Diagnosis

Acute respiratory distress syndrome

Etiology

Causes [oz8]

• Pneumonia (40%)

• Sepsis (32%)

• Aspiration (9%)

• Severe trauma (10%): lung contusion, fat embolism, multiple fractures, burns, drowning

• Acute pancreatitis

• Massive transfusion (>15 RBC)

• Thoracic surgery: Lung transplantation, coronary artery bypass surgery, cardiopulmonary bypass

• Pulmonary embolism

• Hematopoietic stem cell transplantation

• Drugs: Alcohol, aspirin, cocaine, opioids, phenothiazines, tricyclic antidepressants, protamine, nitrofurantoin, chemotherapeutic agents, radiologic contrast

Pathophysiology [oz8]

• Alveolar lung injury --> pro-inflammatory cytokines --> excess fluid in the interstitium / alveoli

• Impaired gas exchange

• Decreased compliance

• Increased pulmonary arterial pressure

Complications [7k8]

• Prolonged mechanical ventilation

  • Barotrauma --> pneumomediastinum, pneumothorax

  • Tracheostomy, laryngeal edema and subglottic stenosis

  • Laryngeal edema and subglottic stenosis

• Infection:

  • Ventilator-associated pneumonia, line sepsis, UTI, Clostridium difficile colitis

• Deep venous thrombosis

• Critical illness neuropathy

• Renal failure

• Stress ulcer

• Anemia

• Post-traumatic stress disorder

Risk factors for ARDS [7k8]

• Advanced age

• Female gender

• Smoking

• Alcohol use

• Aortic vascular surgery

• Cardiovascular surgery

• Traumatic brain injury

• Pancreatitis

• Pulmonary contusion

• Infectious pneumonia

• Drugs (radiation, chemotherapeutic agents, amiodarone)

Epidemiology

Incidence per 100.000 [whg][v5r]

Approach

• Blood test: WBC, BNP, creatinine, liver function, blood culture, serelogic tests (ENA, ANA, ANCA, Myositis blot, aCCP, RF, aGBM)

• Sputum: culture, PCR, antigen tests

• Blood gas: PaO2:FiO2 ratio

• Chest x-ray

• CT thorax

• Bronchoscopy

• Echocardiography

• Biopsy [zr7]

Treatment

1. Treatment of the underlying condition is essential [zr7]

2. Treatment of infection:

   • Early administration of broad antimicrobial therapy

   • Removal of intravascular lines

   • Drainage of infected fluid collections

   • Surgical debridement or resection of an infected site

3. Supportive care: reduce shunt fraction, increase oxygen delivery, decrease oxygen consumption, avoid further injury [7k8]

   • Noninvasive ventilation or mechanical ventilation using low tidal volumes (6 mL/kg based upon ideal body weight)

   • Conservative fluid management and diuretics against fluid overload

   • Nutritional support

   • Thrombosis prophylaxis

Differential diagnoses

Acute eosinophilic pneumonia, Acute interstitial pneumonia, Acute pancreatitis, COVID-19, Diffuse alveolar hemorrhage, Drug side effects, Eosinophilic pneumonia, Fat embolism syndrome, Goodpasture syndrome, Heart failure, Hypervolemia, Inhalation injury, Interstitial lung disease, Myocardial infarction, Pneumocystis jiroveci pneumonia, Pneumomediastinum, Pneumonia, Pneumonitis, Pneumothorax, Pulmonary contusion, Pulmonary edema, Pulmonary embolism, Pulmonary hemorrhage, Respiratory failure, Salicylate intoxication, Sepsis, Shock, Toxic shock syndrome, Tumor lysis syndrome