In patients presenting with acute dyspnea in a pre-hospital setting, the early and correct diagnosis may present a significant clinical challenge. Physical examination, chest radiography, electrocardiography, and standard biological tests often fail to accurately differentiate heart failure (HF) from pulmonary causes of dyspnea. Timely differentiation of HF from other causes of dyspnea may permit the early institution of appropriate medical therapy. Brain natriuretic peptide (BNP) and amino-terminal pro-brain natriuretic peptide (NT-proBNP) have been proposed as early markers of HF and demonstrated to be useful for diagnosing and excluding HF in the emergency department. A combination of BNP or NT-proBNP testing and standard clinical assessment has been suggested to be superior to either tool used in isolation. Some previous studies have also suggested that quantitative capnometry (QC) may be useful in differentiating between cardiac and obstructive causes of respiratory distress. Therefore, the investigators hypothesized that a new combination of NT-proBNP testing, standard clinical assessment, and partial pressure of end-tidal CO2 (PetCO2) would optimize evaluation and differentiation of acute dyspnea in a pre-hospital setting.

The aim of this study was to determine the accuracy of combination of QC, NT-proBNP, and clinical assessment in differentiating acute HF from obstructive pulmonary disease (COPD/asthma) as a cause of acute dyspnea in pre-hospital emergency setting.

Inclusion Criteria:

• patient had to present with shortness of breath as the primary complaint (defined as either the sudden onset of dyspnea without history of chronic dyspnea or an increase in the severity of chronic dyspnea)

Exclusion Criteria:

• age <18 years

• history of renal insufficiency, trauma, severe coronary ischemia (unless patient's predominant presentation was dyspnea), and other causes of dyspnea:

  • pneumonia
  • pulmonary embolism
  • carcinoma
  • pneumothorax
  • pleural effusion
  • intoxications (drugs)
  • anaphylactic reactions
  • upper airway obstruction
  • bronchial stenosis
  • gastroesophageal reflux disorder

• according to the history, clinical status, and additional laboratory tests available in pre-hospital setting (D-dimer, troponin, C-reactive protein)

During the period of the study, 546 consecutive patients with acute dyspnea were treated by emergency teams (emergency physician, register nurse, and medical technician/driver in an ambulance-car or at pre-hospital emergency medical center). After pre-hospital care, all patients were admitted to the University Clinical Center Maribor and followed until discharge.

To be eligible for the study, a patient had to present with shortness of breath as the primary complaint (defined as either the sudden onset of dyspnea without history of chronic dyspnea or an increase in the severity of chronic dyspnea).