Capnography (Exam I) Flashcards
What are the effects of hypercarbia?
- Respiratory Acidosis
- ↑ CBF
- ↑ PVR
- K⁺ shift intravascularly
What are the effects of hypocarbia?
- Respiratory alkalosis
- ↓ CBF
- ↓ PVR
- K⁺ shift intracellulary
- Blunts respiratory drive
What is the Bohr equation?
What is it used for?
Used to calculate physiologic dead space
What is the best method to confirm endotracheal tube placement?
Capnography
Differentiate high-speed (real-time) and low speed (trend capnography).
How much gas do side-stream analyzers utilize?
200 mL/min sample rate
What is the most common method for capnographic sampling, side-stream or main-stream sampling?
Side-stream
What are the benefits of main-stream sampling?
- No time delay
- quicker rise time
What approximate difference is there between PaCO₂ and EtCO₂ ?
5 mmHg
ex. PaCO₂ will be 40 mmHg vs EtCO₂ at 35 mmHg
What color is the CO₂ chemical indicator?
What color does it change to in the presence of CO₂ ?
purple → yellow
When using a capnograph, how close must a CO₂ reading be to the actual value?
+/- 12%
What are the inspiratory phases of the capnograph?
Phase 0
What are the expiratory phases of the capnograph?
Phases I, II, and III
When would the CO₂ reading of a capnograph be 0 mmHg ?
Phase I
Which phase of the capnograph would be representative of alveolar CO₂ ?
Phase III
Where on the capnograph is EtCO₂ measured?
Phase III
What is a phase IV in the capnograph? Why does it occur?
Upstroke at the end of Phase III resulting from collapse of alveoli.
What patient populations might exhibit a Phase IV on their capnograph?
- Obese
- Pregnant
What phases are separated by the β angle?
Phase III and 0
What degree should the α angle have?
What occurs with increase to the angle’s degree?
- 100 - 110°
- Increased angle occurs with expiratory airflow obstruction (COPD, ETT, bronchospasm, etc)
What degree should the β angle have?
90°
What situations/conditions would cause an increase in the β angle?
- Bad inspiratory valve
- Rebreathing
- Low VT w/ tachypnea
What type of capnograph is depicted below?
Mechanical Ventilation
What type of capnograph is depicted below?
Spontaneous Ventilation
What is occurring with the capnograph below?
Inadequate ETT seal
What might be occurring based on the two capnographs below?
Faulty Inspiratory Valve
What is occurring with the capnograph below?
Likely sample line leak
What is occurring with the capnograph below?
Hyperventilation (resulting in a ↓ EtCO₂)
What is occurring with the capnograph below?
Hypoventilation (resulting in steady ↑ EtCO₂)
What is occurring with the capnograph below?
Airway obstruction or breathing circuit obstruction
What is occurring with the capnograph below?
Cardiac oscillations
What is occurring with the capnograph below?
Rebreathing (note the increasing baseline)
What is occurring with the capnograph below?
Curare Cleft (NMBDs are wearing off)
What is occurring with the capnograph below?
Ventilator overbreathing
What is occurring with the capnograph below?
Esophageal Intubation (the ol’ tubed goose)
