Normal and Abnormal etCO2/Capnograph Waveforms
Normal Capnogram
The normal capnogram is a waveform which represents
the varying CO2 level throughout the breath cycle.
etCO2: 35-45 mmHg
CO2 (mmHg)
40
C
Waveform Characteristics:
A-B: Baseline
D: End-Tidal Concentration
B-C: Expiratory Upstroke
D-E: Inspiration
A B
0
D
E
Rebreathing CO2
Resp Rate = 14
etCO2: >45 mmHg
Other Possible Causes:
60
60
• Faulty expiratory valve
40
40
• Inadequate inspiratory flow
20
Rebreathing CO2
• Partial rebreathing
15 sec.
20
15 sec.
• Insufficient expiratory time
C-D: Expiratory Plateau
Bronchospasm/Asthma
Resp Rate = 24
Loss of Plateau
etCO2: >45 mmHg
Curare Cleft
Resp Rate = 16
60
Other Possible Causes:
60
etCO2: 35-45 mmHg
Curare Cleft
Other Possible Causes:
60
• Bronchospasm/COPD
40
40
• Patient is mechanically ventilated
40
40
• Obstruction in the expiratory limb of the
breathing circuit
20
20
• Depth of cleft is proportional to
degree of muscle relaxants
20
20
15 sec.
• Presence of a foreign body in the upper airway
60
15 sec.
• Partially kinked or occluded artificial airway
*Increasing etCO2 (Hypoventilation)
etCO2: >45 mmHg
Resp Rate =8
Other Possible Causes:
60
• Decrease in respiratory rate
40
• Decrease in tidal volume
20
etCO2 rises gradually
60
*Decreasing etCO2 (Hyperventilation)
60
40
• Decreased or absent cardiac output
40
20
• Decreased or absent pulmonary
blood flow
20
15 sec.
Other Possible Causes:
60
• Increase in respiratory rate
40
• Increase in tidal volume
20
• Metabolic acidosis
• Fall in body temperature
etCO2 drops gradually
60
40
20
15 sec.
60
Rescuer Change
Return of Spontaneous
Circulation
Other Possible Causes:
• Increase in cardiac output
• Increase in pulmonary blood flow
40
20
30 min. Trend Graft
• Sudden decrease in CO2 values
etCO2: <35 mmHg
Resp Rate = 22
Resp Rate = 12
Other Possible Causes:
• Increase in metabolic rate
• Rapid rise in body temperature (malignant hyperthermia)
Cardiac Arrest
Resp Rate = 12
60
Successful
Defibrillation
Return of Spontaneous Circulation
40
20
60
40
CPR
20
30 min. Trend Graft
• Gradual increase in CO2 production
*Assumes adequate circulation and alveolar gas exchange
COVIDIEN, COVIDIEN with logo, Covidien logo and positive results for life are U.S. and internationally registered trademarks of Covidien AG. ©2013 Covidien. 13-PM-0231 MN38313