Establishing new biochemical markers in the differential diagnostics and risk stratification in heterogeneous patient collectives is becoming more and more important. The markers should be objective, reliable, reproducible, quick and cost effective as well as specific and sensitive. Concerning the differential diagnostics of "dyspnea", NT-pro-BNP plays the most important role for the evaluation of a cardiac origin. However, a corresponding biochemical marker for pulmonary stress is lacking. The aim of the study at hand therefore was the evaluation of surfactant protein B in the differential diagnostics of pulmonary and cardiac diseases.

Inclusion Criteria:

• patients presenting with dyspnea and giving informed consent

Exclusion Criteria:

• outpatients
• lack or doubt of legal competence
• indication for mechanical ventilation
• pregnancy
• palliative patients
• CPAP/LTOT
• BMI > 30 kg/m2
• sepsis
• anemia
• dialysis

patients presenting with the symptom "dyspnea" in a university hospital emergency room