Although the field of thoracic surgery has been dramatically altered by the development of new technologies, both in imaging and in therapeutics, the history and physical examination remain the most important components of the preoperative evaluation. There is no substitute for a careful history and physical examination when it is performed by an experienced clinician. Table 4-1 highlights the important components of the patient history. Although age is a risk factor for perioperative morbidity and often a factor used by both patient and physician to assess the risk and potential benefit of surgery,12-15 much of this added risk is a consequence of the accompanying comorbidities. Recent publications suggest age alone is not an independent factor predicting mortality. Chambers et al.16 showed that 30-day mortality rates, hospital length of stay, and global quality of life (QoL) were not influenced by age (age <70 years vs. age ≥70 years). Similar findings were found by Okami et al.,17 who reported that octogenarian patients with stage I lung cancer had reasonable long-term outcomes.
Table 4-1Important Components of the History in Preoperative Evaluation ||Download (.pdf) Table 4-1Important Components of the History in Preoperative Evaluation
Presenting symptoms and/or circumstances of diagnosis
Prior diagnosis of pulmonary or cardiac disease
Comorbid conditions such as diabetes mellitus, liver disease, renal disease
Prior experiences with general anesthesia and surgery
Cigarette smoking: never, current, ex-smoker (If ex-smoker, when did the patient stop?)
Inventory of functional capacity of patient
Alcohol use, including prior history of withdrawal syndromes
Although many of the elements of the history are self-explanatory, several bear further exposition.
Patients who are current smokers should be advised to quit. Importantly, there is a better chance of achieving smoking cessation in COPD patients after a lung cancer diagnosis (over 50%)18 compared with smokers without this diagnosis, and better survival has been reported for those who quit after a diagnosis of early-stage lung cancer versus those who continue to smoke.19 In addition, smokers compared with nonsmokers are at greater risk of postoperative complications including delayed wound healing, pulmonary and cardiovascular complications, and mortality as shown in randomized trials.20 A meta-analysis found a relative risk reduction of 41% for prevention of postoperative complications with trials of 4 weeks smoking cessation having the largest treatment effect.20 The ideal time for quitting is still controversial. A small number of observational studies have described a paradoxical increase in the risk of postoperative complications in patients who quit within 2 months of surgery,21 which may be related to a selection bias (sicker subjects at increased risk of complications were more likely to quit).20 A large retrospective study of in-hospital outcomes for 7990 primary lung cancer resections found an increased mortality for current smokers with adjusted odd ratio (AOR) 3.5 and confidence intervals (CIs) 1.1 to 11 and for those who quit for less than a month prior to surgery (AOR: 4.6, CI: 1.2–18).22 However, there was no difference in mortality between current smokers and those who quit within a month. Therefore, it is recommended that patients be advised to quit smoking before surgery regardless of the time and, if possible, allow for a month of smoking abstinence to reduce the risk of postoperative complications to the level of a nonsmoker.23
Pharmacotherapy improves the likelihood of successful abstinence. Combining the use of nicotine replacement therapy and counseling has a higher rate of success.24 Currently available pharmacotherapies include nicotine replacement therapy, bupropion, and nicotine agonist, varenicline.24
A critical component of the preoperative evaluation is the assessment of the patient's functional status. It is well established that there is a broad range of symptoms and functional impairments in patients with similar pulmonary function test results.25 As described below, functional capacity is a major determinant of operative candidacy and an important component of the decision algorithm for both the pulmonary and cardiac elements of the preoperative evaluation. A number of approaches have been taken to determine functional capacity. These include questionnaires, tests of locomotion (e.g., the 6-minute walk or stair climbing tests), and cardiopulmonary exercise testing (CPET) (discussed below).
Although most patients being evaluated for thoracic surgery have a normal or near-normal physical examination, it is an important component of the evaluation. The examination of the patient should include an assessment of general overall appearance, including signs of wasting. Respiratory rate and the use of accessory muscles of respiration should be noted. Careful observation of the patient as he or she moves around the examining room, climbs onto the examination table, lies down, and sits up can provide important information about functional status. Examination of the head and neck should include assessment of adenopathy and focal neurologic deficits or signs, particularly Horner syndrome in patients with a Pancoast tumor. The pulmonary examination should include an assessment of diaphragmatic motion (by percussion) and note of any paradoxical respiratory pattern in the recumbent position. The presence of rales should raise the possibility of pneumonia, heart failure, or pulmonary fibrosis. The cardiac examination should include assessment of a third heart sound to suggest left ventricular failure, murmurs to suggest valvular lesions, and an accentuated pulmonic component of the second heart sound to suggest pulmonary hypertension. The heart rhythm and the absence or presence of any irregular heartbeats should be noted. The abdominal examination should note liver size, presence or absence of palpable masses or adenopathy, and any tenderness. The examination of the extremities should note any edema, cyanosis, or clubbing. The presence of clubbing should not be attributed to COPD and raises the possibility of intrathoracic malignancy or congenital heart disease. The patient's gait should be observed both as an assessment of neurologic function and to confirm the patient's ability to participate in postoperative mobilization.
Pulmonary rehabilitation improves exercise capacity in patients with moderate and severe COPD. This intervention can improve the exercise performance in patients with severely reduced exercise capacity (<10 mL/kg/min or nonsurgical candidates) to a potentially resectable level (mean improvement 2.8 mL/kg/min).26 However, the recommended duration of these programs (6–8 weeks) restricts the implementation of this intervention in the great majority of cases. Although there is evidence that the length of hospital stay could be shortened by 3 days with this intervention,27 there is scarce information of other beneficial effects. Therefore, the use of pulmonary rehabilitation before surgical treatment for lung cancer may have a role limited to those patients with much reduced exercise capacity and early-stage lung cancer.
It is a reasonable practice to check electrolytes, renal function, and clotting parameters and to order a complete blood count as part of the preoperative assessment. In patients with known or suspected malignancy, liver function tests and serum calcium also should be checked. Arterial blood gases may have a role in documenting a patient's baseline for future comparison, but the previously held view that resting hypercarbia (elevated Pco2) in isolation is a contraindication to thoracic surgery is no longer valid.28
The options for radiologic imaging are reviewed in Chapter 3 and are covered with specificity in the surgical technique chapters of this text.
Pulmonary Function Testing
The utility of preoperative pulmonary function testing in part depends on the type of operative procedure being planned. Preoperative pulmonary function testing is unlikely to contribute to the preoperative evaluation of patients undergoing mediastinoscopy, drainage of pleural effusions, or pleural biopsy when there is no prior history of lung disease or unexplained dyspnea. For patients who report dyspnea, significant functional limitation, prior pulmonary resection, or a diagnosis of COPD with a recent change in functional capacity; however, pulmonary function testing is an appropriate component of the evaluation.
Preoperative pulmonary function testing is mandatory for patients who are being considered for pulmonary parenchymal resection. Although a number of pulmonary function tests have been examined in this setting, two have emerged with predictive value for postoperative complications. These are the forced expiratory volume in 1 second (FEV1) measured during spirometry and the diffusing capacity of the lung for carbon monoxide (DLCO). Either of these values can be used to provide an estimate of the risk of operative morbidity and mortality. In addition, they are used to calculate the predicted postoperative (ppo) values for FEV1 and DLCO (ppo-FEV1 and ppo-DLCO, respectively).29
Prediction of Postoperative Lung Function
The ppo lung function has been demonstrated to be an important predictor of operative risk. In general, the available methods for calculating postoperative lung function underestimate actual measured lung function once the patient has recovered from surgery.29 The two common approaches for calculating postoperative lung function are simple calculation (recommended for lobectomies) and regional assessment of lung function (recommended for pneumonectomy).30
Simple calculation is based on the assumption that the patient's lung function is homogeneously distributed. The calculation requires knowledge of the number of segments to be resected and the preoperative value. For FEV1, the formula is ppo-FEV1 = preoperative FEV1 × (1 - (number of unobstructed segments to be resected/total number of unobstructed segments)). The calculation is similar for DLCO. For most patients, this simple approach to calculation is sufficient and, as mentioned earlier, results in a conservative prediction of pulmonary function after recovery from surgery. Traditionally, a ppo-FEV1 or DLCO of 40% or lower was used to categorize a patient as a high risk for lung surgery. However, advances in perioperative management and surgical techniques (concomitant lung volume reduction and minimally invasive surgery) have further reduced the lower ppo limit to 30% in selected cases.29 For patients with ppo-FEV1 or ppo-DLCO values <40%, the predicted postoperative product (PPP) may be used (where PPP = ppo-FEV1 × ppo-DLCO). Patients with PPP<1650 have been shown to have a high risk of operative mortality.31
In certain situations, simple calculation does not predict postoperative lung function accurately. The clinical situations for which regional assessment of lung function is indicated are summarized in Table 4-2. A number of approaches have been used to attempt to assess the regional distribution of lung function, including lateral position testing, bronchospirometry, quantitative radionuclide ventilation/perfusion scanning, and quantitative CT scanning. Although quantitative CT scanning holds promise in this regard, the current standard test is radionuclide scanning. Typically, the data from quantitative radionuclide perfusion scans are reported as the percent function contributed by the six lung regions: upper third, middle third, and lower third of each hemithorax. These data, combined with the preoperative lung function value and the location and planned extent of surgical resection, permit a calculation to be made of the ppo value. Using the quantitative V̇/Q̇ data, the ppo-FEV1 or ppo-DLCO is calculated as ppo value = baseline value × (100 – percent perfusion in the region of planned resection)/100.
Table 4-2Indications for Preoperative Assessment of the Regional Distribution of Lung Function ||Download (.pdf) Table 4-2Indications for Preoperative Assessment of the Regional Distribution of Lung Function
Significant airflow obstruction on spirometry (FEV1 <65% of predicted and FEV1/FVC <0.70)
Reduced exercise capacity: 35%–75% or 10–20 mL/kg
Significant pleural disease
Known or suspected endobronchial obstruction
Central lung mass or planned pneumonectomy
History of prior lung resection
Presence of lobar collapse or major atelectasis on imaging
Assessment of Functional Capacity
In many ways, assessment of functional capacity is the most critical component of the preoperative assessment in patients considering thoracic surgery. It is a decisive factor for determining whether further cardiac evaluation is needed (as outlined below) and is the major factor for determining the operative suitability of patients with significant impairment of lung function. As outlined at the beginning of this chapter, such patients are “overrepresented” in this population by virtue of the additional independent risk engendered by obstructive lung disease. As outlined in Table 4-3, there are reasonable guidelines for identifying patients at low risk for morbidity and mortality after thoracic surgery. Although lung function and calculation of anticipated postoperative function can fairly reliably identify patients at low risk, these factors do less well at defining which high-risk patients have prohibitive risk. For further refinement of risk in this group, an assessment of functional capacity needs to be obtained.
Table 4-3Risk Assessment for Pulmonary Surgery ||Download (.pdf) Table 4-3Risk Assessment for Pulmonary Surgery
|HIGHER RISK ||LOWER RISK |
|Higher extent of resection ||FEV1 >2 L for pneumonectomy; >1 L for lobectomy; >0.6 L for segmentectomy |
|Poor exercise performance ||Predicted postoperative FEV1 >30%–40% of predicted (pneumonectomy > lobectomy > wedge resection) |
|Low predicted postoperative FEV1 ||Stair climbing >5 flights for pneumonectomy; 3 flights for lobectomy |
|Low predicted postoperative DLCO ||Cycle ergometry >83 W |
|High Pco2 or age >70 yrs (controversial) ||Predicted postoperative DLCO >40% of predicted |
Maximal oxygen uptake >15–20 mL/kg/min
Although the clinician can derive an assessment of functional capacity based on the initial history and physical examination, for patients whose history suggests significant functional impairment or who have abnormal pulmonary function tests (FEV1 or DLCO <80% predicted), a test of performance is indicated.
Performance Tests of Functional Capacity
Historically, clinicians have used tests of ambulation as a semiquantitative assessment of functional capacity. Early teaching in the field used stair climbing as a measure of functional reserve, establishing a threshold of performance that connotes acceptable risk. This test has held up remarkably well over time. Patients able to climb three flights of stairs (54 steps) have adequate reserve for lobectomy and approximately five flights for a pneumonectomy.11,32,33 A recent report of 640 patients who underwent lobectomy or pneumonectomy confirmed the utility of stair climbing in assessing postoperative risk; they observed a significant decrease in the risk of postoperative complications and mortality in the group of patients who climbed 22 m or more (110 steps) compared with those who climbed 12 m (approximately 60 steps in the United States).34
More recently, much of the literature has focused on the use of incremental CPET, with expired gas analysis, to quantify cardiopulmonary reserve. Such testing that can be performed with either a treadmill or cycle ergometer (preferred method) allows quantification of maximal exercise capacity, expressed as maximal oxygen uptake rate (MVo2). This can be expressed as an absolute value in units of milliliters of O2 per kilogram of body mass per minute or as a percent of predicted. Studies using this approach have established that patients with an MVo2 of greater than 15 to 20 mL/kg/min have an acceptable risk for pulmonary resection.29,30 Conversely, patients with an MVo2 of less than 10 mL/kg/min have a high risk of postoperative complications and perioperative mortality.29
Most recently, reports have used the ppo exercise capacity (ppo-MVo2) as a predictor of postoperative risk. This value is calculated using the results of both the CPET and quantitative lung function testing in a manner analogous to that used to calculate ppo-FEV1. A ppo-MVo2 of less than 10 mL/kg or 35% predicted is associated with a high postoperative mortality.29
Not surprisingly, in addition to being predictive of mortality, functional capacity is also predictive of perioperative complications and hospital length of stay.35
There is no consensus as to the sequence of testing one should follow in evaluating patients for thoracic surgery. The American Thoracic Society (ATS),36 American College of Chest Physicians (ACCP),30 and European Respiratory Society/European Society of Thoracic Surgery29 have published guidelines for preoperative evaluation of patients with COPD that recommend several approaches to this situation. They differ primarily in respect to whether exercise testing or quantitative lung function assessment is the first test performed in patients with abnormal lung function and/or a history suggestive of a low functional capacity. The ATS has published a validated algorithm that incorporate these concepts (Fig. 4-1) and a second more simplified algorithm that includes stair climbing as the measure of functional capacity (Fig. 4-2). We acknowledge that the particular sequence used often depends on local practice and the availability of testing, particularly CPET. A typical sequence of evaluation is the history, physical examination, screening spirometry, and initial blood tests. For patients with airflow obstruction on spirometry and/or reduced diffusion capacity or those who report substantial functional impairment, further evaluation with a CPET is indicated.29 According to the exercise capacity level, estimation of the ppo lung function by simple calculation or perfusion scintigraphy is indicated. Alternatively, lung function testing and ppo lung function calculation could be estimated first, followed by a CPET when indicated.
Prospectively validated approach to preoperative evaluation. (From ATS/ERS Guidelines.???344??36)
Simplified alternative approach to preoperative evaluation. (From ATS/ERS Guidelines.36)