Sketchy Path: Acute Respiratory Distress Syndrome

Question 1

ARDS is also known as _______________.

Answer 1

acute lung injury

Question 2

The most common cause of pulmonary edema is ________________.

Answer 2

left-sided heart failure (like the floppy heart balloon next to the swimmer with the pulmonary edema life vest)

Question 3

The fluid that leaks into the interstitium in cardiogenic pulmonary edema is ______________.

Answer 3

transudate (like the TRANSatlantic ship sunk near the kid with the floppy heart balloon)

Question 4

In addition to CHF, list two other causes of cardiogenic (i.e., increased post-capillary wedge pressure) pulmonary edema.

Answer 4

• Valvular disease (like the stenotic clam representing mitral stenosis and the bicuspid clam representing bicuspid aortic valves that turn calcific)
• Volume overload (like the tank that has a wave overloading the max fill line)

Question 5

What is Sketchy’s recurring symbol for exudate?

Answer 5

An emergency EXiT sign (like the one by the guy climbing the broken capillary pipe, causing spillage)

Question 6

Review the etiologies of ARDS.

Answer 6

• Infection/pneumonia (like the vintage diver with rusted chest plates)
• Gastric aspiration (like the shark with vomit on his chin)
• Sepsis (like the bag of septic fish carcasses)
• Fat emboli (like the other shark biting the femur and releasing bone marrow)
• Pancreatitis (like the pancreas sea sponge)
• Blood transfusions, called transfusion-associated lung injury or TRALI (like the train car TRALI going by the ARDS tank)

Question 7

Describe the pathophysiology of ARDS.

Answer 7

Cytokines responding to some insult (reviewed in another card) lead to a massive neutrophil respond with proteases damaging the capillary epithelium and the vascular endothelium.

(Think of the cyto-coins near the first responders on the cracked epithelium floor.)

Question 8

Destruction to the capillary epithelium results in ________________.

Answer 8

atelectasis because of the destruction of type II pneumocytes (like the anemones closing above the cracked epithelium floor)

Question 9

The hyaline membranes are composed of ________________.

Answer 9

exudate mixed with cell debris

Question 10

ARDS often presents with what timeline criteria?

Answer 10

Hours to days after the initial problem

Think of ARDS when you have a patient who had some infection/trauma/metabolic derangement who gets suddenly worse on day two or three of their hospital admission.

(This is represented by the “DELAYED” sign on the shark tank.)

Question 11

Describe the patient presentation of ARDS.

Answer 11

• Cyanosis (blue guy in tank)
• Tachypnea
• Accessory muscle use
• Bilateral crackles on auscultation (like the bilateral bubbles coming out of the snorkel mask)
• White out on CXR (like the white life vest)

Question 12

List the three phases of ARDS.

Answer 12

1) Exudative phase (caused by the sudden epithelial/endothelial damage and resultant hyaline membranes)
2) Proliferative phase (when the type II pneumocytes differentiate into type I pneumocytes)
3) Fibrotic phase (occurs sometimes when the type II pneumocytes deposit excess collagen into the alveoli)

(Think of the exudative anemones, the proliferating tile on the floor, and the fibrotic lungs in the tank with the collagen sharks.)

Question 13

In order to diagnose ARDS, you need to rule out cardiogenic pulmonary edema. How can you do this?

Answer 13

• Physical exam will show normal heart sounds in ARDS and S3 or S4 in cardiogenic PE.
• JVD, hepatomegaly, and peripheral edema should be absent in ARDS.
• BNP should be normal in ARDS.