Introduction

Dyspnoea has many causes which vary from benign and innocent to conditions which carry significant morbidity and mortality. Classification can be based upon either:

• The organ system in which the pathology lies
• The acuity/time-critical nature of the cause

It can be a diagnostic challenge for the emergency physician to determine the primary cause in a patient presenting with dyspnoea because of the broad range of pathophysiology which can produce this symptom.  One of the key steps is determining the primary physiological system involved and, in particular, whether it is the respiratory system, the cardiovascular system, neither or both. It has been estimated that 85% of all cases of dyspnoea are accounted for by asthma, cardiac failure, COPD, pneumonia, interstitial lung disease and psychogenic disorder [5].

Learning Bite

There is a broad range of pathophysiology which can cause dyspnoea; one of the key initial steps for the emergency physician is to determine the primary physiological system involved.