13 year-old, Male, Castrated, Domestic Short Hair, Feline

History: The patient presented to the ER service for respiratory effort. Previously in the week, he had a urinary obstruction, and was anesthetized on several occasions for procedures to resolve the urinary bladder obstruction.

Images:  Survey images of the patient were obtained.

    

Findings:

  1. There is extensive pneumomediastinum, pneumoretroperitoneum, and pneumothorax that is primarily right-sided, and extensive subcutaneous emphysema.
  2. There is reduced abdominal serosal contrast.
  3. Mineral-opaque urinary bladder content is present.
  4. A urinary catheter is present.
  5. A sacrocaudal malformation and caudal thoracic spondylosis deformans are present. These are not clinically significant.

Conclusions:

  1. The abnormal collection of air in the thoracic and abdominal cavities is most consistent with a tear in a major airway.
  2. The reduced abdominal contrast could be due to superimposition or crowding, but a small amount of abdominal fluid, such as from uroabdomen or peritonitis cannot be ruled out.
  3. The opaque urinary bladder content is consistent with urocystoliths and/or grit.

Recommendations:  A CT study could be performed to better confirm the cause and better localize a site of the suspected airway tear.

Transverse CT images in a lung window obtained before and after positive pressure ventilation, after partially retracting the endotracheal tube. The positive pressure allowed identification of a tear of the dorsal membrane of the caudal cervical trachea (seen in the image on the right) that was not initially visible. These images also show marked pneumomediastinum, pneumothorax, and subcutaneous emphysema. Pneumoretroperitoneum, (presumably from caudal tracking of gas from the pneumomediastinum) and urocystoliths were also confirmed but are not shown in the CT images above.

Follow-up:  

The tracheal rent was surgically repaired (click to enlarge images below).
The patient is currently doing well at home, and in repeat radiographs after a diet change, there was dissolution of urocystoliths.

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3 comments

  1. Severe subcutaneous emphysema, pneumothorax, pneumomediastinum, and pneumoretroperitoneum are highly suspicious for tracheal tear, probably secondary to repeated intubation. Recommend CT of the head through thorax and/or a tracheoscopy to assess for a tear.

  2. Hi everyone,

    Again, this is a very interesting case! Here is my impression:

    Radiographic findings:
    Associated with the caudal-most extent of the S3 vertebral body, there is an irregularly marginated, ill-defined, transverse fracture, causing mild to moderate ventral displacement of the caudal segment. The Cd4 vertebral segment is abnormally shortened and tapered, with smooth margins. No pelvic or rib (incompletely evaluated) fractures are present.

    Within the subcutaneous tissues and deep fascial planes of the thoracic body wall, thoracic limbs, and abdominal body wall, a large amount of gas is present, peripherally displacing the cutaneous margins. A large amount of gas is also seen throughout the pleural space, causing retraction and rounding of all lung lobes from the thoracic body wall, a diffuse increase in soft tissue opacity within the pulmonary parenchyma (resulting in decreased conspicuity of the pulmonary vasculature and bronchi), and dorsal displacement of the cardiac silhouette. Additionally, throughout the mediastinum, a moderate amount of gas is present, causing increased conspicuity of the mediastinal structures. This mediastinal gas extends caudally beyond the diaphragm and into the retroperitoneal space to the level of L6.

    The visualized portions of the left kidney appear small; the right kidney is not appreciated. Superimposed over the region of the urinary bladder there is a mineral opaque urinary catheter. The urinary bladder is small in size and contains a moderate amount of granular to rounded mineral opaque material. In the peritoneal space, there is decreased abdominal serosal margin detail, best appreciated superimposed on the falciform fat.

    Radiographic Diagnosis:
    1. Severe pneumothorax, moderate pneumomediastinum (with concurrent moderate pneumoretroperitoneum), and severe subcutaneous and deep fascial emphysema. Consider a hollow viscus rupture, secondary to a prior endotracheal tube placement given the history of anesthesia.
    2. Mild to moderately displaced, S3 transverse fracture, likely traumatic. Given the ill-defined nature, a pathologic fracture or artifactually ill-defined secondary to superimposed soft tissue structures are also considered. The shortened Cd4 vertebra is likely secondary to prior amputation and is likely of no clinical significance.
    3. Moderate urinary bladder sand-like and possible small calculi with the presence of a urinary catheter over the plane of the urinary bladder and mild peritoneal effusion.
    4. Small left kidney; consider chronic renal disease. The decreased visualization of the right kidney may be due to superimposition of the abdominal body wall changes.

    Notes:
    The cause of the urinary obstruction may be secondary to the S3 fracture as the pelvic nerve (S1-S3), which parasympathetically innervates the detrussor muscle, can be inappropriately blocked, causing urine retention. However, the presence of the sand-like and possible small urinary bladder calculi may also be attributable to a urethral obstruction.

    Next steps:
    1. Thoracocentesis.
    2. Three view, collimated, thoracic radiographs to rule out a tracheal rupture (as the cranial extent of the trachea is not visualized in this study), however, this may be low yield. To definitively rule out a tracheal rupture, tracheoscopy should be considered if clinically indicated.
    3. Neurologic examination to assess the pelvic (S1-S3) and pudendal nerves (S1-S3) for long term effects of micturition.

    Thanks everyone!

    -Elizabeth Huynh

  3. Pneumomediastinum, pneumoretroperitoneum, and severe subcutaneous emphysema.

    These finding are most consistent with a tracheal tear, likely secondary to repeated intubation and also has been associated with overinflation of the endotracheal cuff.

    Recommendations:
    A diagnosis could be confirmed on Computed Tomography (reported in cats and humans) as well as via Tracheoscopy.

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