Acute cardiothoracic and respiratory diseases frequently remain a challenge to diagnose and
differentiate in the emergency setting. The main diseases that manifest with chest pain include
ischemic heart disease, myocarditis, acute pericarditis, aortic dissection/rupture and pulmonary
embolism (PE). Diseases that primarily present with dyspnea include heart failure (HF), acute
respiratory distress syndrome (ARDS), pneumonia, asthma exacerbations and chronic obstructive
pulmonary disease. Pre-test probabilities of clinical findings play a vital part in diagnostic
decisions, and the use of a Bayesian approach to these greatly improves the ability to stratify
patients more accurately. However, blood tests (biomarkers) are increasingly used to assist in rapid
decision-making in the emergency setting in combination with imaging methods such as chest
radiograph, ultrasound and increasingly computed tomography, as well as physiological tests such
as the electrocardiogram in addition to physical examination. Specific tests for ischemic heart
disease and myocarditis (cardiac troponins), HF (B-type natriuretic peptide [BNP] and NTproBNP),
aortic dissection (smooth muscle markers) and PE (D-dimer) have been developed.
Surfactant protein-D and interleukin-8 have been developed for ARDS. Additionally, circulating
microRNAs have emerged as promising biomarker candidates in cardiovascular disease. With this
increasing array of biochemical markers to aid in the diagnosis of chest diseases presenting with
chest pain and dyspnea, we herein review the clinical usefulness of these markers, in particular in
differentiating cardiac from pulmonary diseases. A symptom-oriented assessment as necessary for
use in the critical setting is described in addition to discussion of individual biomarkers.