Pneumothorax and Bronchopleural Fistula




PNEUMOTHORAX


DEFINITIONS





  • A pneumothorax is a condition in which air has entered and becomes entrapped within the pleural space.



  • A spontaneous pneumothorax is either primary or secondary and occurs because of parenchymal (lung) disruption.



  • An acquired pneumothorax most often is iatrogenic in nature but can also occur secondary to blunt or penetrating trauma.



  • Tension pneumothorax is a condition in which increasing positive pleural pressure leads to hemodynamic compromise as a result of severe hypoxemia, impaired venous return, and occlusive mechanical shift and compression.





ETIOLOGY


The more common causes of pneumothorax are listed in Table 49-1 . Spontaneous primary pneumothorax is most commonly caused by the rupture of an apical subpleural bleb in patients without clinically apparent underlying lung disease. Spontaneous secondary pneumothoraces occur in patients with known underlying parenchymal disorders, such as bullous disease related to chronic obstructive pulmonary disease (COPD), malignancy, or as a sequelae of infectious disorders. Acquired pneumothorax occurs most commonly in a hospital setting secondary to complications of central venous access, pacemaker insertion, lung biopsy, thoracentesis, mechanical ventilation, or thoracic and abdominal operations. Traumatic pneumothorax is also secondary and associated with blunt and penetrating thoracic injuries.



TABLE 49-1 ▪

CLASSIFICATION OF PNEUMOTHORAX











Spontaneous



  • Primary




    • Subpleural apical bleb rupture




  • Secondary




    • COPD—bullous disease



    • Esophageal rupture



    • Infection—pneumonia, lung abscess



    • Catamenial



    • Malignancy—lung cancer, metastatic sarcoma




      • AIDS—pneumocystis pneumonia



      • Interstitial lung disorders



Acquired



  • Iatrogenic




    • Transbronchial or transthoracic needle biopsy



    • Subclavian or internal jugular venous access



    • Percutaneous pacemaker insertion



    • Thoracentesis



    • Laparoscopic (foregut) surgery



    • Barotrauma




  • Traumatic




    • Penetrating trauma




      • Stab or gunshot wounds




    • Blunt trauma




      • Motor vehicle collisions



      • Falls



      • Contact sports-related injuries




AIDS, acquired immunodeficiency syndrome; COPD, chronic obstructive pulmonary disease.




KEY FACTS


Spontaneous Primary Pneumothorax





  • Occurs more commonly in men with a male-to-female ratio of 6:1. Often taller and thinner individuals. A familial tendency has been described.



  • More common in smokers than non-smokers.



  • Tends to occur in late adolescence or early adulthood in patients with excellent pulmonary reserve.



  • May be secondary to a Valsalva maneuver, such as a severe coughing spell, straining, or with physical activity (rare presentation, however).



  • Etiology obscure but may be associated with distal airway inflammation and obstruction and bronchial abnormalities. Small airway inflammation associated with smoking may contribute. Bronchial abnormalities include smaller than usual bronchial dimensions, and anatomic variations including missing bronchi or accessory airways. Broad swings in atmospheric pressure can result in bleb overdistension and rupture. In addition, in taller individuals, base-to-apex pleural pressure gradients are greater, with apical blebs subjected to increased distending forces ( Fig. 49-1 ).




    Figure 49-1


    Computed tomography scan of the chest demonstrating significant and numerous blebs at both apices of the lungs (R > L), with an accompanying pneumothorax on the right side.



  • The chief physiologic consequence is a reduction in vital capacity and hypoxemia. In young healthy individuals, this is usually well tolerated. The larger the pneumothorax, the more severe the impact on gas exchange. Hypoxemia is due to shunt and low V/Q units.



  • Is associated with a 30% recurrence rate when managed by observation, needle aspiration, or chest tube drainage.



Spontaneous Secondary Pneumothorax





  • Occurs in patients with underlying lung disorders and poor pulmonary reserve.



  • When associated with bullous disease from emphysema or in patients with cystic fibrosis, it is usually poorly tolerated by patients, even with small pneumothoraces.



  • May be the primary manifestation of a ruptured esophagus.



  • May be associated with metastatic cancer, especially sarcoma, or may rarely be a primary manifestation of lung cancer.



  • Occasionally develops in patients with acquired immunodeficiency syndrome in association with Pneumocystis pneumonia ( Fig. 49-2 ). Microscopically, extensive tissue necrosis is evident. Similarly, spontaneous secondary pneumothorax can complicate any cause of necrotizing pneumonia ( Fig. 49-3 ).




    Figure 49-2


    Chest x-ray study in a patient with Pneumocystis pneumonia with residual subpulmonic pneumothorax who is on mechanical ventilation.





    Figure 49-3


    Computed tomography scans of the chest demonstrating a left-sided pyopneumothorax in a patient with severe bilateral bacterial pneumonia and adult respiratory distress syndrome.



  • Catamenial pneumothorax is defined as a spontaneous pneumothorax occurring within 72 hours before or after the onset of menses. The pathogenesis is not entirely clear, with evidence in some patients of intrathoracic endometriosis or diaphragm defects, or both. However, this is not universally identified in women with catamenial pneumothorax. (See later for more details.)



Acquired Iatrogenic Pneumothorax





  • Commonly associated with complications secondary to placement of subclavian or jugular venous central lines, percutaneous pacemaker insertion via the subclavian vein, or with thoracentesis in which the underlying lung is punctured with a needle allowing air to escape into the pleural space. Pneumothorax following ultrasound-assisted thoracentesis with good visualization may relate to uneven pleural pressure gradients developed as the lung re-expands in an uneven fashion.



  • May occur secondary to barotrauma associated with alveolar overdistension and rupture. Air dissects into the perivascular adventitia and then tracks along the perivascular bundles into the mediastinum, producing a pneumomediastinum. The gas may decompress to other areas (e.g., fascial planes of the neck), but if decompression is inadequate, the pressure rises with rupture of the mediastinal parietal pleura and production of a pneumothorax. Risk factors for barotrauma include high positive end expiratory pressure (PEEP), high tidal volume ventilation, and high peak and mean inspiratory pressures. Patient factors include disease setting such as acute lung injury/adult respiratory distress syndrome (ARDS), emphysema (alveolar overdistension at lower pressures), status asthmaticus, pulmonary fibrosis, necrotizing pneumonia and so on.



  • May also occur after transthoracic needle biopsy or transbronchial lung biopsy.



  • Occurs in the operative setting during open or laparoscopic abdominal procedures involving the diaphragmatic hiatus (Nissen fundoplication, Heller myotomy, paraesophageal hernia repair, or gastric bypass surgery).



Acquired Traumatic Pneumothorax





  • May occur secondary to blunt or penetrating injuries.



  • With blunt injuries associated with rib fractures, fractured segments can violate parietal pleura and puncture underlying lung parenchyma.



  • Can also occur in high-speed collisions without obvious signs of trauma because of parenchymal disruption associated with high intrathoracic pressure at the moment of impact or from shearing injuries related to sudden deceleration. (Sudden nonuniform increase in alveolar pressures, overdistension and membrane shearing injury)



Tension Pneumothorax





  • May occur with any of the aforementioned etiologies.



  • In this case, intrapleural pressure exceeds atmospheric pressure during expiration. It likely occurs secondary to a one-way valve effect, whereby gas enters the pleural space during inspiration with no return flow during expiration, producing increasing positive pleural pressure ( Fig. 49-4 ).




    Figure 49-4


    Chest x-ray study in a patient with left-sided tension pneumothorax. Note: Marked expansion of the left hemithorax (also wide rib spaces and downward displacement of the left hemi-diaphragm), together with marked shift of the heart and mediastinum to the right.



  • The key pathophysiologic events include severe hypoxemia, which occurs early and precedes hypotension. The latter is due to impaired venous return because of increased resistance, as well as occlusive mechanical compression (late event), which decrease stroke volume and cardiac output, despite compensatory tachycardia.



  • This condition is a true emergency and is associated with rapid clinical deterioration that requires prompt needle or tube decompression.





CLINICAL FEATURES


Symptoms





  • Sudden onset of chest pain, dyspnea, and cough ranging from mild to severe without a precipitating event



Signs





  • With a small pneumothorax, clinical findings may be absent.



  • With moderate to large pneumothorax




    • Decreased breath sounds over ipsilateral hemithorax



    • Hyperresonance to percussion over ipsilateral hemithorax



    • Hypoxia




  • With tension pneumothorax, physical findings are accentuated and include




    • Hypotension and tachycardia




  • Absent breath sounds and hyperresonance to percussion over the ipsilateral hemithorax



  • Tracheal deviation towards the contralateral side.



  • Hypoxia



  • Note: in patients on mechanical ventilation, an abrupt increase in peak and plateau pressures (volume-cycled ventilation) or abrupt fall in expired tidal volume (pressure preset ventilation) may be observed.





DIAGNOSIS





  • The chest radiograph is the standard modality for establishing the diagnosis.



  • Should be obtained as an upright, expiratory position.



  • Supine films can easily obscure the diagnosis because air will not be visualized in the apex in this position.



  • Lateral films can also assist in the diagnosis by evaluating the anterior and posterior aspects of the chest.



  • In patients with signs or symptoms of tension pneumothorax or in patients with impending cardiovascular collapse, prompt needle or chest tube decompression of the suspected side can be both diagnostic and therapeutic and should be instituted without any delay for diagnostic imaging.



  • Computed tomography (CT) obtained for other reasons may identify a pneumothorax (occult pneumothorax) that is not evident on plain chest films but should not be routinely employed as a diagnostic modality for primary spontaneous pneumothorax.



  • Although some physicians use a chest CT scan to look for blebs in cases of spontaneous pneumothorax, the American College of Chest Physicians consensus is that a chest CT scan is not routinely recommended.





TREATMENT


Spontaneous Primary Pneumothorax


Treatment Options





  • Observation (inpatient versus outpatient) ( Fig. 49-5 )




    Figure 49-5


    Treatment algorithm for primary spontaneous pneumothorax.



  • Needle aspiration



  • Tube thoracostomy



  • Thoracoscopy



  • Thoracotomy





CONSIDERATIONS





  • Age



  • Clinical condition



  • Size of pneumothorax




    • Small (<3 cm or <20%)



    • Large (≥3 cm or ≥20%)




  • Duration of symptoms



  • Patient compliance (social situation)



  • Proximity to emergency services



  • Occupation or hobby (pilot, scuba diver, athlete)



First Episode





  • Clinically stable patients with small pneumothoraces can be treated on an outpatient basis with a catheter and a Heimlich valve, observed in the emergency department, or as an in-patient and discharged home within 6 to 24 hours if repeat chest radiograph excludes enlargement of pneumothorax. We prefer to proceed with either percutaneous catheter or chest tube placement in all but the smallest of pneumothoraces to allow for complete lung re-expansion, but we acknowledge that practice patterns vary widely.



  • Clinically stable patients with large pneumothoraces should undergo an intervention to remove air from the pleural space and reexpand the lung. Options include needle aspiration or chest tube insertion with attachment to 20-cm suction or waterseal. Controversy exists in the literature regarding the ideal treatment and this also is influenced by practice patterns among individual physicians. We prefer chest tube placement for large pneumothoraces.



  • In clinically unstable patients, regardless of pneumothorax size, tube thoracostomy should be the treatment of choice.



  • Chest tubes can be removed after the lung has expanded, the pneumothorax has resolved, and the air leak has subsided.



  • Patients can be discharged and followed-up as outpatients.



  • Consider early surgical intervention for patients with occupational or lifestyle hazards ( Table 49-2 ). Although some physicians perform a pleurodesis through a chest tube, that is not a common practice and there is no convincing literature to support that practice.



    TABLE 49-2 ▪

    SURGICAL INDICATIONS















    Persistent air leak for >5 days
    Recurrent spontaneous pneumothorax
    Patients with prior pneumonectomy
    Patients with occupational hazards or leisure pursuits in which a recurrence may pose excessive risk
    Bilateral pneumothoraces
    Long-distance from medical facilities



Recurrent Primary Spontaneous Pneumothorax





  • Recurrent pneumothorax occurs in approximately 30% of patients, regardless of initial treatment (observation, simple aspiration, catheter, or chest tube management) and usually warrants surgical intervention.



  • Goals of surgery




    • Find and remove offending agent (bleb/bullae)



    • Minimize recurrence with pleural abrasion to create pleural symphysis




  • Options



  • Video-assisted thoracoscopic surgery (VATS)



  • Thoracotomy




    • Limited axillary thoracotomy



    • Traditional posterolateral thoracotomy




  • Chemical pleurodesis




    • Should be reserved for patients unwilling to consent to a surgical procedure, those with associated malignancy, and those deemed unfit for surgery



    • Complicates future surgical intervention secondary to adhesion formation



    • Is associated with a higher failure rate compared with surgery (10%–20% versus 0–5%)




  • Techniques




    • Patients with apical bullae visualized at surgery should undergo bullectomy, most commonly performed using stapling techniques.



    • Intraoperative pleurodesis should also be performed with parietal pleural abrasion (using a dry gauze or electrocautery scratch pad) to encourage adhesion formation between the visceral and parietal pleura.



    • We recommend against the routine use of chemical pleurodesis (talc or doxycycline) in benign disease.



    • Concerns about acute lung injury with use of talc pleurodesis have been reported as case reports (see review by Kennedy and Sahn for details).



    • Several large case series have published on the successful use of talc pleurodesis for primary spontaneous pneumothorax. These reported no cases of acute respiratory complications, 95% or greater success rate in several large series, preserved lung function on long-term follow-up, and feasibility of repeat VATS talc insufflation after prior talc pleurodesis.



    • In patients in whom no bleb is found, pleurectomy or talc pleurodesis may be considered.




  • Recommendations




    • Surgical approaches via thoracoscopy or thoracotomy have yielded excellent long-term results, with success rates of 95% to 100%.



    • Either approach provides acceptable visualization although thoracoscopic approaches have been associated with less postoperative pain, shorter recovery and hospitalization time, and improved cosmesis.



    • A limited axillary thoracotomy through a 5- to 6-cm incision provides excellent visualization and is an acceptable alternative to thoracosopy with equivalent morbidity.



    • Mechanical pleurodesis and resection of apical blebs/bullae, if present, is the current standard.




Secondary Spontaneous Pneumothorax





  • In general, patients have underlying lung disease, limited pulmonary reserve, and associated comorbidities that are likely to influence treatment decisions.



  • Usually require more early and aggressive intervention ( Fig. 49-6 )




    Figure 49-6


    Treatment algorithm for secondary spontaneous pneumothorax.



  • Clinically stable patients with small pneumothoraces should be hospitalized and can be treated with observation or chest tube placement depending on their course and symptoms. We prefer to manage patients with secondary pneumothorax with a chest tube because of associated comorbidities, underlying lung disease, and the limited cardiopulmonary reserve of these patients in the event of progression of the pneumothorax.



  • All patients with large pneumothoraces or those who are clinically unstable should be treated with chest tube placement.



  • Computed tomography of the chest is a useful adjunct to plain radiographs to provide additional diagnostic information about underlying pulmonary or chest wall pathology (bullous disease, malignancy, infection).



  • In patients who are suitable for operation, surgical intervention via thoracoscopy or limited thoracotomy is usually indicated to provide diagnostic information (biopsy) as well as to treat the underlying disorder (bullectomy). Mechanical or chemical pleurodesis is an important adjunct to encourage adhesion formation and prevent recurrence.



  • In patients deemed high-risk or those unfit for surgery and general anesthesia, chemical pleurodesis through a previously placed chest tube can be used to minimize recurrence, albeit not as effectively as surgical approaches.



  • Owing to the presence of underlying thoracic pathology, surgical intervention is not as effective for secondary pneumothorax compared with primary pneumothorax, yet it remains the best treatment option for these patients.


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Jun 24, 2019 | Posted by in CARDIAC SURGERY | Comments Off on Pneumothorax and Bronchopleural Fistula
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