CO2 Waveforms +Pulse oximetry Flashcards
(57 cards)
What does the baseline of the CO2 Waveform represents what phase is it?
Exhalation of anatomic dead space (flat region before it becomes positive)
Phase I
What does the UPSTROKE of the CO2 Waveform represents ? what phase?
Exhalation of anatomic dead space + ALVEOLAR GAS
Phase II
What does the PLATEAU phase of the CO2 waveform represents
Exhalation of Alveolar gas
Phase III
What does the return to baseline, DOWNSTROKE phase of the CO2 waveform represents
Inspiration of fresh gas that DOES NOT CONTAIN CO2
What is CO2?
Carbon dioxide, which is the final product of Aerobic metabolism
Where is End Tidal CO2 measured on the waverform?
End of Plateau phase.
What is ventilation
Process of removing CO2 from the body.
If you’re using a Mapleson circuit, what is the primary cause of an increase in CO2 ?
Inadequate fresh gas flow (no unidirectional valves, no CO2 canisters)
Dead space and CO2
increasing dead space, can increase rebreathing and CO2 retention
Valves and CO2 retention
A stuck open inspiratory valve rebreathing can occur because during expiration, alveolar gas can back fill the inspiratory limb of the circle
A defective expiratory valve can lead to rebreathing of CO2 also because during inspiration, the negative pressure generated by the patient can bring alveolar gas from the expiratory limb of the circuit.
Malfunction of the _______can also cause CO2 rebreathing
CO2 absorber
If the CO2 absorbent malfunction midcase, what do you do?
Increase the Fresh gas flow
Classic rebreathing pattern on the capnography will show
elevation of the waveform baseline that does not return to and HIGHER ETCO2 , PaCO2 may be normal
What is the Capnometer?
Device that measures and displays the concentration of CO2.
What is a Mainstream sampling?
INSIDE the tracheal tube with all inhaled and exhaled gas.
Advantage of mainstream sampling vs sidestream sampling
ADV: response time is faster
DIS: bulkiness of the device, need to be heated to 40C –> risk of burning patient skin, INCREASE DEAD SPACE
Most common sampling method? What does it require?
Sidestream ; Water trap to prevent contamination
What is the average sampling flow rate?
150-250 ml/min
If less than 150, too slow
if > 250, may be contaminated with fresh gas
What is use to deal with water condensation?
Water trap systems
CO2 measurements done by
MASS Spectometry
Mass spectometry work by
separating gases and vapors according to difference in their mass-to-charge ratios.
Colorimetric detection consists of a
ph sensitive paper within a chamber place between tracheal tube and ventilation device.
Yellow ETCO2>15
CO2 measures 3 vital parameters which are
Metabolism
Circulation
Ventilation
Normal ETCO2
35-45 mmHg
