine various HCT levels of human blood from 0% to 65%, with a correlation coefficient of 0.9885 compared with the conventional method (Sysmex XE 5000, Kobe, Japan). A mathematical model was developed to quantitatively evaluate the impact of HCT on the results of two sample types (whole blood vs. plasma). Combining the established HCT method and mathematical model with CLIA on MAGICL 6000, the precision was significantly improved by almost 20%. Comparison studies using whole blood samples and corresponding plasma samples showed that the square of the correlation coefficients of troponin I (cTnI), myoglobin (MYO), creatine kinase MB (CK-MB), and N-terminal pro-hormone brain natriuretic peptide (NT-proBNP) were increased to 0.9992, 0.9997, 0.9996, and 0.9994, respectively, showing a great potential for clinical application.

Anemia Diagnostic System Based on Impedance Measurement of Red Blood Cells

Anemia is a condition in which red blood cells or the hemoglobin in the blood is lower than in healthy people. Red blood cells transport and supply oxygen needed to various organs in the human body. Anemia is caused by hypoxemia due to the lack of red blood cells and causes other serious health problems, such as heart problems, pregnancy complications, severe fatigue, or death. There are many causes of anemia, and it can be diagnosed by measuring hematocrit or hemoglobin levels in the blood. Even though there are various diagnostic devices on the market, these devices are inconvenient because their systems are bulky, heavy, expensive, or inaccurate. This study proposed a new anemia diagnostic system based on the impedance measurement of red blood cells. The proposed system consists of a test strip that collects a blood sample from the finger and a hemoglobin meter that measures the impedance of the blood and converts it into the concentration of hemoglobin. The proposed test strip that does not contain enzymes or reagents was designed in accordance with class 1 approval by the Food and Drug Administration (FDA). The hemoglobin meter was designed to include a hardware block, an algorithm block and a calibration block through empirical work. We also compared it to reference impedance to prove the accuracy of the hemoglobin meter. The experimental results with human blood indicated the superiority of the anemia diagnostic system. As a result, the overall standard deviation of impedance measurements was less than 1%, and the coefficient of variance of the proposed system was 1.7%, which was better than that of other commercial systems.

Heat acclimation training with intermittent and self-regulated intensity may be used as an alternative to traditional steady state and power-regulated intensity in endurance cyclists

The study aimed to determine the effects of self-regulated and variable intensities sustained during short-term heat acclimation training on cycling performance. Seventeen competitive-level male athletes performed a 20-km cycling time trial before (TT-PRE), immediately after (TT-POST1) and one week after (TT-POST2) a 5-day acclimation training program, including either RPE-regulated intermittent (HA-HIT, N = 9) or fixed and low-intensity (HA-LOW, N = 8) training sessions in the heat (39 °C; 40% relative humidity). Total training volume was 23% lower in HA-HIT compared to HA-LOW. Physiological responses were evaluated during a 40-min fixed-RPE cycling exercise performed before (HST-PRE) and immediately after (HST-POST) heat acclimation. All participants in HA-LOW group tended to improve mean power output from TT-PRE to TT-POST1 (+8.1 ± 5.2%; ES = 0.55 ± 0.23), as well as eight of the nine athletes in HA-HIT group (+4.3 ± 2.0%; ES = 0.29 ± 0.31) without difference between groups, but TT-POST2 results showed that improvements were dissipated one week after. Similar improvements in thermal sensation and lower elevations of core temperature in HST-POST following HA-LOW and HA-HIT training protocols suggest that high intensity and RPE regulated bouts could be an efficient strategy for short term heat acclimation protocols, for example prior to the competition. Furthermore, the modest impact of lowered thermal sensation on cycling performance confirms that perceptual responses of acclimated athletes are dissociated from physiological stress when exercising in the heat.

Point-of-Care Laboratory Data Collection During Critical Care Transport

OBJECTIVE

Critical care transport involves a high level of intensive clinical care in a resource-limited environment. These patients require multiple assessments guiding specialty treatments, including blood product administration, intravenous electrolyte replacement, ventilator management, and extracorporeal membrane oxygenation. This study aims to measure the usage of point-of-care (POC) laboratory data during critical care transport.

METHODS

Data were collected via electronic medical record review over 1 year of use in a hospital-based critical care rotor wing, fixed wing, and ground critical care transport team in the Southeastern United States.

RESULTS

One hundred twenty POC tests were performed during 1,075 critical care transports over the 1-year period (8.9%). Patient transportations involved 35 extracorporeal membrane oxygenation, 21 medical, 17 cardiac, 13 neonatal, 11 respiratory failure, 8 gastrointestinal bleeding, 6 neurologic, 5 pediatrics, 3 trauma, and 1 organ donor. Seventy-eight POC laboratory tests (65%) required intervention, including ventilator changes (39.7%), electrolyte replacement (35.8%), blood products (7.6%), and other (12.8%). The remaining 42 (35%) POC laboratory tests confirmed no intervention was necessary (n = 35) and that ongoing treatments were effective (n = 7).

CONCLUSION

POC laboratory testing performed during critical care transport guides providers in performing essential emergent interventions in a timelier manner that may benefit critically ill patients.

Dermal Calcium Loss Is Not the Primary Determinant of Parathyroid Hormone Secretion during Exercise

INTRODUCTION

Exercise can cause a decrease in serum ionized calcium (iCa) concentration, which stimulates parathyroid hormone (PTH) secretion and activates bone resorption. We postulated that dermal Ca loss during cycling exercise is the major determinant of the serum iCa, PTH, and bone resorption (C-terminal telopeptide of type 1 collagen [CTX]) responses.

METHODS

To investigate this, women (n = 13) and men (n = 12) age 18 to 45 yr performed the same exercise bout under cool (18°C) and warm (26°C) conditions. Exercise was 60 min of cycling at ~75% of peak aerobic power. Sweat samples were obtained during exercise using a skin patch method, and blood samples were obtained before and during exercise and during 60 min of recovery.

RESULTS

Sweat volume and estimated sweat Ca loss were 50% higher for the warm condition than the cool condition. Despite this, there were no differences between thermal conditions in the changes (mean, 95% confidence interval [95% CI]) in iCa (cool, -0.07 mg·dL; 95% CI, -0.16 to 0.03); warm, -0.07 mg·dL; 95% CI, -0.20 to 0.05), PTH (cool, 34.4 pg·mL; 95% CI, 23.6-45.2; warm: 35.8 pg·mL; 95% CI, 22.4-49.1), or CTX (cool, 0.11 ng·mL; 95% CI, 0.08-0.13; warm, 0.15 ng·mL; 95% CI, 0.11-0.18). Adjusting for exercise-related shifts in plasma volume revealed a marked decline in vascular iCa content in the first 15 min of exercise (cool, -0.85 mg·dL; 95% CI, -1.01 to -0.68; warm, -0.85 mg·dL; 95% CI, -1.05 to -0.66), before substantial sweat Ca loss had occurred.

CONCLUSIONS

This indicates that dermal Ca loss was not the primary trigger for the increases in PTH and CTX during exercise. Further research is necessary to understand the causes and consequences of the disruption in Ca homeostasis during exercise and specifically the extravascular shift in iCa.

Daily home monitoring of potassium, creatinine, and estimated plasma volume in heart failure post-discharge

Aims

Congestive status, serum potassium, and renal function are major determinants of outcomes as well as critical elements for adjusting drug therapy in heart failure (HF) patients. This study aimed at describing the daily variations in estimated plasma volume (ePV, a surrogate of congestion computed from haemoglobin and haematocrit), blood potassium, and estimated glomerular filtration rate during 2 months post‐hospitalization for decompensated HF with reduced ejection fraction.

Methods and results

The study was conducted in a single tertiary referral centre. Capillary blood samples were drawn by study nurses at home (7–12 am), and haematocrit, blood haemoglobin, creatinine, and potassium were measured using an approved home‐based device (ABOTT i‐STAT) (http://ClinicalTrials.gov: NCT01655134). Among the 15 home‐monitored patients, two patients died (one suddenly), and one was readmitted for ischaemic acute pulmonary oedema, with a subsequent acute coronary syndrome, and did not have a complete 2‐month follow‐up. The 5‐day‐a‐week biological home monitoring revealed an ePV >5.5 mL/g Hb, suggestive of undiagnosed residual congestion at discharge in 3 out the 15 patients. It was possible to document a number of episodes of hyperkalaemia (>5: mean ± standard deviation: 2.2 ± 2.2 or 5.5: 1.7 ± 1.6 mmol/L), hypokalaemia (<4: 1.9 ± 2.4 or 3.5: 0.5 ± 1.2 mmol/L), worsening renal function (drop in estimated glomerular filtration rate > 20%: 1.3 ± 1.8 or 30%: 0.7 ± 1.2) and recongestion (ePV rise above 10%: 1.4 ± 1.5, 15%: 2.3 ± 2.4, 5.5 mL/g Hb: 1.8 ± 2.6) episodes indicative of clinically relevant and potentially actionable cardiorenal and electrolytic patterns.

Conclusions

Our findings demonstrate that a 5‐day‐a‐week home monitoring combining haemoglobin/haematocrit, potassium, and creatinine measurements was able to capture a substantial number of clinically relevant cardiorenal and electrolyte events which are frequently overlooked and potentially actionable. Whether acting on these events may help optimizing renin angiotensin aldosterone system inhibitors and diuretic therapy warrants further dedicated testing. The ongoing HERMES HF study (NCT04050904) is assessing the short‐term feasibility and safety of such a monitoring strategy, complemented by a decision support system, and generating recommendations based on ESC clinical guidelines in patients discharged after an episode of worsening heart failure with reduced ejection fraction.

Acoustofluidic hematocrit determination

Hematocrit (HCT) measurements of blood from patients, blood donors and athletes are routinely performed on a daily basis. These measurements are often performed in centralized hospital labs by whole blood analyzers, which leads to long time-to-result. On site measurements, based on centrifugation can be done, but these assays require manual handling, are slow and can just measure HCT in contrast to the central lab whole blood analyzers. In this work, we present a microfluidic based method to measure HCT in blood samples by acoustic separation of whole blood into discrete regions of plasma and red blood cells. Comparison of the areas of the red blood cell and plasma regions gives an accurate HCT value, with a linear correlation to the centrifugation-based reference method. A readout can be performed within 2 s of acoustic actuation providing a readout accuracy of approximately 3% points (pp) HCT. Additional accuracy can be achieved by extending the acoustic actuation to 20 s, yielding an error of less than 1 pp HCT. This acoustic tool is optimal for integration into a lab-on-a-chip device with in-line measurements of different clinical parameters.

Measures of Blood Hemoglobin and Hematocrit During Cardiac Surgery: Comparison of Three Point-of-Care Devices

OBJECTIVE

The primary objective was to compare I-Stat, HemoCue, and RapidLab in measurements of the hemoglobin concentration during cardiac surgeries using cardiopulmonary bypass.

DESIGN

Prospective analysis.

SETTING

Single-center, academic, tertiary care cardiovascular center.

PARTICIPANTS

Thirty-four consecutive patients undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

Blood samples have been collected intraoperatively, and the hemoglobin concentration in each sample was measured, or calculated, simultaneously by the 3 point-of-care devices, HemoCue, RapidLab, and I-Stat.

MEASUREMENTS AND MAIN RESULTS

Correlation coefficients from the regression analysis for HemoCue versus I-Stat, RapidLab versus HemoCue, and RapidLab versus I-Stat were 0.89, 0.96, and 0.88, respectively. Results of the Bland-Altman analysis of the hemoglobin concentration measurements for each device against one another (Fig 1) were as follows: RapidLab versus I-Stat (bias 0.42; 95% confidence interval [CI], -1.05 to 1.89), I-Stat versus HemoCue (bias 0.23; 95% CI, -1.14 to 1.59), and RapidLab versus HemoCue (bias 0.65; 95% CI, -0.17 to 1.47). It appears that I-Stat slightly underestimated the concentration of hemoglobin when compared with both RapidLab and HemoCue. The results of Bland-Altman analysis of each device to a mean Z value (Fig 2) were as follows: RapidLab versus Z (bias 0.36; 95% CI, -0.29 to 1.01), I-Stat versus Z (bias -0.07; CI -0.97 to 0.84), and HemoCue versus Z (bias -0.29; 95% CI, -0.86 to 0.28). Based on the 174 paired samples used for the Pearson moment analysis, the R² values for I-Stat versus HemoCue, I-Stat versus RapidLab, and RapidLab versus HemoCue were 0.79, 0.80, and 0.87, respectively CONCLUSIONS: These data support the interchangeability of these 3 devices for the intermittent intraoperative point-of-care assessment of hemoglobin concentrations in cardiac surgery patients. It is important, however, to consider the possible pitfalls associated with each device when making a clinical decision to transfuse.

Multianalyte Physiological Microanalytical Devices

Advances in scientific instrumentation have allowed experimentalists to evaluate well-known systems in new ways and to gain insight into previously unexplored or poorly understood phenomena. Within the growing field of multianalyte physiometry (MAP), microphysiometers are being developed that are capable of electrochemically measuring changes in the concentration of various metabolites in real time. By simultaneously quantifying multiple analytes, these devices have begun to unravel the complex pathways that govern biological responses to ischemia and oxidative stress while contributing to basic scientific discoveries in bioenergetics and neurology. Patients and clinicians have also benefited from the highly translational nature of MAP, and the continued expansion of the repertoire of analytes that can be measured with multianalyte microphysiometers will undoubtedly play a role in the automation and personalization of medicine. This is perhaps most evident with the recent advent of fully integrated noninvasive sensor arrays that can continuously monitor changes in analytes linked to specific disease states and deliver a therapeutic agent as required without the need for patient action.