Capnography

Question 1

What is capnography?

Answer 1

• Non-invasive way to measure partial pressure of carbon dioxide (CO2) in exhalation.​
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• When measurement is taken at the end of a breath it is called end tidal (etCO2)​
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• It’s represented via a waveform over time ​
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• Measured in millimeters of mercury (mmHg)

Question 2

Low etCO2

Answer 2

Reduced pulmonary perfusion​

• Low cardiac output​
• Pulmonary Embolism ​
• Cardiac arrest ​

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Alveolar ventilation​

• Hyperventilation​
• Apnoea ​
• Total airway obstruction (not high airway pressures on your ventilator
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Other ​

• Hypothermia (metabolic rate decrease by 6% for every degree below 36)​
• Leaks

Question 3

High etCO2

Answer 3

Pulmonary perfusion​

• Increased cardiac output/MAP​

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Alveolar ventilation​

• Hypoventilation​
• Partial airway obstruction (secretions, kinks)​

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Other ​

• Hyperthermia​
• Wet/Old etCO2 (check patients pCO2 on ABG)