Preoperative evaluation of the prospective thoracic surgical patient is a complex process, as patients presenting for major noncardiac thoracic surgery today tend to be older, have underlying chronic obstructive lung disease, and often have multiple comorbidities. Pulmonary and cardiovascular complications occur frequently in the postoperative period and should be aggressively identified and mitigated where possible. The ability to predict and stratify which patients are at a higher risk of complications allows appropriate patient selection and helps guide operative approaches. Preoperative evaluation, therefore, serves two purposes: (a) determining the risk and morbidity associated with the proposed surgical procedure and (b) identifying any patient conditions or factors that could be addressed in the preoperative period to decrease the risk of morbidity and mortality.¹

There is no substitute for a thorough history and physical examination combined with the sound clinical judgment of an experienced physician. There are several specific components in the history of a potential thoracic surgical patient that should be investigated. These important components include presenting symptoms, previous diagnosis of cardiopulmonary disease, comorbid conditions such as diabetes mellitus, renal and liver dysfunction, current medications and allergies, tobacco use, and alcohol use.¹ As the most frequent complications are pulmonary and cardiovascular, the history should focus on these areas.

The physical examination should likewise focus on several signs that indicate important comorbidities. Examination begins with an assessment of overall appearance, looking especially for evidence of cachexia and generalized wasting. Cervical and supraclavicular lymphadenopathy can indicate metastatic disease. Cardiovascular examination should note murmurs (valvular disease), arrhythmias (atrial fibrillation), and presence of peripheral edema (congestive heart failure). Pulmonary examination should note respiratory rate, use of accessory respiratory muscles, and presence of wheezing or rales. Abdominal examination can confirm the presence of regional tenderness, organomegaly, masses, or adenopathy. The extremities should be examined for equality of pulses, cyanosis, or clubbing. Neurologic examination should focus on motor strength and gait, both of which are important because deficits can affect postoperative mobilization and rehabilitation.

Following the history and physical examination, it is critical to estimate the patient’s performance and functional status. Performance status assesses the patient’s ability to partake in activities of everyday life. The two most common methods are the Karnofsky score² and Zubrod (Eastern Cooperative Oncology Group [ECOG]) system.³ Patients with a Karnofsky score of 80 to 100 percent or an ECOG score of 0 to 1 have essentially normal risk of morbidity and mortality. As the performance status declines, the operative risk increases.

The functional status assesses the patient’s current ability to perform physical activity. This can be done with a physical test of locomotion (e.g., 6-min walk or stair climbing), cardiopulmonary exercise testing (CPEx), or self-administered questionnaires such as the Duke Activity Status Index (DASI).⁴ A healthy adult should be able to walk at least 1600 ft in 6 min and climb at least five flights of stairs. An alternative to stair climbing is the shuttle walk. Patients who are unable to perform at least 25 shuttles are considered a prohibitive operative risk because this equates to a maximal oxygen uptake of less than 10 mL/kg/min.⁵ Oxygen desaturation during testing is considered significant when the Spo₂ drops by 4 percent or more with activity.^6,7

Standard blood work should include a complete blood count, electrolyte panel, and clotting parameters. Liver function tests and serum calcium levels should be checked in patients with suspected or confirmed malignancy.

Pulmonary function testing is the cornerstone of risk assessment for patients undergoing pulmonary resection. Unfortunately, no single pulmonary function test can perfectly predict the likelihood of postoperative morbidity or mortality. Slinger and Darling⁸ have therefore proposed a simple “3-legged stool” of prethoracotomy respiratory assessment that provides a more robust foundation for preoperative respiratory assessment. This algorithm evaluates pulmonary function in three areas: respiratory mechanics (forced expiratory volume in 1 s [FEV₁]), parenchymal function (diffusing capacity for carbon monoxide [DLCO]), and cardiopulmonary interaction (Vo₂max).

In 2007, the American College of Chest Physicians stated that a patient may proceed directly to surgical resection with no further pulmonary testing if the preoperative FEV₁ is greater than 2 L for pneumonectomy candidates and greater than 1.5 L for lobectomy candidates.⁹ In addition to providing an estimate of operative risk, preoperative values of FEV₁ and DLCO can be used to calculate predicted postoperative values for both FEV₁ (ppo-FEV₁) and DLCO (ppo-DLCO), which are themselves predictors of operative risk. The ppo-FEV₁ can be calculated using the equation of ppo-FEV₁ = FEV₁ × (1 − [segments resected/19]/100).¹⁰ The ppo-DLCO is calculated using a similar equation.¹¹ Patients with postoperative FEV₁ or a postoperative DLCO greater than 40 percent are generally considered low-risk surgical patients. Although no single test can unilaterally predict the likelihood of major postoperative morbidity, ppo-DLCO has been shown to be a strong predictor of postoperative morbidity and mortality following pulmonary resection.¹²

CPEx is recommended when the ppo-FEV₁ or ppo-DLCO is less than 40 percent, or if the product of ppo-FEV₁ × ppo-DLCO is less than 1650. The most commonly used result of CPEx is the MVo₂, which is the most specific predictor of postoperative pulmonary complications following pulmonary resection.¹³ Patients with an MVo₂ greater than 15 to 20 mL/kg/min are at low or “acceptable” risk for postoperative morbidity or mortality. Conversely, a patient is considered high risk for surgery if the MVo₂ is less than 10 to 12 mL/kg/min.¹⁴

It is imperative that any patient being considered for major noncardiac thoracic surgery also undergo assessment of cardiovascular risk, as cardiac complications are the second most common cause of morbidity and mortality in the thoracic surgical patients. In general, patients who are on any cardiac medication have a history of a cardiac condition (prior myocardial infarction, congestive heart failure, diabetes, and cerebrovascular disease), or are unable to climb more than two flights of stairs should be referred for cardiology evaluation. The American Heart Association recommends noninvasive testing as a minimum for such patients, with additional invasive testing and intervention as indicated.