As long as surgery remains the primary therapy for the curative treatment of lung cancer, patients will continue to require pneumonectomy to treat lung cancer, as well as other occasional problems.¹ However, no other operation done by surgeons carries as high a risk. Operative mortality from pneumonectomy has been reported to be between 5% and 20%.^2–8 These numbers are probably somewhat conservative because most of the published articles report only 30-day mortality—the real operative mortality is likely higher. For this reason, appropriate selection, operative technique, and postoperative management of patients who potentially may undergo pneumonectomy is crucial. The term potentially applies because patients scheduled for pneumonectomy ultimately may undergo pneumonectomy, sleeve resection, or exploration without resection depending on the findings at surgery.

Surprisingly, low preoperative lung function has not been demonstrated consistently to increase the perioperative risk of pneumonectomy, although some authors have found preoperative lung function to be an important factor.^9–11 This may be the result of diligent efforts to identify and eliminate patients with poor pulmonary function from the surgical pool. Other factors have been shown to increase the perioperative risk, includiung increased age,^7,8,10,12,¹³ right-sided procedures,^8,11–14 preoperative chemo/radiation,^11,15 large intraoperative fluid volumes,^11,15,16 perioperative cardiac dysrhythmias,¹² and immediate preoperative smoking history.^11,17

This chapter concerns the preoperative evaluation and management of pneumonectomy patients, the decision to perform pneumonectomy rather than sleeve resection, the technical aspects of the operation, and the postoperative management, all with the goal of decreasing perioperative mortality.

PREOPERATIVE EVALUATION AND MANAGEMENT

Staging

Patients who undergo pneumonectomy first should undergo preoperative staging (Table 64-1). At this time, a complete history and a physical examination that focuses on the identification of lymph nodes and liver masses, followed by a chest CT scan and a PET scan, are appropriate. This evaluation will rule out distant metastases other than brain metastases. Patients without symptoms of headache are unlikely to have brain metastases, and brain CT scans or MRIs are not obligatory. However, the risk of the procedure supports appropriate evaluation to rule out brain metastases (see Chap. 78).

Patients who are candidates for pneumonectomy typically have large or hilar masses and a high likelihood of having mediastinal metastases. Although PET scans are quite sensitive for detecting mediastinal metastases, they remain less accurate than mediastinoscopy¹⁸ (see Chap. 61). For this reason, preoperative mediastinoscopy is indicated for patients who may undergo pneumonectomy, even if they have a PET-negative mediastinum. The PET scan remains a useful study for ruling out distant metastases but should not be the only study used to evaluate the mediastinum.

Thoracoscopic examination and staging of the pleural space benefit patients undergoing pneumonectomy in two specific ways¹⁹:

1. Thoracoscopy helps to rule out pleural metastases that usually cannot be identified in any other way.

2. Thoracoscopy can be used to determine the incision used for resection.

Cardiopulmonary Evaluation

An extensive but complicated literature describes various modalities that can be used to evaluate preoperative lung function as a means to predict postoperative complications. A preoperative forced expiratory volume in 1 second (FEV₁) of more than 2.0 L has been relatively arbitrarily chosen as a threshold for resection without further pulmonary evaluation and has been confirmed by experience.

Because of the obstructive nature of cancers that may lead to pneumonectomy, many patients have less than 50% perfusion to the affected lung. Quantitative perfusion scanning has been used successfully for almost 30 years to determine the relative contribution of each lung to the patient's lung function.⁶ Patients with a predicted postoperative FEV₁ of more than 800 mL are considered to have adequate pulmonary reserve to undergo resection. This technique has been found to be accurate in long-term follow-up (up to 5 years),²⁰ especially with respect to predicting the postoperative FEV₁²¹ (Table 64-2).

Left Lung Resection

Left pneumonectomy generally is safer than right pneumonectomy, at least in terms of overall perioperative postoperative mortality. However, the procedure may be technically more difficult, especially in patients with large hilar masses. Hilar cancers are truly in challenging territory adjacent to the main pulmonary artery, aorta, and esophagus.

These lesions can approach the aortic arch, recurrent laryngeal nerve, phrenic nerve, pericardium, and the main pulmonary artery before it bifurcates into the right and left main pulmonary arteries (the left main pulmonary artery is very short). The primary procedures are described separately to account for the varying anatomy and dissections used on the left and right sides. We then discuss factors that can complicate the procedure.

TECHNIQUE

Left Pneumonectomy

The mediastinal pleura is divided circumferentially around the hilum using either scissors or ligature. Harvesting the lymph nodes in the aortopulmonary window gives better exposure to the proximal pulmonary artery. This must be done carefully, however, to avoid injuring the recurrent nerve, which branches off the vagus nerve on the inferior surface of the aortic arch and then dives into the mediastinum immediately inferior and adherent to the arch. Similarly, the phrenic nerve should be preserved, unless it is directly involved with tumor.

The vagus superior to the aorta or the recurrent nerve can be harvested if either is involved with cancer. However, resection of either of these nerves will lead to vocal cord paralysis. Vocal cord paralysis is dangerous in all lung resection patients (especially in pneumonectomy patients) because it causes a diminished ability to cough and increased chance of aspiration. A patient who has undergone recurrent nerve resection should not be allowed to drink until a postoperative swallowing study is performed to rule out aspiration. Patients who have evidence of aspiration should not drink or eat. Rather, they should receive intravenous nutrition and be considered for vocal cord medialization shortly after surgery.

Evaluation for Sleeve Resection

The lung is examined carefully to determine whether sleeve resection is possible. This is done after the pleura is divided circumferentially and the inferior pulmonary ligament is taken down. Sometimes complete parenchymal separation of the upper and lower lobes is necessary to completely evaluate the possibility of sleeve resection. Factors that make sleeve resection difficult include

1. Tumors that invade the pericardium at either pulmonary vein, but especially at the superior pulmonary vein.

2. Tumors that involve both the main pulmonary artery and the left mainstem bronchus.

3. Tumors that involve artery or bronchus but extend into the fissure to involve the other lobe. Thus upper lobe tumors that extend inferiorly to involve the fissure extensively or lower lobe tumors that extend superiorly can be difficult to resect and reconstruct.

The pulmonary artery is dissected away from the vein anteroinferiorly and the bronchus posteriorly (Fig. 64-1). This dissection is made safer by proceeding posteriorly to separate the artery from the bronchus (Fig. 64-2). Quite often this can be done bluntly, either with Kittner dissectors or with an index finger (as seen in Fig. 64-1), and usually can be done before mobilizing or dividing the superior vein. However, in patients with an inferiorly positioned artery or superiorly positioned vein, the vein can be dissected and divided first.

The artery should be occluded with either a vascular clamp, a tourniquet, or a vascular stapler (closed but not fired) for approximately 5 minutes to ensure that right ventricular failure or pulmonary hypertension will not result after pneumonectomy. After the artery is clamped, systolic blood pressure and oxygenation are assessed, and if stable, they indicate that the patient can tolerate pneumonectomy. If hemodynamic instability or hypoxia develops, a pulmonary artery catheter may be inserted to direct pressor treatment, but in most cases, it is necessary to perform a sleeve resection or abandon the procedure altogether.

Additional length on the artery (to allow complete resection) can be obtained by two specific maneuvers:

1. Dividing the ligamentum arteriosum (being careful to avoid injury to the recurrent nerve).

2. Opening the pericardium to identify the very short left main pulmonary artery within the pericardium. In this maneuver, it is obligatory to test clamp the artery before it is divided because the anatomy may be distorted by the malignancy, which can lead to inadvertent division of the main pulmonary artery.

The artery is divided by one of several techniques: vascular stapler (two fires with division between two stapler lines or with an endostapler that cuts between two stapler lines) (Table 64-3) or vascular clamps proximal and distal with a double suture line of 5-0 Prolene or some combination of the preceding techniques (Fig. 64-3).

The pulmonary veins are now divided. If the tumor invades the pericardium, or if the pericardium has been opened to gain arterial control, the veins can be controlled and divided by extending the pericardial opening inferiorly, just posterior to the phrenic nerve. The pulmonary veins form a single branch as they enter the left atrium and can be divided at this level with any of the techniques described for the artery. Blue (3.5 mm) staplers, rather than vascular-load staplers, should be used to control the atrium because vascular loads can fail on this thicker tissue (Table 64-3).

Dividing the veins outside the pericardium requires identifying the superior and inferior veins separately. The inferior vein begins at the superior edge of the inferior pulmonary ligament, and the superior vein is the most anterior structure of the hilum. These veins can be divided with vascular stapler loads or controlled with vascular clamps and oversewn with 4-0 or 5-0 Prolene (Fig. 64-4).

Careful management of the bronchus decreases the chance of bronchial stump leak with its attendant dangers (Table 64-4). The table lists aspects of dissection that can affect the chances of bronchial stump devitalization or devascularization.

The bronchus is usually the last structure divided (Fig. 64-5). The lung is grasped and used to deliver the bronchus inferiorly into the chest. The anesthesiologist is asked to hold ventilation and to back out the double-lumen tube or blocker used to control ventilation. The bronchial clamp or bronchial stapler then is positioned across the bronchus to close the bronchus in an anterior-to-posterior fashion. If a stapler is used, the heavy-load (green) or 4.8-mm stapler is chosen. The bronchus then is divided and closed with the stapler or with absorbable suture (typically 2-0 or 3-0 PDS or Vicryl).

The bronchus must be tested to 30 cm H₂O of pressure. If no leak is seen, the bronchus then is covered with vascularized tissue. I prefer pericardial fat pad or thymus, but an intercostal muscle bundle or vascularized pericardium can be used. It should be sutured either to the bronchus itself or to tissues around the bronchus. I typically add sealant (Tisseal, Floseal, or some type of seal), more for my own psychological comfort than for the surgical care of the patient.

Right Pneumonectomy

Patients who undergo right pneumonectomy are more likely to die from this procedure than left pneumonectomy patients. Mortality typically is the result of complications of surgery rather than the surgery itself. Consequently, for right pneumonectomy, postoperative management is crucial.

As on the left side, I perform thoracoscopy to eliminate pleural metastases and to determine the appropriate incision. The pleura around the hilum is divided completely, and the inferior pulmonary ligament is taken down (Fig. 64-6). For lesions in the hilum, I divide the azygos vein and completely harvest the right paratracheal nodes first. This gives better exposure to the proximal pulmonary artery and proximal right mainstem bronchus.

As for left pneumonectomy, the tumor and lung should be evaluated to determine whether sleeve resection, rather than pneumonectomy, can be done. The right upper lobe sleeve is the most straightforward sleeve resection to perform—both the airway and the artery can be sleeved.

Once the decision to proceed to pneumonectomy is made, the artery is dissected away from the bronchus and vein. A patient who has had previous chemoradiation therapy or has a history of granulomatous disease in the mediastinal lymph nodes often will have dense scarring between the posterior arterial plane and the anterior plane of the bronchus. Proximal control of the artery then is needed.

Several maneuvers permit proximal control of the right main pulmonary artery. The first, and simplest, is to divide the azygos vein and perform a right paratracheal node dissection. For tumors with more extensive involvement of the mediastinum, the proximal pulmonary artery can be approached medial to the superior vena cava because the right main pulmonary artery is very long (Fig. 64-7). It can be divided just after the bifurcation of the pulmonary artery (this is often left of the patient's midline), and the artery then is delivered back into the right hemithorax posterior to (or underneath) the superior vena cava. This markedly diminishes the chance of hemorrhage.

Pericardiectomy and Reconstruction

Some textbooks state that pericardial reconstruction after resection must be done on the right side to prevent cardiac torsion on the axis defined by the superior and inferior vena cavae, but it is not necessary to do so on the left side. I have had patients arrest after left-sided pericardiectomy without reconstruction and believe that the extent rather than the side of resection is the important factor.

The primary goal during resection is to ensure adequate and negative margins. These should be checked with frozen sections. The only goal for reconstruction is to fill the pericardial defect in such a way as to prevent cardiac herniation. For limited resections (<2 cm in diameter), reconstruction may not be necessary at all—the heart cannot herniate through such small defects. Larger defects sometimes can be filled using the vascularized flap to buttress the bronchus, especially if a bulky pericardial fat pad is used.

Most surgeons use a nonabsorbable material—PROLENE (Ethicon, Inc., Somerville, NJ) or Gore-Tex® (W.L. Gore and Associates, Flagstaff, AZ) mesh—to reconstruct the pericardium (Fig. 64-8). These patches should be sewn into place using interrupted sutures placed approximately 1 cm or more apart because the goal is to anchor the patch in place but not to make it watertight. The patch also should be loose to avoid constricting the heart, which will assume a different shape and position when the patient is upright. The patch can be loose to the point of being described as floppy, with special attention to avoiding constriction of the superior vena cava. Finally, limited experience indicates that absorbable material, such as Vicryl mesh, can be used to reconstruct pericardial defects.

PERIOPERATIVE MANAGEMENT

There is insufficient space to discuss every aspect of the perioperative management for lung resections. However, several specific problems deserve attention and can prevent complications in patients undergoing pneumonectomy.

Vocal Cord Paralysis

Patients who undergo left pneumonectomy occasionally have left vocal cord paralysis owing to traction on the nerve or as a consequence of the need to resect the nerve. Vocal cord paralysis causes two specific problems—weak cough and risk of aspiration with swallowing. The latter is especially important in patients with altered mental status secondary to recovery from anesthesia or medicines used for pain control.

When vocal cord paralysis is suspected because of the nature of the resection or for patients who wake up with a weak voice, a swallowing evaluation is imperative before beginning any diet. The evaluation can be as limited as having the patient sip a cup of water at the bedside while observing for evidence of cough or difficulty swallowing. If the patient's swallowing function is at all questionable, a formal swallowing study is required.

Once the patient's ability to swallow safely has been verified, the diet can be advanced gradually. However, a weak cough still may prevent adequate pulmonary toilet, and if there is evidence of progressive atelectasis and hypoxia, temporary vocal cord medialization is indicated. Medializing the vocal cord is preferable to tracheostomy for several reasons. With medialization, patients are able to speak and swallow, and a tracheostomy in a patient with a paralyzed vocal cord almost always requires some other means of nutrition.

Fluid Management

As discussed earlier, several studies indicate that excessive fluid given during the perioperative period can lead to increased postoperative mortality. Nevertheless, in the immediate perioperative period, 2–5 L of fluid will accumulate in the chest. This amount must be added to the patient's basic needs for fluid. Renal function laboratory values (blood urea nitrogen and creatinine) can be used to guide fluid resuscitation, as can urine output. Perhaps the main caveat for these patients is that they do not develop the third-space accumulation that laparotomy or cardiac patients do and therefore should be either run relatively dry (approximately 80% of predicted needs) or at euvolemia.

SUMMARY

The high risk of pneumonectomy underscores the importance of proper preparation and experience in both the conduct of the surgery and the perioperative management. Review of the idiosyncrasies of the pulmonary anatomy and other common pitfalls is warranted.

EDITOR'S COMMENT

The author correctly points out that all pneumonectomy candidates should be assessed to determine if a sleeve resection might be feasible. In contrast to the above-described technique, we have used endoscopic vascular staplers for all pneumonectomies. An important technical consideration is the liberal use of intrapericardial dissection, especially with left-sided pneumonectomies. In patients undergoing pneumonectomy after neoadjuvant chemoradiation, we routinely use muscle flaps, including the intercostal as well as the serattus anterior muscles.

–MJK

REFERENCES