Lack of Evidence Regarding Markers Identifying Acute Heart Failure in Patients with COPD: An AI-Supported Systematic Review.

Background: Due to shared symptoms, acute heart failure (AHF) is difficult to differentiate from an acute exacerbation of COPD (AECOPD). This systematic review aimed to identify markers that can diagnose AHF underlying acute dyspnea in patients with COPD presenting at the hospital. Methods: All types of observational studies and clinical trials that investigated any marker's ability to diagnose AHF in acutely dyspneic COPD patients were considered eligible for inclusion. An AI tool (ASReview) supported the title and abstract screening of the articles obtained from PubMed, Scopus, Web of Science, the Cochrane Library, Embase, and CINAHL until April 2023. Full text screening was independently performed by two reviewers. Twenty percent of the data extraction was checked by a second reviewer and the risk of bias was assessed in duplicate using the QUADAS-2 tool. Markers' discriminative abilities were evaluated in terms of sensitivity, specificity, positive and negative predictive values, and the area under the curve when available. Results: The search identified 10,366 articles. After deduplication, title and abstract screening was performed on 5,386 articles, leaving 153 relevant, of which 82 could be screened full text. Ten distinct studies (reported in 16 articles) were included, of which 9 had a high risk of bias. Overall, these studies evaluated 12 distinct laboratory and 7 non-laboratory markers. BNP, NT-proBNP, MR-proANP, and inspiratory inferior vena cava diameter showed the highest diagnostic discrimination. Conclusion: There is not much evidence for the use of markers to diagnose AHF in acutely dyspneic COPD patients in the hospital setting. BNPs seem most promising, but should be interpreted alongside imaging and clinical signs, as this may lead to improved diagnostic accuracy. Future validation studies are urgently needed before any AHF marker can be incorporated into treatment decision-making algorithms for patients with COPD. Protocol Registration: CRD42022283952.

Fluorimetric analysis of hydrogen peroxide with automated measurement.

UNLABELLED: In the pathophysiology of chronic obstructive pulmonary disease (COPD) oxidative stress plays an important role, which can be determined by measuring hydrogen peroxide. Hydrogen peroxide can be measured fluorimetrically in exhaled breath condensate (EBC), however, not standardized. The objective of this study was to investigate the sensitivity and reproducibility of measuring the hydrogen peroxide concentration in EBC of COPD patients using an automated flow injection device with varying flow rates and measurements. METHODS: 10 microl p-hydroxyphenylacetic acid (1.0 mmol/l) and 10 microl horseradish peroxidase (15 mU/l) were manually added to several hydrogen peroxide containing solutions and EBC of patients suffering from COPD. The fluorescence of the reaction product was measured with an automated sampler, flow injection and scanning fluorescence detector, excitation wave 295 nm, emission wave 405 nm, at different flow rates. The degree of fluorescence was expressed as either the area under the curve or the peak value. RESULTS: A flow rate of 1 ml/min gave the best results. There were no significant differences in calibration curves or detection limits using area under the curve or peak value (respectively 0.007 and 0.005 micromol/l) (flow rate 1.0 ml/min). The mean volume of EBC was 2.8 ml, the mean hydrogen peroxide concentration in the patient group was 0.2 micromol/l and the standard deviation of duplication 0.009 micromol/. CONCLUSIONS: The low detection limit may be explained by using flow injection, because it measures the fluorescence over a period of time. It is important to choose an appropriate flow rate. There is no difference in the detection limit between measuring the fluorescence as area under the curve or as peak value.