Abstract

Dyspnoea, defined as breathing difficulty or discomfort [1], is a common symptom of cardiorespiratory distress, seen in ~27% of the global population [2]. Furthermore, lung disease is becoming one of the most prevalent types of disease globally, with chronic obstructive pulmonary disease (COPD) expected to become the third commonest cause of death by 2030 [3]. This underlines the importance of ensuring accurate diagnostic testing of lung function. Investigations such as pulse oximetry, chest radiography, ECGs and spirometry are some of the recommended tests to investigate the cause of suspected dyspnoea [4]. When COPD is suspected, alongside patient history of exposure to harmful chemicals and lifestyle choices, one of the most crucial diagnostic tools for measuring lung function is the use of spirometry for dynamic lung volume measurements. Broadly, pulmonary function tests (PFTs) categorise lung pathologies into obstructive or restrictive patterns based on the forced expiratory volume in 1 s (FEV1) or forced vital capacity (FVC) or the ratio between FEV1/FVC. Examples of common obstructive pathologies include asthma, COPD and bronchiectasis; common restrictive diseases include pulmonary fibrosis, asbestosis and sarcoidosis [1].