Mediastinitis

Home / Mediastinitis

Issues

Mediastinitis

 

The mediastinum occupies the central portion of the chest and is defined anatomically by the thoracic inlet cranially, the diaphragm caudally, the mediastinal pleura laterally, the paravertebral gutters and ribs dorsally, and the sternum ventrally. It is lined on both sides by parietal pleura, contains the major organs in the central thorax, and separates these organs from the left and right lung lobes.

  • Mediastinitis—an inflammatory process involving the mediastinal space, usually the result of bacterial or fungal infection.
  • Acute disease—severe infection may be life-threatening and can spread to the pleural space; sepsis can occur.
  • Chronic—mediastinal granuloma or abscess can develop and result in cranial vena cava syndrome or chronic smoldering internal abscessation.
  • Systems affected—cardiovascular system through interference with venous return; respiratory system secondary to intrathoracic mass effect or pleural effusion; gastrointestinal system through esophageal obstruction.

 

SIGNALMENT

Rare in dogs and cats

 

SIGNS

  • Lethargy and weakness.
  • Dysphagia and regurgitation.
  • Edema of head, neck, and forelimbs.
  • Polypnea, respiratory difficulty or obstructed breathing, and cough.
  • The presence of a fever should raise the suspicion for an infectious process.

 

CAUSES & RISK FACTORS

  • Acute disease—usually result of esophageal perforation, tracheal tear, foreign body migration, or neck wound; mediastinal abscesses can develop subsequent to infections or neoplastic disorders arising in the mediastinum or adjacent tissues.
  • Chronic disease—usually result of a bacterial (e.g., Actinomyces and Nocardia spp.) or fungal (e.g., Coccidioides, Cryptococcus, Blastomyces, and Histoplasma spp.) infection. Spirocerca lupi infection possible in certain geographic regions.
  • Predisposing factors—esophageal foreign body; cervical or thoracic trauma.

 

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

  • Isolated pericarditis, pyothorax, and pneumonia.
  • Cranial mediastinal mass—lymphosarcoma; thymoma, thyroid, or parathyroid tumor; neurogenic tumor; mesenchymal tumor; mediastinal cyst.
  • Esophageal motor dysfunction, sliding hiatal hernia.
  • Gastroesophageal disorders, causing gastroesophageal reflux, chronic vomiting, and other upper GI conditions.

 

CBC/BIOCHEMISTRY/URINALYSIS

High WBC count with left-shift.

PCV and total protein—may be high owing to volume depletion/dehydration.

OTHER LABORATORY TESTS

Additional laboratory tests to rule-out other possible causes of clinical signs.

 

IMAGING

  • Thoracic radiographs—usually demonstrate a focal or diffuse widening of the mediastinum; can be accompanied by pneumothorax or bilateral pleural effusion, depending upon the underlying disease process.
  • Esophageal contrast study—investigate esophageal perforation or other abnormality; use a water-soluble contrast medium with suspected perforation (i.e., iohexol or iopamidol).
  • Thoracic ultrasonography—differentiate between mediastinal fluid accumulation (e.g., cyst and abscess), inflammatory reaction, and tumor.
  • Computed tomography—more definitive than ultrasound.

 

DIAGNOSTIC PROCEDURES

  • Cytology—thoracocentesis of any pleural effusion; transthoracic fine-needle aspirate or cutting-needle biopsy of a mediastinal mass that is not cardiac or vascular in origin.
  • Ultrasound-guided aspirate or biopsy most helpful in accurate sampling of tissues.
  • Submit samples for aerobic and anaerobic bacterial culture and sensitivity testing.

 

TREATMENT

  • Antibiotic or antifungal therapy as indicated.
  • Drainage and debridement of abscessed material.
  • Inpatient therapy with restricted activity until infection is controlled and condition is stable.
  • Pleural effusion of marked quantity or pyothorax of any degree—managed by tube thoracostomy or possibly surgery.
  • Intravenous fluid therapy, parenteral nutrition or esophageal feeding tube—until oral water and food intake returns to normal or near normal.
  • Esophageal perforation—surgical emergency; after surgery, use either parenteral nutrition or gastric tube feeding for 3–5 days.
  • Chronic disease—surgical exploration needed when associated with an abscess or a granuloma.
  • Tube thoracostomy—maintain post-surgery by continuous water seal suction or intermittent lavage and suction for 5–7 days or until negligible fluid is removed.

 

MEDICATIONS

DRUG(S)

  • Broad-spectrum bactericidal antibiotic—based on bacterial culture and sensitivity testing; should be administered parenterally for at least the first week of treatment, then orally.
  • Antifungal treatment—indicated for mycotic infection. Recommended agents include itraconazole, fluconazole, and amphotericin B; treatment usually required for 3–6 months.

 

FOLLOW-UP

PATIENT MONITORING

Daily temperature recording.

Hemogram—every 2–3 days during hospitalization (usually 7–10 days).

Thoracic radiographs—at 7- to 10-day intervals (more often if drainage is needed).

Antibiotics—generally continue for 1 week after hemogram and radiographs return to normal; with abscessation, continue an additional 4–6 weeks.

 

POSSIBLE COMPLICATIONS

  • Pyothorax
  • Sepsis
  • Mediastinal fibrosis

 

EXPECTED COURSE AND PROGNOSIS

Advise clients of guarded prognosis.

With early diagnosis and aggressive treatment—prognosis fair to good.

With mediastinal fibrosis—long-term prognosis guarded to poor.

Recognized complications—esophageal dysmotility; compression of the cranial or caudal vena cava; phrenic or recurrent laryngeal nerve paralysis.

MISCELLANEOUS

ABBREVIATIONS

GI = gastrointestinal

PCV = packed cell volume

WBC = white blood cell

Visit your veterinarian as early recognition, diagnosis, and treatment are essential.

You may also visit – https://www.facebook.com/angkopparasahayop