Oximetry and Pulse Ox

Question 1

What is the respiratory quotient?

Answer 1

Amount of CO2 produced / % of O2 consumed

Question 2

Why is oximetry measured?

Answer 2

Der b/c we need O2 to live

Question 3

What is the normal O2 consumption of a 70 kg patient?

Answer 3

3.3 mL / kg

Question 4

On room air (21% FiO2) what is the normal FeO2 and that means we consume approximately how much O2?

Answer 4

Normal FeO2 = 18%

so that means we consume about 3% of minute ventilation

Question 5

According to the normal O2 consumption of a 70 kg patient, how much O2 is that per min?

Answer 5

3.3 mL / kg and 70 kg

= 250 mL of O2 / min

Question 6

Hypoxemia and hypoxia both give a determination of what?

Answer 6

Amount of O2 in the blood and tissues

Question 7

What is an easy deadspace calculation?

Answer 7

The pt’s weight in lbs

Question 8

What is the minimum tidal volume to maintain oxygenation and to reduce amount of atelectysis?

Answer 8

3-4 x deadspace

Question 9

What is the minimum oxygen percent you can give to your patient that has 0 V/Q mismatch and no circuit leaks of any kind?

Answer 9

5%

Question 10

What is carboxyhemoglobin?

Who does this occur in?

Answer 10

Carbon monoxide bound hemoglobin

Smokers

Question 11

What is methemoglobin?

Answer 11

Where the heme molecule losses an electron of iron (Fe) and causes hemoglobin molecule to lose its shape

Question 12

What is sulfhemoglobin? Who does this occur in?

Answer 12

Sulfar bound Hb

Diabetics

Question 13

What is sickle cell hemoglobin?

Answer 13

Sickled Hb which decreases the O2 carrying capacity

Question 14

What is fetal Hemoglobin?

Answer 14

haha according to Biggs, the fetal people Hb

Question 15

What is the oxygen content equation?

Answer 15

CO2 = 0.0031 x PO2 + 1.31 x O2 Hb x SO2

Question 16

What does your minute ventilation approximately need to be equal to?

Answer 16

Cardiac output

Question 17

What is oxyhemoglobin?

Answer 17

O2 bound hemoglobin

Question 18

What is deoxyhemoglobin?

Answer 18

Reduced O2 bound hemoglobin

Question 19

What is the standard for measuring oximetry? (we don’t use in OR)

Answer 19

Laboratory Bench Co-oximeters

Question 20

What do we use in the OR for measuring oxygen saturation?

Answer 20

Pulse Oximeter

Question 21

What is the fractional SaO2 formula used in the Co-oximeters?

Answer 21

O2 Hb /

O2 Hb + Deoxy Hb + CO Hb + Met Hb + HbF

Question 22

What is the functional SaO2 formula used in pulse ox?

Answer 22

O2 Hb / O2 Hb + deoxy Hb

Question 23

What are the 2 wavelenths used in pulse ox readings?

Answer 23

Red @ 660 nm

Infrared @ 940 nm

Question 24

KNOW THE GRAPH ON PAGE 6 which is of the Hemoglobin extinction curves. If someone knows how to put pics in please do on the answer part of this question.

Answer 24

INSERT YOUR THINGY HERE

Question 25

What does someone who has carboxyhemoglobin read on the pulse ox?

Answer 25

90%

Question 26

What does someone who has methemoglobin read on the pulse ox?

Answer 26

85%

Question 27

What kind of pulse ox is used in adults?

Answer 27

Transmission | LED and photodetectors on opposite sides

Question 28

What kind of pulse ox is used in fetal monitoring?

Answer 28

Reflectance | LED and photodetectors on same side and reflects off bone

Question 29

Where can you put the pulse ox we use in the OR?

Answer 29

``` Any protuberance :fingers :ears :tongue :nose :toes :lip :penis ```

Question 30

Which light wavelength is shown on the screen when using a pulse ox and why?

Answer 30

Infrared (940 nm) because it shows the greatest amplitude and is stronger at 100% O2 sat

Question 31

What is the assumed difference between what the screen shows and what the actually saturation may be?

Answer 31

+/- 2%

Question 32

What is the isobestic point?

Answer 32

Point at which frequency the two wavelengths absorb exactly the same amount of two hemoglobins

Question 33

What is the isobestic point of oxyhemoglobin and deoxyhemoglobin?

Answer 33

800 nm

Question 34

What causes right shifts in the oxygen-hemoglobin dissociation curve?

Answer 34

``` R (rightward) I (increase of CO2) G (2,3 DPG increase) H (H+ increase) T (Temp increase) ```

Question 35

What does a rightward shift indicate on the curve?

Answer 35

A decreased affinity for O2 binding or increased oxygen uploading

Question 36

What causes left shifts in the oxygen-hemoglobin curve?

Answer 36

``` Exact opposite of right :Decreased CO2 : decreased 2,3 DPG) : decreased H+ : decrease in temp But also: :Fetal hemoglobin :CO poisoning ```

Question 37

What does a leftward shift indicate on the curve?

Answer 37

Increased affinity for O2 binding and therefore decreased oxygen unloading

Question 38

In white patients, SpO2 of >92% predicted PaO2 of 60 mmHg. However in black patients SpO2 of _______ predicted PaO2 of 60 mmHg

Answer 38

>95%

Question 39

What are some causes of low perfusion?

Answer 39

Vasoconstriction Severe PVD Hypothermia Hypovolemia

Question 40

What kind of lights obscure pulse ox readings?

Answer 40

Fluorescent

Question 41

What causes blood to become a very bright red color?

Answer 41

Carbon monoxide

Question 42

Will anemia have any affect on pulse ox readings?

Answer 42

No because just because there are fewer Hb molecules available does not change the saturation of the ones that are present

Question 43

In the masimo SET instrument, what does the SET stand for and what does it do?

Answer 43

Signal extraction technology Separates the signal from noise

Question 44

Of the dyes that effect Pulse ox, which has the greatest effect?

Answer 44

Methylene blue

Question 45

What are the dyes that have effects on pulse ox in order from greatest distortion to least?

Answer 45

``` Methylene blue Lympharzurine blue Indocyanine green Indigo carmine Fluorescein (no effect) ```

Question 46

What colors of nail polish may effect absorbance of pulse ox?

Answer 46

Blues and blacks

Question 47

How much lower of a SO2 will wearing nail polish produce because of low signal strength? What can be done to alleviate this problem?

Answer 47

6% lower Rotate probe 90* from normal so it is looking across the finger

Question 48

What is the only real hazard of pulse ox today?

Answer 48

Pressure necrosis

Question 49

What is PI?

Answer 49

Perfusion Index | is a relative assessment of the pulse strength at the monitoring site

Question 50

CO binds hemoglobin how many more times than 02 binds?

Answer 50

240 x

Question 51

On page 26 and 27, read the Clinical moments part , biggs said there would be 1 or 2 questions from these.

Answer 51

Again if someone wants can copy and paste them into here

Question 52

What is NIRS?

Answer 52

Near infrared spectroscopy

Question 53

What does NIRS give you?

Answer 53

Will give you absorption of the brain tissue but not the blood, so is referred to rSO2

Question 54

What is difference of rSO2 and tSO2?

Answer 54

regional SO2 and tissue SO2 rSO2 is for brain tSO2 is for other tissues in the body

Question 55

How many probes come with Cerebral oximetry and why?

Answer 55

2 probes so you can measure oxygenation of both hemispheres at same time

Question 56

Most anesthetics increase or decrease cerebral blood flow ?

Answer 56

Increase

Question 57

What are the average values for cerebral oximetry?

Answer 57

55 - 75 %

Question 58

What are the main problems with cerebral oximetry ?

Answer 58

Depends on partition of arterial and venous blood which depend on: PaCO2 Hypoxia pH

Question 59

What is SvO2?

Answer 59

Mixed venous oxygen saturation

Question 60

Where do you usually obtain SvO2?

Answer 60

PA catheter advanced near a capillary

Question 61

What are some variables that affect SvO2?

Answer 61

Q (blood flow) Hb concentration SaO2 (arterial oxygenation) VO2 (oxygen uptake - metabolic rate - perfusion)

Question 62

What does SjvO2 measure?

Answer 62

Jugular venous saturation

Question 63

Which way do you place the catheter that reads SjvO2?

Answer 63

Towards the brain