Capnography

Question 1

PACO2

Answer 1

concentration of CO2 in the alveoli

Question 2

PaCO2

Answer 2

concentration of CO2 in the arteries

Question 3

EtCO2

Answer 3

concentration of CO2 in expired gas

Question 4

how much higher is PaCO2 than EtCO2 normally?

Answer 4

3-5mmHg

dilutes as it travels to the capnograph

Question 5

Do PaCO2 and EtCO2 normally correlate?

Answer 5

yes if PaCO2 increases so does EtCO2

Question 6

When is the exception to PaCO2 and EtCO2 correlation?

Answer 6

pulmonary embolism
PaCO2 increase
EtCO2 decrease

Question 7

what are the effects of hypercarbia? (6)

Answer 7

1. repiratory acidosis
2. central (pulmonary) vasoconstriction
3. peripheral and cerebral vasodilation
4. sympathetic response/catecholamine release
5. CO2 narcosis
6. possible death

Question 8

respiratory acidosis

Answer 8

pH decrease b/c H increases

catecholamines (vaspressors) don’t work as well

Question 9

central (pulmonary) vasoconstriction

Answer 9

increased PVR

Question 10

when should hypercarbia be avoided specifically?

Answer 10

neurosurgery

Question 11

CO2 narcosis

Answer 11

CO2 acts as a sedative if it reaches 70mmHg

Question 12

What PaCO2 is equal to 1 MAC?

Answer 12

200mmHg

Question 13

What PaCO2 could cause death?

Answer 13

> 120mmHg

Question 14

What are the effects of hypocarbia (3)

Answer 14

1. respiratory alkalosis
2. central (pulmonary) vasodilation
3. peripheral and cerebral vasoconstriction

Question 15

what is the gold standard for confirmation of ETT placement?

Answer 15

etCO2

Question 16

how fast does PaCO2 rise during apnea?

Answer 16

first min= 6mmHg

each min after 3-4mmHg

Question 17

Phase 0

Answer 17

inspiration

CO2 = 0

Question 18

Phase I

Answer 18

beginning expiration
CO2 = 0
represents anatomic deadspace

Question 19

Phase II

Answer 19

portion of expiration where CO2 is first seen

Question 20

Phase III

Answer 20

CO2 plateau

Question 21

Phase IV

Answer 21

end of plateau

Question 22

curare cleft

Answer 22

when there is a dip in the plateau

pt is trying to breath over the ventilator

Question 23

what else can cause a curare cleft?

Answer 23

surgeon is pushing on the chest

Question 24

what are the two options to treat a curare cleft

Answer 24

1. suppress their drive to breath

2. turn off the vent and let the patient breathe

Question 25

how do you suppress a patients drive to breathe?

Answer 25

propofol
narcotic/ paralytic
increase minute ventilation (lower etCO2)

Question 26

what is the first thing you do when the patient is “bucking” on the vent

Answer 26

TURN THE VENT OFF

Question 27

COPD/Emphysema etCO2 waveform

Answer 27

upsloping waveform

prolonged exhalation times

Question 28

esophageal intubation etCO2 waveform

Answer 28

small waves then nothing after a few breaths

Question 29

hypocapnea waveform causes (3)

Answer 29

hyperventilation
hypotension/low Q
loose circuit connection

Question 30

cardiogenic oscillations

Answer 30

heart contractions that displace air from alveoli

Question 31

when do you normally see cardiogenic oscillations? (2)

Answer 31

low RR

end of expiration

Question 32

what are the three things the capnograph measures?

Answer 32

etCO2
etvolatile agent
RR

Question 33

what if the EtCO2 wave never reaches 0?

Answer 33

the CO2 absorbent is exhausted

Question 34

at what flow is the CO2 absorber not necessary?

Answer 34

5L/min

Question 35

when does the etCO2 wave look like a chair?

Answer 35

loose connection or circuit leak

Question 36

At what stage to patients usually go through irregular breathing?

Answer 36

Stage II

Question 37

when could exhaling during inspiration happen?

Answer 37

mapleson circuit or faulty expiratory valve

Question 38

When would you see decreased CO2 at the end of the plateau phase?

Answer 38

emergence

Question 39

What is the value of capnography during sedation?

Answer 39

RR
detect apnea (before hypoxic)