Pulmonary function testing is important in many clinical situations. It is indicated for evaluation of patients with history or symptoms suggestive of lung disease (eg, cough, wheezing, dyspnea, chest pain), response to bronchodilator therapy, and when risk factors for lung disease are present in patients with occupational exposure to agents with known lung toxicity. It can also be used to assess severity and progression of lung diseases, such as asthma, chronic obstructive lung disease, and various restrictive diseases. 

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Spirometry is used to measure forced expiratory flow rates and volumes. It is the most commonly used pulmonary function test and is useful in the evaluation of patients with respiratory symptoms or risk factors for respiratory disease.