Lung diseases, such as chronic obstructive pulmonary disease (COPD), also called emphysema, affect an individual's ability to tolerate surgical procedures. Lung function, the ability of the lungs to provide oxygen to the body and remove carbon dioxide, is a critical factor in an individual's perioperative (the time period surrounding an operation) well-being. To reduce risk of pulmonary problems during and after an operation, your doctors may order tests and medications. Doctors involved in preparing you for a procedure may include your primary care physician, your surgeon, your anesthesiologist, and other specialists including pulmonologists (doctors with specialized education in treating lung diseases). The type of anesthesia you receive may depend on your lung function. Sometimes persons with severe lung disease need to remain on a ventilator (breathing machine) after surgery; others may require oxygen and respiratory treatments afterward. COPD also increases the risk of pneumonia after surgery. The May 16, 2007, issue of JAMA includes an article about evaluating COPD and other lung diseases in preparation for surgical procedures.