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ASG Specialties:

  • Hip Dysplasia
  • Patella Luxation
  • Medial Patella Luxation
  • Elbow Dysplasia
  • Fragmented Coronoid Process
  • OCD Osteochondritis Dissecans Fractures
  • Arthritis
  • Ruptured Cruciate Ligament
  • Ruptured Cranial Cruciate Ligament
  • Ruptured Anterior Cruciate Ligament

Acute Respiratory Distress Syndrome (ARDS)

2 year old French bulldog with ARDS secondary to vomiting and aspiration pneumonia

Fig. 1: Radiograph of a 2 year old French bulldog with ARDS secondary to vomiting and aspiration pneumonia.

Acute Respiratory Distress Syndrome (ARDS) is a condition affecting the lungs that requires intensive medical support, including oxygen therapy and often mechanical ventilation.

by Michael Becker, DVM,
and Brian Young, VMD,
Diplomate American College of Veterinary Internal Medicine,
Diplomate American College of Veterinary Emergency/Critical Care

Diagnosing ARDS

The diagnosis of ARDS requires the following: bilateral pulmonary infiltrates on thoracic radiographs, severe hypoxemia (PaO2:FiO2 < 200), an acute onset of respiratory distress, and absence of heart failure. Acute Lung Injury (ALI) is similarly diagnosed, with a less severe PaO2:FiO2 of < 300.

Causes of ARDS

ARDS can occur secondary to a primary lung condition or can be caused by a problem elsewhere in the body. ARDS can be thought of as an inappropriate inflammatory response by the local immune system of the lung. Examples of ARDS caused by primary pulmonary disease include pneumonia, aspiration of gastric contents, pulmonary thromboembolism, and severe pulmonary contusions.

Examples of non-pulmonary causes include sepsis, severe trauma, pancreatitis, and transfusion reactions (TRALI: Transfusion Related Acute Lung Injury). Increased inflammatory cells in the lungs result in severe proteinaceous pulmonary edema, making oxygenation difficult for the patient. Later changes include possible pulmonary fibrosis as the lungs heal from the initial insult.

Treatment for ARDS

Patients with ARDS require intensive supportive care. In addition to treating the underlying cause of ARDS (e.g. cardiovascular support and antimicrobials for sepsis), the mainstay of treatment is oxygen therapy and mechanical ventilation. Canine or feline patients being ventilated require heavy sedation to remain intubated. They also require intensive nursing care, including intravenous fluids, tube feedings or intravenous nutrition, passive range of motion exercises, oral cleanings, eye lubrication, and recumbency care, all multiple times per day.

ARDSNet: A group of researchers in human medicine (collectively named ARDSNet) has been working for over a decade on several large, multicenter trials to search for treatments that may help improve outcomes. Multiple promising prospective research studies have been attempted based on previous successful treatments in smaller studies or case reports. Thus far the following pharmacologic therapies have not proven efficacious: albuterol, ketoconazole, lysofylline, and late steroid rescue. The trials with improved mortality outcomes have focused on lung-protective ventilation strategies, including lower tidal volumes and lower plateau pressures to avoid volutrauma and barotrauma (VILI: Ventilator Induced Lung Injury), higher PEEP (Positive End Exporatory Pressure) to avoid cyclic opening/closing of alveoli which causes systemic and local inflammation, and conservative fluid management strategies.

Canine thorax with normal lungs from a 14 year old corgi-mix.

Fig. 2: Radiograph of canine thorax with normal lungs from a 14 year old corgi-mix.

Prognosis for ARDS

More humans are surviving ARDS now than in the past. Mortality rates in people range from 30 – 40%. Few studies have been performed in veterinary medicine. The prognosis for any veterinary patient requiring mechanical ventilation for a primary pulmonary problem ranges from 10 – 40% survival. Dogs requiring mechanical ventilation have improved survival compared to cats. Some survivors recover completely, whereas others have permanent damage to their lungs and may experience other health problems.

REFERENCES: [1] AE DeClue and LA Cohn. Acute respiratory distress syndrome in dogs and cats: a review of clinical findings and pathophysiology. J Vet Emerg Crit Care 2007;17(4):340–347. [2] AJ Frank and B Taylor Thompson. Pharmacological treatments for acute respiratory distress syndrome. Curr Opin in Crit Care 2010;16:62-68. [3] PA Wilkins. Acute lung injury and acute respiratory distress syndromes in veterinary medicine: consensus definitions: The Dorothy Russell Havemeyer Working Group on ALI and ARDS in Veterinary Medicine. J Vet Emerg Crit Care 2007;17(4):333–339.

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