Anemia

Question 1

What does a oxyhemoglobin dissociation curve explain?

Answer 1

Explains affinity that Hgb has for O2

Question 2

If the oxyhemoglobin dissociation curve shifts to the right… what does it mean?

Answer 2

Easier to free O2 from hemoglobin to the capillaries more than it hinders O2 uptake in the lungs

Question 3

If the oxyhemoglobin dissociation curve shifts to the left… what does it mean?

Answer 3

Harder to free O2 from hemoglobin

Question 4

What causes a shift to the right on the oxyhemoglobin dissociation curve?

Answer 4

• Temperature is increased
• CO2 is increased
• Acidity is increased (pH decreased)
• Concentration of 2,3 DPG is increased

Question 5

What causes a shift to the left on the oxyhemoglobin dissociation curve?

Answer 5

• Temperature is decreased
• CO2 is decreased
• Acidity is decreased (pH increased)
• Concentration of 2,3 DPG is decreased

Question 6

What does it mean if overall PaO2 and SaO2 decrease?

Answer 6

it is relatively easier for the oxygen that remains in the blood to be transferred to the tissues

Question 7

At rest, average tissue O2 extraction ((a-v)O2 difference) is about ___%

Answer 7

25%

Question 8

VO2 in the tissues will drop when oxygen delivery or extraction is low enough to cause the tissues to shift to (aerobic/anaerobic) metabolism

Answer 8

anaerobic metabolism

Question 9

(true/false) There’s a lag of several hours between the time that tissue VO2 drops, and lactate levels rise, in critically ill patients.

Answer 9

true

Question 10

When cardiac output is decreased or when a person is anemic, (a-v)O2 difference can exceed ____%.

Answer 10

30%

Question 11

Oxygen extraction at the tissue level up to about 50% still allows unchanged VO2; beyond this, the tissues become ____ (with an increase in lactic acid production, other waste products).

Answer 11

hypoxic

Question 12

At rest, an increase in (a-v)O2 difference above 50% occurs with a Hct of 10% or less- that’s a Hgb of about ___ g/dL

Answer 12

4 g/dL

Question 13

What does a decrease in Hgb cause?

Answer 13

• decrease blood viscosity
• tissues increasing O2 extraction to maintain a constant VO2

Question 14

With a decrease in viscosity (related to a decreased Hgb), flow can, and at least initially does, (decrease/increase)

Answer 14

increase

–> has to (at higher workloads) to meet the oxygen demands of the tissues.

Question 15

Studies have shown that an initial blood lactate level >___ mM/L in critically ill patients correlates with a high likelihood of death

Answer 15

> 4 mM/L

Question 16

Additionally, patients whose lactate levels normalized in <___ hours had better outcomes than those whose did not.

Answer 16

< 24 hours

Question 17

(true/false) Lactate is good as a marker.

Answer 17

FALSE (only good as a substance)

–> In critically ill patients, there is evidence that the body uses lactate as a fuel.
- Same caloric density as glucose
- Cardiac lactate oxidation is increased in patients with septic shock
- Neuronal tissue suffering from hypoxia and ischemia oxidize lactate as well

Question 18

(true/false) It has been proven that serum Hgb, by itself, is NOT a good representative of tissue oxygenation.

Answer 18

true

Question 19

What is PaO2 values useful for?

Answer 19

examining gas exchange in the lungs

–> NOT for evaluating blood oxygenation

Question 20

What does PRBC transfusions place the patient at an increased risk for?

Answer 20

• Hemolytic and non-hemolytic reactions
• Urticaria and anaphylactic shock
• TRALI (transfusion-related acute lung injury)

Question 21

17/18 studies showed that receiving a PRBC transfusion was an independent risk factor for _____.

Answer 21

death

–> Fatal outcome was 70% higher in patients who received PRBC transfusion than in those without transfusion.