The indications for testing depend on the characteristics of the patient and on the planned surgical procedure. Table 10-1 lists the characteristics of the patient and the surgical procedures for which testing is recommended. We believe that preoperative testing should be done on all patients scheduled for any lung resection. We also recommend testing before upper abdominal and thoracic operation in patients with known lung disease and for smokers older than 40 (up to one-fourth of such smokers have abnormal lung function) because these procedures present the greatest risk for patients with impaired lung function. When a significant abnormality is detected, appropriate perioperative intervention may reduce the morbidity and mortality related to operation. Such intervention includes the use of bronchodilators and postoperative use of incentive spirometry. Although the benefit of smoking cessation before operation has not been proved, it is common practice to recommend that smokers, especially those with impaired lung function, stop smoking several weeks before surgery.

For patients with obstructive disorders, spirometry before and after bronchodilator therapy may be sufficient preoperative testing. However, for those with moderate-to-severe airway obstruction, arterial carbon dioxide tension (blood gases) should also be measured. Table 10-2 lists general guidelines for interpreting the test results in terms of risk to the patient.

The risk of surgical procedures for patients with restrictive disorders is less well studied than that for patients with obstructive disorders. We recommend following similar guidelines, but keeping in mind the cause of
restriction (lung parenchymal disease, chest wall disorders, muscle weakness, and obesity).