Answer:

The main goal of preoperative evaluation is to identify in advance those at risk for major postoperative complications and optimize their functional status. The first step should include a complete history, physical examination, and laboratory tests (e.g., complete blood count, basic metabolic profile, coagulation study, electrocardiogram, chest radiography, and computed tomographic imaging). A positive smoking history, especially if current, and in the presence of cough, sputum production, orthopnea, and dyspnea, requires further investigation. An abnormal exercise tolerance, such as the inability to climb at least three flights of stairs or walk for 6 minutes, may indicate a compromised cardiorespiratory function and the inability to tolerate the stress of anesthesia and surgery. In this subgroup of patients, further cardiopulmonary function testing may be indicated to define cardiac disease or customize a prehabilitation program. A brief review of symptoms, physical limitations, interval changes, and airway anatomy is usually performed before entering the operating room.

In addition to routine preoperative testing, patients scheduled for lung resection usually undergo pulmonary function testing to help define the relative risks of the planned resection. Respiratory function can be assessed by the following:

• Respiratory mechanics is evaluated via forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), and the ratio between residual volume and total lung capacity (RV/TLC). Flow-volume loops may be helpful to document the location of the obstruction (small vs. large airway) and its severity. Post-bronchodilator FEV₁ and FEV₁/FVC paired with clinical symptoms are used to determine the severity of COPD.

• Cardiopulmonary reserve evaluation includes maximal oxygen uptake (O_2max), stair climbing, 6-minute walk, and shuttle walk. In case of poor performance in these tests, cardiopulmonary exercise tolerance testing (CPET) can be added to identify patients who are not surgical candidates. _2max is the gold standard for aerobic capacity and cardiorespiratory fitness. Patients with _2max value less than 10 mL/kg/min are at increased risk for postoperative morbidity and mortality.

• Lung parenchymal function include diffusing lung capacity for carbon monoxide (DLCO), PaO₂, and partial pressure of arterial carbon dioxide (PaCO₂). Predicted postoperative DLCO and FEV₁ less than 40% to 44% are significant independent predictors for increased postoperative morbidity and mortality.

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