A 60-Year-Old Man Comes to the Physician for Preoperative Evaluation

A 60-year-old man comes to the physician for preoperative evaluation prior to right total knee replacement.  He continues to smoke half a pack of cigarettes daily and has a 25-pack-year history.  He reports mild shortness of breath when walking 4 blocks and up 2 flights of stairs and thinks that his dyspnea may have progressed slowly over the past 2 years.  He uses a cane and admits to walking slowly due to knee pain.  The patient has never been hospitalized but he gets bronchitis every winter that usually responds well to rescue albuterol.  He was diagnosed with asthma and mild emphysema 4 years ago and takes tiotropium and fluticasone/salmeterol daily.  His other medical problems include hypertension, degenerative joint disease, and anemia.  The patient takes hydrochlorothiazide and as-needed tramadol for pain.  His temperature is 36.7 C (98 F) , blood pressure is 120/76 mm Hg, pulse is 80/min, and respirations are 16/min and unlabored.  Oxygen saturation is 95% on room air.  General physical examination (including lung examination) is unremarkable. Laboratory study results are as follows:
Which of the following additional studies should be performed to make an appropriate risk assessment prior to the planned surgery?

A) 6-minute walk test
B) Arterial blood gas analysis
C) Cardiopulmonary exercise testing
D) No further testing is indicated
E) Pulmonary function testing