Acute Respiratoty Distress syndrome

1. ARDS
Acute Respiratory distress Syndrome

2. Introduction
• ALI or ARDS was first described by Ashbaugh and
Petty in 1967
• 1994 AECC (American European Consensus
conference ) definition became globally accepted,
but had limitations
• The current definition is the ‘Berlin Definition’
published in 2013
• Created by a consensus panel of experts
• European Society of Intensive Care Medicine
endorsed by the American Thoracic Society and
the Society of Critical Care Medicine

3. Berlin definition
• ARDS is an acute diffuse, inflammatory lung
injury, leading to increased pulmonary
vascular permeability, increased lung weight,
and loss of aerated lung tissue…[with]
hypoxemia and bilateral radiographic
opacities, associated with increased venous
admixture, increased physiological dead space
and decreased lung compliance

4. Risk factors
• Bacteremia
• Sepsis
• Trauma, with or without pulmonary contusion
• Fractures, particularly multiple fractures and long bone
fractures
• Burns
• Massive transfusion
• Pneumonia
• Aspiration
• Drug overdose
• Near drowning
• Postperfusion injury after cardiopulmonary bypass
• Pancreatitis
• Fat embolism

5. Pathophysiology
• Initial "exudative" stage-diffuse alveolar damage
within the first week
• “Proliferative" stage-resolution of pulmonary
edema, proliferation of type II alveolar cells,
squamous metaplasia, and early deposition of
collagen.
• Some patients progress to a third "fibrotic" stage,
characterized by obliteration of normal lung
architecture, diffuse fibrosis, and cyst formation

7. Clinical features
The defining features of ARDS are:
1. Severe refractory (resistant to treatment)
hypoxemia
2. Presence of pulmonary oedema with normal
hydrostatic pressure in the pulmonary
vasculature
3. Appearance of diffuse bilateral pulmonary
infiltrates on chest X-ray
4. Falling pulmonary compliance (<50 mL/cmH2O).

8. Clinical features
• Increased breathlessness
• Tachypnea
• Hypoxemia
• Patients struggle to breathe through lungs
that feel like a wet sponge

9. Investigations
• ABG analysis – PaO2 decreased 60 mmHg
– PaCO2 initially normal than later increased
• PFT – FRC, VC, VT reduced
• Chest X ray – symmetrical bilateral and diffuse
snowstorm infiltrates
• CT scan – opacities of atelectasis
• Auscultation – rales more common, some time wheeze

12. Management
• Treatment divided in four areas, they are
1. Treat the cause of ARDS
2. Treatment for hypoxemia
3. Supporting treatment like nutritional
4. Prevent and treat complications

13. Management
• Treat the cause of ARDS
– Based on cause treat the root cause of ARDS
• Treatment for hypoxemia
– Support adequate gas exchange and tissue
oxygenation
– Ventilator with PEEP
• Supporting treatment
– Management of patient nutritional status and fluid
balance
– Management of input and output

14. Management
• Prevent and treat complications
– Common complication are:
– Nosocomial infections
– Barotrauma
– Coagulation disturbances

15. Pharmacology
• Surfactant replacement therapy
• Inhaled B2-agonists which may improve lung
compliance (Moriiia, 1997)
• Steroids are sometimes given In the later
stages but tend to encourage infection in
critically ill patients (Bass et ai., 1997)