B-type Natriuretic Peptide for Diagnosis of Heart Failure in Emergency Department Patients: A Critical Appraisal

A microfluidic platform with digital readout and ultra-low detection limit for quantitative point-of-care diagnostics

Quantitative assays are of great importance for point-of-care (POC) diagnostics because they can offer accurate information on the analytes. However, current POC devices often require an accessory instrument to give quantitative readouts for protein biomarkers, especially for those at very low concentration levels. Here, we report a microfluidic platform, the digital volumetric bar-chart chip (DV-chip), for quantitative POC diagnostics with ultra-low detection limits that are readable with the naked eye. Requiring no calibration, the DV-chip presents a digital ink bar chart (representing multiple bits composed of 0 and 1) for the target biomarker based on direct competition between O2 generated by the experimental and control samples. The bar chart clearly and accurately defines target concentration, allowing identification of disease status. For the standard PtNP solutions, the detection limit of the platform is approximately 0.1 pM and the dynamic range covers four orders of magnitude from 0.1 to 1000 pM. CEA samples with concentrations of 1 ng mL(-1) and 1.5 ng mL(-1) could be differentiated by the device. We also performed the ELISA assay for B-type natriuretic peptide (BNP) in 20 plasma samples from heart failure patients and the obtained on-chip data were in agreement with the clinical results. In addition, BNP was detectable at concentrations of less than 5 pM, which is three orders of magnitude lower than the detection limit of the previously reported readerless digital methods. By the integration of gas competition, volumetric bar chart, and digital readout, the DV-chip possesses merits of portability, visible readout, and ultra-low detection limit, which should offer a powerful platform for quantitative POC diagnostics in clinical settings and personalized detection.

Lung cancer patients frequently visit the emergency room for cancer-related and -unrelated issues

Lung cancer patients visit the emergency room (ER) for cancer-related and -unrelated reasons more often compared to patients with other types of cancer. This results in increased admissions and deaths in the ER. In this study, we retrospectively reviewed the characteristics of lung cancer patients visiting the ER in order to optimize the utilization of emergency medical services and improve the patients' quality of life. Lung cancer patients visiting the ER of a single institution over a 2-year period (2010-2011) were analyzed. The patients' chief complaints and diagnoses at presentation in the ER were classified as cancer-related and -unrelated. Hospital admission, discharge from the ER, hospital mortality and survival of advanced lung cancer patients hospitalized through admission to the ER was surveyed. A total of 113 patients visited the ER 143 times. Seventy visits (49.0%) were cancer-related and 73 (51.0%) were cancer-unrelated. Respiratory symptoms, pain, gastrointestinal and neurological events and fever were the most common cancer-related issues recorded. With the progression of cancer stage, the number of ER visits, admissions, ambulance use and hospital mortalities increased. In visits due to cancer-unrelated issues, including infection, cardiovascular and gastrointestinal diseases, fever was the most common complaint. Emergency admissions of advanced-stage patients for cancer-related issues revealed a significantly shorter median survival time compared to that for patients admitted for cancer-unrelated issues (61 vs. 406 days, respectively; P<0.05). It was observed that outpatients with lung cancer visited the ER for cancer-related and -unrelated reasons with a similar frequency. Therefore, accurate differential diagnosis in the ER is crucial for patients with lung cancer.

Factors Affecting the B-Type Natriuretic Peptide Levels in Stroke Patients

Introduction: This study aims to evaluate the relationship between increased B-type natriuretic peptide (BNP) levels in stroke patients and clinical parameters such as age, sex, medical history, blood pressure, Glasgow Coma Score (GCS) and National Institutes of Health Stroke Scale (NIHSS). Materials and Methods: This is a prospective study of 123 stroke patients at the Emergency Department. The patients were divided into 3 groups according to the NIHSS scores. The analysis of the mean difference between continuous variables and plasma BNP levels was assessed using the Mann-Whitney and Kruskal-Wallis. Spearman correlation analysis was performed for BNP and other clinical parameters. Results: The BNP levels of patients who had a medical history of hyperlipidaemia, chronic obstructive pulmonary disease, diabetes mellitus and coronary artery disease were significantly higher than in patients without these diseases. Patients who had atrial fibrillation (AF) in their electrocardiography had significantly higher BNP levels than patients with sinus rhythm. A positive correlation was found between plasma BNP levels with age, blood urea nitrogen (BUN) and NIHSS and a negative correlation was found between plasma BNP levels and GCS. There was a significant difference between the BNP levels of NIHSS groups. Conclusion: We consider that plasma BNP levels could help us in interpreting the general clinical severity, functional capacity and clinical progress of stroke patients at the time of admission in the Emergency Department. In evaluating the high BNP levels in stroke patients, we must keep in mind that age, AF, BUN and medical history can affect the BNP levels. Key words: Emergency Department, Progress, Relationship

Medical and Economic Long-term Effects of B-Type Natriuretic Peptide Testing in Patients with Acute Dyspnea

Background: The objective of this prospective study was to assess the medical and economic long-term effects of using B-type natriuretic peptide (BNP) concentrations in the management of patients with acute dyspnea.

Methods: We performed follow-up analysis of the B-Type Natriuretic Peptide for Acute Shortness of Breath Evaluation, a randomized study including 452 patients who presented to the emergency department with acute dyspnea. Participants were randomly assigned to a diagnostic strategy involving the rapid measurement of BNP concentrations (n = 225) or standard assessment (n = 227). Mortality was assessed at 720 days, morbidity and economic data at 360 days.

Results: BNP testing induced several important changes in initial patient management, including a reduction in the initial hospital admission rate, the use of intensive care, and initial time to discharge. At 720 days, 172 deaths had occurred. Cumulative all-cause 720-day mortality was not different between the BNP group (37%) and the control group (36%, P = 0.6). Morbidity as reflected by days spent in-hospital at 360 days was significantly lower in the BNP group [median 12 days ([interquartile range 2–28 days)] compared with the control group [median 16 (7–32)] days, P = 0.025]. Functional status was similar in both groups. Economic outcome as quantified by total treatment cost at 360 days was significantly improved in the BNP group (mean $10 144 vs $12 748 in the control group, P = 0.008).

Conclusions: Rapid BNP testing in patients with acute dyspnea has no effect on long-term mortality. However, morbidity as quantified by days spent in-hospital and economic outcome are still improved at 360 days.

Cautionary tales in the clinical interpretation of studies of diagnostic tests

The use of investigational tests in making a diagnosis is a core activity of physicians and one that requires an understanding of the accuracy and usefulness of specific tests in discriminating between several diagnostic possibilities. Studies of diagnostic tests are frequently methodologically flawed and their results are often not well understood or applied in clinical practice. This article defines the performance characteristics of diagnostic tests, describes several commonly encountered deficiencies in study design which may invalidate reports of new diagnostic tests, and explains a Bayesian approach to interpreting test results in terms of disease probability.

The utility of B-type natriuretic peptide in the diagnosis of heart failure in the emergency department: a systematic review

BACKGROUND

Dyspnea is a common chief complaint in the emergency department (ED); differentiating heart failure (HF) from other causes can be challenging. Brain Natriuretic Peptide (BNP) is a new diagnostic test for HF for use in dyspneic patients in the ED. The purpose of this study is to systematically review the accuracy of BNP in the emergency diagnosis of HF.

METHODS

We searched MEDLINE (1975-2005) supplemented by reference tracking. We included studies that reported the sensitivity and specificity of BNP for diagnosing HF in ED patients with acute dyspnea. Two reviewers independently assessed study quality. We pooled sensitivities and specificities within five ranges of BNP cutoffs.

RESULTS

Ten studies including 3,344 participants met inclusion criteria. Quality was variable; possible verification or selection bias was common. No studies eliminated patients with obvious medical causes of dyspnea. Most studies used the Triage BNP assay; all utilized a clinical reference standard. Pooled sensitivity and specificity at a BNP cutoff of 100-105 pg/ml were 90% and 74% with negative likelihood ratio (LR) of 0.14; pooled sensitivity was 81% with specificity of 90% at cutoffs between 300 and 400 pg/ml with positive LR of 7.6.

CONCLUSION

Our analysis suggests that BNP has moderate accuracy in detecting HF in the ED. Our results suggest utilizing a BNP of less than 100 pg/ml to rule out HF and a BNP of greater than 400 pg/ml to diagnose HF. Many studies were of marginal quality, and all included patients with varying degrees of diagnostic uncertainty. Further studies focusing on patients with diagnostic uncertainty will clarify the real-world utility of BNP in the emergency management of dyspnea.