Basic training in Veterinary Capnography

1. Capnogram

2. Normal Capnograph Waveform Characteristics
Normal Wave
• A-B Baseline
• B-C Expiratory Upstroke
• C-D Expiratory Plateau
• D End Tidal Concentration
• D-E Inspiration Begins
This is the normal capnograph. A wave
form is present; the wave form begins
at the base line, raises steeply, plateaus
with a gradual upslope, and quickly
returns to the baseline. Finally, the end
tidal CO2 reading is within the normal
range of 35-45 mmHg.

3. Possible Causes Actions
Esophageal Intubation
• The ET tube may be placed in
the esophagus, either no CO2 is
sensed or only small transient
waveforms are present.
• Check that ET tube is correctly
positioned and that proper
ventilation is occurring.

4. Possible Causes Actions
Inadequate ET Tube Seal
• A leaky or deflated endo-tracheal
or tracheostomy cuff
• An artificial airway that is too
small for the patient
• Check cuff and breathing circuit

5. Possible Causes Actions
Airway Obstruction
• Obstruction in the expiratory limb
of the breathing circuit
• Presence of a foreign body in the
upper airway
• Partially kinked or occluded artifi-
cial airway
• Bronchospasm
• Check the breathing circuit
• Tracheal suctioning

6. Possible Causes Actions
Rebreathing/Increased Baseline
• Faulty expiratory valve
• Inadequate inspiratory flow
• Malfunction of a CO2 absorber
system
• Insufficient expiratory time
• Check the expiratory valve and
CO2 absorbant
• Check O2 flow
• Decrease mechanical dead space

7. Possible Causes Actions
Increasing EtCO2
• Decrease in respiratory rate
(hypoventilation)
• Decrease in tidal volume
(hypoventilation)
• Increase in metabolic rate
• Rapid rise in body temperature
(malignant hyperthermia)
• Ventilate the patient
• Check temperature
Possible Causes Actions

8. Possible Causes Actions
Decreasing EtCO2
• Increase in respiratory rate
(hyperventilation)
• Increase in tidal volume
(hyperventilation)
• Decrease in metabolic rate
• Fall in body temperature
• Check the patient
• Assess anesthetic depth
• Check the breathing circuit

9. Possible Causes Actions
Loss of Alveolar Pattern
• Bronchoconstriction
• Asthma
• COPD
• Airway obstruction
• Administer bronchodilators
• Tracheal suctioning