Postoperative Complications in Patients Undergoing Thoracic Surgery

Postoperative Complications in Patients Undergoing Thoracic Surgery

Lung cancer is on the rise with the number of reported cases up from approximately 200,000 in 2007 to an estimated 220,000 in 2011. The advent of CT scanning has allowed more of these tumors to be diagnosed early. In turn, earlier detection of tumors has shown that they are more likely to be resectable. As such, more patients are undergoing pulmonary resections. Major complications occur in approximately 10% of patients undergoing pulmonary resections, and cardiopulmonary complications occur in more than 50% of these patients. Thus, it behooves the nonthoracic intensivist to become familiar with the common postoperative issues in patients who have undergone lung resection.

Nonoperative Complications
Patients are prone to developing atelectasis and pneumonia after thoracic surgery. It is important that these patients are able to clear their own secretions. Three complementary approaches are used, which are adequate pain control; chest physiotherapy, including early mobility; and bronchoscopy. Pain control in a patient following thoracic surgery can be achieved with systemic opioids, nonsteroidal antiinflammatory agents, intercostal blocks, paravertebral blocks, epidural analgesia, and interpleural analgesics. A meta-analysis ( Joshi et al. Anesth Analg. 2008;107[3]:1026) suggests that a thoracic epidural with local anesthetic plus an opioid is the most effective approach; however, thoracic paravertebral block with local anesthetic is a comparable alternative.

Regardless of the pain management strategy, the crucial element is the ability of patients to comfortably generate a good cough and clear their own secretions.

Chest physiotherapy, a vital adjunct in minimizing respiratory complications, includes incentive spirometry, coughing, chest percussion and vibration, and postural drainage. When performed by specialized therapists, the rates of pulmonary morbidity have been reported to improve from 15.5% to 4.7% (Novoa N et al. Eur J Cardiothorac Surg. 2011;40[1]:130).

However, patients must have adequate pain control in order to be motivated to undergo chest physiotherapy and be out of bed in a chair and ambulating on postoperative day one. For those patients who are unable to effectively clear their own secretions with noninvasive means, bronchoscopy may be warranted.

Postoperative acute lung injury (ALI) occurs in up to 7% of patients who undergo pulmonary resection, and the mortality rate is approaching 50%. Primary ALI occurs within 3 days of surgery, and its etiology is not well established. Risk factors are mostly unmodifiable and are thought to include preoperative alcohol abuse, large resection, transfusions, and increased intraoperative airway pressures. Secondary ALI occurs 3 days after surgery and results from identifiable causes such as pneumonia or aspiration. The primary perioperative risk factor that is modifiable is fluid management. Evidence shows that increased perioperative fluid administration increases the incidence of postoperative ALI.

One study (Alam N et al. Ann Thorac Surg. 2007;84[4]:1085) suggests that, for every 500-mL increase in perioperative fluids, there is an odds ratio of 1.17 for developing ALI. A proposed guideline suggests administering a maximum of 20 mL/kg of fluid in the first 24 h after surgery. Urine output of 0.5 mL/kg/h is acceptable in this period, and vasopressors may be used if tissue perfusion is inadequate (Slinger. J Cardiothorac Vasc Anesth. 1995;9[4]:442). Diuresis can be considered after the second postoperative day. Renal failure may occur from such fluid restriction, but this condition is usually reversible.

Atrial fibrillation is a common complication following pulmonary resections. The incidence increases with the greater extent of resection and the increasing age of the patient. Atrial fibrillation usually occurs within 2 to 3 days postoperatively and increases the hospital length of stay. The immediate therapeutic goal is rate control. Beta-blockade is usually the first-line treatment; however, calcium-channel blockers and digoxin have also been used. Good results have been observed with amiodarone, but some surgeons are wary of its use for the treatment of postoperative atrial fibrillation due to the risk of pulmonary toxicity in approximately 5% of patients. In fact, some surgeons do not use it in patients following a pneumonectomy for fear of harming the remaining lung.

Operative Complications
Bleeding is always a concern after surgery. The chest tube drainage system offers an excellent tool to monitor for postoperative hemorrhage. A rate of >100 mL/h for more than 2 h is cause for concern. Thick, red fluid is more concerning than thin, pink fluid. Checking a pleural fluid hematocrit can be performed; however, it is not indicated if clinical suspicion is high for postoperative bleeding. In fact, it may delay definitive treatment. Any coagulopathy should be corrected. Sometimes the chest tube may become clotted and stop draining effectively. In these cases, the radiograph will show a dramatic increase in pleural effusion. If there is no decrease in chest tube output or if a large effusion appears on chest radiograph despite functioning drainage catheters, the patient may need to undergo reexploration. (Fig 1).

Fig 1. Left: Immediate postoperative chest radiograph after decortication. Right: Postoperative day 1 chest radiograph showing interval accumulation of hemothorax. Chest tube was noted to be clotted on reexploration.

Lobar torsion following thoracic surgery is a rare entity; however, the outcome may be fatal if left undiagnosed. Most cases involve the middle lobe following a right upper lobectomy. Patients can have fever, tachycardia, dyspnea, and diminished breath sounds. A high index of suspicion is required for this diagnosis. Chest radiograph shows a homogeneous consolidation in the superomedial right lung field. Bronchoscopy should be performed immediately, and if there is difficulty passing the scope into the middle lobe bronchus, the patient should be emergently reexplored.

Depending on the promptness of diagnosis, the patient may need a lobectomy.

Patients may have persistent air leaks, defined as an air leak lasting >7 days following pulmonary resection.

These air leaks can result from iatrogenic tears in the lung parenchyma or from parenchymal staple line dehiscence following a wedge resection. These patients may develop significant subcutaneous emphysema (Fig 2).

Fig 2. Subcutaneous emphysema after rightsided wedge resection.

The development of subcutaneous emphysema signifies that the size of the leak is greater than the ability of the chest tube to evacuate the air, which is dependent on the chest tube management.

If the tube is placed on water seal when this occurs, it will need to be placed on suction. In contrast, if the chest tube is already on suction, the amount of suction will need to be increased (eg, from –20 to –40 cm H₂O of suction) or another chest tube may need to be inserted.

Management strategies for a continuous air leak differ depending on the size of the leak and the doctor’s surgical mindset. If a patient is able to tolerate the chest tube placed on water seal, a Heimlich valve can be placed, the closed thoracotomy drainage system can be removed, and the leak can then be managed in an outpatient setting.

Other options include pleurodesis, blood patch, or reexploration to repair the leak.

Of particular concern is the persistent leak in a patient with a bronchial staple line, such as a patient who undergoes a lobectomy or pneumonectomy. In these patients, it is imperative to rule out the presence of a bronchopleural fistula. In a patient following pneumonectomy, a bronchopleural fistula may be seen with a decrease in air-fluid level on chest radiograph as the fluid leaks out of the pleural space (Fig 3).

Fig 3. Left: Four-week postoperative chest radiograph after right-sided pneumonectomy showing near opacification of right-sided hemithorax with sterile fluid. Right: Five-week postoperative chest radiograph showing a decrease in the amount of fluid in the right-sided hemithorax with concomitant aspiration-like changes on the contralateral side.

Often, there is concomitant aspiration pneumonia on the contralateral side. This occurs as the fluid in the postpneumonectomy space empties into the contralateral airways via the fistula. In essence, the patient has “aspirated” his postpneumonectomy effusion. Should this be the case, a chest tube should be placed immediately. Bronchoscopic evaluation is then necessary to determine the presence of a bronchopleural fistula. These patients likely require reexploration and reclosure of the bronchial stump with a flap.

One final issue is management of the pleural space following a pneumonectomy. Some surgeons place a chest tube and either leave it on water seal or clamp the tube. Others do not place a chest tube at all; instead, they aspirate air from the pleural space at the end of the operation.

The key element to ensure is that the mediastinum is midline in the postoperative chest radiograph. If the patient subsequently becomes hemodynamically unstable, a tension hemithorax may be developing on the side of the lung removal. In this circumstance, air within the chest must be directly aspirated if there is no chest tube.

If a chest tube is in place but is clamped, the tube should be unclamped. However, if air removal does not improve the hemodynamic collapse, the rare complication of cardiac herniation should be considered, especially if an intrapericardial pneumonectomy was performed, and the patient taken to the operating room for immediate reduction.

Summary
It is important for pulmonologists, internists, and intensivists to be aware of postoperative issues in patients who undergo thoracic surgery. Although these physicians may not always be involved in the definitive treatment of certain complications, they remain a vital cog in the prompt diagnosis of problems encountered in the postoperative period. It is important to remember that the focus should not be on a single abnormal finding but rather on the whole picture (eg, clinical stability + tube output + chest radiograph) when managing these complications.

Dr. Dong-Seok Lee
Assistant Professor
Division of Thoracic Surgery
and
Dr. Raja M. Flores
Ames Professor of Surgery
Chief, Division of Thoracic Surgery
The Mount Sinai Medical Center
New York, NY