Co2 monitoring

Question 1

Indications for non-invasive C02 monitoring

3 reason

Answer 1

-Check for ETT position – Tracheal? Esophageal?
Note : CO2 detection does not assure correct placement
-Reduce trauma to targeted blood vessel, if can’t obtain sample, in neonates
-Allow for continuous monitoring

Question 2

What are 2 devices for non-invasive C02 monitoring?

Answer 2

• End Tidal CO2 (ETCO2) Monitoring

- Transcutaneous Monitoring

Question 3

What are the 2 methods that Capnometers sample gas?

Answer 3

Mainstream (analyses the c02 in line)

Sidestream (takes a sample of gas from the line and sends it to analyzer)

Question 4

With regards to Pac02 and Petco2 levels, what readings can you expect to see when comparing the 2 in healthy and un-healthy lungs?

Answer 4

In healthy lungs, they should be the same but can have a petCo2 level about 5 lower than Pac02.

in un-healthy lungs, Pac02 can be much higher due to heterogeneous degrees of lung tissue with inability to remove it due to decreased perfusion.

Question 5

When reading a capnograph, explain phase 1,2,3

Answer 5

Phase 1 - after the end of inhalation, patient is exhaling dead space, mostly 02
Phase 2 - deadspace gas and gas coming from alveoli are mixing creating a spike in graph.
Phase 3 - This is the plateau phase where the remaining gas from the alveolar level is being exhaled. right before inhalation and steep drop.

Question 6

What can cause an elevated baseline in a capnograph?

Answer 6

Rebreathing

Question 7

What can cause a Petc02 level of 0 or near 0?

Answer 7

• system leak
• cardiac arrest
• esophageal intubation

Question 8

What can cause a sudden rise in Petc02?

Answer 8

• sudden increase in Cardiac output
• sudden release of a tourniquet
• injection of Bi-Carb

Question 9

What can cause a sudden decrease in petco2?
(3 troubleshooting)
(4 patient symptoms or conditions)

Answer 9

DISCONNECTION FROM VENT
OBSTRUCTION OF ETT TUBE
LEAK 
sudden hyperventilation
sudden decrease in cardiac output
massive pulmonary embolism
air embolism

Question 10

What can cause a gradual rise in Petco2?

Answer 10

hypo ventilation

increase in co2 production

Question 11

What can cause a gradual decrease in Petco2?

Answer 11

hyperventilation
decrease in 02 consumption
decrease pulmonary perfusion

Question 12

How is Petco2 measured?

3 ways

Answer 12

infrared absorption
colormetric techniques (intubation kit)
mass spectrometry (less common, more expensive)

Question 13

What can cause false positive readings on a colormetric c02 detector?
how can you tell the difference?

Answer 13

• Gastric contents
• mucous contamination
• drugs like lidocaine or epi

false positives change it permanently. normally it should change it breath by breath

Question 14

What are some causes of false negatives?

Answer 14

Cardiac arrest

patients with low cardiac output.

Question 15

What is the normal value for dead space/tidal vol? (Vd/Vt)

Answer 15

.20-.40

Critical is greater than .60

Question 16

What happens on a bi-phasic wave on a capnograph?

Answer 16

Where areas of the lung have very different time constants and V/Q ratios

exhalation will plateau but the patient wants to take in another breath. this will momentarily drop the wave but instantly rise.

Question 17

A patient in the OR who’s paralytics are wearing off would show what capnograph wave abnormality?

Answer 17

Curare cleft

Patient will take a weak breath during exhalation

Question 18

What are some reasons for a false negative reading on a C02 detector?

Answer 18

Cardiac Arrest

Patients with a Low cardiac output