Capnography (Exam 1) Flashcards
Airflow obstruction
Prolonged Phase III and increased alpha angle
Ex: COPD, kinked ETT
Cardiac Oscillations
Heart beating against lungs
More common in pediatric patients
Low EtCO2
Phase III is well below normal
Occurs with hypoventilation (light anesthesia), decrease CO2 production (hypothermia), or increase alveolar dead space (pulmonary embolism)
Curare Cleft
Spontaneous breathing during mechanical ventilation
Suggests inadequate muscle relation
Elevated Et CO2 with normal Phase III
Suggests increase metabolism (malignant hyperthermia, sepsis, hyperthyroidism) or decreased alveolar ventilation (hypoventilation, narcotized)
Inspired CO2
Suggests rebreathing (exhausted CO2 absorbent, inadequate FGF, incompetent expiratory valve)
Widened Beta Angle
Suggests rebreathing related to incompetent unidirectional valve, Phase 1 may reach zero depending on the fresh gas flow
Normal Capnography Reading
Phases of Capnography
Phase I – Exhalation of anatomic dead space
Phase II - Exhalation of anatomic dead space + dead space
Phase III – Exhalation of alveolar gas
Phase IV – Inspiration of fresh gas that does not contain CO2
Points of the Capnography
Point C - alpha angle – normally 100 degrees, an increase suggests an airflow obstruction (e.g. COPD, kinked tube)
Point D – beta angle – normally 90 degrees, an increase suggests rebreathing due to faulty unidirectional valves.
Point D – Where end tidal CO2 is measured (normally 35 – 40 mmHg)
Exhausted CO2 absorbent will have increase baseline normal beta angle
Capnography continuously monitors ____.
perfusion, metabolism and ventilation
CO2 is a byproduct of ____.
aerobic metabolism, ventilation is the process by CO2 is removed from the body
Capnography measures _____.
end-tidal CO2 over time
