History
A 2-year-old Pug was evaluated for a 4-month history of dyspnea. Physical examination revealed a rapid respiratory rate, harsh lung sounds during expiration, and muffled heart sounds. Thoracic radiography revealed a right-sided diaphragmatic hernia. The dog subsequently underwent surgical repair of the diaphragmatic defect. Postoperative thoracic radiographic views were obtained the following day because the dog's respiratory rate had increased from 50 breaths/min at the time of submission to 90 breaths/min after surgery (Figure 1).
Left lateral (A) and ventrodorsal (B) radiographic views of the thorax in a 2-year-old Pug evaluated 24 hours after surgical repair of a right-sided diaphragmatic hernia.
Citation: Journal of the American Veterinary Medical Association 232, 3; 10.2460/javma.232.3.355
Left lateral (A) and ventrodorsal (B) radiographic views of the thorax in a 2-year-old Pug evaluated 24 hours after surgical repair of a right-sided diaphragmatic hernia.
Citation: Journal of the American Veterinary Medical Association 232, 3; 10.2460/javma.232.3.355
Left lateral (A) and ventrodorsal (B) radiographic views of the thorax in a 2-year-old Pug evaluated 24 hours after surgical repair of a right-sided diaphragmatic hernia.
Citation: Journal of the American Veterinary Medical Association 232, 3; 10.2460/javma.232.3.355
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Radiographic Findings and Interpretation
On the right side of the thorax, the lungs are retracted from the body wall and there are wide pleural fissures consistent with mild pleural effusion (Figure 2). A moderate generalized alveolar pattern is evident in the right lung lobes, and an air bronchogram is evident in the right cranial lung lobe. A focus of gas is in the caudal, intrathoracic portion of the esophagus. The primary differential diagnoses were aspiration pneumonia or reexpansion pulmonary edema (RPE). Because the dog's CBC values and rectal temperature were within reference limits and there was no evidence of aspiration during recovery from anesthesia, RPE was considered the most likely diagnosis.
Same radiographic views as in Figure 1. Notice retraction of the lungs from the body wall (large black arrows) and the wide pleural fissures. A moderate generalized alveolar pattern is in the right lung lobes, and an air bronchogram is in the right cranial lung lobe (small black arrow). Notice the mild focus of gas in the caudal intrathoracic portion of the esophagus (white arrow).
Citation: Journal of the American Veterinary Medical Association 232, 3; 10.2460/javma.232.3.355
Same radiographic views as in Figure 1. Notice retraction of the lungs from the body wall (large black arrows) and the wide pleural fissures. A moderate generalized alveolar pattern is in the right lung lobes, and an air bronchogram is in the right cranial lung lobe (small black arrow). Notice the mild focus of gas in the caudal intrathoracic portion of the esophagus (white arrow).
Citation: Journal of the American Veterinary Medical Association 232, 3; 10.2460/javma.232.3.355
Same radiographic views as in Figure 1. Notice retraction of the lungs from the body wall (large black arrows) and the wide pleural fissures. A moderate generalized alveolar pattern is in the right lung lobes, and an air bronchogram is in the right cranial lung lobe (small black arrow). Notice the mild focus of gas in the caudal intrathoracic portion of the esophagus (white arrow).
Citation: Journal of the American Veterinary Medical Association 232, 3; 10.2460/javma.232.3.355
Comments
Examination of pulmonary biopsy specimens is required for definitive diagnosis of RPE. Re-expansion pulmonary edema is a form of noncardiogenic edema that develops from metabolic and hemodynamic changes within collapsed and suddenly re-expanded pulmonary parenchyma. The pathophysiology is multifactorial. Mechanical disruption of the vessels caused by negative intrapleural pressure and increased vascular permeability associated with ischemia-reperfusion injury may be potential pathogenetic causes. Other proposed causes include variation in the pulmonary arterial pressure and surfactant abnormalities.1
The basic mechanism of ischemia-reperfusion injury has been attributed to the presence of fluids, air, or entrapped organs in the pleural cavity causing lung lobe compression and atelectasia. Subsequently there is a mismatched ventilation-perfusion ratio and arteriovenous shunting to bypass the malfunctioning lung lobe, which also causes ischemia.2
The condition is more frequently diagnosed in cats than in dogs and is often fatal.3 Clinical signs of RPE, including progressive dyspnea and tachypnea, are usually observed within hours after surgery.4 In the dog of this report, pleural effusion was attributed in part to RPE. However, other causes likely contributing to the effusion included residual lavage fluid and increased vascular permeability attributable to tissue handling during surgery.
Following surgery, the dog's condition was stable and the RPE was self-limiting. Repeat radiography performed 48 hours after surgery revealed a resolving alveolar lung pattern. The next day, the dog's respiratory rate was within reference limits and it was discharged from the hospital. To our knowledge, RPE following diaphragmatic hernia repair has not been reported in dogs.
References
- 1.↑
Worth AJ, Machon RG. Prevention of reexpansion pulmonary edema and ischemia-reperfusion injury in the management of diaphragmatic herniation. Compend Contin Educ Pract Vet 2006;28:531–540.
- 2.↑
Boudreaux RJ, Muir WW. Pathophysiology of traumatic diaphragmatic hernia in dogs. Compend Contin Educ Pract Vet 1987;9:379–386.
- 3.↑
Garson HL, Dodman NH, Baker GJ. Diaphragmatic hernia. Analysis of fifty-six cases in dogs and cats. J Small Anim Pract 1980;21:469–481.
- 4.↑
Fossum TW. Surgery of the lower respiratory system: lungs and thoracic wall. In: Fossum TW, ed. Small animal surgery. 2nd ed. St Louis: Mosby Inc, 2002;760–787.
