Inclusion Criteria:  Patients will be included, if they suffer from acute dyspnoea and at least one of the two following signs of respiratory failure:  Respiratory rate >20 breaths per minute Peripheral oxygen saturation without oxygen supplementation <90%  Exclusion Criteria:  under the age of 18 if PEU will lead to a delay of live-saving treatment or transportation if patient rejects the PEU, the patient will be excluded