End Tidal CO2

Question 1

What is End Tidal CO2?

Answer 1

The level of carbon dioxide released at the end of an exhaled breath. Also called capnography.

Question 2

How is it Represented?

Answer 2

On a graph as a number.

Question 3

What is Normal Range?

Answer 3

From 35 - 45 mm Hg or 4.0 – 5.7 kPa.

Question 4

Why is it used?

Answer 4

Its a way of assessing ventilation and whether its been compromised. Gives indication into three crucial aspects: the patient’s airway patency, breathing adequacy and circulatory status

Question 5

How to Use

Answer 5

• Plug orange chord into the side cap
• Measure a good length of tubing from the rest of the nasal cannula

Question 6

Features of Normal Capnograph (4)

Answer 6

• The waveform shape always starts at zero and returns to zero
• A maximum CO2is reached with each breath, corresponding to EtCO2
• The width of the waveform depends on expiratory time
• The 4 Phases

Question 7

What are the 4 Phases of End Tidal Graphs?

Answer 7

1. Start of exhalation, CO2concentration is initially 0
2. CO2increases rapidly as alveolar gas exits the airway
3. CO2concentration is relatively constant (reflects the concentration of CO2in the alveolar gas). This phase ends with a value of maximum CO2 concentration
4. Start of inhalation, CO2decreases to zero as atmospheric air enters the airway

Question 8

PQ (PQRST) Assessment

Answer 8

P roper - Check if readings are usual for patient, considering any metabolic, ventilatory or perfusion problems

Q uantity - Readings should be between 35 - 45 mm Hg or 4.0 – 5.7 kPa

Question 9

R (PQRST) Assessment

Answer 9

R ate - too quick or too slow

• Ventilation should be 12-20 breaths per minute (bpm) for adults who are breathing by themselves
• 10-12 bpm if being ventilated.
• Children should be ventilated at a rate of 15-30 bpm
• 25-50 bpm for infants.
• Ventilating too quickly won’t let enough CO2 build up in the alveoli, resulting in lower EtCO2readings.
• Ventilating too slowly will allow extra CO2 to build up, resulting in higher readings

Question 10

ST (PQRST) Assessment

Answer 10

S hape - Waveform should normally be a rectangle with rounded corners

T rend - Trending of the quantity, rate and shape of EtCO2 should be stable or improving

Question 11

What does a low EtCO2 Mean? And Causes

Answer 11

Low EtCO2 with other signs of shock indicates poor systemic perfusion, which can be caused by hypovolemia, sepsis or dysrhythmias

Question 12

What does it mean during Cardiac Arrest? + Other Uses

Answer 12

• It is used to indicate effectiveness of chest compressions.
• An EtCO2 less than 10 mm Hg indicates that compressions are not fast or deep enough
• If circulation is restored, a spike in EtCO2 often appears before a pulse is detected.
• It is also used to confirm endotracheal tube placement and effective ventilation.