Week 9- Capnography

Question 1

What is Capnography?

Answer 1

• Continuous analysis and recording of CO2 concentration in respiratory gases
• Uses waveforms and numbers

Question 2

Respiratory cycle

Answer 2

• Metabolism, perfusion, ventilation

Question 3

Waveform Capnometry

Answer 3

• Adds continuous waveform display to the ETCO2 value
• Additional information in waveform shape can provide clues about causes of poor oxygenation

Question 4

ETCO2 Values

Answer 4

• Normal 35-45 mmHg
• Hypoventilation >45 mmHg
• Hyperventilation <35 mmHg

Question 5

Physiology

Answer 5

Relationship between CO2 and RR

• High RR = Low CO2- Hyperventilation
• Low RR = High CO2- Hypoventilation

Question 6

Pulse Oximetry vs Capnography

Answer 6

Pulse Oximetry
- Oxygen saturation
- Reflects oxygenation
- SPO2 changes lag when patient is hypoventilating or apneic
- Should be used with capnography

Capnography
- Carbon dioxide
- Reflects ventilation
- Hypoventilation/ apnea detected immediately
- Should be used with pulse oximetry

Question 7

Normal Waveform

Answer 7

• Square box waveform
• ETCO2 35-45 mmHg
• Management: Monitor Patient

Question 8

Dislodged ETT Waveform

Answer 8

• Loss of waveform
• Loss of ETCO2 reading
• Managements: Replace ETT

Question 9

Esophageal Intubation Waveform

Answer 9

• Absence of waveform
• Absence of ETCO2
• Management: Re-intubate

Question 10

CPR Waveform

Answer 10

• Square box waveform
• ETCO2 10-15 mmHg (possibly higher) with adequate CPR
• Management: Change rescuers if ETCO2 falls below 10 mmHg

Question 11

Obstructive Airway Waveform

Answer 11

• Shark fin waveform
• With or without prolonged expiratory phase
• Can be seen before actual attack
• Indicative of bronchospasm (asthma, COPD, allergic rxn)

Question 12

ROSC (Return of Spontaneous Circulation) Waveform

Answer 12

• During CPR sudden increase of ETCO2 above 10-15 mmHg
• Management: Check for pulse

Question 13

Hypoventilation Waveform

Answer 13

• Prolonged waveform
• ETCO2 >45 mmHg
• Management: Assist ventilations or intubate as needed

Question 14

Hyperventilation Waveform

Answer 14

• Shortened waveform
• ETCO2 <35 mmHg
• Management: If conscious gives biofeedback. If ventilating slow ventilations

Question 15

What does this all mean?

Answer 15

• ETCO2 is a great tool to help monitor the patient’s breath to breath status
• Can help recognize airway obstruction before the patient has signs of attacks
• Helps you control the ETCO2 of head injuries
• Can help identify ROSC in cardiac arrest