ASRD DSA

Question 1

What measures can be taken to prevent the progression of ARDS and prevent morbidity and mortality?

Answer 1

• 1. Transferring to high level of care (ICU) sooner
• 2. ID predisposing syndromes
• 3. Initiate ICU measures.

Question 2

Acute respiratory distress syndrome can be distinguished from other causes of respiratory distress by a(n) __________

Answer 2

Inciting event

Question 3

The Berlin Definition of Acute Respiratory Distress Syndromes (ARDS)

• Timing
• Chest imaging
• Oxygenation
  
  • Mild
  • Moderate
  • Secere

Answer 3

Timing: within 7 days of precipitating cause or onset of new/worsening respiratory symptoms

Chest imaging: Bilateral diffuse airway infiltrates that cannot be explained by anything else (cardiac failure or volume overload). If predisposing cause is not present, run echo to exclude hydrostatic edema

Oxygenation:

• Mild: PaO2 (less than or equal to 300) with PEEP or CPAP greater than or equal to 5cm H20
• Moderate: PaO2 (less than or equal to 200) with PEEP greater than or equal to 5cm H20
• Severe: PaO2 (less than or equal to 100) with PEEP greater than or equal to 5cm H20

Question 4

The hypoxia that occurs in the acute respiratory distress syndrome (ARDS) is a result of

Answer 4

Ventilation-perfusion mismatch

Question 5

What are the most common causes of ARDS?

Answer 5

Pulmonary and nonpulmonary sepsis

Question 6

How do we differentiate ARDS from other causes of respiratory diseases that cause hypoexemia?

Answer 6

ID inciting event.

Question 7

How long does it take from for the inciting event to cause ARDS?

Answer 7

3-5 days

Question 8

What can patients with ARDS experience that is EXTREMLY worrisome and if noticed, needs medical attention.

Answer 8

• Hypercapnia (high CO2) in the face of tachypnea.

Question 9

What are common predispoing causes of ARDS that involve DIRECT injury to the lungs?

Answer 9

• 1. Pneumonia
• 2. Gastric aspiration
• 3. Chest trauma/lung contusion
• 4. Inhalation injury
• 5. Near drowning

Question 10

What are common predispoing causes of ARDS that involve INDIRECT injury to the lungs?

Answer 10

1. Nonpulmonary sepsis
2. Acute pancreatitis
3. Severe nonchest trauma
4. Blood transfusions
5. Surface burns

Question 11

In ARDS, as hypoxemia requires higher amounts of inspired supplimental O2, what does this suggest?

Answer 11

Evolving acute lung injury with worsening ventilation-perfusion (V/Q) mismatching and worsening shunt physiology.

Question 12

When should we give a patient with ARDS endotracheal intubation?

Answer 12

1. Altered mental status
2. Hypercapnia

Question 13

As ARDS worsens, what changes do we see on chest radiography?

Answer 13

Patchy infiltrates become more confluent

Question 14

In general, how does ARDS cause acute respiratory failure?

Answer 14

• 1. Increase in permeability d/t direct injury or inflammation
• 2. Decrease lung compliance that fucks up gas exchange.

Question 15

If we think the patient has coexistant or predomina,nt HF what tests should we run to rule other causes and confirm diagnosis of ARDS?

Answer 15

• 1. Echo
• 2. CT
• 3. Pulmonary artery catherization

Question 16

The pathophysiology of ARDS involves 2 stages: exudative stage and proliferative stage. Describe the exudative stage.

Answer 16

• Exudative stage: Predisposing injury damages the aveolar-capillary barrier, causing it to loose its ability to limit fluid, proteins and debris from vascular space,
  
  • Type 1 pneumocytes support alveoli and fluid/solute transport through aquaporin 5 protein.
  • Type 2 pneumocytes can differentiate into type 1 and make surfactant
• Injury to type 1 disrupts barrier in acute exudative phase.
• Injury to type 2 => atelectasis and worse compliance.
• Forms a proteinaceous edema by moving fluid from plasma space => institial sub-compartment.
  
  • Worsening V/Q mismatch
  • Physiologic shunt

Question 17

In the early phase of ARDS, what dominates the clinical picture?

Answer 17

• 1. Shunting
• 2. Hypoxemia

Question 18

How does atelectasis affect the lungs in ARDS?

Answer 18

Requires higher pressures to maintain alveoli so that we can breathe.

Question 19

What worsens dead space ventilation?

Answer 19

• 1. Increase in pulmonary arterial pressure d/t hypoexmia causing pulmonary a vasoconstriction
• 2. Decrease in pulmonary circulation d/t microthrombi
• Both worsen dead space ventilation and cause increase work of breathing.

Question 20

The pathophysiology of ARDS involves 2 stages: exudative stage and proliferative stage. Describe the proliferative stage.

Answer 20

• Proliferative stage: Type 2 pneumocytes regnerate surfactant and type 1 rebuild epithelium.
  
  • If repair goes well: recover from ARDS in 7-21 days.
  • If procollagen 3 is depostited in interstitial space + fibrosis => increase risk for morbidity and mortality => pt needs prolonged mechanical ventiliation.
• -As vascular changes that occur in phase 1 becomes irreversible => pulmonary HTN occurs.

Question 21

How do we diagnose ARDS?

Answer 21

Based on clinical criteria and exlusion of other diseases.

Question 22

What can our differentials be for a patient that presents with ARDS?

Answer 22

Acute infectious pneumonias. like:

1. Pneumocytis jivoveci pneumonia
2. Community acquired bacterial pneumonia

Similar CXR and refractory hyoxemia, but without cellular toxicity.

These can also cause ARDS

Question 23

Patients with ARDS have to work harder to breathe and ventilate.

How do we often fix hypoxemia?

Answer 23

• Invasive mechanical ventilation.
• Non-invase methods only fix the problem temporarily.

Question 24

How does mechanical ventilation work?

Answer 24

• Makes it easier to breath by easing resp muscles and improving effective minute ventilation.
  
  • ​CO2 decreases and acid-base levels are restored.

Question 25

What is a downside of **mechanical ventillators?**

Answer 25

* Lungs are vulnerable to **postive pressure,** esp: * atelectic parts: can overstretch * alveoli can excessively close during expiration

Question 26

What strategy is used to improve survival from **ARDS** and **prevent ventilator associated lung injury**?

Answer 26

**_Low tidal volume ventilation._**

Question 27

What is used as a **rescue therapy** in patients with **_refractory_ hypoxemia?**

Answer 27

* **High-frequency oscillatory ventilation (HFOV)** * Has **high RR** with **very small tidal volumes**

Question 28

What are nonventilatory strategies to treat ARDS?

Answer 28

* 1. **Conservative fluid management;** reduces number of days on ventalator and ICU * 2. No pharmcotherapy has been ID'd * 3. Corticosteroids are not benefit * 4. **Extracorporeal membrane oxygenation (ECMO) c**an help w hypoxemia w/o injurous ventilator

Question 29

What preventative measures should be taken to prevent ICU-related complications in patients with **ARDS**?

Answer 29

* 1. **Prophalyxis** against stress ulcers, bleeding, DVT * 2. **Raise head 30 degrees** to prevent ventilatory-assx pneumonia * **3. Screen daily to free from ventilator**

Question 30

What is the best predictor of outcome as we employ ventilator techniques?

Answer 30

**Berlin definition of hypoxia**

Question 31

Patients that do not have lower O2 requirements by day 7 have what outcomes?

Answer 31

* **1. Longer time in ICU** * **2. Increase risk for long-term ventilator dependency** * **3. Longer recovery**

Question 32

What are managment strategies of ARDS?

Answer 32

* 1. Low tidal volume (6 cc/kg tidal volume) * 2. Prone ventilation 16 hrs a day * 3. Manage fluids * 4. Central venous catheter directed fluid management Not corticosteroids or pulmonary artery catheterization.

Question 33

Survival of ARDS depends on what

Answer 33

patient population and where investigation occured.

Question 34

What are complications in those who survive ARDS?

Answer 34

* **Few respiratory system problems** * **Lung fx goes back to nL** * Most have **funtional limitation** d.t weak muscle and fatigue