Acute Respiratory Distress Syndrome (ARDS)

Question 1

ARDS is a condition characterized by appearance of _ on histology and _ on chest x-ray

Answer 1

ARDS is a condition characterized by appearance of hyaline cartilage on histology and “white out” on chest x-ray

Question 2

ARDS is a cascade of events that ultimately occurs due to _

Answer 2

ARDS is a cascade of events that ultimately occurs due to damage to the alveolar-capillary interface

Question 3

Explain the pathogenesis of ARDS

Answer 3

1. Type I pneumocyte injury
2. Release of DAMPs (damage-associated molecular patterns)
3. Macrophages ingest these DAMPs and release cytokines
4. Cytokines recruit neutrophils to come and and drive the exudative phase
5. Neutrophils release granules like ROS and proteases; increases alveolar membrane permeability
6. Neutrophil extravasation has also increased capillary permeability
7. Now exudate (fluid + proteins) can move from the blood into the alveoli
8. Hyaline formation

Question 4

ARDS must occur within _ time from a known injury to the lungs

Answer 4

ARDS must occur within 1 week from a known injury to the lungs
* Sepsis (indirect via inflammatory mediators circulating the blood)
* Pancreatitis (indirect)
* Pneumonia
* Gastric acid secretion
* Trauma

Question 5

The exudative phase of ARDS is characterized by (dead space/shunt)

Answer 5

The exudative phase of ARDS is characterized by increased shunting
* Hyaline deposits disrupts surfactant –> atelectasis

Question 6

Following the exudative phase of ARDS, comes the _ phase (1-2 weeks)

Answer 6

Following the exudative phase of ARDS, comes the proliferative phase (1-2 weeks)
* Proliferation of type II pneumocytes
* Fibroblast activity

Question 7

The third phase of ARDS is _

Answer 7

The third phase of ARDS is fibrotic
* Fibrosis and scarring will proceed in patients with very severe ARDS

Question 8

Treatment of ARDS usually involves mechanical ventilation with _

Answer 8

Treatment of ARDS usually involves mechanical ventilation with positive end expiratory pressure