Oxyhemoglobin Dissociation curve Flashcards Preview

► Med Misc 44 > Oxyhemoglobin Dissociation curve > Flashcards

Flashcards in Oxyhemoglobin Dissociation curve Deck (28)
1
Q

what is the P50

A

P50 is the partial pressure of O2 at which hemoglobin is 50% saturated by O2

2
Q

what is the normal value for P50?

A

26-28mmHg

3
Q

what SO2 corresponds to PO2 of 40 and 60

A

SPO2 90 = PaO2 60

SPO2 70 = PaO2 40

(start at SpO2 90 and PaO2 60 then go down by 10’s 80 is 50, 70 is 40, 60 is 30 so on)

4
Q

is the following normal for a mixed venous blood gas?

PO2 40mmHg and O2 sat 70%

A

yes

5
Q

ODC Graph:

just look and see it

A
6
Q

ODC Graph:

what part of the graph is the loading region? mark w/ blue

A
7
Q

ODC Graph:

what part of the graph is the unloading region? mark with yellow

A
8
Q

ODC Graph:

point out the P50

A
9
Q

ODC Graph:

show the PO2 if the O2 sat in 90 and 70

A

90 = 60

70 = 40

10
Q

what is the significance of the flat portion of the ODC?

A

it facilitates the loading of O2 by the blood, bc in the flat portion of this curve, large changes in the partial pressure of O2 in artial blood (PaO2) produce only small changes in Oxygen saturation (SaO2)

11
Q

what is the significance of the steep portion of the ODC?

A

it facilitates unloading of O2 at tissues b/c large amounts of O2 are unloaded from Hgb (large decrease in O2 sat) in response to small chages in the partial presuure of oxygen

12
Q

Shifts in the OCD:

where do you look to see if a shift occured?

A

P50 normal 26-28

13
Q

Shifts in the OCD:

is this a right or left shift

A

Left shift

14
Q

Shifts in the OCD:

is this a right or left shift

A

right shift

15
Q

Shifts in the OCD:

does the left or right shift havea GREATER affinity (hold on to) for oxygen?

A

Left shift

16
Q

Shifts in the OCD:

does a right or left shift have a lesser affinity ( give off) to oxygen

A

right shift

17
Q

Shifts in the OCD:

a P50 of what indicates left shift?

A
18
Q

Shifts in the OCD:

A P50 of what indocates a right shift?

A

P50 > 28 mmHg

19
Q

Shifts in the OCD:

what factors cause a left shift?

A
• Decreased temp
• Increased pH (alkolosis/ decreased H+ concentration)
• Decreased PcO2
• Decreased concentration of 2,3-DPG
• Fetal Hemoglobin (HbF)
• Carboxyhemoglobin (200xs affinity than O2)
• Methemoglobin
20
Q

Shifts in the OCD:

in general is a left shift increased or decreased metabolism

A

Decreased metabolism

21
Q

Shifts in the OCD:

what factors cause a right shift?

A
• Increased temp
• Decreased pH (acidosis, increased H+ concentration)
• Increased PcO2
• Increased 2,3-DPG
• Maternal Hb
• Sickle cell (Hbs)
22
Q

Shifts in the OCD:

is a right shift considered an increase or decrease in metabolism?

A

Increased

23
Q

Shifts in the OCD:

mneumonic for right shift

A

R- rightward shift

I- Increased PcO2

increased 2,3-DPG- G

H- hydrogen ions increased

T- temp increased

S- sickle cell

24
Q

what is the Bohr Effect

A

dr. bohr studied factors that shifted the OCD curve

Specifically Bohr assessed how CO2 shifts the OCD

so the Bohr effect refers to the shift in the OCD in response to increase ir decrease in PCO2

25
Q

Shifts in the OCD:

Administration of opioids shift the OCD curve in which direction? why?

A

opioids produce respiratory depression, so CO2 accumulates and the OCD curve shifts to the right

26
Q

Shifts in the OCD:

when there is a _____ shift in the OCD curve the amount of O2 carried by Hgb increases (loading of O2 is facilitated)

A

Leftward

27
Q

Shifts in the OCD:

when there is a _____ shift in the OCD curve the amount of O2 carried by Hgb is reduced (unloading of O2 is facilitated)

A

rightward

28
Q

is the Oxygen release from Hgb to the tissue increased or decreased by acidosis? alkolosis? explain.

A
• Acidosis there is a right shift, which facilitates the unloading of O2 at the tissues, therby increasing O2 delivery.
• Alkalosis there is a left shift, which diminishes unloading of O2 at the tissues, so O2 delivery is decreased