ARDS

Question 1

A patient presents with severe dyspnea, bilateral infiltrates on chest X-ray, and PaO2/FiO2 ratio of 180. What diagnosis does this suggest?

Answer 1

Acute Respiratory Distress Syndrome (ARDS), moderate severity.

Question 2

In ARDS, what histologic change is characteristic of the exudative phase within the first 7 days?

Answer 2

Hyaline membrane formation due to alveolar capillary injury and edema.

Question 3

A patient with sepsis develops ARDS. What would you expect on chest X-ray and PCWP?

Answer 3

Diffuse bilateral infiltrates; PCWP ≤18 mmHg.

Question 4

What gas exchange abnormality defines ARDS and is often refractory to oxygen therapy?

Answer 4

Hypoxemia due to intrapulmonary shunting and poor V/Q matching.

Question 5

How does prone positioning improve oxygenation in ARDS patients?

Answer 5

By recruiting dorsal alveoli and improving ventilation-perfusion matching.

Question 6

What ventilator strategy is recommended to reduce mortality in ARDS?

Answer 6

Low tidal volume ventilation (6 mL/kg of predicted body weight).

Question 7

Why is PEEP used in the ventilator management of ARDS?

Answer 7

To prevent alveolar collapse and maintain oxygenation.

Question 8

What are three phases of ARDS in terms of pathology and timing?

Answer 8

Exudative (0-7 days), Proliferative (7-21 days), Fibrotic (>21 days).

Question 9

What distinguishes ARDS from cardiogenic pulmonary edema on imaging?

Answer 9

ARDS shows peripheral infiltrates with no cardiomegaly or pleural effusion.

Question 10

A patient with ARDS has a PEEP of 12 and compliance < 40 mL/cmH2O. What does this indicate?

Answer 10

Severe lung injury with reduced lung compliance.