Oxygen and CO2 Transport

Question 1

What does a rightward shift in the oxygen dissociation curve represent?

Answer 1

increased oxygen off loading

Question 2

What causes increased oxygen offloading?

Answer 2

• increased PCO2
• increase temperature
• increase [H+]
• increased 2,3 diphosphoglycerate due to hypoxia

Question 3

How do you calculate oxygen delivery?

Answer 3

minute DO2 = minute Q x CaO2

- minute DO2: volume of O2 delivery in one minute

Question 4

What is oxygen carrying capacity (CaO2)?

Answer 4

maximum oxygen that can be carried by a particular amount of hemoglobin

Question 5

how do you calculate oxygen carrying capacity (CaO2)?

Answer 5

CaO2 = SaO2 x [Hb] x 1.39 mL O2/gm Hb

Question 6

How do you calculate oxygen consumption?

Answer 6

minute Vo2 = minute Q x (Sa02 - SvO2) x [Hb] x 1.39 mL O2/gm Hb

Question 7

What is the definition of hypoxemia is reaction to torr pressures at sea level and denver?

Answer 7

PaO2

Question 8

What are 3 cause of hypoxia?

Answer 8

• Low Q (CO)
• Low SaO2 associated with low PaO2
• Delivery problems (low Hb or CO poisoning)

Question 9

What is the enzyme involved in transition of CO2 and H20 to carbonic acid?

Answer 9

Carbonic anhydrase located in RBCs

Question 10

What is the Bohr effect?

Answer 10

Binding of CO2 to allosteric locations on hemoglobin reduces hemoglobin affinity for O2

Question 11

What is the Haldane effect?

Answer 11

Binding of O2 to hemoglobin reduces CO2 affinity for hemoglobin

Question 12

How do you measures someones PaO2?

Answer 12

Directly measure with blood gas

Question 13

How to you measure PAO2?

Answer 13

estimated from PaCO2 through:

• PACO2 = PaCO2
• Alveolar gas equation

Question 14

What is the A-a gradient?

Answer 14

Difference in PAO2 and PaO2

nl is less than 20 torr gradient

Question 15

What happens to PaO2, SaO2, PaCO2, and A-a gradient in low PIO2 (high altitude)? And what are special tests for this condition.

Answer 15

• PaO2 decreases
• SaO2 decreases
• PaCO2 decreases
• A-a gradient is normal
  Special tests are to measure the PaCO2

Question 16

What happens to PaO2, SaO2, PaCO2, and A-a gradient in low PAO2 (hypoventilation)? What are special tests?

Answer 16

• PaO2 decreases
• SaO2 decreases
• PaCO2 increases
  -A-a gradient is normal
  Special tests are to measure PaCO2

Question 17

What happens to PaO2, SaO2, PaCO2, and A-a gradient in diffusion problem (interstitial lung disease)?

Answer 17

• PaO2 decreases
• SaO2 decreases
• PaCO2 normal
  -A-a gradient increases
  Special tests are CO single breath test

Question 18

What happens to PaO2, SaO2, PaCO2, and A-a gradient in V/Q mismatch (moderate COPD)

Answer 18

• PaO2 decreases
• SaO2 decreases
• PaCO2 normal
• A-a gradient increases

Question 19

What happens to PaO2, SaO2, PaCO2, and A-a gradient in shunt (pneumonia)?

Answer 19

• PaO2 decreases
• SaO2 decreases
• PaCO2 normal
• A-a gradient increases

Question 20

how test can you use to differentiate between a high and low V/Q mismatch?

Answer 20

use 100% oxygen to see if ventilation problem or perfusion problem