Oxygenation

Question 0

What are the causes of hypoxemia?

Answer 0

• hypoventilation
• v/q mismatch
• diffusion defect
• shunt

Question 1

What are the types of hypoxia?

Answer 1

• hypoxemia (low PaO2)
• anemic (low hb)
• circulatory (poor perfusion, dec cmo)
• histotoxic (cyanide poisoning)

Question 2

What does oxygen delivery depend on?

Answer 2

• FIO2
• CaO2
• CMO

Question 3

To avoid oxygen toxicity, what should you keep the FIO2 at?

Answer 3

Under 60%

Question 4

What are the strategies to improve oxygenation?

Answer 4

• increase FIO2
• improve ventilation and reduce Vd
• assess hb
• peep/cpap
• improve circulation

Question 5

What is a good rule of thumb for expected PaO2?

Answer 5

FIO2 x 5

Question 6

What should the A-a gradient be?

Answer 6

< or = to 20

Question 7

For COPD patients, what should you keep the PaO2 at and why?

Answer 7

50-60 torr or you take away the drive to breathe

Question 8

What should you keep the PaO2 at for normal patients?

Answer 8

60-90 torr

Question 9

What kind of relationship is there between PaO2 and FIO2?

Answer 9

Linear

Question 10

What is the equation for finding the appropriate FIO2?

Answer 10

PaO2 known = PaO2 desired
————— —————-
FIO2 known FIO2 desired

Question 11

What is a normal P/F ratio?

Answer 11

500

Question 12

What should you adjust your FIO2 to before adding peep?

Answer 12

60

Question 13

How much peep should you come down to before coming down on the FIO2?

Answer 13

5

Question 14

How much of an increase in CO2 will result in how much of a decrease in O2?

Answer 14

Increase in CO2 by 1mmhg will decrease O2 by 1.25mmhg

Question 15

Excessively high FIO2 will result in the formation of what free oxygen radicals?

Answer 15

• superoxide
• hydrogen peroxide
• hydroxyl groups

Question 16

Excessively high FIO2 causes inflammatory response of the lung causing what?

Answer 16

• alveolar capillary membrane injury

- pulmonary edema

Question 17

What kind of oxygenation issue does not respond to oxygen?

Answer 17

Shunt

Question 18

What are increased shunt fraction conditions?

Answer 18

• atelectasis
• pulmonary edema
• pneumonia
• pneumothorax
• complete airway obstruction

Question 19

What is atelectasis?

Answer 19

• shrunken airless state

- blockage of air passages, shallow breathing or surfactant deficiency

Question 20

What is helpful with treating atelectasis?

Answer 20

Peep (can rein flare alveoli)

Question 21

What worsens are the % shunt increases?

Answer 21

Hypoxemia

Question 22

An increase in mean airway pressure (paw) can increase what?

Answer 22

PaO2

Question 23

What does mean airway pressure affect?

Answer 23

Mean alveolar pressure and alveolar recruitment, therefore affecting oxygenation

Question 24

What else can increase mean airway pressure?

Answer 24

• peep
• hfov
• aprv

Question 25

What is the 50/50 rule?

Answer 25

If you can’t keep a PaO2 of 50 on 50% FIO2 then consider peep

Question 26

How does peep treat ARDS?

Answer 26

• improves oxygen transfer

- protective effect by preventing repetitive collapse and reinflation of alveoli

Question 27

What else responds to peep?

Answer 27

Refractory hypoxemia

Question 28

What are the goals of peep?

Answer 28

• enhance oxygenation
• maintain PaO2>60, SpO2>90 at acceptable ph
• recruit and maintain alveoli
• reduce FRC, shunting and FIO2 to safe level
• cardiac tamponade
• compliance varies

Question 29

How does peep affect compliance?

Answer 29

• decreases in normal lung

- increases in ARDS lung

Question 30

What happens to VD/VT as you add peep?

Answer 30

Ou

Question 31

Who are poor candidates for peep?

Answer 31

• unilateral or localized lung disorders
• highly compliant lungs
• head injuries

Question 32

How is cpap applied?

Answer 32

• mask cpap
• nasal cpap
• high flow oxygen

Question 33

What are flow resistors?

Answer 33

Create resistance to airflow during all of expiration. The diameter determines the peep/cpap. BAD.