Атлас по рентгенологии травмированных собак и кошек / an-atlas-of-radiology-of-the-traumatized-dog-and-cat

122 Radiology of Thoracic Trauma

2

Day 4

Radiographic diagnosis (day 4): Radiographs made on day 4 showed almost a complete disappearance of the pneumothorax. The right middle and caudal lobes were more aerated as indicted by the decrease in fluid density. The amount of subcutaneous air continued to decrease.

Treatment/Management: “Shorty” was treated conservatively and experienced a spontaneous clearing of his chest lesions.

Comments: Note the fluid density within the affected lung lobes on the first study is more than would be expected with only pulmonary contusion and was the result of atelectasis as well. The return to near normal was to be expected in this type of trauma patient.

Tension pneumothorax 123

2.2.9Tension pneumothorax

Case 2.59

2

Signalment/History: “Sam” was a 4-year-old, female mixed breed dog who had been hit by a truck.

Physical examination: The dog was in shock and dyspneic and the examination was limited.

Radiographic procedure: Radiographs were made of the thorax.

Radiographic diagnosis: The thoracic cavity was distended with a tension pneumothorax and collapse of the lung lobes on the left. Pulmonary contusion of the lobes on the right could also be seen. An air-bronchogram pattern was present in the right lobes. The mediastinal shift was to the right.

Treatment/Management: “Sam” responded to immediate treatment to relieve the pneumothorax. She was kept under observation in an intensive care unit and the pneumothorax did not recur. She was discharged within several days.

124 Radiology of Thoracic Trauma

Case 2.60

2

Day 1, Noncontrast

Signalment/History: “Felix” was a 1-year-old, male DSH cat with a 4-month history of left sided pyothorax with frequent drainage. Streptococcus fecalis and E. coli had been cultured from the lesion. Treatment was thought to be effective and he was discharged from the clinic. The owner reported that clinical signs had not improved and that the cat remained lethargic and had problems in breathing.

Radiographic procedure: Progressive thoracic radiographs were made.

Radiographic diagnosis (day 1): Noncontrast radiographs showed a massive loculated pneumothorax in the caudal hemithorax on the left, with a marked mediastinal shift to the right. The heart shadow was against the right chest wall. The right lung was partially atelectic. The left lung could not be identified and was assumed to be collapsed.

Tension pneumothorax 125

2

Day 1, Barium swallow

Radiographic diagnosis (day 1): A barium swallow showed normal passage of the contrast meal through an esophagus that was markedly displaced to the right. A minimal amount of contrast agent had been inhaled and was demon-

strated in the bronchi.

126 Radiology of Thoracic Trauma

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Day 8

Radiographic diagnosis (day 8): This study followed needle aspiration of the air, but showed no change in the volume of the loculated pneumothorax that was being treated as a tension pneumothorax.

Tension pneumothorax 127

2

Day 15

Radiographic diagnosis (day 15): Following a thoracotomy in which a tear in the left lung was sutured, re-inflation of the lung had occurred, although not completely. The pneumothorax could not be identified on these radiographs. Pleural scarring plus the chest wall incision site had left a persistent fluid-density shadow on the left side. The surgical incision on the left was just caudal to the heart shadow as could be identified on the lateral view.

Treatment/Management: Failure of a pneumothorax to heal quickly suggested a more severe pulmonary lesion or the creation of a flap-like lesion that permitted the tension pneumothorax to develop. The surgery was successful, although it might be thought to have been delayed a bit too long.

128 Radiology of Thoracic Trauma

Case 2.61

2

Tension pneumothorax 129

Signalment/History: “Sly” was a 4-year-old, male Siamese cat with no history of medical problems until 24 hours previously when he stopped breathing for some minutes. The owners suspected trauma since the cat had been away from the house for a few hours. The acute onset of dyspnea was remarkable.

Physical examination: The severity of the dyspnea was severe and as a consequence, a complete physical examination was not possible. In addition, the cat was aggressive and frightened. Despite this, the examination suggested that an upper airway problem was not likely.

Radiographic procedure: Radiographs were made of the thorax.

Radiographic diagnosis: The thoracic cavity was distended with a prominent mediastinal shift to the left. A unilateral tension pneumothorax on the right had caused the cardiac silhouette to move away from the sternum. The left lung was partially atelectic. Most important was the failure to visualize the air-filled lumen in the distal trachea that suggested a possible intratracheal foreign body (arrows).

Treatment/Management: Unfortunately, a decision was made to treat only the pneumothorax. Following placement of a chest drain, the dyspnea continued and the owners elected euthanasia rather than surgical exploration to determine the cause of the pneumothorax.

On necropsy examination, a distal tracheal foreign body

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(chicken bone) at the level of the origin of the bronchus to the left cranial lobe had caused a severe necrotizing tracheitis/bronchitis. The mediastinum was edematous, emphysematous, and congested. Because of chronicity, adhesions prevented a pneumomediastinum and instead a flap-like opening in the wall of the mediastinum led directly to the production of a tension pneumothorax. It was, therefore, understandable that despite the placement of a chest drain, the pneumothorax had persisted. The mediastinitis was not appreciated clinically or radiographically; however, the abnormality in the distal trachea should have received more immediate attention. Probably the increased lung density noted on the lateral view was from the mediastinal effusion superimposed over the density from the lungs.

130 Radiology of Thoracic Trauma

2.2.10 Pneumomediastinum

Case 2.62

2

Signalment/History: “Clyde”, a 4-year-old, male Beagle, was found by the owner to be “enlarged” and “distended”.

Radiographic procedure: Whole body radiographs were made.

Radiographic diagnosis: A prominent subcutaneous emphysema and pneumomediastinum were evident. The increased lung pattern was thought to be due to the subcutaneous air surrounding the thorax. No signs of injury to the thoracic wall were noted. The multiple metallic subcutaneous foreign bodies were shotgun pellets and although widely distributed, were probably not associated with the current clinical problem.

Treatment/Management: The origin of the subcutaneous air could not be ascertained radiographically. A careful search of the skin located a small injury in the cervical region. At surgery, a small hole in the trachea was found at the level of C3. The overlying muscles were torn, suggesting a bite wound. Any tear or rupture of the trachea or main-stem bronchi can leak air.

An opening in the skin, especially in the axilla, can permit a “pump-like” action that fills the subcutaneous space with air. “Clyde” inflated the subcutaneous space on each inspiration with air entering through the skin lesion and from the hole in the trachea until he “pumped” himself up like a balloon. The air had moved through the thoracic inlet and filled the mediastinal space.

Pneumomediastinum 131

Case 2.63

2

Signalment/History: A cat was found lying on the road by a pedestrian and was brought to the clinic.

Physical examination: Subcutaneous emphysema was easily palpated over the thorax.

Radiographic procedure: Radiographs were made of the thorax and the whole body.

Radiographic diagnosis: Prominent subcutaneous emphysema was evident, in addition to a pneumomediastinum and retroperitoneal air. No signs of injury to the thoracic wall could be seen.

Comments: Air will dissect from the subcutaneous space into the mediastinal space. If the amount of air is sufficient, it is possible that it will then dissect from the mediastinal space into the retroperitoneal space. In this cat, the cause of the subcutaneous air was not known. The presence of the air suggests a more severe lesion than is actually present. Determination of the origin of the air is probably more critical in assigning its clinical importance.