Reply To: Radiograph Quiz!
Great thoughts everyone!
I know the megaoesophagus was the easier one, but I wanted to share as it was a good example! I think they can sometimes be quite tricky to spot! We did manage to get this radiograph conscious. Sedation and GA can in themselves cause megaoesophagus, so I always try and get conscious when I can. We found no underlying cause, so I think idiopathic.
The pneumomediastinum was a real surprise in the other case! We really struggled to understand. The CT did not give us an answer… could it have been the blood sample!??! This dog presented with significant vitamin D toxicity. Hypercalcaemia resolved but respiration worsened. Severe interstitial pattern on CT. Sadlt we put dog to sleep, we got consent for PM, so will keep you posted. Still no explanation for the pneumomediastinum…
Pneumomediastinum is the abnormal accumulation of air within the mediastinum and it can be caused by a variety of mechanisms. Tracheal disruption can leak air into the mediastinum, and has been reported with cervical trauma, mechanical ventilation, transtracheal aspiration, tracheostomy, tracheal intubation and overinflation, or central venous catheter placement. Similar to tracheal trauma, oesophageal or pharyngeal rupture can result in pneumomediastinum. Subcutaneous emphysema from any location can eventually enter the mediastinum via the cervical soft tissues and thoracic inlet. Less commonly, air can enter the mediastinum from gas accumulation in the retroperitoneal space. In some cases, the cause of pneumomediastinum is not determined (spontaneous pneumomediastinum).
The presence of air in the mediastinum creates enhanced contrast and detail, allowing radiographic visualization of individual mediastinal structures (best seen on lateral images), including cranial vena cava, brachiocephalic trunk and left subclavian artery, oesophagus, and azygos vein. Visualization of the tracheal wall is enhanced due to the presence of both intraluminal and extraluminal air.