The common chronic respiratory disorders diagnosed in primary care—asthma and chronic obstructive pulmonary disease (COPD)—are both characterised by airway obstruction. In asthma, this varies markedly with time and treatment, while in COPD, the airway obstruction is typically fixed and permanent. Some people have fixed obstruction with some degree of reversibility—the so-called asthma COPD overlap syndrome (ACOS).

This article will cover the use of peak flow monitoring and microspirometry in primary care as aids to the objective demonstration of airway obstruction, reversible or otherwise.