ARDS - clinical approach

Question 1

Define ARDS

Answer 1

alveolar damage –> impaired oxygenation & non-compliant lungs —> severe hypoxemia

Question 2

ARDS presentation

Answer 2

1. involvement of both lungs
2. event (illness; COVID) leads to develops w/in 2-7 days
3. severe dyspnea

Question 3

mortality rate of ARDS

Answer 3

25-45%

Question 4

sx of hypoxemia (4)

Answer 4

1. confusion
2. SOB
3. tachycardia
4. blue nail beds, lips

Question 5

pathophysiology of ARDS

Answer 5

flooding of alveoli w/proteins, fibrin which decreases oxygen exchange space & collapse of alveoli

alveoli is the problem

Question 6

Dx? Why?

Answer 6

ARDS: not milliary like TB, its more “fluffy”

Question 7

ARDS criteria dx (4)

Answer 7

1. 2-7 days
2. bilateral airspace opacities
3. PaO2 < 300 mm Hg
4. not explained by HF or volume overload

Question 8

MC causes of ARDS (5)

Answer 8

1. sepsis
2. pneumonia
3. COVID-19
4. Drug OD
5. pancreatitis

Question 9

ARDS signs (5)

Answer 9

1. accessory msk use
2. tachypnea
3. cyanosis (impaired gas exchange)
4. confusion
5. acidosis

Question 10

ARDS physical exam findings (2)

Answer 10

1. crackles
2. pulmonary HTN

Question 11

ARDS xray findings

Answer 11

patchy bilateral infiltrates –> rapidly become confluent
(heart size normal)

Question 12

ARDS ddx

Answer 12

cardiogenic pulmonary edema (comes from LV)

back pressure hydrostatic forces

Question 13

How do you r/o cardiogenic pulmonary edema (3)?

Answer 13

1. US inferior vena cava
2. echo: measure EF
3. BNP or NT-proBNP

Question 14

ARDS management (2)

Answer 14

1. treat trigger (COVID)
2. restore O2

Question 15

How do you restore O2 in ARDS (4)?

Answer 15

1. higher FiO2
2. recruit atelectatic alveoli
3. avoid barotrauma
4. tx inflammatory response

Question 16

Goals of O2 sat in ARDS

Answer 16

1. PaO2 > 55-80 mmHg
2. SpO2 > 88-95%

Question 17

How to increase FiO2 (3)

Answer 17

1. low flow O2: nasal cannula or non-rebreather masks
2. BPAP or CPAP
3. High Flow Nasal Cannula
4. mechanical ventilation

Question 18

Which tx delivers 100% FiO2?

Answer 18

1. mechanical ventilation (decreases work of breathing, increases PEEP)
2. prone patient up 12-18 hours per day

Question 19

How do you recruit alveoli in ARDS?

Answer 19

mechanical vent provides end-expiratory pressure to keep alveoli open (they collapse due to lack of surfactant

Question 20

How do you avoid oxygen toxicity in ARDS management?

Answer 20

FIO2 >0.5 for 10 or more hours
(formation of oxygen free radicals damages alveolar epithelium)

Question 21

How do you avoid barotrauma in ARDS management?

(overinflating the alveoli)

Answer 21

Plateau pressure (Pplat) < 30 cm H2O

(Pplat= pressure in airways 0.5 sec after inspiration)

Question 22

permissive pressure (3)

Answer 22

1. vent brings TV from 10-12 ml/KG to 4-8 ml/KG –> lowers Pplat
2. pH > 7.2
3. CO2 between 45-80mmHg

Question 23

Should anemia in ARDS be transfused?

Answer 23

not unless they are actively bleeding bc it can cause an immune response

Question 24

How do you downregulate the immune response in ARDS (2)?

Answer 24

1. glucocorticoids (not if on vent)
2. monoclonal Ab for IL-6 (tocilizumab)