Capnography in Respiratory Emergencies Flashcards
What Phase of normal capnography waveform is the respiratory baseline?
Phase I (A-B)
What occurs during Phase I of the normal capnography waveform?
Dead space air is exhaled from the body - air that does not contain CO2
What Phase of the normal capnography waveform is the respiratory upstroke?
Phase II (B-C)
What occurs during phase II of the normal capnography waveform?
air from the alveoli that contains CO2 is being exhaled from the body
What phase of the normal capnography waveform is the expiratory plateau?
Phase III (C-D)
What occurs during phase II of the normal capnography waveform?
The last of the CO2 laden air from the most distal alveoli is exhaled. ETCO2 is measured at the end of exhalation, point D
What phase of the normal capnography waveform is the inspiratory downslope?
Phase IV (D-E)
What occurs during Phase IV of the normal capnography waveform?
carbon dioxide is rapidly purged from the airways and alveoli
What is the five step approach of evaluating a capnography waveform?
Look at the waveform Look at the respiratory baseline Look at the respiratory upstroke Look at the expiratory plateau Read the ETCO2 value
When reading a capnography waveform, what does a respiratory baseline that slopes upward and increases with each breath suggest?
Patient is rebreathing carbon dioxide
When reading a capnography waveform what does a prolonged respiratory upstroke that is not vertical represent?
uneven alveolar emptying as a result of brochospasm
When reading a capnography waveform, what does the loss of plateau suggest?
uneven alveolar emptying secondary to severe brochospasm that leads to air trapping. Suggest dynamic hyperinflation, also called auto-PEEP
What does an ETCO2 measurement greater than 45mmHg suggest?
hypercapnia - caused by respiratory failure
What does an ETCO2 less than 35mmHg suggest?
hypocapina, which may be caused by hyperventilation or hypoperfusion
