Pulmonary Intraoperative monitoring/Difficult Airway Algorithm

Question 1

At what light wavelength is oxyhemoglobin absorb from a pulse oximeter?

Answer 1

940nm=infrared light

Question 2

At what light wavelength is deoxyhemoglobin absorbed from a pulse oximeter?

Answer 2

660nm=red light

Question 3

Why were these two wavelengths of light picked for the pulse ox?

Answer 3

The difference between deoxyhemoglobin and oxyhemoglobin absorption of light was significantly different at these two numbers

Question 4

Rough rule for PaO2 and Sat correlation?

Answer 4

70, 80, 90 spO2= 40, 50, 60 PaO2

Question 5

What detects change quicker: finger probe spO2 or ear prove spO2?

Answer 5

Ear probe spO2

Question 6

What is a rough rule on ETT depth based on tube size?

Answer 6

ETT depth is 3 x tube size

Question 7

Will endobronchial intubation be detected by pulse ox?

Answer 7

Typically goes undetected in the absense of lung disease and low FiO2.

Question 8

What depth in cm is the carina typically located?

Answer 8

27cm

Question 9

What are some limitation of pulse oximetry?

Answer 9

1. No pulse present or low peripheral perfusion.
2. Hemoglobin variants
3. Severe hypoxemia
4. Severe anemia.
5. Venous pulsations

Question 10

What are the three hemoglobin variants we talked about?

Answer 10

1. Carboxyhemoglobin.
2. Methemoglobin
3. Fetal hemoglobin/bilirubin

Question 11

What would be seen on the pulse ox with CO poisoning?

Answer 11

SpO2=100%

Question 12

What would be seen on the pulse ox with methemoglobinemia?

Answer 12

85%

Question 13

What are some causes of methemoglobinemia?

Answer 13

Benzocaine spray (hurricaine), sulfonamides, nitrates/nitrites.

Question 14

What is tx for methemoglobinemia?

Answer 14

methylene blue or ascorbic acid

Question 15

What effect does fetal hemoglobin have on the pulse ox?

Answer 15

No effect on pulse oximetry

Question 16

At what SpO2 does the accuracy become poor in severe hypoxemia?

Answer 16

<30%

Question 17

At what severely anemic level will the pulse oximeter not function well?

Answer 17

If Hb <3-4gm/dL

Question 18

What is the penumbra effect on the pulse oximeter?

Answer 18

When the probe is half off the finger. It refers to the full or partial eclipse of the sun

Question 19

What number does the penumbra effect normally show as the SpO2?

Answer 19

90-95%

Question 20

What is the GOLD STANDARD for tracheal intubation?

Answer 20

ETCO2

Question 21

What is the difference between a capnograph and capnometer?

Answer 21

Capnometer displays a number but no display/reading.

Capnograph records and displays.

Question 22

Does ETCO2 reliably detect endobronchial intubation?

Answer 22

No

Question 23

Does ETCO2 reliably detect endotracheal intubation?

Answer 23

Yes= gold standard.

Question 24

Why might a flow-through (mainstream capnography be used instead of an aspiration capnography?

Answer 24

More used in NICU where the patient may not tolerate large aspiration rates.

Question 25

Approximately how much is aspirated by a sidestream capnograph system?

Answer 25

50-250ml/min

Question 26

D point on a capnogram is what?

Answer 26

Highest point at which we get ETCO2.

Question 27

What is the BC segment on a capnogram?

Answer 27

Exhalation and mixing of gases.

Question 28

What is CD segment on a capnogram?

Answer 28

Alveolar plateau, alveolar rich gas.

Question 29

What is AB segment on capnogram?

Answer 29

Beginning of exhalation, dead space gas mostly.

Question 30

What is the DE segment on a capnogram?

Answer 30

The start of inhalation

Question 31

If a curare cleft is noted on capnography, what tx would you perform next?

Answer 31

1. may need more muscle relaxant, 2. Could sedate. 3. Could increase rate to overdrive.

Question 32

What about a capnogram might change with a faulty inspiratory valve?

Answer 32

Beta angle is not 90degrees because exhalation volume is going up the inspiratory limb.

Question 33

What capnograph changes would you see with an expiratory valve failure?

Answer 33

Never returning to baseline and continuing to increase.

Question 34

What also resembles a depleted CO2 absorber on capnograpy (faulty inspiratory or expiratory valve?

Answer 34

Faulty expiratory valve

Question 35

What is normal ETCO2 to PaCO2 gradient?

Answer 35

Arterial CO2 is 2-5mmHg higher

Question 36

Does reduction in lung perfusion increase or decrease alveolar dead space and increases or decreases dCO2?

Answer 36

Increases deadspace which is an increase in dCO2

Question 37

What is dCO2?

Answer 37

The gradient between ETCO2 and PaCO2.

Question 38

What is dCO2 a reflection of?

Answer 38

Alveolar dead space

Question 39

What are normal ABG values?

Answer 39

``` pH 7.35-7.45 PCO2 35-45. PO2 75-105 HCO3 20-26 BASE -3to +3 ```

Question 40

What does COPD do to dCO2?

Answer 40

Increases