1. Acute Respiratory Distress Syndrome
ARDS

2. Overview
• Previously called Adult Respiratory Distress Syndrome
• Defined in 1994 American-European Consensus
Conference on ARDS:
• Most sever Acute Lung Injury
• Diffuse alveolar damage
• Severe hypoxemia (PaO2/FIO2 < 200)
• Bilateral pulmonary infiltrates
• Absence of cardiogenic pulmonary edema (PCWP <18
mmHg)

3. Epidemiology
• 75 cases/ 100,000 population
• Can occur at any age
• Risks
• advanced age
• No sex preference
• female sex (only in trauma)
• cigarette smoking
• alcohol use.
• High APACHE score (any underlying cause)

4. Pathophysiology
• Diffuse alveolar damage
• Increased permeability
• Damage to alveolar or capillary endothelium
• Inflammation (cytokines, leukotrienes, TNF)
• Increased neutrophils ? Reactive
• Severe pulmonary shunting  hypoxemia
• Pulmonary hypertension

5. Causative Insults
• Sepsis • Aspiration
• Trauma • Drug overdose
• Fractures • Near drowning
• Burns • Cardiopulmonary
• Massive bypass
transfusion • Pancreatitis
• Pneumonia • Fat embolism

6. Presentation
• Acute dyspnea and hypoxemia
• within hours to days of an inciting event
• Critically ill
• Dyspnea, rapidly progressing
• Tachypnea
• Agitation
• Increasing O2 demands
• Often multisystem organ failure

7. Physical Exam
• Unspecific
• Tachypnea
• Tachycardia
• Cyanosis
• Rales
• Sepsis
• Hypotension
• Peripheral vasoconstriction
• Manifestation of the underlying cause
• i.e abdominal finding pancreatitis

8. Differential Diagnosis
• Pulmonary hemorrhage • Transfusion-related
• Near drowning acute lung injury (TRALI)
• Drug reaction • Acute eosinophilic
• Noncardiogenic pneumonia
pulmonary edema • Reperfusion injury
• Hamman-Rich • Leukemic infiltration
syndrome • Fat embolism syndrome
• Retinoic acid syndrome • Acute hypersensitivity
pneumonitis

9. Workup
• ABG
• Hypoxemia
• Respiratory alkalosis initially
• Respiratory Acidosis ( late)
• BNP- exclude cardiogenic pulmonary edema
• CXR diffuse bilateral infiltrates
• Echocardiogram
• Possible CT

10. Treatment
• Treatment is supportive + underlying cause
• No effective drug for prevention nor management
• Xigris
• Nitric Oxide
• Liquid surfactant
• New hopes
• Simvastatin
• TNF and interleukin antibodies

11. Treatment
• Fluid management
• Resuscitation vs. maintenance
• Negative fluid balance “dry side of normal”
• Ventilation
• Lung protective
• High PEEP ( , low TV ( 6 mL/kg)
• Neuromuscular block- improved 90 day survival
• ECMO- no improved survival
• Proning- no improve survival
• Nutrition
• Enteral, antioxidants, eicosapentaenoic acid, and gamma-linoleic acid

12. Prognosis
• Mortality
• Before 1990 , 40-70%
• Recent 30-40%
• Better understanding and treatment of sepsis.
• Increased in older patients
• Morbidity
• VAP
• Weight loss/muscle weakness
• Only 49% survivors return to work