Thoracic Surgery

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Chapter 12 Thoracic Surgery

In this chapter the care of patients undergoing noncardiac thoracic surgery is discussed. The emphasis is on postoperative care, but preoperative evaluation and intraoperative management are also reviewed. Thoracic surgery patients, particularly those undergoing pulmonary resection or lung volume reduction surgery (LVRS), are commonly elderly, current or former heavy smokers, and highly likely to have other smoking-related diseases. Careful preoperative selection and optimization are essential for good postoperative outcomes.

This chapter is divided into two sections: (1) pulmonary resection; (2) other thoracic surgery. Pulmonary resection is essentially a discussion of the diagnosis, selection, treatment, and postoperative care of patients undergoing surgery for lung cancer. Other topics covered include LVRS, mediastinal tumors, and esophageal resection. Thoracic trauma, massive hemoptysis, and empyema are covered in Chapters 25, 26, and 35.

PULMONARY RESECTION

Major pulmonary resection is sometimes undertaken for infective lung disease but the great majority of patients who undergo pulmonary resection do so for lung cancer.

Surgery for Lung Cancer

Diagnosis

Patients usually have one or more symptoms related to their tumors, such as cough, chest pain, dyspnea, wheeze, or weight loss. Central tumors can obstruct a large airway, causing atelectasis or pneumonia. Other symptoms and signs are suggestive of tumor extension beyond the lung. Pleuritic chest pain may indicate direct tumor invasion of the chest wall. Dysphagia may indicate esophageal involvement. Hoarseness, Horner syndrome, and arm pain are indicative of recurrent laryngeal nerve, sympathetic chain, and brachial plexus involvement, respectively. Lung cancers commonly metastasize to the brain, skeleton, liver, and adrenals. Extrapulmonary or metastatic spread generally precludes surgery. A number of paraneoplastic syndromes are associated with lung cancer (Table 12-1).

Table 12-1 Paraneoplastic Syndromes Associated with Lung Cancer

Syndrome (hormone secretion) Clinical Manifestation Cancer
Hypercalcemia (parathyroid) Hypercalcemia, polyuria, hypovolemia, confusion NSCLC
SIADH (ADH) Hypernatremia SCLC/NSCLC
Cushing syndrome (ACTH, CRH) Hypertension, fluid retention, weakness, hypokalemia, hyperglycemia SCLC/Carcinoid
Acromegaly (GH, GHRH) Bony overgrowth SCLC/Carcinoid
Gynecomastia (HCG) Breast enlargement SCLC/NSCLC
Myositis/myopathy Proximal weakness, myalgia SCLC/NSCLC
Myasethenic syndrome Weakness, fatigability SCLC
Brain/spinal cord/peripheral neuropathy Multiple SCLC

ACTH, adrenocorticotropic hormone; ADH, antidiuretic hormone; CRH, corticotropin releasing hormone; GH, growth hormone; GHRH, growth hormone releasing hormone; HCG, human chorionic gonadotropin; NSCLC, non-small cell lung cancer; SCLC, small cell cancer; SIADH, syndrome of inappropriate antidiuretic hormone secretion.

Occasionally, lung cancer is asymptomatic and is an incidental finding on a routine chest radiograph. The presence of a large noncalcified mass (<3 cm in diameter) with spiculated margins is highly suggestive of malignancy. The chest radiograph may show consolidation distal to the mass, mediastinal lymphadenopathy, or pleural effusion. Recently, there has been interest in screening high-risk, asymptomatic patients by means of computed tomography (CT) scanning.1

Surgical Suitability for Resection

Lung cancer is staged according to the TNM (tumor, node, metastases) classification (Tables 12-2 and 12-3). All patients being considered for surgery should have a CT scan of the chest, liver, and adrenal glands. Percutaneous needle biopsy may be considered for peripheral lesions but is not mandatory. Patients with mediastinal lymph nodes greater than 1 cm diameter on CT scan should undergo a staging biopsy or mediastinoscopy prior to lung resection. The presence of a malignant effusion is a contraindication to surgery, but an effusion due to consolidation distal to an obstructing lesion is not; if there is doubt, a pleural aspirate should be obtained.

Table 12-2 TMN Classification of Lung Cancer

Primary Tumor (T)
Tx Primary tumor cannot be assessed or proven
T0 No evidence of primary tumor
Tis Carcinoma in situ
T1 Tumor <3 cm in greatest dimension, surrounded by lung or visceral pleura, without evidence of invasion more proximal than lobar bronchus
T2 Tumor with any of the following features: >3 cm in greatest dimension involves main bronchus >2 cm distal to the carina invades the visceral pleura associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung
T3 Tumor of any size that directly invades the following: chest wall, diaphragm, mediastinal pleura, parietal pericardium; or tumor in the main bronchus <2 cm distal to the carina but without carinal involvement; or associated atelectasis or obstructive pneumonitis of the whole lung
T4 Tumor of any size that involves any of the following: mediastinum, heart, great vessels, trachea, esophagus, vertebral body, carina; or tumor with a malignant pleural or pericardial effusion or with satellite tumor nodule within the ipsilateral primary tumor lobe of the lung
Regional Lymph Nodes (N)
Nx Regional nodes cannot be assessed
N0 No regional lymph node metastases
N1 Metastases to ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes involved by direct extension of primary tumor
N2 Metastases to ipsilateral mediastinal and/or subcarinal nodes
N3 Metastases to contralateral mediastinal, contralateral hilar, ipsilateral, or contralateral scalene or supraclavicular lymph nodes
Distant Metastases (M)
Mx Presence of distant metastases cannot be assessed
M0 No distant metastases
M1 Distant metastases present (includes those in a different lobe of the same lung)

British Thoracic Society, Society of Cardiothoracic Surgeons of Great Britain and Ireland Working Party: BTS guidelines: guidelines on the selection of patients with lung cancer for surgery. Thorax 56:89-108, 2001.

Patients who have non-small cell cancer in stage I or II are considered operable: stage I disease has a high chance of cure with surgery alone; stage II disease has a moderate chance of cure with surgery alone. Patients with stage IIIA have a low chance of cure with surgery alone but may be considered for operation in conjunction with chemotherapy. Stage IIIB with known N2 involvement and stage 4 tumors are generally considered inoperable. Adjuvant chemotherapy in all but stage IA leads to improved survival rates, but benefits resulting from postoperative radiotherapy following complete primary tumor resection have not been proven.

Fitness for Pulmonary Resection

Curative lung resection involves the removal of a considerable amount of tissue, which results in permanent loss of pulmonary function. Quantitative assessment of pulmonary function is therefore important for stratifying a patient’s surgical risk. However, given that the outcome of nonsurgical treatment of lung cancer is very poor, it may still be appropriate to proceed with pulmonary resection in a patient deemed to be at high risk based on the results of lung function tests.25

Pulmonary Assessment of High-Risk Patients

Patients who are not clearly suitable for pulmonary resection on the basis of simple spirometry should undergo further testing for pulmonary function.

Predicted Postoperative FEV1.

The predicted postoperative FEV1 (ppoFEV1) is calculated from the preoperative FEV1 (preopFEV1) and the proportion of functional lung that is to be removed (Fig. 12-1). The most accurate way to measure the functional contribution of the lung tissue to be resected is by means of split perfusion scanning using technetium (Tc99) macroaggregates or quantitative CT scanning.6 A simple alternative is to estimate the proportion on the basis of the number of anatomic pulmonary segments that are to be removed (Fig. 12-2). To allow safe resection, the predicted postoperative FEV1 should be greater than 40% of normal.

Preoperative Cardiovascular Evaluation

Patients undergoing pulmonary resection are at increased risk for coronary artery disease. All patients should have a preoperative electrocardiogram and, if a murmur is present, an echocardiogram. Surgery should be delayed for at least 6 weeks following a myocardial infarction.

Clinical predictors of increased perioperative cardiac risk are summarized in Table 12-4. Patients at major risk should have a formal cardiologic assessment, and those with severe coronary artery or valvular lesions should be considered for a revascularization procedure or valve surgery prior to pulmonary resection. Patients at intermediate risk who have good functional capacity do not require further cardiac investigation but, in the presence of poor functional capacity, referral to a cardiologist and cardiac stress testing are warranted. Patients at increased risk for cerebrovascular disease (e.g., a carotid bruit or a history of stroke or transient ischemic attack) should undergo a preoperative carotid Doppler ultrasound study.

Table 12-4 Predictors of Increased Cardiovascular Risk Following Major Noncardiac Surgery

Major Predictors
Unstable coronary syndromes: recent myocardial infarction with evidence of important ischemic risk based on symptoms or noninvasive study; unstable or severe angina
Decompensated congestive cardiac failure
Significant cardiac arrhythmias: high-grade atrioventricular block; symptomatic ventricular arrhythmias in the presence of underlying heart disease; supraventricular arrhythmias with uncontrolled ventricular rate
Severe valvular heart disease
Intermediate Predictors
Mild angina
Previous myocardial infarction based on history of pathologic Q waves
Compensated or prior congestive cardiac failure
Diabetes
Minor Predictors
Advanced age
Abnormal ECG findings (e.g., left ventricular hypertrophy, left bundle branch block, ST or T wave abnormalities)
Rhythm other than sinus rhythm (e.g., atrial fibrillation)
History of stroke
Poorly controlled hypertension

Adapted from Eagle KA, Berger PB, Calkins H, et al: ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). J Am Coll Cardiol 39:542-553, 2002; and from British Thoracic Society, Society of Cardiothoracic Surgeons of Great Britain and Ireland Working Party: BTS guidelines: guidelines on the selection of patients with lung cancer for surgery. Thorax 56:89-108, 2001.

Intraoperative Management

Pulmonary resection for cancer is usually carried out via a lateral thoracotomy incision and involves a lobectomy, bilobectomy, or pneumonectomy. Selective lung ventilation is usually achieved using a double-lumen endotracheal tube. Pneumonectomy is required for a centrally located carcinoma, particularly when the tumor is adherent to hilar structures. Pneumonectomy or bilobectomy is required for tumors that have crossed a lung fissure. Resection of part of the pericardium (intracardiac pneumonectomy) or chest wall may be required for tumor clearance. For tumors involving a bronchus, a “sleeve lobectomy” may be performed; in this surgery a segment of bronchus along with a lobe are excised. The remaining lobes are then reattached to the residual bronchus. Sleeve lobectomy is performed as an alternative to pneumonectomy with the aim of preserving lung function. Bronchotracheal resection with bronchial reattachment is required in cases in which tumors involve the carina. Limited wedge or segmental resection is appropriate for benign tumors, for metastases, and for primary lung cancer in a patient who would not tolerate full lobectomy. However, in patients with primary lung cancer, sublobar resection is associated with increased local recurrence rates compared to lobectomy. Concurrent with pulmonary resection, mediastinal lymph node sampling is usually performed for the purpose of staging the tumor.

Blood loss with routine lobectomy or pneumonectomy is usually modest but can be substantial in settings of previous thoracotomy, chronic infection, and extrapleural pneumonectomy; the latter is occasionally performed for tuberculous disease and mesothelioma.

Routine Postoperative Care Following Pulmonary Resection

For patients undergoing major pulmonary resection and those with significant cardiac or respiratory comorbidity, postoperative admission to a high-dependency or intensive care unit is appropriate. Monitoring of hourly urine output, invasive arterial pressure, and central venous pressure (if available) is warranted.

Ideally, patients are extubated following pulmonary resection to minimize air leak and to reduce the tension on bronchial or pulmonary staple lines. However, a period of elective postoperative ventilation is justified for patients with severely impaired gas exchange, hypothermia, acidosis, or ongoing bleeding. Hypothermia significantly increases the incidence of myocardial ischemia; therefore, patients who are hypothermic (<35.5°C) should be warmed to 36.5°C using a forced-air warming blanket.10 Immediately following surgery, a chest radiograph should be obtained to assess lung expansion and the position of drains and to rule out hemothorax. The absence of significant mediastinal shift should be confirmed after a pneumonectomy.

Routine supplemental oxygen via nasal cannulas (2 to 3 l/min) is appropriate but if, despite this, the arterial oxygen saturation is less than 93% to 96%, facemask oxygen should be administered. A relatively restrictive approach to postoperative fluids (e.g., 1 ml/kg/hr of a balanced crystalloid solution, maintained until the patient is able to drink) is appropriate. As with all major surgery, patients tend to retain fluid for the first few days following thoracotomy. Patients who are warm and hemodynamically stable but have relative oliguria (0.5 to 1 ml/kg/hr) should not receive aggressive fluid therapy.

Following lobectomy or bilobectomy, the residual lung lobes normally expand to fill up the hemithorax—with some shift of the mediastinum to the operative side (see subsequent material). Following pneumonectomy, the hemithorax gradually fills up with fluid at a rate of about two rib spaces per day. Thus, 1 to 2 days after surgery, it is usual to see an air-fluid level on chest radiograph on the operative side.

Analgesia

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