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Pulmonary Resection in Patients with Impaired Pulmonary Function
Symposium on Surgery in the MedicaUy Compromised Patient
Pulmonary Resection in Patients with Impaired Pulmonary Function G. Valter Brindley, Jr., M.D.,* R. E. Walsh, M.D.,t W. T. Schnarr, M.D.,f G. W. Allen, M.D.;§ M. K. Mendenhall, M.D.,II and E. W. Ahlgren, M.D., ~
Patients with pulmonary lesions warranting. consideration of pulmonary resection often are seen with varying degrees of impaired pulmonary function. Refinements in evaluation of pulmonary function, special preoperative preparation, optimal anesthetic management, utilization of operative procedures adapted to the individual patient and his or her lesion, and effective postoperative care will permit many of these patients to have their lesions removed with acceptable morbidity and low mortality. Close cooperation between the specialists in medical diseases of the chest, pulmonary physiologists, cardiologists, anesthesiologists, and the surgeon is essential in the care of these high risk patients. The thoracic surgeon will make a decision as to the feasibility of pulmonary resection after collaborative evaluation of the nature and extent of the disease and the physiologic status of the host.
MALIGNANT LESIONS As a general theorem, practically all patients with non-small cell carcinoma, Stage I and Stage II, and selected patients with Stage III disease are candidates for surgical treatment if their physiologic status permits. l Surgery seldom is indicated for small cell carcinoma of the lung. However, if the tumor presents as an isolated peripheral pulmonary nodule, classified as Tl *Senior Consultant, Departments of General and Thoracic Surgery, Scott and White Clinic; Professor of Surgery, Texas A. and M. University College of Medicine, Temple, Texas tDivision of Pulmonary Medicine, Scott and White Clinic; Professor of Medicine, Texas A. and M. University College of Medicine, Temple, Texas :f:Division of Pulmonary Medicine, Scott and White Clinic; Assistant Professor of Medicine, Texas A. and M. University College of Medicine, Temple, Texas §Department of Anesthesiology, Scott and White Clinic; Associate Professor of Anesthesiology, Texas A. and M. University College of Medicine, Temple, Texas "Department of Anesthesiology, Scott and White Clinic; Professor of Anesthesiology, Texas A. and M. University College of Medicine, Temple, Texas 'Department of Anesthesiology, Scott and White Clinic; Professor of Anesthesiology, Texas A. and M. University College of Medicine, Temple, Texas
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NO MO or T2 NO MO, lobectomy with mediastinal lymphadenectomy should be considered. Most patients with small cell carcinoma have disseminated disease at the time of initial presentation to the physician and receive maximal palliation by a combination of radiation and chemotherapy. We are initiating an evaluation of the feasibility of thoracotomy and removal of the residual localized primary small cell carcinoma after a favorable response to chemotherapy and irradiation. We hope that some of these patients will have a better prognosis after such an aggressive approach. Staging of all patients with bronchogenic carcinoma is essential. Meticulous physical examination and radiographic studies, including tomography when'indicated, are fundamental initial studies. Bronchoscopy is essential even for the patient with the small, solitary, peripheral nodule, since a central bronchial lesion might also be present. Excision of a palpable scalene lymph node may be helpful, since proven supraclavicular lymph node metastasis is evidence of inoperability. Mediastinoscopy should be performed in all patients with suspected lung cancer except those with peripheral "coin" lesions and a mediastinum that appears normal radiographically. Extrapleural mediastinotomy through the bed of the resected segment of the left second costal cartilage is preferred in assessing mediastinal metastasis from lesions in the left lung. Contraindications to resection based on mediastinal assessment include (1) metastasis from a small cell carcinoma, (2) peri nodal or lymph node metastasis extending beyond the capsule of the node, (3) involvement of contralateral paratracheal lymph nodes, (4) extensive involvement of unilateral upper paratracheal lymph nodes, and (5) direct invasion of heart or major blood vessels. Computerized tomography, scanning, and pulmonary angiography may be helpful in determining resectability in central or posterior paramediastinallesions. 14 When the lesion is a small cell tumor or there is clinical suggestion of distant metastasis, radionuclide scans of liver, bone, and brain, as well as bone marrow aspiration, may be elected. When the lesion is not accessible to bronchoscopy, needle biopsy may provide a diagnosis if the tumor is nonresectable or the patient is inoperable. Refinements in cytologic techniques and the availability of thin needles make this approach practical and feasible. The diagnostic accuracy is high and the morbidity is quite low.
Surgical Treatment of Primary or Metastatic Lung Cancer The rare indication for surgical treatment of small cell carcinoma has already been mentioned. Very seldom is resection indicated for a patient known to have this type of cancer. Complete removal of non-small cell bronchogenic carcinoma is the only treatment at this time that offers a prospect of cure. The type of operation should be carefully planned and be consistent with the type and extent of the lesion and the patient's biologic status. The goal of the surgeon is to remove all of fhe tumor with maximal conservation of uninvolved pulmonary tissue. Lobectomy. Lobectomy with mediastinal lymphadenectomy is our most frequent operation for bronchogenic carcinoma. The tumor must be confined within the lobe, there should be a tumor-free bronchial margin of at least 1.5 cm for resection, and any lymph node extension should be confined to the first level of lobar drainage and available for complete removal byan
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en bloc dissection. When the tumor extends to the origin of the lobar bronchus and the patient has limited pulmonary reserve, sleeve resection and bronchoplasty may permit complete removal of the tumor and avoid a pneumonectomy that might result in severe morbidity and mortality. Segmentectomy. In the patient with poor pulmonary reserve we have used segmental resection for a peripheral lesion, well confined to the segment and without evidence of lymph node metastasis. This procedure has been particularly appropriate for nodular alveolar cell carcinoma, a second primary pulmonary carcinoma, and some pulmonary metastases. Wedge Resection. In the surgical treatment of malignant lesions, we have use.d wedge excision primarily for diagnosis of small peripheral nodular lesions without evidence of metastasis. This operation seldom is sufficient for primary pulmonary cancers and is used mostly for removal of pulmonary metastases. Such conservative resection is especially indicated for removal of multiple lesions in more than one lobe or on more than a single occasion. If the removal of a small peripheral lesion reveals a primary bronchogenic carcinoma of non-small cell type, lobectomy with lymphadenectomy usually should follow. Pneumonectomy. Pneumonectomy seldom is indicated or justified for the patient with diminished pulmonary reserve. Pneumonectomy ordinarily is reserved for patients with Stage III disease. Should evaluation reveal that most of the patient's pulmonary function is occurring in the uninvolved lung and his or her status be improved enough by medical management to predict adequate ventilation after pneumonectomy, the procedure could be considered. The predicted residual forced expiratory volume in one second (FEV l ) should be at least 0.80 liters for functional survival to be expected. Metastases should be intranodal and all gross tumor should be removable. Extended Resection. Superior Sulcus Tumors. Shaw and Paulson showed many years ago that preoperative irradiation followed by an en bloc removal of the upper lobe of the lung and involved tissues of the chest wall provides maximal opportunity for survival or palliation.I 2 These tumors often are peripheral to the mediastinum and distant metastasis is relatively rare. Chest Wall or Diaphragmatic Extension. For many years, most thoracic surgeons considered any malignant pulmonary tumor extending onto the chest wall or diaphragm to be inoperable. Resection is not justified when such a tumor involves the mediastinum or hilus or diffusely extends through the lung. However, when the lesion is entirely peripheral, the hilus and mediastinum often are free of tumor and en bloc removal of these lesions may give a satisfactory result if all of the tumor can be removed and there is no evidence of distant metastasis. The defect in the chest wall or diaphragm can be repaired using a variety of techniques.
INFLAMMATORY LESIONS Tuberculosis Decreased incidence and improved medical management of pulmonary tuberculosis have greatly decreased the necessity for surgical treatment. Surgery is considered only for complications of the disease that are refracI
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tory to good medical management, and the patient must be considered to be a reasonable risk for the procedure. Indications for consideration of surgery include destroyed lung or lobe of lung, thick-walled cavity with positive sputum and/or hemorrhage, bronchiectasis with significant symptoms, severe irreversible bronchial stenosis, nodular lesion that is increasing in size and could contain carcinoma, persistent or severe hemoptysis, or bronchopleural fistula that does not close with adequate chemotherapy.
Types of Operations Segmental Resection. This technique is most valuable in treating patients with localized disease sensitive to the primary drugs. The necessity for maximal preservation of pulmonary tissue is especially important in the management of patients with limited pulmonary reserve. Lobectomy. This remains the most frequently used method of resection. The remaining lobe or lobes usually fill the pleural cavity and postoperative space problems are rare. When a space problem is apparent, concomitant thoracoplasty should be performed. Pleuropneumonectomy. This is the technique of choice in the management of a patient with a lung destroyed by tuberculosis. It avoids invasion of the chronically infected pleura and results in fewer postoperative problems than does a transpleural pneumonectomy.
LUNG ABSCESS Surgical intervention is seldom needed any more for chronic pulmonary abscess. Proper use of antibiotics for pulmonary infections, early and effective bronchoscopic removal of endobronchial foreign bodies or aspirated material, and transbronchial drainage of an acute abscess usually will prevent the development of a chronic pulmonary abscess. Should such an abscess necessitate surgery, the tissue destroyed by the abscess should be removed. The extent of the resection will depend upon the size and location of the abscess. Usually a lobectomy is sufficient and effective.
FUNGAL DISEASES OF THE LUNG The need for pulmonary resection in fungal diseases is rare, as these diseases usually respond well to drug therapy. A chronic thick-walled cavity that persists in spite of appropriate chemotherapy may require resection, usually by lobectomy. Occasionally single or multiple nodules may present a diagnostic problem, and open pulmonary excision of a nodule may be required to establish the diagnosis.
BRONCHIECTASIS The overall incidence of bronchiectasis has declined remarkably as a result of more effective antimicrobial therapy; however, the thoracic surgeon
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should be familiar with bronchiectasis and pulmonary sequestration. The etiology, pathology, and diagnosis of bronchiectasis were well presented in a recent paper by Bolman and Wolfe and will not be reviewed here. 5 Treatment Bronchiectasis initially should be treated medically with antibiotics, postural drainage, avoidance of air pollutants, and effective management of associated diseases. Surgery should be considered for those patients with persistent or progressive symptoms after an adequate trial of good medical management. Preferably, the disease should be localized, in one lobe or in contiguous segments in two lobes. When surgery is indicated, removal of the involved segments should be performed, preserving as much normal lung as possible. Occasionally, bilateral resections will be necessary. After careful preoperative evaluation and preparation, the lung with the greatest involvement is operated on first, with effective postoperative medical management. An additional contralateral operation is usually not required. However, if chronic hemoptysis, foul sputum, and recurrent pneumonitis persist, consideration should be given to resection in the opposite lung. These patients require careful and effective medical and anesthesiology management before, during, and after the operation. The thoracic surgeon will limit the resection to removal of as little pulmonary tissue as necessary with maximal conservation of all normal lung.
BRONCHOPULMONARY SEQUESTRATION Bronchopulmonary sequestration is an uncommon congenital malformation of the lung involving separation of a portion of lung early in embryonic development. 9 The arterial supply to this portion of the lung is atypical, coming directly from the aorta or a branch of the aorta. This ectopic pulmonary tissue may be intralobar or extralobar, usually in the lower lobes and more often on the left. Treatment for symptomatic bronchopulmonary sequestration is resection of the abnormal tissue. The thoracic surgeon must be very careful not to overlook the anomalous artery, which usually passes through the inferior pulmonary ligament. Preoperative angiography can be very helpful in identifying this artery, especially in small infants.
BENIGN TUMORS OF THE LUNG Benign tumors of the lung and bronchus are of many varieties. The majority of the parenchymal lesions are present as asymptomatic, solitary, peripheral nodules in the lung. These tumors are rare compared with malignant and circumscribed inflammatory lesions.1 5 Hamartoma is the most common benign tumor in the lung. Computerized tomography and percutaneous needle biopsies may be helpful in establishing the nature of these parenchymal tumors, although often excisional biopsy is necessary to exclude a possible malignant tumor. Most of the small, peripheral nodular lesions can be removed by wedge resection. Fiberoptic bronchoscopy will reveal
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the diagnosis of most endobronchial tumors. Small, pedunculated lesions· confined to the bronchial mucosa may be removed endoscopically, but usually thoracotomy, bronchotomy with total excision of the lesipn, and bronchoplasty are preferred. If the lesion has produced chronic bronchial obstruction, atelectasis, bronchiectasis, and chronic pneumonitis may be present peripheral to the tumor. Under these conditions, segmentectomy or lobectomy with removal of this diseased tissue is indicated.
TECHNICAL CONSIDERATIONS Incision The anterior or anterolateral incision is usually preferred for thoracotomy in the patient with reduced or marginal pulmonary function, as this position allows optimal pulmonary performance during anesthesia. The incision can be done quickly and the patient has less associated postoperative pain and can cough and breathe easier than after the posterolateral approach. However, when the lesion is fixed posteriorly and does not appear to be easily accessible, the posterolateral incision should be chosen. Postoperative Chest Pain Great care is taken to handle the ribs as gently as possible at thoracotomy. The incision should be of adequate length to permit the ribs to be separated easily. Retraction of the ribs should be done slowly, avoiding undue stress or rib fracture. At the conclusion of the pulmonary resection, intercostal nerve block anesthesia is done with bupivacaine and repeated postoperatively as needed. Antibiotics If the patient has been on appropriate antibiotics prior to thoracotomy, such as for tuberculosis or lung abscess, these medications are continued during and after pulmonary resection. Cultures and sensitivity studies are made from the resected specimen, and adjustment in antibiotic coverage is made accordingly. Since many of the patients with malignant lesions of the lung and limited pulmonary function are at increased risk for postoperative infection and the consequences of their infection could be catastrophic, we ordinarily use perioperative antibiotics for these patients. Most often we elect one of the cephalosporins for this purpose. The medication is initiated prior to surgery and continued during the operation and postoperatively until there is no evidence of an air leak, drainage is minimal, drains have been removed, and there is no clinical evidence of infection. PREOPERATIVE EVALUATION OF THE PATIENT WITH RESPIRATORY DISEASE During the past 10 to 15 years significant advancement has been made in the preoperative evaluation of patients with respiratory disease about to undergo lung .resection. In assessing these patients the goal is to reduce the
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incidence and severity of postoperative complications. The complications can be divided into two types. The first is postoperative respiratory failure due to insufficient residual lung to sustain the patient. I6 The second type of complication is that seen in patients undergoing pulmonary resection, thoracotomy without pulmonary resection, and intra-abdominal procedures, namely, microatelectasis signified by widening of the alveolar-arterial gradient, macroatelectasis secondary to segmental collapse, and respiratory infection associated with fever, purulent secretions, and parenchymal infiltrate. IS The first step in the approach to these patients is appreciating preoperative risk factors that predispose to postoperative respiratory complications. These factors are as follows: History of heavy smoking and cough Obesity Age greater than 60 years Intrathoracic or upper abdominal surgery Known pulmonary disease Mean pulmonary artery pressure above 35 mm Hg Anesthesia time greater than three hours
A complete evaluation of patients with increased risk of postoperative complications includes a detailed history of cardiopulmonary disease, with a thorough physical examination, and selective laboratory investigations to define the degree of respiratory dysfunction. Pertinent components of the history include smoking habits, cough, character and quality of sputum, history of wheezing, and exercise limitation. Pertinent physical findings include wheezing, prolongation of expiration, ineffective cough, and pulsus parodoxus. Chest x-ray film, electrocardiogram, and complete blood count are done routinely on patients who are considered candidates for thoracotomy. Pulmonary function testing and arterial blood gas determinations are routinely performed on all thoracotomy patients. It is usually not too difficult to determine which patients will be able to tolerate a lobectomy, but at the time of thoracotomy it may be necessary to do a pneumonectomy. The preoperative pulmonary function evaluation determines which patients can tolerate this procedure. Many different tests of pulmonary function have been used to make this determination, but no single test has been entirely adequate (Table 1).7,16 We have found that evaluating patients in a stepwise fashion allows us to determine those patients who can tolerate pulmonary resection with an acceptable postoperative mortality and morbidity. Once it is determined that the patient is operable from the standpoint of pulmonary function, no further testing is required. Table 1.
Criteria for Further Evaluation Prior to Pneumonectomy
Forced vital capacity < 50% of predicted Forced expiratory volume in 1 second < 50% predicted or < 2 liters Maximum voluntary ventilation < 50% predicted Residual volume: total lung capacity ratio> 50% Diffusing capacity < 50% of predicted Could not complete 2 minutes on treadmill at 3 MPH, 10% incline Could not climb two flights of stairs without undue stress
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Arterial Blood Gases on Room Air. An elevated arterial CO 2 pressure (Paco 2 ) is a contraindication to pulmonary resection. A low Pao 2 is not as critical, since it may represent shunting and abnormal ventilation perfusion relationships in diseased lungs. In some instances, the Pao2 actually increases postoperatively. 7 Pulmonary Function Testing. When the forced vital capacity (FVC) and forced expiratory volume in one second (FEV!) are greater than 50 per cent of predicted and the FEV! is greater than 2 liters, the patient is a candidate for pneumonectomy.l6 An FEV! of more than 1.4 liters is adequate for a lobectomy. Split Function Testing. Patients who do not meet the foregoing criteria may still be candidates for surgery, but they must be evaluated by further testing. We prefer to do one of the split function tests. In the past, this required measuring the function of each lung separately after the insertion of a double lumen endotracheal tube such as the Carlens tube. This was an expensive, uncomfortable, invasiv_e test that presented some risk to the patient. It has been shown that similar information can be obtained from a quantitative perfusion lung scan obtained with a system that measures radioactivity from each lung separately. The percentage of perfusion to the noninvolved lung multiplied by the preoperative FEV! gives a predicted postoperative FEV! after pneumonectomy. A value of 0.8 liter or greater indicates that the patient is a reasonable operative risk. 6 The lateral position test, in which the functional residual capacity (FRC) is measured in the supine and both lateral decubitus positions gives similar information, but it is not as widely available as the perfusion lung scan.ll Pulmonary Artery Balloon Occlusion. Most patients who do not meet the foregoing criteria will be treated with nonoperative therapy. If surgery is still considered, a right ventricular catheterization may be done with the balloon occlusion of the pulmonary artery on the side of the lesion. The patient exercises; if the pulmonary artery pressure is greater than 35 mm Hg or the arterial oxygen tension falls to 45 mm Hg, the patient is not a surgical candidate. 6 Several other tests (see Table 1) have been used to determine operability and each has some usefulness. Each physician and institution must determine which tests work best in their particular situation. Patients who fail to meet the criteria for pulmonary resection may have enough improvement in ptilmonary function after a short course of pulmonary hygiene to enable them to tolerate pulmonary resection.
Preoperative Preparation Preoperative pulmonary preparation of patients with chronic obstructive pulmonary disease for a period as short as 48 hours has been shown to reduce postoperative complications by nearly one-half.lO Table 2 lists prophylactic measures that have proved helpful. All patients should stop smoking. Even a few days of abstinence will decrease the volume of sputum produced. Patients with chronic obstructive pulmonary disease benefit from oral therapy with one of the theophylline preparations such as Aminophyllin, 200 mg four times daily. Isoetharine or metaproterenol are given by in-
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Preoperative and Postoperative Pulmonary Therapy PREOPERATIVE
Stop smoking Oral bronchodilators Inhaled bronchodilators Heated aerosol Chest physiotherapy Antibiotics Corticosteroids Incentive spirometer
POSTOPERATIVE
Stir-up program Early ambulation Oxygen Minimize sedative and narcotics
halation four times daily using either an air compressor or an intermittent positive pressure breathing machine if the patient cannot take an adequate inspiration. Patients who produce over two ounces of sputum daily are treated with a heated sterile water aerosol by mask for 20 minutes after the inhaled bronchodilator. Chest physiotherapy, consisting of postural drainage and percussion, is done at least twice daily. If respiratory infection is present, one of the broad-spectrum antibiotics is appropriate. Some patients with reversible brochospasm or reactive airways respond rather dramatically to corticosteroids. All patients should be instructed prior to surgery in techniques of coughing, de~p breathing, and the use of one of the incentive breathing devices that emphasize sustained inspiration. It is much more diTficult to teach patients these techniques in the postoperative period while they are sedated or in pain. Part of the patient education includes describing the postoperative routines. This is particularly important if it seems likely. that the patient will require mechanical ventilation after surgery. Patients seem to tolerate ventilators better if they know beforehand that they may wake up with an endotracheal tube in place with very limited ability to communicate with those around them.
ANESTHESIA
Preoperative Considerations Anesthetic rpanagement of the thoracic surgical patient who has normal or nearly normal pulmonary function is relatively simple and straightforward. Many patients, however, have decreased pulmonary reserve or can expect significant reduction in pulmonary function in order to achieve an opportunity for cure of their disease. The latter group requires the' most thorough assessment of preoperative risk factors and the most careful planning of anesthetic and postanesthetic management. Consistently low arterial blood oxygen tension (Pao2 ) mandates the choice of techniques allowing increased inspired oxygen levels (F10 2 ). Markedly elevated arterial carbon dioxide tensions (Paco2 ) are more ominous than Pao2 disturbances and are a matter for grave concern. Almost inevitably, postoperative mechanical ventilation will be required and this will affect the choice of the route for establishment of an of endotracheal airway.
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Other diminished pulmonary function variables detected in the preoperative evaluation will also have great impact upon the anesthetic plan. Obstructing lesions of the trachea or distortion of mediastinal contents may present the anesthesiologist with profound mechanical and physiologic problems. Positional changes in pulmonary function should be determined preoperatively in patients suspected by history or pathologic process of being subject to deleterious alterations in pulmonary or cardiovascular function with change of position. In addition, anesthesia with the chest wall open on the operative side may produce profound changes in ventilation-perfusion (V/Q) relationships for the following reasons: 1. The abdominal contents and mediastinum exert pressure on the dependent lung, increasing the height of the diaphragm and decreasing lung volume. A decrease in lung volume favors airway closure, atelectasis, and shunting in the dependent lung. 2. Sighing and the normal inspiratory muscle tone, which tend to open closed airways and keep them open by maintaining adequate lung volume, are lost during anesthesia. 3. Because of the open chest on the operative side, compliance of the upper lung increases, favoring ventilation of that lung. 4. Blood flow is directed preferentially by gravity to the dependent lung.
Arterial blood gas determinations during thoracotomy usually demonstrate the large changes in V/Q and shunting that occur. These abnormalities are enhanced by age, pre-existing pulmonary disease, and obesity and may be predicted by careful preoperative assessment. Entities that may be aggravated by anesthesia must also be mentioned. The myasthenic syndrome, frequently associated with small cell bronchial carcinomas, significantly augments drug-induced neuromuscular blockade. s The anticholinesterases, such as physostigmine and pyridostigmine, are of only limited value in reversal of weakness.
Monitoring For thoracic surgery patients we routinely monitor arterial blood pressure by cuff, the heart by electrocardiogram, heart and breath sounds continuously by esophageal stethoscope, and temperature by a nasopharyngeal probe. In patients with diminished pulmonary capacity as demonstrated preoperatively, it is advisable to obtain at least one determination of arterial blood gases early in the operative procedure to determine adequacy of oxygenation (Pao2 ) and of ventilation (Paco2 ). If gross abnormalities of gas exchange are present, resection of large portions of lung tissue is anticipated, postoperative ventilation is expected, or significant cardiovascular instability is present, an indwelling arterial catheter may be extremely useful for repeatedly measuring blood gases and for monitoring arterial blood pressure. This also facilitates replacement of blood loss and determination of the ability of the patient to be weaned from mechanical ventilation and extubated postoperatively. If a ventilator is used, tidal volume, rate of ventilation, and peak inspiratory pressure should be carefully followed and recorded. Changes in these variables may demonstrate increased dead space (when compared with measured Paco2 ), decreased compliance (indicating accumulations of secre-
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tions, development of pulmonary edema, or contralateral pneumothorax), or changes in resistance (bronchospasm). Finally, if congestive heart failure or cor pulmonale is present, a SwanGanz catheter may be placed via the jugular or subclavian route to detect increases in pulmonary artery pressure on clamping of a main stem pulmonary artery or its branches. Pulmonary capillary wedge pressure is also a useful guide for administration of fluid and blood.
Anesthetic Management Induction of anesthesia is preceded by denitrogenation of the patient's lungs with 100 per cent oxygen administered by mask for a period of two to five minutes. This guarantees adequate oxygenation during the period prior to securing the airway by endotracheal intubation. Thiopental administered intravenously is most commonly used for induction and provides a smooth, rapid sleep. In patients who have severe cardiac dysfunction or are in shock, diazepam and a narcotic or ketamine may be used intraveneously. Ketamine has sympathomimetic actions that tend to suppori: the blood pressure and cardiac output. After narcosis is induced and ability to ventilate the patient has been demonstrated, succinylcholine is administered to obtain muscle relaxation for tracheal intubation. After intubation, anesthesia is maintained with a volatile anesthetic agent such as halothane, enflurane, or isoflurane, with a 50:50 mixture of nitrous oxide and oxygen. Volatile agents allow the administration of higher concentrations of oxygen if that need is demonstrated by a low Pao2 • Indeed, these agents are potent enough to provide surgical anesthesia even when given with 100 per cent oxygen. They depress airway irritability, limit secretions, and may be eliminated rapidly at the end of the procedure. All volatile agents produce cardiac depression, and their concentration may need to be decreased if significant hypotension occurs. Under these circumstances, if the patient begins to move or cough, a muscle relaxant may be given. If severe hypotension occurs, anesthesia may be maintained with ketamine, for amnesia and analgesia, and oxygen. Muscle relaxants are often used to facilitate electrical transection of the thoracic wall musculature and to facilitate rib spreading. Generally, a nondepolarizing agent such as pancuronium is used for this purpose. Patients who require corticosteroids and theophylline preparations preoperatively should be maintained on adequate doses of these drugs quring the perioperative period. The corticosteroids are given either intravenously or intramuscularly and theophylline preparations are usually given intravenously until the patient is able to take oral fluids. Ventilation during the procedure should be controlled since the chest is open. Assisted ventilation may produce unpredictable fluctuations in Paco2 and Pao2 • Return of spontaneous ventilatory effort during surgery usually indicates light anesthesia, hypercapnia, or hypoxemia. Arterial blood gases should be measured frequently if changes from normal are suspected or predicted on the basis of the preoperative pulmonary status. If there is a danger of contamination of the dependent lung with infected material (as with lung abscess or bronchiectasis) or with blood (en-
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dobronchial bleeding), it is desirable to isolate one lung from the other. This may be done with a double lumen endotracheal tube. The lungs are separated by cuffs that when inflated permit separate ventilation of the right and left lungs and that prevent mixing of ventilator gases or contamination of one lung by the other. These catheters might be considered for other uses such as directing ventilation to one lung only, when a larg~ bronchopleural fistula or giant bullous emphysema is present, or simply for exposure so that the lung to be resected is not continually in motion. Problems and complications associated with the use of double lumen tubes include the following: 1. 2. 3. 4. 5.
Increased resistance to airflow Further compromise of ventilation-perfusion Malposition of the catheter Blockage of one or both lumens with secretions Tracheal or bronchial rupture
Following discontinuation of the anesthetic and reversal of muscle relaxants at the end of the procedure, spontaneous ventilation is allowed to resume. If the tidal volume appears adequate at this time and protective pharyngeal reflexes have returned, the patient may be extubated and taken to the recovery room. If ventilation appears inadequate or is marginal when measured by respirometer (less than 400 ml tidal volume), the patient should remain intubated and be transported to recovery with assisted ventilation and supplemental oxygen. Patients who have undergone pneumonectomy are not extubated until they have recovered sufficiently to provide evidence of an adequate vital capacity (10 ml per kg of body weight) and have physiologically acceptable blood gases.
Postanesthetic Management The postanesthetic recovery phase represents the biggest hurdle of the perioperative period for the patient and the physician. In addition to routine monitoring, specific attention should be directed toward the following: 1. Chest x-ray film. The postoperative chest x-ray film documents the end result of the surgery and serves as a baseline for subsequent films; more importantly, free air atelectasis, mediastinal shifts, improper functioning of chest tubes, and other alterations can be detected and subsequently managed. 2. Tidal volume. Measurements can be made, especially ifhypoventilation is suspected. The tidal volume should be comparable to preoperative determinations but may be less because of splinting. 3. Arterial blood ga~es. Blood gases in the immediate postoperative period can alert the physician to any trends and predict the need to continue mechanical ventilation or other oxygen therapy.
There must be a high index of suspicion for life-threatening complications, which include massive hemorrhage and bronchial stump rupture. Significant bleeding in the period immediately following thoracic surgery is rare and usually is caused by loosening of a ligature from a pulmonary or intercostal vessel. It is heralded by signs of hypovolemia, and mediastinal shift to the opposite side may occur if chest tube drainage is inadequate. Immediate thoracotomy may be necessary to obtain manual control of bleeding and may be life-saving.
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A bronchopleural fistula or ait; leak may result in tension pneumothorax if the patient is on controlled mechanical ventilation and a chest tube is not employed. This catastrophic complication can be immediately identified by a high inflation pressure required for ventilation, sudden shift of the mediastinum to the opposite side, circulatory collapse, subcutaneous emphysema, and serosanguinous sputum. In this situation, immediate decompression of the pleural space is necessary and may be accomplished by insertion of a large bore needle or chest tube, or by reopening the chest. Postoperative pain can be managed at three levels. Injection of"bupivacaine (Marcaine) into the intercostal bundles at the thoracotomy site has proven efficacy. A transcutaneous nerve stimulator applied in the postanesthesia recovery room can be adjusted to help with the pain management. The use of narcotics can be considered a final balance of the three. The initial pain control can be achieved with intravenous narcotics such as meperidine, 0.25 or 0.5 mg per kg. The onset of analgesia results within two to five minutes and the duration of action is approximately one hour. Meperidine can be ordered for the long term management of pain at approximately 1 mg per kg, intramuscularly, every three to four hours as necessary and requested by the patient. Patients in whom respiratory depression has been identified preoperatively must have the narcotic administration tailored to their specific needs. If there is doubt, rapid determination of the arterial blood gases can give insight into the degree of narcotic shift of the carbon dioxide response curve. The treatment of pain following thoracotomy is important not only for patient comfort but also to minimize the pulmonary complications by enabling patients to breathe deeply, cough effectivdy, and ambulate early. During recovery from anesthesia, the level of respiratory support may range from spontaneous breathing with an inspired oxygen concentration of 50 per cent or greater to intermittent mandatory ventilation (IMV) with a rate of 8 to 10 breaths per minute and a tidal volume of approximately 10 to 12 ml per kg or controlled mechanical ventilation (CMV) with 10 to 12 breaths per minute at a tidal volume of 10 to 12 ml per kg. If an arterial oxygen tension of 90 torr cannot be obtained on 50 per cent oxygen during IMV or CMV, positive end-expiratory pressure (PEEP) of 5 to 20 cm H 20 may be employed to increase oxygenation. If the patient can achieve the baseline tidal volume of approximately 7 ml per kg, a vital capacity of approximately 10 to 15 ml per kg, and an inspiratory effort of greater than 25 cm H 20, spontaneous ventilation and extubation can be considered.
POSTOPERATIVE PULMONARY MANAGEMENT Postoperative Physiologic Changes The major postoperative physiologic respiratory changes are as follows: Change in pattern of breathing Decrease in lung volumes Alteration in gas exchange Increased work of breathing Altered defense mechanisms
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As early as the mid-1930s Beecher demonstrated a decrease in total lung capacity, vital capacity, residual volume, and functional residual capacity (FRC) in patients who underwent laparotomy.2 Bartlett reviewed the events following anesthesia and identified reductions in FRC and lung compliance and an increase in work of breathing. 2 Arterial blood oxygen tension both in patients undergoing laparotomy and in those undergoing thoracotomy have also been shown to diminish by an average of 20 torr in the postoperative period. Bendixin in 1964 also demonstrated that patients ceased sighing when given narcotic analgesia postoperatively.4 The changes in ventilatory pattern with loss of sighs lead to airway closure in dependent portions of the lung and subsequent changes in lung volumes, changes in compliance, and decrease in oxygen concentration. These changes become maximal at 48 to 72 hours after operation and usually return to normal within seven days without becoming clinically evident. Host defense mechanisms are also altered in the postoperative period. Atropine, narcotics, and oxygen itself decrease mucociliary clearance in large and small airways. Closure of small airways predisposes the patient to bacterial multiplication and subsequent bronchial pneumonia in distal airspaces. I8 Depressed coughing secondary to pain and sedation suppresses the major mechanism by which airway secretions are removed. Prevention of Pulmonary Complications Pulmonary complications, which occur in 20 to 40 per cent of patients following thoracic procedures, are the single largest cause of postoperative morbidity and mortality,lo In this group of patients, the physiologic changes described earlier lead to progressive pulmonary abnormalities characterized by decreased tidal volume, inability to sigh, decreased arterial Pao 2, diminished breath sounds in both lung bases, fever, and an abnormal chest x-ray film. Bartlett showed that if the patient was able to institute maximal inflations to a total lung capacity in the intraoperative and postoperative period, either by positive pressure inflation or by voluntary maximal inspiration, these decreases in lung volume, compliance, and shunting could be reversed. 2 He felt that respiratory maneuvers to prevent these complications should emphasize maximum alveolar inflation and maintenance of normal functional residual capacity. Meyers and associates found that when the FRC reduction was greater than 40 per cent, severe complications occurred. I3 They found that intermittent positive pressure breathing was effective in reversing the postoperative decreases in FRC. Moreover, not until the third or fourth postoperative day were they able to increase the FRC with the incentive spirometer, probably indicating that patient cooperation is necessary to achieve the maximum effectiveness of any device for improving postoperative pulmonary functions. Various voluntary and involuntary methods are currently being utilized to reverse the postoperative pulmonary complications of atelectasis, retained secretions,. bronchospasm, airway edema, and infection (Table 3). All of these modalities have advantages and disadvantages. It would appear that the most ideal procedure in respiratory therapy would be a therapeutic maneuver performed by the patient with minimal cost and maximal effectiveness. Therefore, if the patient is cooperative, voluntary maneuvers for deep breaths such as provided by an incen-
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Table 3.
Voluntary and Involuntary Respiratory Methods INVOLUNTARY
VOLUNTARY
Intermittent positive pressure breathing Deep breathing and coughing Incentive spirometry
CO 2 rebreathing or 5% CO2 inhalation Chest physiotherapy and postural drainage Ultrasonic nebulization of distilled H 20 Nasotracheal suctioning Percutaneous tracheal catheterization Therapeutic bronchoscopy
tive spirometer would be the best and least expensive method. If the patient is uncooperative, involuntary methods may be necessary. With adequate selection of patients and preoperative preparation, most individuals will come through the operation without significant complications. The same measures used in preoperative preparation should be resumed as soon after surgery as possible. In addition, patients should be treated with what has been referred to as "the stir-up program" with frequent coughing, turning, and deep breathing. They should be encouraged to use the incentive spirometer frequently, and early ambulation is essential (see Table 2).
Long-Term Ventilation Since we are dealing with a group of patients with limited pulmonary reserve and since thoracotomy, even without resection, results in a significant decrease in pulmonary function fot at least a week postoperatively, we would expect that a small percentage of patients, especially those requiring pneumonectomy, will require long-term ventilation. The process of weaning them becomes an important consideration. The patient should be stable or improving with a fraction of inhaled oxygen (FI0 2 ) of less than 60 per cent. Sedative drugs should be minimized and the patient should be well rested. If the patient meets the criteria, weaning can be started using either a T-tube or IMV. Most patients can be weaned quickly by either method. Patients who cannot be weaned easily will need careful re-evaluation for additional contributing problems such as neuromuscular disease, diaphragmatic dysfunction, inadequate nutrition, acid base status, and psychologic factors.I 7
CONCLUSION With our aging population and the increasing incidence of carcinoma of the lung and its strong association with chronic obstructive pulmonary disease and cigarette smoking, we are going to continue to see a large group of patients referred for thoracic surgery with very limited pulmonary reserve. Surgical resection of the primary pulmonary neoplasm offers the only hope of cure for those patients with non-small cell carcinoma of the lung. This requires that we accept patients for surgical therapy who are at increased
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risk for postoperative morbidity and mortality. Careful preoperative pulmonary function evaluation along with preoperative preparation allows us to pick a group of patients who should have an acceptable postoperative morbidity and mortality. Optimal anesthetic management in the perioperative period, surgical procedures adapted to the individual patient and his or her lesion, and effective postoperative care allow a large percentage of these patients to have definitive surgery.
REFERENCES 1. American Joint Committee for Cancer Staging and End Results Reporting, Task Force on Lung: Staging of Lung Cancer. 1979. 2. Bartlett, R. H., Gazzaniga, A. B., and Geraghty, T. R: Respiratory maneuvers to prevent postoperative pulmonary complications. A critical review. J.A.M.A., 224:1017-1021,1973. 3. Beecher, H. K.: Effect of laparotomy on lung volume. J. Clin. Invest., 12:651, 1933. 4. Bendixin, H. H., Smith, G. M., and Mead, J.: Patterns of ventilation in young adults. J. Appl. Physiol., 19:195, 1964. 5. Bolman, R. M., III, and Wolfe, W. G.: Bronchiectasis and pulmonary sequestration. SURG. CLIN. NORTH AM., 60:867-881, 1980. 6. Boysen, P. G., Block, A. J., et al.: Prospective evaluation for pneumonectomy using the technetium lung scan. Chest, 72:442, 1977. 7. Byrd, R C.: Minimizing complications when lung patients need surgery. J. Respir. Dis., 1:21, 1980. 8. Churchill-Davidson, H. D., (ed.): A Practice of Anesthesia, 4th ed. Philadelphia, W. B. Saunders Co., 1978. 9. Conley, M., Flye, M. W., and Silver, D.: Spectrum of pulmonary sequestration. Ann. Thorac. Surg., 22:480, 1976. 10. Gracey, D. R., Divertie, M. B., and Didier, E. P.: Preoperative pulmonary preparation of patients with chronic obstructive pulmonary disease. Chest, 76:123, 1979. 11. Hazlett, D. R., and Watson, R. L.: The lateral position test: A simple, inexpensive yet accurate method of studying the separate functions of the lungs. Chest, 59:576, 1971. 12. Key, J. L., Jr., Paulson, D. L., and Shaw, R. -R.: Treatment of the superior sulcus tumor by irradiation followed by resection. Ann. Surg., 154:29, 1969. 13. Meyers, J. R, Lembeck, L., O'Kane, H., et al.: Changes in functional residual capacity of the lung after operation. Arch. Surg., 110:576, 1975. 14. Mountain, C. F., and Murphy, W. K.: Differential diagnosis and clinical evaluation of lung cancer patients. The Cancer Bulletin, 32:96-97, 1980. 15. Newland, H., Jr., and Oldham, H.: Benign tumors of the lung and bronchus. SURG. CLIN. NORTH AM., 60:825, 1980. 16. Olsen, G. N., and Block, A. J.: Pulmonary function evaluation of the lung resection candidate: A prospective study. Am. Rev. Respir. Dis., 11:379,1975. 17. Sahn, S. A., Lakshminarayan, S., and Petty, T. L.: Weaning from mechanical ventilation. J.A.M.A., 235:2209, 1976. 18. Tisi, G. M.: Preoperative evaluation of pulmonary function. Am. Rev. Respir. Dis., 119:293, 1979. Division of Thoracic and Cardiovascular Surgery Scott and White Clinic Temple, Texas 76508
Pulmonary Resection in Patients with Impaired Pulmonary Function G. Valter Brindley, Jr., M.D.,* R. E. Walsh, M.D.,t W. T. Schnarr, M.D.,f G. W. Allen, M.D.;§ M. K. Mendenhall, M.D.,II and E. W. Ahlgren, M.D., ~
Patients with pulmonary lesions warranting. consideration of pulmonary resection often are seen with varying degrees of impaired pulmonary function. Refinements in evaluation of pulmonary function, special preoperative preparation, optimal anesthetic management, utilization of operative procedures adapted to the individual patient and his or her lesion, and effective postoperative care will permit many of these patients to have their lesions removed with acceptable morbidity and low mortality. Close cooperation between the specialists in medical diseases of the chest, pulmonary physiologists, cardiologists, anesthesiologists, and the surgeon is essential in the care of these high risk patients. The thoracic surgeon will make a decision as to the feasibility of pulmonary resection after collaborative evaluation of the nature and extent of the disease and the physiologic status of the host.
MALIGNANT LESIONS As a general theorem, practically all patients with non-small cell carcinoma, Stage I and Stage II, and selected patients with Stage III disease are candidates for surgical treatment if their physiologic status permits. l Surgery seldom is indicated for small cell carcinoma of the lung. However, if the tumor presents as an isolated peripheral pulmonary nodule, classified as Tl *Senior Consultant, Departments of General and Thoracic Surgery, Scott and White Clinic; Professor of Surgery, Texas A. and M. University College of Medicine, Temple, Texas tDivision of Pulmonary Medicine, Scott and White Clinic; Professor of Medicine, Texas A. and M. University College of Medicine, Temple, Texas :f:Division of Pulmonary Medicine, Scott and White Clinic; Assistant Professor of Medicine, Texas A. and M. University College of Medicine, Temple, Texas §Department of Anesthesiology, Scott and White Clinic; Associate Professor of Anesthesiology, Texas A. and M. University College of Medicine, Temple, Texas "Department of Anesthesiology, Scott and White Clinic; Professor of Anesthesiology, Texas A. and M. University College of Medicine, Temple, Texas 'Department of Anesthesiology, Scott and White Clinic; Professor of Anesthesiology, Texas A. and M. University College of Medicine, Temple, Texas
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NO MO or T2 NO MO, lobectomy with mediastinal lymphadenectomy should be considered. Most patients with small cell carcinoma have disseminated disease at the time of initial presentation to the physician and receive maximal palliation by a combination of radiation and chemotherapy. We are initiating an evaluation of the feasibility of thoracotomy and removal of the residual localized primary small cell carcinoma after a favorable response to chemotherapy and irradiation. We hope that some of these patients will have a better prognosis after such an aggressive approach. Staging of all patients with bronchogenic carcinoma is essential. Meticulous physical examination and radiographic studies, including tomography when'indicated, are fundamental initial studies. Bronchoscopy is essential even for the patient with the small, solitary, peripheral nodule, since a central bronchial lesion might also be present. Excision of a palpable scalene lymph node may be helpful, since proven supraclavicular lymph node metastasis is evidence of inoperability. Mediastinoscopy should be performed in all patients with suspected lung cancer except those with peripheral "coin" lesions and a mediastinum that appears normal radiographically. Extrapleural mediastinotomy through the bed of the resected segment of the left second costal cartilage is preferred in assessing mediastinal metastasis from lesions in the left lung. Contraindications to resection based on mediastinal assessment include (1) metastasis from a small cell carcinoma, (2) peri nodal or lymph node metastasis extending beyond the capsule of the node, (3) involvement of contralateral paratracheal lymph nodes, (4) extensive involvement of unilateral upper paratracheal lymph nodes, and (5) direct invasion of heart or major blood vessels. Computerized tomography, scanning, and pulmonary angiography may be helpful in determining resectability in central or posterior paramediastinallesions. 14 When the lesion is a small cell tumor or there is clinical suggestion of distant metastasis, radionuclide scans of liver, bone, and brain, as well as bone marrow aspiration, may be elected. When the lesion is not accessible to bronchoscopy, needle biopsy may provide a diagnosis if the tumor is nonresectable or the patient is inoperable. Refinements in cytologic techniques and the availability of thin needles make this approach practical and feasible. The diagnostic accuracy is high and the morbidity is quite low.
Surgical Treatment of Primary or Metastatic Lung Cancer The rare indication for surgical treatment of small cell carcinoma has already been mentioned. Very seldom is resection indicated for a patient known to have this type of cancer. Complete removal of non-small cell bronchogenic carcinoma is the only treatment at this time that offers a prospect of cure. The type of operation should be carefully planned and be consistent with the type and extent of the lesion and the patient's biologic status. The goal of the surgeon is to remove all of fhe tumor with maximal conservation of uninvolved pulmonary tissue. Lobectomy. Lobectomy with mediastinal lymphadenectomy is our most frequent operation for bronchogenic carcinoma. The tumor must be confined within the lobe, there should be a tumor-free bronchial margin of at least 1.5 cm for resection, and any lymph node extension should be confined to the first level of lobar drainage and available for complete removal byan
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en bloc dissection. When the tumor extends to the origin of the lobar bronchus and the patient has limited pulmonary reserve, sleeve resection and bronchoplasty may permit complete removal of the tumor and avoid a pneumonectomy that might result in severe morbidity and mortality. Segmentectomy. In the patient with poor pulmonary reserve we have used segmental resection for a peripheral lesion, well confined to the segment and without evidence of lymph node metastasis. This procedure has been particularly appropriate for nodular alveolar cell carcinoma, a second primary pulmonary carcinoma, and some pulmonary metastases. Wedge Resection. In the surgical treatment of malignant lesions, we have use.d wedge excision primarily for diagnosis of small peripheral nodular lesions without evidence of metastasis. This operation seldom is sufficient for primary pulmonary cancers and is used mostly for removal of pulmonary metastases. Such conservative resection is especially indicated for removal of multiple lesions in more than one lobe or on more than a single occasion. If the removal of a small peripheral lesion reveals a primary bronchogenic carcinoma of non-small cell type, lobectomy with lymphadenectomy usually should follow. Pneumonectomy. Pneumonectomy seldom is indicated or justified for the patient with diminished pulmonary reserve. Pneumonectomy ordinarily is reserved for patients with Stage III disease. Should evaluation reveal that most of the patient's pulmonary function is occurring in the uninvolved lung and his or her status be improved enough by medical management to predict adequate ventilation after pneumonectomy, the procedure could be considered. The predicted residual forced expiratory volume in one second (FEV l ) should be at least 0.80 liters for functional survival to be expected. Metastases should be intranodal and all gross tumor should be removable. Extended Resection. Superior Sulcus Tumors. Shaw and Paulson showed many years ago that preoperative irradiation followed by an en bloc removal of the upper lobe of the lung and involved tissues of the chest wall provides maximal opportunity for survival or palliation.I 2 These tumors often are peripheral to the mediastinum and distant metastasis is relatively rare. Chest Wall or Diaphragmatic Extension. For many years, most thoracic surgeons considered any malignant pulmonary tumor extending onto the chest wall or diaphragm to be inoperable. Resection is not justified when such a tumor involves the mediastinum or hilus or diffusely extends through the lung. However, when the lesion is entirely peripheral, the hilus and mediastinum often are free of tumor and en bloc removal of these lesions may give a satisfactory result if all of the tumor can be removed and there is no evidence of distant metastasis. The defect in the chest wall or diaphragm can be repaired using a variety of techniques.
INFLAMMATORY LESIONS Tuberculosis Decreased incidence and improved medical management of pulmonary tuberculosis have greatly decreased the necessity for surgical treatment. Surgery is considered only for complications of the disease that are refracI
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tory to good medical management, and the patient must be considered to be a reasonable risk for the procedure. Indications for consideration of surgery include destroyed lung or lobe of lung, thick-walled cavity with positive sputum and/or hemorrhage, bronchiectasis with significant symptoms, severe irreversible bronchial stenosis, nodular lesion that is increasing in size and could contain carcinoma, persistent or severe hemoptysis, or bronchopleural fistula that does not close with adequate chemotherapy.
Types of Operations Segmental Resection. This technique is most valuable in treating patients with localized disease sensitive to the primary drugs. The necessity for maximal preservation of pulmonary tissue is especially important in the management of patients with limited pulmonary reserve. Lobectomy. This remains the most frequently used method of resection. The remaining lobe or lobes usually fill the pleural cavity and postoperative space problems are rare. When a space problem is apparent, concomitant thoracoplasty should be performed. Pleuropneumonectomy. This is the technique of choice in the management of a patient with a lung destroyed by tuberculosis. It avoids invasion of the chronically infected pleura and results in fewer postoperative problems than does a transpleural pneumonectomy.
LUNG ABSCESS Surgical intervention is seldom needed any more for chronic pulmonary abscess. Proper use of antibiotics for pulmonary infections, early and effective bronchoscopic removal of endobronchial foreign bodies or aspirated material, and transbronchial drainage of an acute abscess usually will prevent the development of a chronic pulmonary abscess. Should such an abscess necessitate surgery, the tissue destroyed by the abscess should be removed. The extent of the resection will depend upon the size and location of the abscess. Usually a lobectomy is sufficient and effective.
FUNGAL DISEASES OF THE LUNG The need for pulmonary resection in fungal diseases is rare, as these diseases usually respond well to drug therapy. A chronic thick-walled cavity that persists in spite of appropriate chemotherapy may require resection, usually by lobectomy. Occasionally single or multiple nodules may present a diagnostic problem, and open pulmonary excision of a nodule may be required to establish the diagnosis.
BRONCHIECTASIS The overall incidence of bronchiectasis has declined remarkably as a result of more effective antimicrobial therapy; however, the thoracic surgeon
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should be familiar with bronchiectasis and pulmonary sequestration. The etiology, pathology, and diagnosis of bronchiectasis were well presented in a recent paper by Bolman and Wolfe and will not be reviewed here. 5 Treatment Bronchiectasis initially should be treated medically with antibiotics, postural drainage, avoidance of air pollutants, and effective management of associated diseases. Surgery should be considered for those patients with persistent or progressive symptoms after an adequate trial of good medical management. Preferably, the disease should be localized, in one lobe or in contiguous segments in two lobes. When surgery is indicated, removal of the involved segments should be performed, preserving as much normal lung as possible. Occasionally, bilateral resections will be necessary. After careful preoperative evaluation and preparation, the lung with the greatest involvement is operated on first, with effective postoperative medical management. An additional contralateral operation is usually not required. However, if chronic hemoptysis, foul sputum, and recurrent pneumonitis persist, consideration should be given to resection in the opposite lung. These patients require careful and effective medical and anesthesiology management before, during, and after the operation. The thoracic surgeon will limit the resection to removal of as little pulmonary tissue as necessary with maximal conservation of all normal lung.
BRONCHOPULMONARY SEQUESTRATION Bronchopulmonary sequestration is an uncommon congenital malformation of the lung involving separation of a portion of lung early in embryonic development. 9 The arterial supply to this portion of the lung is atypical, coming directly from the aorta or a branch of the aorta. This ectopic pulmonary tissue may be intralobar or extralobar, usually in the lower lobes and more often on the left. Treatment for symptomatic bronchopulmonary sequestration is resection of the abnormal tissue. The thoracic surgeon must be very careful not to overlook the anomalous artery, which usually passes through the inferior pulmonary ligament. Preoperative angiography can be very helpful in identifying this artery, especially in small infants.
BENIGN TUMORS OF THE LUNG Benign tumors of the lung and bronchus are of many varieties. The majority of the parenchymal lesions are present as asymptomatic, solitary, peripheral nodules in the lung. These tumors are rare compared with malignant and circumscribed inflammatory lesions.1 5 Hamartoma is the most common benign tumor in the lung. Computerized tomography and percutaneous needle biopsies may be helpful in establishing the nature of these parenchymal tumors, although often excisional biopsy is necessary to exclude a possible malignant tumor. Most of the small, peripheral nodular lesions can be removed by wedge resection. Fiberoptic bronchoscopy will reveal
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the diagnosis of most endobronchial tumors. Small, pedunculated lesions· confined to the bronchial mucosa may be removed endoscopically, but usually thoracotomy, bronchotomy with total excision of the lesipn, and bronchoplasty are preferred. If the lesion has produced chronic bronchial obstruction, atelectasis, bronchiectasis, and chronic pneumonitis may be present peripheral to the tumor. Under these conditions, segmentectomy or lobectomy with removal of this diseased tissue is indicated.
TECHNICAL CONSIDERATIONS Incision The anterior or anterolateral incision is usually preferred for thoracotomy in the patient with reduced or marginal pulmonary function, as this position allows optimal pulmonary performance during anesthesia. The incision can be done quickly and the patient has less associated postoperative pain and can cough and breathe easier than after the posterolateral approach. However, when the lesion is fixed posteriorly and does not appear to be easily accessible, the posterolateral incision should be chosen. Postoperative Chest Pain Great care is taken to handle the ribs as gently as possible at thoracotomy. The incision should be of adequate length to permit the ribs to be separated easily. Retraction of the ribs should be done slowly, avoiding undue stress or rib fracture. At the conclusion of the pulmonary resection, intercostal nerve block anesthesia is done with bupivacaine and repeated postoperatively as needed. Antibiotics If the patient has been on appropriate antibiotics prior to thoracotomy, such as for tuberculosis or lung abscess, these medications are continued during and after pulmonary resection. Cultures and sensitivity studies are made from the resected specimen, and adjustment in antibiotic coverage is made accordingly. Since many of the patients with malignant lesions of the lung and limited pulmonary function are at increased risk for postoperative infection and the consequences of their infection could be catastrophic, we ordinarily use perioperative antibiotics for these patients. Most often we elect one of the cephalosporins for this purpose. The medication is initiated prior to surgery and continued during the operation and postoperatively until there is no evidence of an air leak, drainage is minimal, drains have been removed, and there is no clinical evidence of infection. PREOPERATIVE EVALUATION OF THE PATIENT WITH RESPIRATORY DISEASE During the past 10 to 15 years significant advancement has been made in the preoperative evaluation of patients with respiratory disease about to undergo lung .resection. In assessing these patients the goal is to reduce the
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incidence and severity of postoperative complications. The complications can be divided into two types. The first is postoperative respiratory failure due to insufficient residual lung to sustain the patient. I6 The second type of complication is that seen in patients undergoing pulmonary resection, thoracotomy without pulmonary resection, and intra-abdominal procedures, namely, microatelectasis signified by widening of the alveolar-arterial gradient, macroatelectasis secondary to segmental collapse, and respiratory infection associated with fever, purulent secretions, and parenchymal infiltrate. IS The first step in the approach to these patients is appreciating preoperative risk factors that predispose to postoperative respiratory complications. These factors are as follows: History of heavy smoking and cough Obesity Age greater than 60 years Intrathoracic or upper abdominal surgery Known pulmonary disease Mean pulmonary artery pressure above 35 mm Hg Anesthesia time greater than three hours
A complete evaluation of patients with increased risk of postoperative complications includes a detailed history of cardiopulmonary disease, with a thorough physical examination, and selective laboratory investigations to define the degree of respiratory dysfunction. Pertinent components of the history include smoking habits, cough, character and quality of sputum, history of wheezing, and exercise limitation. Pertinent physical findings include wheezing, prolongation of expiration, ineffective cough, and pulsus parodoxus. Chest x-ray film, electrocardiogram, and complete blood count are done routinely on patients who are considered candidates for thoracotomy. Pulmonary function testing and arterial blood gas determinations are routinely performed on all thoracotomy patients. It is usually not too difficult to determine which patients will be able to tolerate a lobectomy, but at the time of thoracotomy it may be necessary to do a pneumonectomy. The preoperative pulmonary function evaluation determines which patients can tolerate this procedure. Many different tests of pulmonary function have been used to make this determination, but no single test has been entirely adequate (Table 1).7,16 We have found that evaluating patients in a stepwise fashion allows us to determine those patients who can tolerate pulmonary resection with an acceptable postoperative mortality and morbidity. Once it is determined that the patient is operable from the standpoint of pulmonary function, no further testing is required. Table 1.
Criteria for Further Evaluation Prior to Pneumonectomy
Forced vital capacity < 50% of predicted Forced expiratory volume in 1 second < 50% predicted or < 2 liters Maximum voluntary ventilation < 50% predicted Residual volume: total lung capacity ratio> 50% Diffusing capacity < 50% of predicted Could not complete 2 minutes on treadmill at 3 MPH, 10% incline Could not climb two flights of stairs without undue stress
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Arterial Blood Gases on Room Air. An elevated arterial CO 2 pressure (Paco 2 ) is a contraindication to pulmonary resection. A low Pao 2 is not as critical, since it may represent shunting and abnormal ventilation perfusion relationships in diseased lungs. In some instances, the Pao2 actually increases postoperatively. 7 Pulmonary Function Testing. When the forced vital capacity (FVC) and forced expiratory volume in one second (FEV!) are greater than 50 per cent of predicted and the FEV! is greater than 2 liters, the patient is a candidate for pneumonectomy.l6 An FEV! of more than 1.4 liters is adequate for a lobectomy. Split Function Testing. Patients who do not meet the foregoing criteria may still be candidates for surgery, but they must be evaluated by further testing. We prefer to do one of the split function tests. In the past, this required measuring the function of each lung separately after the insertion of a double lumen endotracheal tube such as the Carlens tube. This was an expensive, uncomfortable, invasiv_e test that presented some risk to the patient. It has been shown that similar information can be obtained from a quantitative perfusion lung scan obtained with a system that measures radioactivity from each lung separately. The percentage of perfusion to the noninvolved lung multiplied by the preoperative FEV! gives a predicted postoperative FEV! after pneumonectomy. A value of 0.8 liter or greater indicates that the patient is a reasonable operative risk. 6 The lateral position test, in which the functional residual capacity (FRC) is measured in the supine and both lateral decubitus positions gives similar information, but it is not as widely available as the perfusion lung scan.ll Pulmonary Artery Balloon Occlusion. Most patients who do not meet the foregoing criteria will be treated with nonoperative therapy. If surgery is still considered, a right ventricular catheterization may be done with the balloon occlusion of the pulmonary artery on the side of the lesion. The patient exercises; if the pulmonary artery pressure is greater than 35 mm Hg or the arterial oxygen tension falls to 45 mm Hg, the patient is not a surgical candidate. 6 Several other tests (see Table 1) have been used to determine operability and each has some usefulness. Each physician and institution must determine which tests work best in their particular situation. Patients who fail to meet the criteria for pulmonary resection may have enough improvement in ptilmonary function after a short course of pulmonary hygiene to enable them to tolerate pulmonary resection.
Preoperative Preparation Preoperative pulmonary preparation of patients with chronic obstructive pulmonary disease for a period as short as 48 hours has been shown to reduce postoperative complications by nearly one-half.lO Table 2 lists prophylactic measures that have proved helpful. All patients should stop smoking. Even a few days of abstinence will decrease the volume of sputum produced. Patients with chronic obstructive pulmonary disease benefit from oral therapy with one of the theophylline preparations such as Aminophyllin, 200 mg four times daily. Isoetharine or metaproterenol are given by in-
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Table 2.
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Preoperative and Postoperative Pulmonary Therapy PREOPERATIVE
Stop smoking Oral bronchodilators Inhaled bronchodilators Heated aerosol Chest physiotherapy Antibiotics Corticosteroids Incentive spirometer
POSTOPERATIVE
Stir-up program Early ambulation Oxygen Minimize sedative and narcotics
halation four times daily using either an air compressor or an intermittent positive pressure breathing machine if the patient cannot take an adequate inspiration. Patients who produce over two ounces of sputum daily are treated with a heated sterile water aerosol by mask for 20 minutes after the inhaled bronchodilator. Chest physiotherapy, consisting of postural drainage and percussion, is done at least twice daily. If respiratory infection is present, one of the broad-spectrum antibiotics is appropriate. Some patients with reversible brochospasm or reactive airways respond rather dramatically to corticosteroids. All patients should be instructed prior to surgery in techniques of coughing, de~p breathing, and the use of one of the incentive breathing devices that emphasize sustained inspiration. It is much more diTficult to teach patients these techniques in the postoperative period while they are sedated or in pain. Part of the patient education includes describing the postoperative routines. This is particularly important if it seems likely. that the patient will require mechanical ventilation after surgery. Patients seem to tolerate ventilators better if they know beforehand that they may wake up with an endotracheal tube in place with very limited ability to communicate with those around them.
ANESTHESIA
Preoperative Considerations Anesthetic rpanagement of the thoracic surgical patient who has normal or nearly normal pulmonary function is relatively simple and straightforward. Many patients, however, have decreased pulmonary reserve or can expect significant reduction in pulmonary function in order to achieve an opportunity for cure of their disease. The latter group requires the' most thorough assessment of preoperative risk factors and the most careful planning of anesthetic and postanesthetic management. Consistently low arterial blood oxygen tension (Pao2 ) mandates the choice of techniques allowing increased inspired oxygen levels (F10 2 ). Markedly elevated arterial carbon dioxide tensions (Paco2 ) are more ominous than Pao2 disturbances and are a matter for grave concern. Almost inevitably, postoperative mechanical ventilation will be required and this will affect the choice of the route for establishment of an of endotracheal airway.
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Other diminished pulmonary function variables detected in the preoperative evaluation will also have great impact upon the anesthetic plan. Obstructing lesions of the trachea or distortion of mediastinal contents may present the anesthesiologist with profound mechanical and physiologic problems. Positional changes in pulmonary function should be determined preoperatively in patients suspected by history or pathologic process of being subject to deleterious alterations in pulmonary or cardiovascular function with change of position. In addition, anesthesia with the chest wall open on the operative side may produce profound changes in ventilation-perfusion (V/Q) relationships for the following reasons: 1. The abdominal contents and mediastinum exert pressure on the dependent lung, increasing the height of the diaphragm and decreasing lung volume. A decrease in lung volume favors airway closure, atelectasis, and shunting in the dependent lung. 2. Sighing and the normal inspiratory muscle tone, which tend to open closed airways and keep them open by maintaining adequate lung volume, are lost during anesthesia. 3. Because of the open chest on the operative side, compliance of the upper lung increases, favoring ventilation of that lung. 4. Blood flow is directed preferentially by gravity to the dependent lung.
Arterial blood gas determinations during thoracotomy usually demonstrate the large changes in V/Q and shunting that occur. These abnormalities are enhanced by age, pre-existing pulmonary disease, and obesity and may be predicted by careful preoperative assessment. Entities that may be aggravated by anesthesia must also be mentioned. The myasthenic syndrome, frequently associated with small cell bronchial carcinomas, significantly augments drug-induced neuromuscular blockade. s The anticholinesterases, such as physostigmine and pyridostigmine, are of only limited value in reversal of weakness.
Monitoring For thoracic surgery patients we routinely monitor arterial blood pressure by cuff, the heart by electrocardiogram, heart and breath sounds continuously by esophageal stethoscope, and temperature by a nasopharyngeal probe. In patients with diminished pulmonary capacity as demonstrated preoperatively, it is advisable to obtain at least one determination of arterial blood gases early in the operative procedure to determine adequacy of oxygenation (Pao2 ) and of ventilation (Paco2 ). If gross abnormalities of gas exchange are present, resection of large portions of lung tissue is anticipated, postoperative ventilation is expected, or significant cardiovascular instability is present, an indwelling arterial catheter may be extremely useful for repeatedly measuring blood gases and for monitoring arterial blood pressure. This also facilitates replacement of blood loss and determination of the ability of the patient to be weaned from mechanical ventilation and extubated postoperatively. If a ventilator is used, tidal volume, rate of ventilation, and peak inspiratory pressure should be carefully followed and recorded. Changes in these variables may demonstrate increased dead space (when compared with measured Paco2 ), decreased compliance (indicating accumulations of secre-
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tions, development of pulmonary edema, or contralateral pneumothorax), or changes in resistance (bronchospasm). Finally, if congestive heart failure or cor pulmonale is present, a SwanGanz catheter may be placed via the jugular or subclavian route to detect increases in pulmonary artery pressure on clamping of a main stem pulmonary artery or its branches. Pulmonary capillary wedge pressure is also a useful guide for administration of fluid and blood.
Anesthetic Management Induction of anesthesia is preceded by denitrogenation of the patient's lungs with 100 per cent oxygen administered by mask for a period of two to five minutes. This guarantees adequate oxygenation during the period prior to securing the airway by endotracheal intubation. Thiopental administered intravenously is most commonly used for induction and provides a smooth, rapid sleep. In patients who have severe cardiac dysfunction or are in shock, diazepam and a narcotic or ketamine may be used intraveneously. Ketamine has sympathomimetic actions that tend to suppori: the blood pressure and cardiac output. After narcosis is induced and ability to ventilate the patient has been demonstrated, succinylcholine is administered to obtain muscle relaxation for tracheal intubation. After intubation, anesthesia is maintained with a volatile anesthetic agent such as halothane, enflurane, or isoflurane, with a 50:50 mixture of nitrous oxide and oxygen. Volatile agents allow the administration of higher concentrations of oxygen if that need is demonstrated by a low Pao2 • Indeed, these agents are potent enough to provide surgical anesthesia even when given with 100 per cent oxygen. They depress airway irritability, limit secretions, and may be eliminated rapidly at the end of the procedure. All volatile agents produce cardiac depression, and their concentration may need to be decreased if significant hypotension occurs. Under these circumstances, if the patient begins to move or cough, a muscle relaxant may be given. If severe hypotension occurs, anesthesia may be maintained with ketamine, for amnesia and analgesia, and oxygen. Muscle relaxants are often used to facilitate electrical transection of the thoracic wall musculature and to facilitate rib spreading. Generally, a nondepolarizing agent such as pancuronium is used for this purpose. Patients who require corticosteroids and theophylline preparations preoperatively should be maintained on adequate doses of these drugs quring the perioperative period. The corticosteroids are given either intravenously or intramuscularly and theophylline preparations are usually given intravenously until the patient is able to take oral fluids. Ventilation during the procedure should be controlled since the chest is open. Assisted ventilation may produce unpredictable fluctuations in Paco2 and Pao2 • Return of spontaneous ventilatory effort during surgery usually indicates light anesthesia, hypercapnia, or hypoxemia. Arterial blood gases should be measured frequently if changes from normal are suspected or predicted on the basis of the preoperative pulmonary status. If there is a danger of contamination of the dependent lung with infected material (as with lung abscess or bronchiectasis) or with blood (en-
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dobronchial bleeding), it is desirable to isolate one lung from the other. This may be done with a double lumen endotracheal tube. The lungs are separated by cuffs that when inflated permit separate ventilation of the right and left lungs and that prevent mixing of ventilator gases or contamination of one lung by the other. These catheters might be considered for other uses such as directing ventilation to one lung only, when a larg~ bronchopleural fistula or giant bullous emphysema is present, or simply for exposure so that the lung to be resected is not continually in motion. Problems and complications associated with the use of double lumen tubes include the following: 1. 2. 3. 4. 5.
Increased resistance to airflow Further compromise of ventilation-perfusion Malposition of the catheter Blockage of one or both lumens with secretions Tracheal or bronchial rupture
Following discontinuation of the anesthetic and reversal of muscle relaxants at the end of the procedure, spontaneous ventilation is allowed to resume. If the tidal volume appears adequate at this time and protective pharyngeal reflexes have returned, the patient may be extubated and taken to the recovery room. If ventilation appears inadequate or is marginal when measured by respirometer (less than 400 ml tidal volume), the patient should remain intubated and be transported to recovery with assisted ventilation and supplemental oxygen. Patients who have undergone pneumonectomy are not extubated until they have recovered sufficiently to provide evidence of an adequate vital capacity (10 ml per kg of body weight) and have physiologically acceptable blood gases.
Postanesthetic Management The postanesthetic recovery phase represents the biggest hurdle of the perioperative period for the patient and the physician. In addition to routine monitoring, specific attention should be directed toward the following: 1. Chest x-ray film. The postoperative chest x-ray film documents the end result of the surgery and serves as a baseline for subsequent films; more importantly, free air atelectasis, mediastinal shifts, improper functioning of chest tubes, and other alterations can be detected and subsequently managed. 2. Tidal volume. Measurements can be made, especially ifhypoventilation is suspected. The tidal volume should be comparable to preoperative determinations but may be less because of splinting. 3. Arterial blood ga~es. Blood gases in the immediate postoperative period can alert the physician to any trends and predict the need to continue mechanical ventilation or other oxygen therapy.
There must be a high index of suspicion for life-threatening complications, which include massive hemorrhage and bronchial stump rupture. Significant bleeding in the period immediately following thoracic surgery is rare and usually is caused by loosening of a ligature from a pulmonary or intercostal vessel. It is heralded by signs of hypovolemia, and mediastinal shift to the opposite side may occur if chest tube drainage is inadequate. Immediate thoracotomy may be necessary to obtain manual control of bleeding and may be life-saving.
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A bronchopleural fistula or ait; leak may result in tension pneumothorax if the patient is on controlled mechanical ventilation and a chest tube is not employed. This catastrophic complication can be immediately identified by a high inflation pressure required for ventilation, sudden shift of the mediastinum to the opposite side, circulatory collapse, subcutaneous emphysema, and serosanguinous sputum. In this situation, immediate decompression of the pleural space is necessary and may be accomplished by insertion of a large bore needle or chest tube, or by reopening the chest. Postoperative pain can be managed at three levels. Injection of"bupivacaine (Marcaine) into the intercostal bundles at the thoracotomy site has proven efficacy. A transcutaneous nerve stimulator applied in the postanesthesia recovery room can be adjusted to help with the pain management. The use of narcotics can be considered a final balance of the three. The initial pain control can be achieved with intravenous narcotics such as meperidine, 0.25 or 0.5 mg per kg. The onset of analgesia results within two to five minutes and the duration of action is approximately one hour. Meperidine can be ordered for the long term management of pain at approximately 1 mg per kg, intramuscularly, every three to four hours as necessary and requested by the patient. Patients in whom respiratory depression has been identified preoperatively must have the narcotic administration tailored to their specific needs. If there is doubt, rapid determination of the arterial blood gases can give insight into the degree of narcotic shift of the carbon dioxide response curve. The treatment of pain following thoracotomy is important not only for patient comfort but also to minimize the pulmonary complications by enabling patients to breathe deeply, cough effectivdy, and ambulate early. During recovery from anesthesia, the level of respiratory support may range from spontaneous breathing with an inspired oxygen concentration of 50 per cent or greater to intermittent mandatory ventilation (IMV) with a rate of 8 to 10 breaths per minute and a tidal volume of approximately 10 to 12 ml per kg or controlled mechanical ventilation (CMV) with 10 to 12 breaths per minute at a tidal volume of 10 to 12 ml per kg. If an arterial oxygen tension of 90 torr cannot be obtained on 50 per cent oxygen during IMV or CMV, positive end-expiratory pressure (PEEP) of 5 to 20 cm H 20 may be employed to increase oxygenation. If the patient can achieve the baseline tidal volume of approximately 7 ml per kg, a vital capacity of approximately 10 to 15 ml per kg, and an inspiratory effort of greater than 25 cm H 20, spontaneous ventilation and extubation can be considered.
POSTOPERATIVE PULMONARY MANAGEMENT Postoperative Physiologic Changes The major postoperative physiologic respiratory changes are as follows: Change in pattern of breathing Decrease in lung volumes Alteration in gas exchange Increased work of breathing Altered defense mechanisms
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As early as the mid-1930s Beecher demonstrated a decrease in total lung capacity, vital capacity, residual volume, and functional residual capacity (FRC) in patients who underwent laparotomy.2 Bartlett reviewed the events following anesthesia and identified reductions in FRC and lung compliance and an increase in work of breathing. 2 Arterial blood oxygen tension both in patients undergoing laparotomy and in those undergoing thoracotomy have also been shown to diminish by an average of 20 torr in the postoperative period. Bendixin in 1964 also demonstrated that patients ceased sighing when given narcotic analgesia postoperatively.4 The changes in ventilatory pattern with loss of sighs lead to airway closure in dependent portions of the lung and subsequent changes in lung volumes, changes in compliance, and decrease in oxygen concentration. These changes become maximal at 48 to 72 hours after operation and usually return to normal within seven days without becoming clinically evident. Host defense mechanisms are also altered in the postoperative period. Atropine, narcotics, and oxygen itself decrease mucociliary clearance in large and small airways. Closure of small airways predisposes the patient to bacterial multiplication and subsequent bronchial pneumonia in distal airspaces. I8 Depressed coughing secondary to pain and sedation suppresses the major mechanism by which airway secretions are removed. Prevention of Pulmonary Complications Pulmonary complications, which occur in 20 to 40 per cent of patients following thoracic procedures, are the single largest cause of postoperative morbidity and mortality,lo In this group of patients, the physiologic changes described earlier lead to progressive pulmonary abnormalities characterized by decreased tidal volume, inability to sigh, decreased arterial Pao 2, diminished breath sounds in both lung bases, fever, and an abnormal chest x-ray film. Bartlett showed that if the patient was able to institute maximal inflations to a total lung capacity in the intraoperative and postoperative period, either by positive pressure inflation or by voluntary maximal inspiration, these decreases in lung volume, compliance, and shunting could be reversed. 2 He felt that respiratory maneuvers to prevent these complications should emphasize maximum alveolar inflation and maintenance of normal functional residual capacity. Meyers and associates found that when the FRC reduction was greater than 40 per cent, severe complications occurred. I3 They found that intermittent positive pressure breathing was effective in reversing the postoperative decreases in FRC. Moreover, not until the third or fourth postoperative day were they able to increase the FRC with the incentive spirometer, probably indicating that patient cooperation is necessary to achieve the maximum effectiveness of any device for improving postoperative pulmonary functions. Various voluntary and involuntary methods are currently being utilized to reverse the postoperative pulmonary complications of atelectasis, retained secretions,. bronchospasm, airway edema, and infection (Table 3). All of these modalities have advantages and disadvantages. It would appear that the most ideal procedure in respiratory therapy would be a therapeutic maneuver performed by the patient with minimal cost and maximal effectiveness. Therefore, if the patient is cooperative, voluntary maneuvers for deep breaths such as provided by an incen-
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Table 3.
Voluntary and Involuntary Respiratory Methods INVOLUNTARY
VOLUNTARY
Intermittent positive pressure breathing Deep breathing and coughing Incentive spirometry
CO 2 rebreathing or 5% CO2 inhalation Chest physiotherapy and postural drainage Ultrasonic nebulization of distilled H 20 Nasotracheal suctioning Percutaneous tracheal catheterization Therapeutic bronchoscopy
tive spirometer would be the best and least expensive method. If the patient is uncooperative, involuntary methods may be necessary. With adequate selection of patients and preoperative preparation, most individuals will come through the operation without significant complications. The same measures used in preoperative preparation should be resumed as soon after surgery as possible. In addition, patients should be treated with what has been referred to as "the stir-up program" with frequent coughing, turning, and deep breathing. They should be encouraged to use the incentive spirometer frequently, and early ambulation is essential (see Table 2).
Long-Term Ventilation Since we are dealing with a group of patients with limited pulmonary reserve and since thoracotomy, even without resection, results in a significant decrease in pulmonary function fot at least a week postoperatively, we would expect that a small percentage of patients, especially those requiring pneumonectomy, will require long-term ventilation. The process of weaning them becomes an important consideration. The patient should be stable or improving with a fraction of inhaled oxygen (FI0 2 ) of less than 60 per cent. Sedative drugs should be minimized and the patient should be well rested. If the patient meets the criteria, weaning can be started using either a T-tube or IMV. Most patients can be weaned quickly by either method. Patients who cannot be weaned easily will need careful re-evaluation for additional contributing problems such as neuromuscular disease, diaphragmatic dysfunction, inadequate nutrition, acid base status, and psychologic factors.I 7
CONCLUSION With our aging population and the increasing incidence of carcinoma of the lung and its strong association with chronic obstructive pulmonary disease and cigarette smoking, we are going to continue to see a large group of patients referred for thoracic surgery with very limited pulmonary reserve. Surgical resection of the primary pulmonary neoplasm offers the only hope of cure for those patients with non-small cell carcinoma of the lung. This requires that we accept patients for surgical therapy who are at increased
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risk for postoperative morbidity and mortality. Careful preoperative pulmonary function evaluation along with preoperative preparation allows us to pick a group of patients who should have an acceptable postoperative morbidity and mortality. Optimal anesthetic management in the perioperative period, surgical procedures adapted to the individual patient and his or her lesion, and effective postoperative care allow a large percentage of these patients to have definitive surgery.
REFERENCES 1. American Joint Committee for Cancer Staging and End Results Reporting, Task Force on Lung: Staging of Lung Cancer. 1979. 2. Bartlett, R. H., Gazzaniga, A. B., and Geraghty, T. R: Respiratory maneuvers to prevent postoperative pulmonary complications. A critical review. J.A.M.A., 224:1017-1021,1973. 3. Beecher, H. K.: Effect of laparotomy on lung volume. J. Clin. Invest., 12:651, 1933. 4. Bendixin, H. H., Smith, G. M., and Mead, J.: Patterns of ventilation in young adults. J. Appl. Physiol., 19:195, 1964. 5. Bolman, R. M., III, and Wolfe, W. G.: Bronchiectasis and pulmonary sequestration. SURG. CLIN. NORTH AM., 60:867-881, 1980. 6. Boysen, P. G., Block, A. J., et al.: Prospective evaluation for pneumonectomy using the technetium lung scan. Chest, 72:442, 1977. 7. Byrd, R C.: Minimizing complications when lung patients need surgery. J. Respir. Dis., 1:21, 1980. 8. Churchill-Davidson, H. D., (ed.): A Practice of Anesthesia, 4th ed. Philadelphia, W. B. Saunders Co., 1978. 9. Conley, M., Flye, M. W., and Silver, D.: Spectrum of pulmonary sequestration. Ann. Thorac. Surg., 22:480, 1976. 10. Gracey, D. R., Divertie, M. B., and Didier, E. P.: Preoperative pulmonary preparation of patients with chronic obstructive pulmonary disease. Chest, 76:123, 1979. 11. Hazlett, D. R., and Watson, R. L.: The lateral position test: A simple, inexpensive yet accurate method of studying the separate functions of the lungs. Chest, 59:576, 1971. 12. Key, J. L., Jr., Paulson, D. L., and Shaw, R. -R.: Treatment of the superior sulcus tumor by irradiation followed by resection. Ann. Surg., 154:29, 1969. 13. Meyers, J. R, Lembeck, L., O'Kane, H., et al.: Changes in functional residual capacity of the lung after operation. Arch. Surg., 110:576, 1975. 14. Mountain, C. F., and Murphy, W. K.: Differential diagnosis and clinical evaluation of lung cancer patients. The Cancer Bulletin, 32:96-97, 1980. 15. Newland, H., Jr., and Oldham, H.: Benign tumors of the lung and bronchus. SURG. CLIN. NORTH AM., 60:825, 1980. 16. Olsen, G. N., and Block, A. J.: Pulmonary function evaluation of the lung resection candidate: A prospective study. Am. Rev. Respir. Dis., 11:379,1975. 17. Sahn, S. A., Lakshminarayan, S., and Petty, T. L.: Weaning from mechanical ventilation. J.A.M.A., 235:2209, 1976. 18. Tisi, G. M.: Preoperative evaluation of pulmonary function. Am. Rev. Respir. Dis., 119:293, 1979. Division of Thoracic and Cardiovascular Surgery Scott and White Clinic Temple, Texas 76508