Systemic Oxygenation

Question 0

What is the equation for Hb bound oxygen?

Answer 0

1.34 (O2 binding capacity of hemoglobin in ml) X Hb X SO2 (ml/DL)

Question 1

What is oxygen content?

Answer 1

The amount of oxygen that is Hb bound and dissolved in plasma

Question 2

What happens to oxygen solubility in plasma as the body temperature rises?

Answer 2

The oxygen solubility will decrease

Question 3

What is the equation for dissolved O2 in plasma?

Answer 3

0.003 X PO2

Question 4

What is the arterial O2 content (CaO2)?

Answer 4

CaO2 = (1.34 X Hb x SaO2) + 0.003 X PaO2

Question 5

What is normal arterial O2 content?

Answer 5

20 ml/DL

Question 6

What is normal venous o2 content?

Answer 6

15 ml/DL

Question 7

What is the O2 extracted for a normal person?

Answer 7

5 ml/DL or 50 ml/L

250 ml/min with a cardiac output of 5L/min

Question 8

What is DO2?

Answer 8

The rate of oxygen delivery

Question 9

What is the equation for DO2?

Answer 9

CO x CaO2 X 10

Question 10

What is normal DO2?

Answer 10

900-1100 ml/min

Question 11

What’s VO2?

Answer 11

The rate of O2 transport from the systemic capillaries to the tissues

Question 12

What is the equation for VO2?

Answer 12

VO2 = CO X (CaO2-CvO2) X 10

Question 13

What is the VO2 in healthy patients?

Answer 13

200-300 ml/ min

Question 14

What does DO2 depend on?

Answer 14

Cardiac output

Oxygen content of the blood (Hb concentration and O2 sat)

Question 15

What does VO2 depend on?

Answer 15

Cardiac output
o2 sat
SvO2
Hb concentration

Question 16

What is whole body VO2?

Answer 16

Accounts for O2 uptake in the lungs

VO2 = VE X (FiO2-FeO2)

Question 17

What is the normal O2 consumption of the lungs?

Answer 17

Less than 5%

Question 18

What are the two conditions associated with low VO2?

Answer 18

1. Decreased metabolism

2. Inadequate tissue oxygenation

Question 19

What is oxygen debt?

Answer 19

The cumulative deficit in tissue oxygenation

Question 20

What lab value correlates with a low VO2?

Answer 20

Lactate levels (begin to rise after 6 hours lag time)

Question 21

What is the oxygen extraction ratio?

Answer 21

O2ER = VO2/DO2
Or
O2ER = (SaO2 - SvO2)/SaO2

Question 22

What is normal O2ER?

Answer 22

.25

Question 23

What is the equation for the control of VO2?

Answer 23

VO2 = DO2 X O2ER

Question 24

What is the point at which VO2 begins to decrease?

Answer 24

When O2 extraction is maximal at 50%

Question 25

How is SaO2 monitored?

Answer 25

By pulse oximetry

Question 26

How is SvO2 monitored?

Answer 26

By the pulmonary artery catheter

Question 27

What is normal SaO2-SvO2 or oxygen extraction?

Answer 27

20-30%

Question 28

What does an increase in the oxygen extraction above 30% indicate?

Answer 28

A decrease in O2 delivery

Question 29

What does an increase in O2 extraction that approaches 50% indicate?

Answer 29

Inadequate tissue oxygenation

Question 30

What does a decrease in oxygen saturation below 20% mean?

Answer 30

A defect in O2 utilization (usually sepsis)

Question 31

What is the simplified equation for O2 extraction?

Answer 31

1 - SvO2

Question 32

What is the equation for SvO2 (mixed venous oxygen saturation?

Answer 32

SvO2 = SaO2 -(VO2/ CO X 1.34 X Hb)

Question 33

What is the simplified equation of SvO2 is the arterial blood is fully saturated?

Answer 33

SvO2 = 1 - VO2/DO2

Question 34

What is the normal range for SvO2?

Answer 34

65-75%

Question 35

A change in SvO2 is only significant when....

Answer 35

It changes by more than 5% and lasts longer than 10 minutes

Question 36

What does a decrease in SVO2 mean?

Answer 36

There is a decrease in oxygen delivery (cardiac output or anemia)

Question 37

What does an increase in SvO2 mean?

Answer 37

A defect in O2 utilization

Question 38

What is the normal range for central venous oxygen saturation?

Answer 38

70-89%

Question 39

How is central venous oxygen saturation monitored?

Answer 39

By a central line in the SVC

Question 40

What are the oxygen markers for impaired tissue oxygenation?

Answer 40

VO2 less than 200 ml/min or 110 ml/m2/min SaO2 - SvO2 approaching 50% SvO2 less than 50%

Question 41

What are the chemical markers of impaired tissue oxygenation?

Answer 41

Lactate over 2 mM/l | Base deficit over 2

Question 42

How is lactate used for prognosis?

Answer 42

1. The initial value of lactate | 2. The amount of time is takes to return to normal

Question 43

What is the mechanism of lactate accumulation in sepsis?

Answer 43

Inhibition of pyruvate dehydrogenase which inhibits the movement from glycolysis to the Krebs cycle in mitochondria and therefore o2 utilization

Question 44

What is arterial base deficit?

Answer 44

The amount of base that must be added to one liter of blood to raise the ph to 7.4

Question 45

What is a normal arterial base deficit?

Answer 45

Less than 2