Thoracic Anesthesia

PART 2

Thoracic Anesthesia Practice


CHAPTERS


 

18
Bronchopleural Fistula: Anesthetic Management

Angela Truong
Dam-Thuy Truong
Dilip Thakar
Bernhard Riedel


Key Points

• Bronchopleural fistula is a direct communication between the bronchial tree and the pleural cavity causing an air leak from the lung. In pneumothorax, the communication is peripheral, between a ruptured bleb or alveolar duct and the pleural cavity.

• Anesthesia for patients with a BPF is based on two important techniques central to thoracic anesthesia: effective lung isolation and ventilation of an open airway.

• Prompt lung isolation is essential during anesthetic management in order to minimize the risk of ventilating the pleural cavity and soiling the contralateral lung.



Clinical Vignette


A 72-year-old man with a history of T3N2 supraglottic squamous cell carcinoma, treated with chemoradiotherapy, was found to have a large tumor in the right lower lobe of the lung. Computed tomography (CT)–guided biopsy showed poorly differentiated squamous cell carcinoma. He underwent a right pneumonectomy with mediastinal lymph node dissection and a rotational serratus anterior muscle flap.

Following surgery, he remained intubated and ventilated overnight in the intensive care unit (ICU) and was extubated the following morning. On postoperative day 3 he developed refractory hypoxemia and respiratory failure requiring re-intubation and mechanical ventilation. The following week was characterized by deterioration in his clinical state—with low-grade fever, copious tracheal secretions, and persistent drainage of purulent pleural fluid from a chest tube. Serial chest radiographs and a CT scan revealed an increasing air level and decreasing pleural fluid level in the right pleural cavity, with consolidation of the left lower lobe. Fiber-optic bronchoscopy demonstrated purulent material trickling from a 3-mm-diameter bronchopleural fistula (BPF) in the bronchial stump.

A small open-window thoracostomy was created, and the pleural cavity was drained and thoroughly irrigated, and then packed daily. The patient received intravenous antibiotic therapy based on sensitivity analysis of blood and pleural fluid cultures; enteral feeding via a percutaneous gastrostomy tube; tight glucose control with insulin; and pressure control ventilation using permissive hypercapnea to maintain low mean airway pressures.

Over the next 4 weeks, the infection process was eradicated and the patient’s clinical status improved. The BPF did not close spontaneously, however, as evidenced by a persistent air leak through the thoracostomy tube. This necessitated a return to the operating room for bronchoscopic assessment of the fistula, possible closure of the fistula with fibrin glue and, if needed, thoracotomy for BPF closure.


Bronchopleural fistula is a direct communication between the central bronchial tree and the pleural cavity which results from disruption of a bronchial stump or tracheobronchial anastomosis, causing an air leak from the lung. This contrasts with a pneumothorax, in which the communication is peripheral, between a ruptured bleb or alveolar duct and the pleural cavity. When the fistula or sinus tract of a BPF extends to the skin of the chest wall it is termed a bronchopleural-cutaneous fistula. Although rare, BPF represents a challenging management problem; it is associated with high rates of morbidity and mortality and poses formidable challenges during anesthetic management because of the risks of life-threatening loss of ventilation, tension pneumothorax, and contamination of the remaining lung through the fistula.

Incidence

Bronchopleural fistula is relatively rare, with an overall reported incidence following pulmonary resection between 1.5% and 20%.1,2 About two-thirds of cases occur as a postoperative complication of pulmonary resection, by far the most common cause of BPF. Other less common causes of BPF include necrotizing lung infections, persistent spontaneous pneumothorax, chemotherapy or radiotherapy (for lung cancer), and tuberculosis (Table 18–1). The incidence is higher with pneumonectomy than with lobectomy, since the lobes remaining after lobectomy may offer stabilization and protection to the bronchial stump. Left-sided pneumonectomy is less vulnerable than right-sided pneumonectomy because the bronchial stump is smaller and usually located just under the aortic arch, deriving some protection from it.

Table 18–1. Etiology of Bronchopleural Fistula

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Etiology

The destruction of a bronchial wall that leads to BPF may result from a variety of etiologies; including surgical causes, anesthetic-related causes, and medical causes (Table 18–1).

BPF after Lung Resection: Pathophysiology, Risk Factors, and Types

An understanding of the pathophysiology and risk factors involved in BPF development is essential for its prevention and successful management. Not a distinct disease entity, BPF is rather a pathological process following lung resection. Necrosis of the wall between the bronchial system and the pleural cavity results from the complex interaction of three factors: trauma, infection, and poor wound healing. Each factor can potentiate the harmful effects of the other factors. For instance, infection not only contributes directly to the occurrence of BPF, but can also impede wound healing and render the affected area more vulnerable to trauma during subsequent airway manipulation.

Bronchopleural fistula is classified as acute or chronic, and each has a distinct presentation and treatment. Acute BPF classically occurs within the first week following lung resection, resulting from sudden dehiscence of the bronchial stump suture line. Acute BPF is essentially related to surgical technique, and infection and serious coexisting medical conditions play lesser roles. In contrast, chronic BPF, which may take weeks or months to develop, can occur after lung resection or be associated with nonsurgical conditions such as empyema or lung abscess. It usually occurs in patients with severe chronic debilitating comorbid conditions, and infection plays a primordial role.

The risk factors associated with development of BPF can be classified as preoperative, intraoperative, or postoperative. Preoperative factors include immunosuppression, prolonged corticosteroid therapy, preexisting infection such as active tuberculosis with pathogen-positive sputum, neoadjuvant radiotherapy/chemotherapy, chronic debility, malnutrition, and uncontrolled diabetes mellitus. Intraoperative or surgical risk factors include pneumonectomy, especially right-sided pneumonectomy, a long bronchial stump, and poor surgical technique that results in faulty stump closure and/or compromised blood supply to the bronchial stump. Postoperative factors include prolonged mechanical ventilation, atelectasis, pneumonia, empyema, re-intubation and frequent tracheobronchial suctioning, and residual tumor at the stump.3,4 Importantly, these risk factors usually contribute to BPF formation through a combination of trauma, infection, and poor wound healing (Figure 18–1).

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Figure 18–1. Graphical representation of factors that play central roles in BPF formation.

CLINICAL PRESENTATION

The clinical signs of BPF are determined by the size of the BPF and whether the BPF is acute or chronic in origin. When the fistula is small (of the order of a few millimeters, Figure 18–2), the predominant symptoms are cough, particularly when the patient is lying on the side of the fistula, and severe shortness of breath. A delay in cavity filling after pneumonectomy is also noted. When empyema is present, infectious symptoms dominate. When the fistula is large, formed by sudden massive dehiscence of the bronchial stump, copious expectoration of pleural fluid may be noted. This may result in sudden catastrophic flooding of the airway, and possibly even death by asphyxia due to the large communication between the fluid-filled pleural cavity and the tracheobronchial tree. If the patient is still intubated, positive pressure ventilation with a massive leak through a large BPF will cause severe loss of alveolar ventilation, resulting in acute hypoxia, hypercarbia, and respiratory acidosis. If the correct diagnosis of BPF is not made, desperate attempts to increase positive pressure ventilation will paradoxically worsen the hypoventilation by further increasing the air leak and enlarging the fistula. Furthermore, if a functioning chest tube is not in place, the air leak will quickly result in tension pneumothorax and cardiovascular collapse.

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Figure 18–2. Bronchoscopy showing two small BPFs in the bronchial stump. Abbrev: RMSB, right main stem bronchus; LMSB, left main stem bronchus.

The onset is much more insidious in chronic BPF, with a relatively slow accumulation of purulent material in the pleural cavity and gradual erosion into the bronchial system. The clinical picture often consists of low-grade fever, fatigue, generalized malaise, and cough with purulent or blood-tinged sputum. Hemoptysis, fetid breath, and subcutaneous emphysema are less frequently observed. The clinical picture may be very difficult to differentiate from similar nonspecific symptoms associated with other complications observed during the postpneumonectomy period.

Diagnosis

The diagnosis of BPF is made by clinical examination, diagnostic imaging techniques, nuclear scintigraphy, and bronchoscopy, which is universally accepted as the “gold standard.”

Even though the clinical presentation of BPF is often nonspecific, a high index of suspicion based on the combination of suggestive signs and symptoms should alert clinicians to the potential diagnosis of BPF. In a simple bedside test that has been used to confirm the diagnosis of BPF, methylene blue is injected into the pleural space of a patient with a suspected BPF and the diagnosis confirmed through expectoration of blue-tinged sputum. Diagnostic imaging studies more often used for the detection of BPF include chest x-ray and CT. Bronchography and sinography may also be performed.

In the immediate period following lung resection, chest radiograph and CT scan normally show progressive accumulation of fluid in the postpneumonectomy space coupled with decreasing amounts of air. Because of the large empty space left behind after pneumonectomy, there is normally an accompanying gradual elevation of the ipsilateral hemidiaphragm and a slight shift of the mediastinum toward the side of surgery. In cases of BPF, these trends are reversed: air accumulation increases and fluid level decreases in the postpneumonectomy pleural space, air-fluid level drops by more than 2 cm, and mediastinal shift is absent or a previously shifted mediastinum returns to the unaffected side.5-7 In severe cases, a tension pneumothorax may develop within the postpneumonectomy space, with accompanying mediastinal shift (Figure 18–3). In the immediate postoperative period, these radiographic findings are particularly valuable in making an early diagnosis of BPF in an otherwise asymptomatic patient.8

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Figure 18–3. Chest x-ray showing postpneumonectomy pneumonitis and tension pneumothorax with mediastinal shift as a result of a BPF.

It is much more challenging to directly identify the fistula tract on CT scan (Figures 18–4 and 18–5), especially when the BPF is very small or has an extremely tortuous path. Visualization of the fistula tract on CT scan can be facilitated by special techniques such as spiral CT with thin sections and three-dimensional reconstruction.9 Bronchography or radiography of the bronchial system after intrabronchial instillation of a radio-opaque contrast medium allows visualization of the fistula. Similarly, if a bronchopleural cutaneous fistula is present, sinography or fistulography can be performed by injection of contrast dyes percutaneously into the fistula skin opening to outline the contour of the sinus tract.

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Figure 18–4. CT scan identifying a BPF tract in the main stem bronchial stump following pneumonectomy for mesothelioma.

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Figure 18-5. CT scan identifying a peripheral BPF in a patient 2 weeks after a left lower lobectomy, potentially related to cystic rupture of a subpleural metastasis.

When the BPF is too small to be detected by CT scan, ventilation radionuclide scintigraphy studies of a tracer gas such as Xe-133 or Tc-99m DTPA10,11 or nitrous oxide12 may aid diagnosis. Nitrous oxide is inhaled by the patient and, after gaining access to the pleural cavity through the BPF, is then detected by gas analyzer connected to the chest tube.

While these investigations are all valuable, fiber-optic bronchoscopy is generally considered the optimum tool for establishing a definitive diagnosis, because it allows proper evaluation of the stump, localization of the fistula, determination of fistula size, exclusion of tuberculosis or other infectious etiologies, and visual assessment of the viability of the stump (Figure 18–2). If bronchoscopic findings are inconclusive, methylene blue may be instilled into the bronchial stump during bronchoscopy. If the dye is subsequently seen trickling into the pleural space, the diagnosis of BPF is confirmed. Bronchoscopy also plays a role in therapeutic intervention, allowing introduction of a sealant into the fistulous tract.

Assessment of Air Leak Severity

In most clinical settings, the air leak can be assessed by observing the appearance of bubbles from the chest tube during the respiratory cycle. If the air leak is small, bubbles appear only during inspiration. In larger air leaks, bubbling is continuous during both inspiration and expiration. Some commercially available pleural drainage systems include air leak meters that allow a rudimentary quantification of the air leak (see Chapter 22Figure 18–3). To obtain a more precise estimate of the leak, a semiquantitative assessment can be made by measuring the difference between delivered and exhaled tidal volumes using a spirometer attached to the ventilator, or a tight-fitting face mask in extubated patients. Similarly, the amount of air leak can be measured with a spirometer attached directly to the chest tube.13

Anesthetic Problems Associated with BPF

A logical goal-oriented approach is used to develop an anesthetic plan that is appropriate to the surgical needs and the medical conditions of the patient. Anesthesia for patients with a BPF is based on two important techniques central to thoracic anesthesia: techniques of lung isolation and techniques of ventilation of an open airway.

Care should be taken to avoid complications associated with the fistula, since pleural cavity contents have free access to the bronchial system with potential for soiling with septic material into the “normal” contralateral lung or for flooding of the tracheobronchial tree by pleural fluid, resulting in catastrophic asphyxiation. A patient with BPF may not show any symptoms when awake and breathing spontaneously, but spillage of even small amounts of potentially septic material can cause severe lung damage. Under general anesthesia with mechanical ventilation, the tidal volume delivered may be lost through the low resistance fistula, resulting in severe hypoventilation, hyper-carbia, acute respiratory acidosis, and hypoxemia. Furthermore, if a chest tube is not in place, then positive pressure ventilation may cause pneumothorax that can rapidly progress to a life-threatening tension pneumothorax with resultant cardiovascular collapse.

MANAGEMENT

Therapeutic success has been variable, and the lack of consensus suggests that no optimal therapy is available; rather, current therapeutic options seem to be complementary, and treatment needs to be individualized.

Since infection and trauma constitute two major causative factors of BPF, it is essential to observe meticulous aseptic and atraumatic techniques, especially during airway manipulation. Caution must be exercised to avoid further barotrauma from mechanical ventilation, and if sterility techniques are not adhered to, the chest tube, while indispensable for draining the infected pleural space, can serve as a conduit for introduction of more serious infections. Furthermore, since BPF is often associated with severe predisposing factors such as sepsis, uncontrolled diabetes mellitus, and multisystem organ failure, it is essential to ensure that underlying conditions are optimally managed during the perioperative period.

The first step to managing the actual BPF is to perform a bronchoscopy and drain the chest cavity. Depending on the dimension of the fistula and the time-frame of onset (acute vs chronic), the fistula can be managed by using a variety of surgical and/or medical procedures. Surgical therapy (eg, Clagett procedure, direct repair, or thoracoscopy) is traditionally the treatment of choice, but interest is increasing in bronchoscopic application of various glues, coils, and sealants. Location and size of the fistula may indicate the potential benefits of an endoscopic approach, which may serve as a temporary bridge in high-risk patients, allowing the patient’s clinical status to improve.

Acute BPF

Acute BPF usually manifests within the first week after lung resection. The cause is primarily surgical, with a sudden and often complete dehiscence of the bronchial stump, and it may be associated with suboptimal surgical technique. In such cases, the onset is often very sudden and dramatic, with rapid onset of extreme shortness of breath and catastrophic cardiovascular collapse secondary to tension pneumothorax on the affected side. A chest tube, if not already in place, must be inserted as soon as possible not only to relieve tension pneumothorax but also to drain the pleural fluid to minimize the risk of bronchial and lung contamination. In life-threatening emergencies, the tension pneumothorax can be drained expeditiously by either large-bore needle puncture or reopening of the old chest tube site. At times, emergency reopening of the thoracotomy incision may be life saving. During these critical situations, the goals of anesthetic care are centered on resuscitation and hemodynamic support, allowing the patient to be transported to the operating room for emergency thoracotomy and BPF closure.

Attention must be paid to protecting the healthy lung from contamination and sudden flooding by the pleural contents. Postural drainage achieved by positioning the patient with the affected side dependent and head elevated may help prevent such aspiration. If these maneuvers are insufficient because of large volume output from the open bronchus, emergent intubation should be carried out, with placement of a double-lumen tube (DLT) to isolate the affected lung. In difficult airway situations, intubation of the contralateral lung with a single-lumen cuffed endotracheal tube in a mainstem bronchus may provide an acceptable means to secure the airway. Generally, patients presenting with acute BPF do not have severe comorbid conditions, provided that the healthy lung has not been flooded with pleural fluid (which can lead to aspiration pneumonitis). Once the surgical problem is recognized and addressed in a timely manner by reoperation, the prognosis is usually excellent.

Chronic BPF

BPF is essentially a pathological process and not a distinct and specific disease entity in itself. It is a manifestation of the patient’s underlying serious lung condition, which leads to poor wound healing and fistula formation. Infection remains the chief reason for development of chronic BPF and plays a key role in its continued presence in chronically ill and debilitated patients. For this reason, the underlying factors that contribute to poor wound healing must be vigorously treated. Efforts to improve the patient’s overall medical condition include optimizing nutritional status through parenteral or enteral feeding, preventing thromboembolism through prophylaxis, and managing poorly controlled diabetes to prevent hyperglycemia.

Underlying lung pathologies that can predispose to the formation of a BPF weeks to months following pneumonectomy include severe infections such as pneumonia, empyema, and acute respiratory distress syndrome (ARDS). Efforts to surgically close the fistula without first addressing the underlying causes will ultimately fail. Reversible causes for airway obstruction are treated with bronchodilators, and secretions are cleared with careful suctioning and chest physiotherapy. The empyema associated with chronic BPF is often thick-walled and multiloculated, and drainage by chest tube is usually inadequate, necessitating thorough washing out of the infected pleural space and packing with antibiotic solution. Often a pedicle flap is needed ultimately to fill up the cavity. The main principle of the surgical management of BPF with empyema is centered on elimination of the pleural space.

Treatment of concomitant ARDS in the ICU aims to optimize the patient’s oxygenation while providing adequate minute ventilation. The goal involves limiting flow through the fistula in order to create an environment conducive to healing. Ventilatory management, therefore, centers on decreasing the amount of ventilatory support needed, thereby limiting barotrauma and promoting healing of the BPF. Strategies include limiting peak and mean airway pressures, early weaning from positive pressure support, decreasing the need for positive end-expiratory pressure ventilation (PEEP), permissive hypercapnia, and early extubation. This can be accomplished by restricting tidal volume (3-4 mL/kg if only one lung is present), minimizing inspiratory time, avoiding PEEP (both applied and auto-PEEP), and reducing the number of positive pressure breaths by using pressure support instead of total ventilatory support.

Even though the DLT is the technique of choice for lung isolation in the operating room, one-lung ventilation (OLV) is not usually desirable for prolonged stay in the ICU because the collapsed lung is vulnerable to infection. In the majority of cases, therefore, ventilation of a patient with a chronic BPF in the ICU is through a single-lumen tube (SLT), using the mode of ventilation that produces the lowest peak and mean airway pressures to avoid barotrauma and still ensure adequate oxygenation and CO2 removal. Other methods have been developed to decrease air loss through the BPF. These include application of positive pressure to the pleural space during inspiration to oppose the air leak and placement of unidirectional valves in the chest tube. Unfortunately, the presence of purulent material in the chest cavity quickly disables the proper functioning of these devices.

If conventional ventilation fails, high-frequency ventilation may be used; it has been approved by the US Food and Drug Administration for the management of BPF. The advantages offered by high-frequency ventilation include a lower mean airway pressure to decrease the incidence of barotrauma to the lungs and tracheobronchial tree; improvement of cardiac output by reducing intrathoracic pressure, allowing increased venous return; and improving oxygenation through reduction in the shunt fraction and alveolar-arterial PO2 gradient. These effects promote improved perfusion to the bronchial stump, thereby promoting healing and closure of the BPF.

While isolated reports claim success using various modalities of high-frequency ventilation in this setting, this is not consistent. In other reports, high-frequency ventilation has not been proven to achieve better results than conventional ventilation, particularly in patients with severe lung pathology and bilateral lung disease. This may be explained by the finding that as frequency increases, expiratory time decreases, auto-PEEP quickly occurs and mean airway pressure rises rapidly, thereby defeating the theoretical advantages of high-frequency ventilation in reducing airway pressures. In these circumstances, high-frequency ventilation may worsen oxygenation and CO2 retention as compared to conventional ventilation techniques. For any particular clinical situation, therefore, trial periods of conventional ventilation and high-frequency ventilation are warranted, observing mean airway pressures, oxygenation, and CO2 removal to decide which technique is most suitable. In cases of severe refractory ARDS, the last resort is the use of extracorpo-real membrane oxygenation as a means of providing cardiac and pulmonary support. It is important to recognize that, in these rare situations, extracorpo-real membrane oxygenation is used to manage life-threatening ARDS and not to treat the BPF per se.

Endoscopic Management of BPF

Bronchoscopy has been increasingly recognized as an essential step in the diagnostic evaluation of most respiratory diseases. It is particularly useful in BPF not only for diagnostic purposes but also as an invaluable modality of treatment. Bronchoscopy for BPF is utilized in three different settings, as follows:

1. Diagnosis: As soon as a BPF is suspected in the postoperative period following lung resection, bronchoscopy is performed to confirm the presence of a BPF, estimate the size of the fistula, and evaluate the general conditions and viability of the bronchial stump.

2. Endoscopic closure: Bronchoscopy is done to follow the progressive course of a BPF during conservative management in the ICU. In general, the size of the communication dictates whether the patient is a candidate for instillation of a sealant material such as fibrin glue to close the fistula. If the opening is 3 mm or less, bronchoscopically instilled sealant material is usually successful. A BPF larger than 8 mm diameter requires surgical closure. The fistula must be directly visualized and trials of occlusion must convincingly show a cessation or appreciable decrease in the leak before the sealant is applied to the fistula. A large number of sealant compounds are available, and as yet no consensus exists on which provides the best results.

3. Surgical closure: Bronchoscopy is routinely performed prior to and on completion of a definitive surgical closure of a BPF.

Bronchoscopy can be performed under topical anesthesia or general anesthesia. Topical anesthesia for awake bronchoscopy is similar to that used during awake laryngoscopy and endotracheal intubation, with added topicalization of the bronchial system distal to the carina. An effective technique consists of the combination of ultrasonic nebulization (5 mL of 4% lidocaine nebulized with high O2 flow at 8-10 L/min) followed by more distal spraying under direct visualization during fiberoptic bronchoscopy.14 To promote delivery of the droplets to the distal bronchi, the patient is encouraged to take deep inspirations to generate a high inspiratory flow rate that will carry the droplets into the distal small airways. In severely debilitated patients unable to take deep breaths, the distal airways can be topicalized adequately through the fiberoptic bronchoscope by spraying lidocaine through the suction port either directly or through an epidural catheter inserted through it. As a general rule, meticulous airway topicalization is all that is needed, and other more invasive techniques such as superior laryngeal nerve blocks and transtracheal injection are usually redundant, since they are linked with increased risk for potential complications and minimal effects on the distal airways.

The choice of general anesthesia techniques for bronchoscopy depends on three considerations: (1) risk of pulmonary aspiration of gastric contents, (2) risk of contamination of the airway and the lungs through the fistula, and (3) risk of air leak and loss of alveolar ventilation. If the risk of gastric aspiration is minimal, the pleural cavity has been thoroughly drained, and the air leak is small, then a laryngeal mask airway (LMA) can be safely used. The important advantage is that an LMA allows room to maneuver the adult fiberoptic bronchoscope and offers unobstructed access to the bronchial stump and the fistula. If the risk of aspiration of gastric contents is high, a standard rapid sequence intubation with a single-lumen cuffed endotracheal tube should be considered. The endotracheal tube should be large enough for easy passage and maneuvering of the bronchoscope. In rare cases in which the BPF causes an unacceptable air leak or the risk of lung contamination from pleural fluid is high, a DLT is necessary for lung isolation. Maneuvering the adult bronchoscope through the relatively narrow tracheal lumen of the DLT is more difficult than maneuvering it through the LMA.

In the large majority of cases, bronchoscopy is relatively uneventful. In some high-risk patients, however, bronchoscopy may cause severe bronchoconstriction due to reactive airways and inadequate topicalization. Similarly, airway manipulation can lead to hemodynamic compromise with tachycardia, hypertension, and hypoxemia, resulting in myocardial ischemia. Finally, exaggerated suctioning of the distal airways may lead to diffuse alveolar collapse and atelectasis.

Operative Management of BPF

Optimal anesthetic management of patients requiring surgical closure of a BPF through a thoracotomy involves three important objectives: optimal management of the thoracostomy tube, proper positioning of the patient, and successful lung isolation.

1. Optimal management of the thoracostomy tube: The chest tube plays a vital role in prevention of a life-threatening pneumothorax during positive pressure ventilation under general anesthesia. It is, therefore, imperative to assure that the chest tube is well positioned in the pleural cavity. In many cases of BPF, the chest tube becomes obstructed by the thick purulent material of an empyema. If there is any doubt concerning the patency of the chest tube, the tube should be changed before induction of anesthesia. The chest tube must be kept on continuous suction up to the moment just before induction in order to keep the pleural cavity as empty as possible. After induction and before institution of positive pressure ventilation, the suction should be discontinued to limit the loss of ventilation through the fistula. To avoid the possibility of tension pneumothorax, the chest tube should never be clamped. During manual ventilation of the patient, it is important to carefully observe the amount of bubbling as different levels of inspiratory pressure are applied. This helps in estimating the size of the leak at each level. Obviously, the larger the air leak, the greater is the need for lung isolation using a DLT to prevent inadequate ventilation.

2. Positioning prior to induction: Even though a chest tube may have been in place for several days, it should never be assumed that the pleural cavity is empty and that there is no risk of bronchial contamination. If, as often happens, a collection of pus becomes loculated in the pleural cavity, the chest tube becomes ineffective. It is imperative, therefore, that the patient is properly positioned prior to induction. The head up, lateral decubitus position with the affected side down minimizes the risk of contamination of the tracheobronchial tree and lungs by pleural cavity contents.

3. Lung isolation: In the operating room, insertion of a DLT is the method of choice for securing the airway for the surgical repair of a BPF, like any other thoracotomy. Awake fiberoptic intubation with a DLT tube with the endobronchial lumen placed in the unaffected side is the safest way of managing BPF. Importantly, introduction of the DLT under direct vision with a fiberoptic bronchoscope avoids inadvertent trauma and prevents further injury to the bronchial stump and fistula. The advantage of maintaining spontaneous ventilation is that tension pneumothorax is prevented.

Some important considerations should be taken into account. If awake fiberoptic intubation is elected, it is important that airway topicalization be meticulous, since the DLT is more bulky, more difficult to insert, and involves greater irritation of the bronchus than a SLT; not only the upper part of the trachea must be topicalized, but also the areas deeper into the bronchial tree below the carina. Judicious intravenous sedation may be used sparingly, since it is imperative to maintain spontaneous breathing at all times until the DLT is successfully placed and its position carefully checked with fiber-optic bronchoscopy. Furthermore, it is advisable to use a DLT large enough to be secured in place to avoid movement and dislodgment during repeated surgical manipulations of the stump.

On rare occasions when a patient is unwilling or unable to undergo awake intubation, the DLT may be placed under inhalational anesthesia with the patient breathing spontaneously. Use of a volatile agent such as sevoflurane, which allows rapid induction with minimal airway irritation, is preferred. It is still advisable to topicalize the airway in order to abolish airway reflexes, which may still be present with inhalational anesthesia alone. In case of difficulty inserting a DLT with direct laryngoscopy, a special video laryngoscope for DLT (Airtraq yellow) can be used.

The most common ventilatory technique consists of one-lung ventilation with collapse of the affected lung (obviously not needed in cases of previous pneumonectomy). Should continuous positive airway pressure be needed for the affected lung, then the level of this pressure must be maintained below the critical pressure needed to cause air leak through the BPF. Similarly, the DLT can be ventilated via independent two-lung ventilation, using two ventilators and settings appropriate for each lung. In rare cases, high-frequency ventilation can be used. As in any other thoracotomy, the lung can be isolated with an SLT and a bronchial blocker.

Thoracic epidurals are not used for postoperative pain management because of the risk of infection. Delivery of local anesthetics to the surgical site through a regulated infusion pump and intercostal nerve blocks can supplement the use of intravenous narcotics.

PROGNOSIS

BPF is a serious condition in terms of mortality and associated costs. Depending on the series, mortality rates vary from 25% to 79%.15 In acute bronchial stump dehiscence, fatality is associated with aspiration of pleural contents, causing either fatal asphyxia or pneumonitis. In chronic BPF, sepsis and ARDS are the main causes of death. Even if the patient ultimately recovers, the many weeks or months spent in the ICU and hospital carry considerable costs in human suffering and financial burden. The prevention of BPF is, therefore, essential.

PREVENTION

Prevention of BPF should focus on addressing the risk factors that predispose the patient to this complication. Because lung resection, especially right pneumonectomy, constitutes one of the highest risk surgeries for the development of BPF, careful selection of patients for resection is of utmost importance. Once a patient is deemed suitable for pneumonectomy, attention should be given to optimization of his overall medical condition prior to surgery. This entails treating all underlying infections, optimizing lung function, and aggressively treating comorbid conditions such as congestive heart failure and uncontrolled diabetes mellitus. For debilitated malnourished patients, the preoperative improvement of nutritional status can promote wound healing and prevent formation of a BPF.

Anesthesia and surgery providers must pay attention to maintaining strict intraoperative aseptic technique at all times. Instrumentation of the airway during intubation and placement of invasive monitoring catheters should be done with care to prevent infection. Surgical techniques are important in maintaining stump integrity and preventing stump dehiscence. It is important to meticulously appose the cartilaginous layer of the resected bronchus to the membranous layer and to preserve adequate blood supply to the stump. In high-risk patients, the surgeon may fill the hemithorax with saline solution before surgical closure and ask the anesthesiologist to provide a high inflation airway pressure of 40 cm H2O transiently in order to detect potential bronchial stump leaks. The surgeon can place a sealant such as Gelfoam on the stump as a preventive measure. A prophylactic muscle flap must also be considered to stabilize the bronchial stump.

In the postoperative period, it is essential to extubate the patient as early as possible in order to avoid the detrimental effects of positive pressure ventilation. In cases in which the patient’s respiratory status requires continued ventilatory support after pneumonectomy, the goals include limiting inflation pressures to diminish the risk of barotrauma and using aseptic technique during tracheal suctioning to prevent infection.

SUMMARY

Although rare, BPF represents a challenging management problem and is associated with high rates of morbidity and mortality. This complication is best managed by reducing the risk factors that predispose to BPF formation and in patients with an existing BPF using meticulous perioperative management strategies to reduce the risks of life-threatening loss of ventilation, tension pneumothorax, and contamination of the remaining lung through the fistula.

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