Capnogram

Question 1

Phase I

Answer 1

• -Inspiratory baseline
• -Should have no CO2 reading
• -Inspiration and first part of expiration
• -Dead space gas exhaled

Question 2

Phase II

Answer 2

• -Expiratory upstroke
• -Sharp upstroke represents rising CO2 level in sample
• -Slope determined by evenness of alveolar emptying
• -Mixture of dead space and alveolar gas (mostly dead space)

Question 3

Phase III

Answer 3

• -Alveolar plateau
• -Constant or slight upstroke
• -Longest phase
• -Alveolar gas sampled
• -Peak at end of plateau is where reading is taken (PetCO2).
• -Normal = 30-40 mmHg
• -Reflection of PaCO2

Question 4

Phase IV

Answer 4

• -Beginning of inspiration (should be direct drop off, 0 CO2)
• -CO2 concentration: rapid decline to inspired value

Question 5

Alpha Angle

Answer 5

• -Normal 100-110 degrees

- -Increased = expiratory airflow obstruction (COPD, Bronchospasm, Kinked ETT)

Question 6

Beta Angle

Answer 6

• -Normal 90 degrees
• -Fresh gas does not contain CO2 therefore capnogram should return to baseline (zero)
• -Increased = rebreathing (very specific to faulty inspiratory valve or exhausted CO2 absorbent)