The Physiologic Evaluation of Patients With Lung Cancer Being Considered for Resectional Surgery*

The preoperative physiologic assessment of a patient being considered for surgical resection of lung cancer must consider the immediate perioperative risks from comorbid cardiopulmonary disease, the long-term risks of pulmonary disability, and the threat to survival due to inadequately treated lung cancer. As with any planned major operation, especially in a population predisposed to atherosclerotic cardiovascular disease by cigarette smoking, a cardiovascular evaluation is an important component in assessing perioperative risks. Measuring the FEV₁ and the diffusing capacity of the lung for carbon monoxide (Dlco) measurements should be viewed as complementary physiologic tests for assessing risk related to pulmonary function. If there is evidence of interstitial lung disease on radiographic studies or undue dyspnea on exertion, even though the FEV₁ may be adequate, a Dlco should be obtained. In patients with abnormalities in FEV₁ or Dlco identified preoperatively, it is essential to estimate the likely postresection pulmonary reserve. The amount of lung function lost in lung cancer resection can be estimated by using either a perfusion scan or the number of segments removed. A predicted postoperative FEV₁ or Dlco < 40% indicates an increased risk for perioperative complications, including death, from lung cancer resection. Exercise testing should be performed in these patients to further define the perioperative risks prior to surgery. Formal cardiopulmonary exercise testing is a sophisticated physiologic testing technique that includes recording the exercise ECG, heart rate response to exercise, minute ventilation, and oxygen uptake per minute, and allows calculation of maximal oxygen consumption ( V˙o₂max). Risk for perioperative complications can generally be stratified by V˙o₂max. Patients with preoperative V˙o₂max > 20 mL/kg/min are not at increased risk of complications or death; V˙o₂max < 15 mL/kg/min indicates an increased risk of perioperative complications; and patients with V˙o₂max < 10 mL/kg/min have a very high risk for postoperative complications. Alternative types of exercise testing include stair climbing, the shuttle walk, and the 6-min walk. Although often not performed in a standardized manner, stair climbing can predict V˙o₂max. In general terms, patients who can climb five flights of stairs have V˙o₂max > 20 mL/kg/min. Conversely, patients who cannot climb one flight of stairs have V˙o₂max < 10 mL/kg/min. Data on the shuttle walk and 6-min walk are limited, but patients who cannot complete 25 shuttles on two occasions will have V˙o₂max < 10 mL/kg/min. Desaturation during an exercise test has been associated with an increased risk for perioperative complications. Lung volume reduction surgery (LVRS) for patients with severe emphysema is a controversial procedure. Some reports document substantial improvements in lung function, exercise capability, and quality of life in highly selected patients with emphysema following LVRS. Case series of patients referred for LVRS indicate that perhaps 3 to 6% of these patients may have coexisting lung cancer. Anecdotal experience from these case series suggest that patients with extremely poor lung function can tolerate combined LVRS and resection of the lung cancer with an acceptable mortality rate and good postoperative outcomes. Combining LVRS and lung cancer resection should probably be limited to those patients with heterogeneous emphysema, particularly emphysema limited to the lobe containing the tumor.