Carbon Dioxide Analysis Flashcards
What are components of carbon dioxide?
A polyatomic structure and can be measured using infrared absorption analysis
What are two less common methods for measuring carbon dioxide analysis?
Fluorescence quenching and the Severinghaus CO2 electrode
When is a Colorimetric Carbon Dioxide Sensor used?
A special situation for measuring carbon dioxide is when away from the anesthesia machine (i.e. ICU or code of floor)
What is Colorimetric Carbon Dioxide Sensor used to determine?
Assure correct placement of endotracheal tube (ETT).
What is analyzed in Colorimetric Carbon Dioxide Sensor?
Exhaled CO2
What is the principle of Colorimetric Carbon Dioxide Sensor?
utilizes a change in color of a chemically treated paper
What happens to the Colorimetric Carbon Dioxide Sensor when exposed to C02?
An instant reaction will change the color of the paper indicating the presence of CO2.
What is true about newer Colorimetric Carbon Dioxide Sensor?
Some newer colorimetric sensors will even give estimate of the amount of CO2 detected.
The appearance of a purple color on the Colorimetric Carbon Dioxide Sensor indicates a CO2 of ____ mmHG and _______ % CO2.
<4 mmHg and <0.5%
The appearance of a tan color on the Colorimetric Carbon Dioxide Sensor indicates a CO2 of ____ mmHG and _______ % CO2.
4-15 mmHg and 0.5-2% CO2
The appearance of a Gold color on the Colorimetric Carbon Dioxide Sensor indicates a CO2 of ____ mmHG and _______ % CO2.
CO2 >15 mmHg and >2%
What is the difference about CO2 Fluorescence Quenching?
CO2 does not have the ability to do florescence quenching.
Instead, CO2 will change the pH, liberating hydrogen ions, which react with a quenching agent in the sensor.
CO2 will change the _____, liberating hydrogen ions, which react with a quenching agent in the sensor.
pH
What causes the change in florescence in terms of CO2 Fluorescence Quenching?
Changed florescence is caused by CO2 and this change can be measured
CO2 Fluorescence Quenching- the change is directly proportional to the concentration of _______ present
CO2
What is the severinghaus electrode?
modified glass electrode;
- The electrode contains some sodium bicarbonate, which reacts with the CO2;
- The reaction changes the pH in the electrode, which corresponds to a change in potential difference, and this is measured.
- The CO2is then inferred from the change in pH
Severinghaus PCO2 Electrode: The CO2dissolved in the sample diffuses into the middle compartment of the electrode via a _______________.
thin (silicon polymer) membrane
Severinghaus PCO2 Electrode: Once inside, the CO2finds itself in a _____________
bicarbonate solution
Severinghaus PCO2 Electrode: The reaction which takes place is an old familiar _________________.
Carbonic acid dissociation equilibrium:
CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-
Severinghaus PCO2 Electrode: What cause the generate a current of electrical charge?
Hydrogen ions are liberated
Severinghaus PCO2 Electrode: The ________ of the solution in the middle chamber changes.
pH
Severinghaus PCO2 Electrode: The change in pH is completely dependent on the pCO2, provided the ______ and _______ remain constant.
temperature and pressure
Severinghaus PCO2 Electrode: So from the change in pH, the _____ can be calculated.
PCO2
Severinghaus PCO2 Electrode: This current is _________ to the carbon dioxide concentration present.
proportional
