EtCO2 Theory Flashcards
What is the definition of respiration?
The process by which oxygen and carbon dioxide diffuse in and out of the blood
What is the definition of ventilation?
Ventilation is the act or process of inhaling and exhaling – “movement of air”.
Pulmonary ventilation is the process by which oxygen enters and carbon dioxide exits the alveoli.
What is the definition of oxygenation?
Refers to the process of adding oxygen to the body system – how we get O2 to the tissues.
What are the positives of using EtCO2 monitoring?
- Provides reading for every breath – so results are within seconds
- Not affected by motion/circulatory status
- 100% sensitive and 100% specific
What is dead air space/dead space?
Ventilated Areas that do not participate in gas exchange. Can be extended or made smaller based on airway interventions (example: extended by tubing, made smaller by inflated King LT cuff).
What is a normal EtCO2 measurement?
35-45 mmhg
If EtCO2 is lower than 35 mmHg, what does this generally mean?
Hyperventilation/hypocapnia
If EtCO2 is higher than 45 mmHg, what does this generally mean?
Hypoventilation/hypercapnia
What is quantitative ETCO2?
A measurement tool that gives us a number (ex: 38mmHg)
What is qualitative ETCO2?
Devices that give a range (“low” “medium” “high”), often associated with a colour, instead of a number.
What does PaCO2 stand for?
Partial Pressure of Carbon Dioxide in arterial blood gases.
How will we know what the PaCO2 is?
PaCO2 should equal EtCO2 if ventilation and perfusion are stable.
What does point D represent?
Where ETCO2 is measured.
What does a low ETCO2 mean early in a code?
Likely Poor CPR (or extended down time).
What does a low ETCO2 mean later in a code run?
Decreased likelihood of ROSC/extended downtime.
Low survivability.
Why does bronchospasm result in the sloped “shark fin” waveform?
Because the movement of air at the alveoli is delayed in a person with bronchospasm, the rise to the plateau is more gradual and the plateau itself becomes sloped.
What is a sidestream ETCO2 measurement?
- An indirect method of measuring exhaled CO2 in non-intubated patients.
- Pt’s with Respiratory complaints.
What is a mainstream/inline ETCO2 measurement?
Direct method of measuring exhaled CO2 with intubated patients, or pts being ventilated with a BVM, SGA, or OPA
Can ETCO2 be used with CPAP?
Yes, both sidestream and mainstream can be used, sidestream preferred.
What are some reasons for low ETCO2?
- Anxiety
- Bronchospasm
- Pulmonary embolus
- Cardiac arrest
- Hypotension
- Decreased cardiac output
- Cold
What are some reasons for high ETCO2 measurements?
- Overdose
- Sedation
- Intoxication
- Postictal states
- Head trauma
- Stroke
- Tiring CHF
- Fever
- Sepsis
- SOB
What does ETCO2 measure when Cardiac output (blood flow) is normal?
Ventilation
What does ETCO2 measure when Cardiac Output (blood flow) is decreased?
Cardiac output
(This is why ETCO2 is a good indicator of compression quality in CPR)
During CPR, what ETCO2 is considered too low?
Under 10-15 mmHg.
Why does ETCO2 spike in ROSC?
Large amounts of acidic blood are suddenly returned to the lungs and high amounts of CO2 diffuses into the alveoli. This flood of CO2 causes a sharp rise in ETCO2 levels, much higher then normal.
