Point-of-Care Testing and Cardiac Biomarkers: The Standard of Care and Vision for Chest Pain Centers

Point-of-Care Diagnosis of Acute Myocardial Infarction in Central Vietnam: International Exchange, Needs Assessment, and Spatial Care Paths

OBJECTIVES

Objectives were to (a) advance point-of-care (POC) education, international exchange, and culture; (b) report needs assessment survey results from Thua Thien Hue Province, Central Vietnam; (c) determine diagnostic capabilities in regional health care districts of the small-world network of Hue University Medical Center; and (d) recommend Spatial Care Paths that accelerate the care of acute myocardial infarction (AMI) patients.

METHODS

We organized progressively focused, intensive, and interactive lectures, workshops, and investigative teamwork over a 2-year period. We surveyed hospital staff in person to determine the status of diagnostic testing at 15 hospitals in 7 districts. Questions focused on cardiac rapid response, prediabetes/diabetes, infectious diseases, and other serious challenges, including epidemic preparedness.

RESULTS

Educational exchange revealed a nationwide shortage of POC coordinators. Throughout the province, ambulances transfer patients primarily between hospitals, rarely picking up from homes. No helicopter rescue was available. Ambulance travel times from distant sites to referral hospitals were excessive, longer in costal and mountainous areas. Most hospitals (92.3%) used electrocardiogram and creatine phosphokinase-MB isoenzyme to diagnose AMI. Cardiac troponin I/T testing was performed only at large referral hospitals.

CONCLUSIONS

Central Vietnam must improve rapid diagnosis and treatment of AMI patients. Early upstream POC cardiac troponin testing on Spatial Care Paths will expedite transfers directly to hospitals capable of intervening, improving outcomes following coronary occlusion. Point-of-care coordinator certification and financial support will enhance standards of care cost-effectively. Training young physicians pivots on high-value evidence-based learning when POC cardiac troponin T/cardiac troponin I biomarkers are in place for rapid decision making, especially in emergency rooms.

Studies towards hcTnI Immunodetection Using Electrochemical Approaches Based on Magnetic Microbeads

Different electrochemical strategies based on the use of magnetic beads are described in this work for the detection of human cardiac troponin I (hcTnI). hcTnI is also known as the gold standard for acute myocardial infarction (AMI) diagnosis according to the different guidelines from the European Society of Cardiology (ESC) and the American College of Cardiology (ACC). Amperometric and voltamperometric sandwich magnetoimmunoassays were developed by biofunctionalization of paramagnetic beads with specific antibodies. These bioconjugates were combined with biotinylated antibodies as detection antibodies, with the aim of testing different electrochemical transduction principles. Streptavidin labeled with horseradish peroxidase was used for the amperometric magnetoimmunoassay, reaching a detectability of 0.005 ± 0.002 µg mL-1 in 30 min. Cadmium quantum dots-streptavidin bioconjugates were used in the case of the voltamperometric immunosensor reaching a detectability of 0.023 ± 0.014 µg mL-1.

Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes. J Matern Fetal Neonatal Med 2018;31:228-244. [PMID: 28081646 PMCID: PMC5769687 DOI: 10.1080/14767058.2017.1281904]

OBJECTIVE

Among patients presenting with preterm labor and intact membranes, those with intra-amniotic inflammation have adverse obstetrical and neonatal outcomes. The diagnosis of intra-amniotic inflammation can easily be made by detecting an elevated concentration of the cytokine interleukin (IL)-6 or the enzyme neutrophil collagenase, also known as matrix metalloproteinase (MMP)-8. The diagnostic performances of MMP-8 and IL-6 enzyme-linked immunosorbent assay tests are similar. Recently, a rapid test has become available for point-of-care determination of either MMP-8 or IL-6. The objectives of this study were to compare the diagnostic indices and predictive values between the rapid MMP-8 and IL-6 tests for the identification of intra-amniotic inflammation in patients with preterm labor and intact membranes.

MATERIALS AND METHODS

We performed a retrospective cohort study including 124 women with singleton pregnancies who presented with symptoms of preterm labor and underwent transabdominal amniocentesis for the evaluation of microbial invasion of the amniotic cavity (MIAC). MIAC was defined according to amniotic fluid culture results (aerobic and anaerobic bacteria as well as genital Mycoplasmas). Amniotic fluid white blood cell (WBC) counts were determined using a hemocytometer chamber. An elevated amniotic fluid MMP-8 concentration was assessed using Yoon's MMP-8 Check® (cutoff: 10 ng/mL). An elevated amniotic fluid IL-6 concentration was scored when there was a positive result for the lateral flow-based immunoassay (cutoff: ≥745 pg/mL and ≥1000 pg/mL). In order to objectively compare rapid MMP-8 and rapid IL-6 tests to identify intra-amniotic inflammation, an amniotic fluid WBC count of ≥50 cells/mm3 was used to define intra-amniotic inflammation.

RESULTS

(1) The rapid tests had the same sensitivity for the detection of intra-amniotic inflammation [85.7% (18/21) for all]; (2) the specificity of the rapid MMP-8 test was higher than that of the rapid IL-6 test (cutoff: 745 pg/mL) for the identification of intra-amniotic inflammation [72.8% (75/103) vs. 64.1% (66/103); p < 0.05]; and (3) there were no differences in the sensitivity and specificity between the rapid MMP-8 test and the rapid IL-6 test (cutoff:1000 pg/mL) in the identification of intra-amniotic inflammation. Of 13 patients with discrepant results between the rapid MMP-8 and rapid IL-6 tests, two had a positive MMP-8 but a negative rapid IL-6 test, and both delivered preterm - one within 24 h, and the other within 10 days - and both had acute histologic chorioamnionitis. On the other hand, there were 11 patients with a positive rapid IL-6 but a negative rapid MMP-8 result: 10 delivered preterm, 3 had acute histologic chorioamnionitis and 1 had subacute chorionitis.

CONCLUSION

We conclude that the rapid MMP-8 test has a better specificity than the rapid IL-6 (cutoff: 745 pg/mL) assay for the detection of intra-amniotic infection. Moreover, we observed that among patients who were not identified as having intra-amniotic infection or inflammation by the standard cultivation technique and amniotic fluid WBC count, those who had a positive MMP-8 rapid test delivered preterm and had acute histologic chorioamnionitis.

Highly sensitive amperometric detection of cardiac troponin I using sandwich aptamers and screen-printed carbon electrodes

In this study, we developed a sandwich aptamer-based screen-printed carbon electrode (SPCE) using chronoamperometry for the detection of cardiac troponin I (cTnI), one of the promising biomarkers for acute myocardial infarction (AMI). Disposable three-electrode SPCEs were manufactured using a screen printer, and various modifications such as electrodeposition of gold nanoparticles and electropolymerization of conductive polymers were performed. From the bare electrode to the aptamer-immobilized SPCE, all processes were monitored and analyzed via various techniques such as cyclic voltammetry, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. The quantification of cTnI was conducted based on amperometric signals from the catalytic reaction between hydrazine and H₂O₂. The fabricated aptasensor in a buffer, as well as in a serum-added solution, exhibited great analytical performance with a dynamic range of 1-100 pM (0.024-2.4ng/mL) and a detection limit of 1.0 pM (24pg/mL), which is lower than the existing cutoff values (40-700pg/mL). Furthermore, the developed sensor showed high sensitivity to cTnI over other proteins. It is anticipated that this potable SPCE aptasensor for cTnI will become an innovative diagnostic tool for AMI.

Electrochemical biosensors based on nanofibres for cardiac biomarker detection: A comprehensive review

The vital importance of early and accurate diagnosis of cardiovascular diseases (CVDs) to prevent the irreversible damage or even death of patients has driven the development of biosensor devices for detection and quantification of cardiac biomarkers. Electrochemical biosensors offer rapid sensing, low cost, portability and ease of use. Over the past few years, nanotechnology has contributed to a tremendous improvement in the sensitivity of biosensors. In this review, the authors summarise the state-of-the-art of the application of one particular type of nanostructured material, i.e. nanofibres, for use in electrochemical biosensors for the ultrasensitive detection of cardiac biomarkers. A new way of classifying the nanofibre-based electrochemical biosensors according to the electrical conductance and the type of nanofibres is presented. Some key data from each article reviewed are highlighted, including the mechanism of detection, experimental conditions and the response range of the biosensor. The primary aim of this review is to emphasise the prospects for nanofibres for the future development of biosensors in diagnosis of CVDs as well as considering how to improve their characteristics for application in medicine.

A point of care test for the determination of amniotic fluid interleukin-6 and the chemokine CXCL-10/IP-10

OBJECTIVE

Intra-amniotic inflammation is a mechanism of disease implicated in preterm labor, preterm prelabor rupture of membrane, cervical insufficiency, a short cervix, and idiopathic vaginal bleeding. Determination of interleukin (IL)-6 with immunoassays has been proven for more than two decades to be an excellent method for the detection of intra-amniotic inflammation. However, assessment of IL-6 for this indication has been based on immunoassays which are not clinically available, and this has been an obstacle for the implementation of this test in clinical practice. It is now possible to obtain results within 20 min with a point of care (POC) test which requires minimal laboratory support. This test is based on lateral flow-based immunoassay. The objective of this study was to compare amniotic fluid (AF) IL-6 and interferon-γ - inducible protein 10 (IP-10 or CXCL-10) concentrations determined using lateral flow-based immunoassay or POC test and standard enzyme-linked immunosorbent assay (ELISA) techniques.

MATERIAL AND METHODS

AF samples were collected from patients with singleton gestations and symptoms of preterm labor (n = 20). AF IL-6 and IP-10 concentrations were determined by lateral flow-based immunoassay and ELISA. Intra-amniotic inflammation was defined as AF IL-6 ≥ 2.6 ng/ml. AF IL-6 and IP-10 concentrations between two assays were compared.

RESULTS

(1) Lateral flow-based immunoassay POC AF IL-6 and IP-10 test results were strongly correlated with concentrations of this cytokine/chemokine determined by ELISA (Spearman's ρ = 0.92 and 0.83, respectively, both p < 0.0001); (2) AF IL-6 concentrations determined by the lateral flow-based immunoassay test were, on average, 30% lower than those determined by ELISA, and the median difference was statistically significant (p < 0.0001); and (3) in contrast, AF IP-10 concentrations determined by the lateral flow-based immunoassay test were, on average, only 7% lower than those determined by ELISA, and the median difference was not statistically significant (p = 0.81).

CONCLUSION

AF IL-6 and IP-10 concentrations determined using a lateral flow-based immunoassay POC are strongly correlated with concentrations determined by conventional ELISA. This justifies further studies about the diagnostic indices and predictive values of this POC test.

Use of a 90-minute protocol to evaluate patients presenting to the emergency department with chest pain: a case study

Frustration with emergency department wait times may contribute to patient delays in seeking care for subsequent episodes of chest pain and lower patient satisfaction ratings. In response to patient feedback and the dissemination of new knowledge, the existing emergency chest pain protocol was updated to include point-of-care laboratory testing and evaluation at baseline and 90 minutes. A case study was utilized to illustrate implementation of this protocol in the management of a patient presenting to the emergency department with chest pain.

Diagnostic point-of-care tests in resource-limited settings

The aim of diagnostic point-of-care testing is to minimise the time to obtain a test result, thereby allowing clinicians and patients to make a quick clinical decision. Because point-of-care tests are used in resource-limited settings, the benefits need to outweigh the costs. To optimise point-of-care testing in resource-limited settings, diagnostic tests need rigorous assessments focused on relevant clinical outcomes and operational costs, which differ from assessments of conventional diagnostic tests. We reviewed published studies on point-of-care testing in resource-limited settings, and found no clearly defined metric for the clinical usefulness of point-of-care testing. Therefore, we propose a framework for the assessment of point-of-care tests, and suggest and define the term test efficacy to describe the ability of a diagnostic test to support a clinical decision within its operational context. We also propose revised criteria for an ideal diagnostic point-of-care test in resource-limited settings. Through systematic assessments, comparisons between centralised testing and novel point-of-care technologies can be more formalised, and health officials can better establish which point-of-care technologies represent valuable additions to their clinical programmes.

Point-of-Care Testing at the Disaster-Emergency-Critical Care Interface

Point-of-care (POC) testing allows for medical testing to be performed across the disaster-emergency-critical care continuum. The disaster-emergency-critical care continuum begins with the identification of at-risk patients, followed by patient stabilization, and ultimately transfer to an alternate care facility or mobile hospital for comprehensive critical care. Gaps at the interfaces for each of these settings leads to excess mortality and morbidity. Disaster victims are at risk for acute myocardial infarctions, acute kidney injury (AKI), and sepsis. However cardiac biomarker testing, renal function testing, and multiplex rapid pathogen detection are often unavailable or inadequate during disasters. Cardiac biomarker reagents require refrigeration; traditional renal function tests (i.e., serum creatinine) exhibit poor sensitivity for predicting AKI in critically ill patients, and culture-based pathogen detection is too slow to help initiate early-directed antimicrobial therapy. We propose three value propositions detailing how rapid, POC, and environmentally hardened cardiac biomarker, AKI and multiplex pathogen testing harmonizes the interface between disaster, emergency, and critical care.

Mapping turnaround times (TAT) to a generic timeline: a systematic review of TAT definitions in clinical domains

BACKGROUND

Assessing turnaround times can help to analyse workflows in hospital information systems. This paper presents a systematic review of literature concerning different turnaround time definitions. Our objectives were to collect relevant literature with respect to this kind of process times in hospitals and their respective domains. We then analysed the existing definitions and summarised them in an appropriate format.

METHODS

Our search strategy was based on Pubmed queries and manual reviews of the bibliographies of retrieved articles. Studies were included if precise definitions of turnaround times were available. A generic timeline was designed through a consensus process to provide an overview of these definitions.

RESULTS

More than 1000 articles were analysed and resulted in 122 papers. Of those, 162 turnaround time definitions in different clinical domains were identified. Starting and end points vary between these domains. To illustrate those turnaround time definitions, a generic timeline was constructed using preferred terms derived from the identified definitions. The consensus process resulted in the following 15 terms: admission, order, biopsy/examination, receipt of specimen in laboratory, procedure completion, interpretation, dictation, transcription, verification, report available, delivery, physician views report, treatment, discharge and discharge letter sent. Based on this analysis, several standard terms for turnaround time definitions are proposed.

CONCLUSION

Using turnaround times to benchmark clinical workflows is still difficult, because even within the same clinical domain many different definitions exist. Mapping of turnaround time definitions to a generic timeline is feasible.

Point-of-care diagnostics - is this driven by supply or demand?

The diagnostic point-of-care testing (POCT) market is about one-third of the in vitro diagnostic (IVD) testing market but, although there are many different POCT products, most are for pregnancy and monitoring of diabetes (∼ 70% of all POCT). Despite the small contribution outside these areas there is huge investment from both suppliers and users of POCT to establish new products and increase the infrastructure for their use. The review is focused on determining the balance between the different drivers of supply and demand and how they have impacted the conflicts seen in POCT evolution. The conflicts have been based on a mix of analytical, regulatory, political and commercial aspects and here the supply and demand drivers are examined separately to determine whether the conflicts are real or whether there are hidden synergies. The focus is on recent publications, with reference to some key historical articles, so that the full environment can be assessed. It is concluded that the synergies between supply and demand now overcome the conflicts where clinical and economic benefit can be demonstrated.

Analysis of serum cardiac biomarkers and treadmill exercise test-electrocardiogram for the diagnosis of coronary heart disease in suspected patients

The serum proteins creatine kinase isoenzyme MB (CKMB) and cardiac troponin T are classic biomarkers of cardiac ischemic damage in clinical practice, which can sensitively detect myocardial necrosis, while other two serum proteins, ischemia-modified albumin and N-terminal pro-B-type natriuretic peptide (NT-proBNP), have been recently identified as novel biomarkers of myocardial ischemia. In this study, the four biomarkers were detected in sera from 44 eligible patients with suspected coronary heart disease (CHD) before and after treadmill exercise test (TET), electrocardiogram (ECG) was measured during TET (TET-ECG) and invasive examination of coronary angiography (CAG), which is the 'gold standard' of CHD diagnosis, was also performed. For CAG, 25 patients were positive and 19 were negative, whereas for TET-ECG the numbers were 19 and 25, respectively. Among these four biomarkers, the NT-proBNP level in CAG positive group was much higher than those in CAG negative group both before and after TET, with statistical significance before TET (P=0.008). Furthermore, according to receiver operating characteristic (ROC) curve, the serum biomarker NTproBNP showed diagnostic effect of CHD and its cutoff value was 67 pg/ml, thus 30 of the patients in this study were NT-proBNP positive and 14 were negative. And it was found that NT-proBNP obviously enhanced the sensitivity of examinations whether analyzed alone or in combination with TET-ECG. More importantly, all the patients who were negative in both NT-proBNP and TET-ECG tests turned out to be CAG negative, which means that the combination of these two non-invasive examinations might take the place of invasive examination of CAG for CHD diagnosis. Further studies with more patients are warranted to validate the findings in this paper.

Does POCT reduce the risk of error in laboratory testing?

Point-of-care testing (POCT), the fastest growing segment of the current clinical laboratory testing market, is a rapid means for providing test results in different clinical settings. In theory, this tool eliminates some of the more problematic steps in the testing process, including specimen transport and result distribution. However, POCT has created new challenges, and sources of potential errors; moreover, while the upsurge in its use has generated concerns regarding the quality of test results, few data are available in the literature on errors with POCT. Nor are data available for the evaluation of errors, and the risk of errors in POCT based on all steps in the entire testing process, including test requesting and result utilization. According to a modified Kost model, which takes into account all steps of the testing process and latent conditions for error, POCT reduces errors and the risk of error in only a few steps of the testing process. There is therefore an urgent need for an evaluation of errors and risks of error in POCT that is based on the entire testing process and uses well-designed studies aiming to improve clinical outcomes and increase patient safety.

Assessment of user perspectives of cardiac point of care technologies in chest pain diagnosis

The assessment of the value of point of care technologies for cardiac marker testing in patients presenting with chest pain was carried out using an on-line survey tool to garner the views and opinions of healthcare professionals on point of care testing (POCT). The preliminary results of the survey are presented here. A total of 38 responses were received, from health care professionals within Northern Ireland Health Trusts. A number of concerns were raised relating to the implementation of a POCT service. These included clinical governance, quality assurance, accreditation and regulation, which should be addressed by the central laboratory. The main POCT user groups were clinical, nursing and laboratory staff, with nursing staff being the most frequent users. The general opinion amongst healthcare professionals was that POCT implementation and accreditation should be overseen and regulated by the central laboratory. Troponin I was the most important cardiac marker measured by POCT devices. POCT turnaround times were perceived by survey respondents as shorter between 15-30 minutes compared to laboratory testing, 60-90 minutes. The perception of POCT data quality was considered by the majority of respondents to be of equivalent quality and accuracy to central laboratory cardiac marker testing Laboratory and biomedical scientists indicated that the implementation of a POCT service would alter their relationships to clinical, nursing staff and patients. The survey suggested that POCT may create new roles for biomedical scientists outside the pathology laboratory involving supporting nursing staff at ward level and validation of patient test results.

A rapid MMP-8 bedside test for the detection of intra-amniotic inflammation identifies patients at risk for imminent preterm delivery

OBJECTIVE

Matrix metalloproteinase-8 (MMP-8) is an enzyme that is released during neutrophil activation. MMP-8 amniotic fluid concentrations are elevated not only in patients with intra-amniotic infection, but also in patients with negative amniotic fluid cultures who deliver preterm neonates. The objective of this study was to determine whether the results of a rapid MMP-8 bedside test predict imminent preterm delivery. This test can be performed in 15 minutes and without laboratory equipment.

STUDY DESIGN

Amniotic fluid was retrieved from 331 patients admitted with increased preterm uterine contractions and intact membranes who met the inclusion criteria. Amniotic fluid was processed for microbial cultures, Gram stain, glucose concentration, and white blood cell count. Amniotic fluid samples were stored, and the MMP-8 rapid test was performed after delivery. End points included spontaneous preterm delivery within 48 hours, 7 days, and 14 days. Diagnostic indices, predictive values, and likelihood ratios were calculated.

RESULTS

The prevalence of spontaneous preterm delivery within 48 hours, 7 days, and 14 days was 11.6% (38/327), 20.2% (66/327), and 24.5% (80/327), respectively (4 patients with augmentation of labor were excluded). A positive MMP-8 rapid test had a positive predictive value of 70% (23/33) for the identification of patients who delivered spontaneously within 48 hours, and 94% (31/33) for patients who were delivered within 7 days and 14 days (likelihood ratios: 17.5 [95% CI, 9-33.9], 61.3 [95% CI, 15.1-250], and 50 [95% CI, 12-196], respectively).

CONCLUSION

The MMP-8 rapid test can identify patients at risk for preterm delivery within 7 days and 14 days. Moreover, a positive MMP-8 rapid test result can identify patients with intra-amniotic infection/inflammation with a high sensitivity and specificity. This rapid test will give clinicians a fast and accurate assessment of the inflammatory status of the amniotic cavity and allow for better identification of patients at risk for impending preterm delivery.

Katrina, the tsunami, and point-of-care testing: optimizing rapid response diagnosis in disasters

We assessed how point-of-care testing (POCT), diagnostic testing at or near the site of patient care, can optimize diagnosis, triage, and patient monitoring during disasters. We surveyed 4 primary care units (PCUs) and 10 hospitals in provinces hit hardest by the tsunami in Thailand and 22 hospitals in Katrina-affected areas. We assessed POCT, critical care testing, critical values notification, demographics, and disaster responses. Limited availability and poor organization severely limited POCT use. The tsunami impacted 48 PCUs plus island and province hospitals, which lacked adequate diagnostic instruments. Sudden overload of critical victims and transportation failures caused excessive mortality. In New Orleans, LA, flooding hindered rescue teams that could have been POCT-equipped. US sea, land, and airborne rescue brought POCT instruments closer to flooded areas. Katrina demonstrated POCT value in disaster responses. We recommend handheld POCT, airborne critical care testing, and disaster-specific mobile medical units in small-world networks worldwide.