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Left-sided pulmonary resections

Reza Mehran and Jean Deslauriers

PRINCIPLES AND JUSTIFICATION

The most common indication for left-sided pulmonary resection is lung cancer. Surgery may also be indicated for the management of less common malignancies affecting the lung or for benign diseases such as bronchiectasis.

The objective of any type of resection done for lung cancer is the complete removal of both the tumor and the draining lymph nodes. Indeed, the main difference between resecting lung for carcinoma and resecting lung for benign diseases is the need in cancer procedures to include draining nodes and sometimes adjacent tissues such as the chest wall, which may be directly invaded by the neoplasm. For lung cancer, limited resections such as wedge resections, or “segmentectomies,” are therefore only used under special circumstances. Incomplete or “debulking” procedures also play no role in the management of lung cancer.

For most patients with early stage lung cancer, lobectomy is the procedure of choice. If the tumor cannot be completely resected by lobectomy, pneumonectomy must be considered if the patient’s pulmonary reserve allows it. Left-sided sleeve resections are done infrequently not only because no bronchus intermedius exists on that side but also because left pneumonectomy is better tolerated than right pneumonectomy. Pulmonary arterioplasties have also become standard procedures in some centers. When the tumor involves— either directly or through adjacent nodes—the hilum of the lung, the pulmonary vascular pedicle, or the aortopulmonary window, mobilization and ligation of blood vessels may have to be done from within the pericardium.

PREOPERATIVE ASSESSMENT AND PREPARATION

Evaluation of physiological status

The evaluation of patients prior to left-sided pulmonary resection is somewhat different depending on whether the indication for surgery is lung cancer or a benign process. Regardless of the underlying pathology, proper evaluation of cardiopulmonary function and of other risk factors for morbidity must be carried out. All of these patients should have a thorough history taken and a physical examination. Of particular interest to the surgeon are smoking history, possible occupational exposure, grade of dyspnea, weight loss, and associated comorbidities.

The evaluation of pulmonary function should be complemented by spirometric studies and analysis of arterial blood gases. If the patient has clinical or physiological evidence of impaired pulmonary function (forced expiratory volume in 1 second [FEV1] <2.0 L/s), additional information must be obtained, especially when a strong possibility of pneumonectomy exists. This information is best obtained through exercise testing with measurements of oxygen (O₂) saturation, arterial blood gases, and maximal oxygen consumption (VO₂ max). A VO₂ max lower than 15 mL/kg/min is a warning that postoperative pulmonary complications are likely to occur. Prediction of postoperative pulmonary function through the use of isotope perfusion lung scanning also can be useful. Very often, however, numbers only tell part of the story and experience and clinical judgment are just as important when deciding if a given individual has enough pulmonary reserve to withstand lung resection. Adjustment of bronchodilators, cessation of smoking, and a short period of rehabilitation will often improve the patient’s endurance and reduce the likelihood of complications. Oral corticosteroids should be avoided as much as possible and replaced with inhaled steroids if necessary.

In addition, time and effort also must be spent to evaluate the cardiac function if the patient has a history of coronary heart disease or an abnormal electrocardiogram. For most, an exercise test is all that will be required. If the test is positive, either clinically or electrocardiographically, a thallium isotope scan should be done, and we recommend that all these patients are seen preoperatively by a cardiologist. One area that is frequently overlooked is the carotid arterial system, and in cases of possible compromised circulation, complementary investigation must be done. Similarly, all other comorbidities, such as diabetes mellitus, should be looked at carefully and their treatment optimized prior to operation.

In several cases, the planning of the actual surgery is done at the time of the bronchoscopic examination. Indeed, no patient should undergo any kind of pulmonary resection without prior bronchoscopy. Whether the examination should be done by the surgeon or by an experienced “medical” bronchoscopist remains controversial and may vary from center to center.

Resectability of the tumor

In addition to deciding whether the patient needs surgery and if he or she can withstand pulmonary resection, determination of whether the tumor is technically resectable is necessary. Anatomically, the extent of disease and therefore the type of resection likely to be required are best determined through the interpretation of computed tomography (CT) images and bronchoscopy findings.

1. With specificity in the range of 70%-80%, CT scan can accurately predict the need for chest wall resection. CT scanning is also useful to assess the status of mediastinal nodes. Obviously, bronchoscopic examination is of paramount importance to determine the feasibility of standard lobectomy, sleeve resection, and pneumonectomy. (See Figure 13.1a.)

Due to an overall CT diagnostic accuracy of less than 80% to assess lymph node status, many surgeons almost routinely perform a cervical mediastinoscopy

before resecting a lung cancer. This examination allows for palpation, inspection, and biopsy of mediastinal nodes and is more sensitive and specific than either CT or magnetic resonance imaging to detect metastatic nodes. This is especially important for left-sided lesions, since the level 2 and level 4 nodal stations may be more easily sampled at mediastinoscopy than at thoracotomy because of the position of the aortic arch. When planning to operate on the left side, one must also take into account the predilection for left lower lobe lesions to spread to contralateral lymph nodes that can only be sampled via mediastinoscopy.

Endobronchial ultrasound can also be used to stage the mediastinum. The procedure is less invasive than mediastinoscopy and can reach lymph node stations unreachable by mediastinoscopy, such as the hilar nodes. The procedure, however, still requires general anesthesia and takes longer to perform than a mediastinoscopy.

(See Figure 13.1b.)

Accurate pretreatment staging of the mediastinum has now become an important priority because most patients with clinical N1 or N2 disease should undergo induction systemic therapy. On the left side, upper lobe tumors can metastasize to the aortopulmonary or anterior mediastinal nodes in up to one-third of cases. Since these nodes are not accessible by cervical mediastinoscopy, an anterior second space exploration (Chamberlain procedure) or an extended cervical mediastinoscopy is often added to standard mediastinoscopy.

Positron emission tomography (PET) scanning is very useful to detect abnormal adenopathy and is used for the staging of almost all patients with lung cancer in North America.

The drawback of PET in detecting metastatic mediastinal adenopathy is the false-positive rate, which can be as high as 20% if the patient lives in a geographical area endemic for granulomatous disease. All patients with detectable “hot” mediastinal lymph nodes should therefore undergo surgical staging to confirm the nature of these nodes.

Another issue that must be considered is the need for a tissue diagnosis. Many surgeons feel that if CT scan and bronchoscopy demonstrate a potentially resectable tumor in a fit patient, preoperative biopsy is not indicated because the results of the biopsy are unlikely to alter the decision to operate. In contrast, those who are advocates of preoperative biopsy (often done by fine needle aspiration) point out that having a diagnosis before operation can help streamline the investigation as well as avoid reliance on frozen section analysis at the time of surgery. Indeed, transthoracic needle biopsy (TTNB) can be done with very low morbidity, and in most series, it has a very high diagnostic accuracy (90%-95%). The concern that TTNB may spread tumor cells and adversely affect outcome is not substantiated.

Preparation for surgery

One of the most important steps in the preparation for surgery is the need to have a clear discussion with the patient and the relatives not only of what will happen during or after the operation but also of the risks involved, most common complications, and chances of prolonged survival. Ideally, patients should discontinue cigarette smoking, but this goal is difficult to achieve because of time constraints and the possible increase in patient stress regarding the upcoming operation.

As previously alluded to, a 6-week period of rehabilitation with supervised exercise has been shown to decrease morbidity in high-risk (borderline pulmonary reserve) patients undergoing lung resection for carcinoma. During that time, medication and nutrition are optimized, and the patient’s endurance is improved, as evidenced by increased distances during the 6-minute walking test. Unfortunately, most centers do not follow this approach because they do not have the infrastructure to implement and supervise such programs.

The surgeon’s preparation is also important, and he or she must be able to perform bronchoplasties instead of pneumonectomies in selected cases. The surgeon must also be able to deal with invasive tumors that may require intrapericardial ligation of blood vessels or concomitant chest wall resection for their complete removal.

PAIN MANAGEMENT, ANESTHESIA, AND THE CONCEPT OF ENHANCED RECOVERY AFTER THORACIC SURGERY

All patients are seen preoperatively by an anesthesiologist and are admitted on the day of surgery. Since it is common practice to use epidural analgesia during the postoperative period, the catheter is inserted before operation (awake patient) so that continuous analgesia can be delivered throughout the operation. All patients have an arterial line (radial artery) for monitoring, a central venous line that can be used for massive fluid infusion, and a Foley catheter. All procedures require a general inhalation anesthetic, most often given through the use of a disposable double-lumen tube. These tubes come in right-sided and left-sided models, and their position is verified with a pediatric flexible bronchoscope. If any problems occur during the operation, the tube can easily be repositioned with the bronchoscope. Single lung ventilation also can be achieved with the use of a Fogarty catheter used as a bronchial blocker advanced and inflated in the mainstem bronchus of the operated side. Our policy is to give the first dose of antibiotics and 5000 units of heparin (subcutaneously) prior to incising the skin.

The practice of analgesia for thoracic surgery described has not changed over the last three decades and is still used in most centers in North America. With regard to optimal pain management, the epidural catheter has many drawbacks and its efficacy is very dependent on a number of factors, such as the anatomy of the patient and the skill of the anesthesiologist. It takes time to put one in and the insertion of an epidural indwelling catheter can easily use 1 hour of precious operative time. The epidural is kept in place traditionally for at least 3 days. During this time, patients need a Foley catheter, which increases the risk for urinary tract infection. Urinary tract infections are now considered a preventable outcome by Medicare in the United States and fall into the same category as pressure ulcers. Finally, once an epidural catheter is in place, the use of other narcotics, parenterally or orally, by the surgical team is contraindicated, and all titrations are managed by the anesthesia pain team.

To most efficiently manage the patient and improve her or his overall outcome, care maps and clinical pathways are now available that not only address issues of deep vein thrombosis (DVT) prophylaxis and early ambulation but also streamline the management of common complications after surgery. These changes form the principles of a new concept called “enhanced recovery after thoracic surgery,” or “ERATS.” The treatment of frequent complications is automated by having established order sets for atrial fibrillation, myocardial infarction, and pneumonia that can be immediately initiated by the nursing staff. Care maps have also started to address the management of pain and new concepts have emerged replacing the use of epidural analgesia with better multilevel pain management that is entirely controlled by the surgeon and provides outcomes that are better in many respects than the standard of care centered on epidural analgesia.

ERATS starts by addressing pain issues before the actual surgery. Patients are taught about pain and what to expect from the treating team; the objective is to appease their anxiety associated with pain issues. The visual analog scale and the use of patient-controlled analgesia (PCA) are reviewed. Patients learn that they may be discharged home with a chest tube if the air leak lasts more than 2 days. The day before the surgery, patients are started on gabapentinoids, which are

known to decrease the narcotic requirements after surgery. Arterial lines are replaced with noninvasive monitoring connected to LiDCO devices, which measure constantly the cardiac output and the volume status of the patients. This allows the anesthesiologist to titrate the fluid infusions to exactly what the patient needs.

At the time of surgery, intercostal spaces are injected with very long acting local anesthetics such as preparations of liposomal bupivacaine (Exparel). The thoracotomy is preferably performed via a muscle-sparing non-rib-cutting method (see next section). On closure, additional local anesthesia is injected by the surgeon around the costotransverse joints under direct vision. The chest tube site is also infiltrated. At the end of the operative procedure, the anesthesiologist administers anti-inflammatory drugs, such as Ketorolac supplemented by intravenous acetaminophen. Postoperatively, all patients are continued on oral anti-inflammatory drugs, Tylenol, and oral synthetic narcotics such as Tramadol, around the clock. Patients are also put on PCA. Chest tubes are removed when there is no drainage of air, blood, or chyle (i.e., no A, B, or C). The volume of drainage is not a factor in removing the chest tube anymore. ERATS maneuvers not only allow a more effective usage of operating room time but also permit the optimization of the postoperative time in the hospital. With ERATS, patients with simple thoracotomies can often be discharged within 48 hours of the surgical procedure. Epidural regional analgesia is still useful under special circumstances, such as complex thoracotomies with chest wall resection, pleurectomy, decortication, or bilateral procedures.

OPERATION

Position, incision, and exploration

1. The posterolateral incision is used by most surgeons because it provides considerable exposure to the entire pleural space. This incision is versatile and allows the surgeon the possibility of modifying the operative strategy, if required. The patient is in the lateral decubitus position with the arm extended anteriorly and superiorly, gliding the scapula away from the fifth intercostal space. The head of the patient is supported, and a roll is inserted in the axilla to spread the intercostal spaces at the site of the incision. The table is maximally flexed at the lumbar area to push the pelvis away from the incision and spread the ribs even further. The legs are supported with pillows, and the patient is immobilized on a bean bag. (See Figure 13.2a.)

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