Pneumothorax of many etiologies can affect dogs and cats. For many patients, a single thoracocentesis will resolve the pneumothorax; however, for those with a persistent air leak, more invasive options such as continuous suction through a thoracostomy tube or surgery are often necessary. For select patients, a less invasive, less expensive option may be autologous blood patch pleurodesis. Blood patch pleurodesis is not difficult to perform and, despite a limited amount of published information, it seems to be reasonably successful with minimal complications.<\/p>\n
Take-Home Points<\/strong><\/p>\n <\/div><\/div><\/p>\n Pneumothorax<\/a> is the presence of free air within the pleural cavity, most often resulting from rupture of a portion of an air-containing viscus (e.g., lung, airway, less commonly esophagus) and may be frequently encountered in the veterinary emergency hospital. Pneumothorax may be either spontaneous or acquired.<\/span><\/p>\n Spontaneous:<\/b> Primary spontaneous pneumothorax occurs in the absence of primary lung disease and, in dogs, may result from rupture of pulmonary bullae or blebs. Primary spontaneous pneumothorax is more common in large, deep-chested breeds, especially Siberian huskies.1<\/sup> Secondary spontaneous pneumothorax occurs because of a variety of underlying pulmonary conditions, including infection (parasitic, viral, bacterial, or fungal), neoplasia, migrating foreign objects, thromboembolism, and lower airway disease.1,2<\/sup><\/span><\/p>\n Acquired:<\/b> Acquired pneumothorax may occur as a result of blunt force or penetrating trauma,1,3,4<\/sup> iatrogenic injury during thoracocentesis or thoracostomy tube placement, an adverse anesthetic event (e.g., barotrauma), or a surgical complication following thoracotomy. Tension pneumothorax occurs when a 1-way valve effect leads to significantly increased intrathoracic pressure, compressing the lungs, heart, and large vessels and leading to cardiovascular compromise.<\/span><\/p>\n Clinical signs of pneumothorax may include increased respiratory rate and effort, often with an abdominal component. Patients with mild cases may exhibit cough, weight loss, and lethargy. Signs of severe pneumothorax may include grunting, gasping, anxiety, barrel-shaped chest, cardiovascular collapse, cyanosis, vomiting, or even cardiopulmonary arrest. Physical examination may also detect quiet or muffled cardiac and pulmonary sounds, which may be more pronounced dorsally, as well as signs associated with shock resulting from diminished cardiac output (e.g., diminished pulse quality, tachycardia, cyanotic or pale mucous membranes, prolonged capillary refill time, decreased blood pressure). Pneumothorax reduces tidal volume, which may result in (sometimes very rapid and progressive) hypoxemia, hypercarbia, respiratory acidosis, and death.<\/span><\/p>\n Urgent treatment for pneumothorax requires relief of increased intrathoracic pressure via thoracocentesis, which may need to be performed before imaging studies to ensure that the patient is stable. A single thoracocentesis is easily accomplished after shaving, aseptic preparation, and aspiration with a closed collection system (<\/span>FIGURE 1<\/b><\/span>). Although in some patients the pneumothorax may accumulate slowly and require a thoracocentesis every few days or weeks, in other patients the air will commonly accumulate more rapidly. For patients that require more than 2\u00a0thoracocenteses within 24 hours, or if negative suction (complete resolution of the pneumothorax) is never achieved, more aggressive intervention is required, which may include placement of an indwelling thoracostomy tube for pleural drainage with a continuous suction device (<\/span>FIGURES 2 AND 3<\/b><\/span>). An alternative treatment for patients in which air accumulates only intermittently, although rarely reported, is placement of a subcutaneous pleural access port to facilitate intermittent air removal.5<\/sup><\/span><\/p>\n\n
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Figure 1. Dog in left lateral recumbency, shaved, aseptically prepared, and undergoing thoracocentesis via a closed collection system. To avoid blood vessels, the needle is generally inserted between the 7th to 9th intercostal space, dorsal to the costochondral junction, cranial to the rib, and with the bevel pointing up. Repeated suction and emptying the air into the room is performed until negative suction (no further air removed) is achieved.<\/span><\/a><\/div><\/div>
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