By Aaron Dix
Capnography is an essential tool to assess and treat numerous conditions, ranging from respiratory distress to sepsis. Track expired or exhaled carbon dioxide, known as ETCO2, to monitor the effectiveness of chest compression and correct placement of an endotracheal tube.
While capnography is typically associated with ALS providers, EMTs can easily learn and utilize this assessment tool either to assist the ALS provider or as a triage tool to identify those patients who require ALS interventions.
Here are five patient scenarios to teach capnography to BLS providers while utilizing simulation as an educational tool.
In this educational experience, simulation is utilized as an interactive adult centered mode of education.
Learning objectives for capnography training simulations
At the completion of this training the BLS provider is able to:
- Identify four primary capnography waveform patterns: normal, hypoventilation, hyperventilation and bronchial constriction.
- Predict ETCO2 levels based upon respiratory rate and lung sounds.
- Recognize endotracheal tube displacement.
- Identify patients who could benefit from ALS care based upon the capnography waveform and numerical value.
Scenario 1: Healthy patient
This simulation should begin with a pathologically healthy 40-year-old male with normal vital signs. Most high-fidelity simulators have a healthy patient mode that allows for basic functioning of the simulator without any programing. Use the healthy patient to show the normal capnography waveform with a basic discussion of its shape, rate and size. Also, discuss the waveform’s direct correlation with respiratory rate.
Scenario 2: Hyperventilation (hypocapnea)
Brief students on this patient presentation. A 26-year-old female presents to EMS complaining of shortness of breath after an assault. She is awake and alert, clearly upset, speaking in short sentences and states she has a history of asthma. Program the simulator with these parameters for hyperventilation:
- Heart rate 110
- B/P 118/76
- Respiratory rate 40
- SpO2 98% on ambient air
- ETCO2 of 20 mm HG
- Clear lung sounds
Discuss with students the pathophysiology of hyperventilation with particular attention paid to the direct inverse correlation between respiratory rate and ETCO2 levels. A further discussion of the waveform shape along with clear lung sounds should follow.
Scenario 3: Hypoventilation (hypercapnia)
Brief students on this patient presentation. EMS finds a 30-year-old male unresponsive on the sidewalk with no other information available. Program the simulator with these parameters for hypoventilation.
- Heart rate 110
- B/P 100/60
- Respiratory rate 6
- SpO2 92% on ambient air
- ETCO2 of 70 mm HG
- Clear lung sounds.
During the debrief with students, discuss the pathophysiology of hypoventilation with particular attention paid to the direct inverse correlation between respiratory rate and ETCO2 level. In this scenario as the respiratory rate decreased, ETCO2 rose.
A further discussion of patient severity while comparing hyper- and hypoventilation to should occur. In addition, explain to students the sensitivity of capnography compared to pulse oximetry to recognize acuity.
Upon the conclusion of this case, provide a basic summary which covers normal ventilation, hyperventilation and hypoventilation with particular attention paid to the normal shape of the capnporgaphy waveform and the direct inverse correlation between rate and ETCO2 levels.
Scenario 4: Bronchial constriction
Brief students on this patient presentation. A 55-year-old female presents to EMS with a history of asthma, heart failure and hypertension. She complains of increasing shortness of breath over the past hour with no relief from her metered dose inhaler. Program the simulator with these parameters:
- Heart rate 110
- B/P 150/72
- Respiratory rate 30
- SpO2 94% on ambient air
- ETCO2 of 55 mm HG
- Wheezing bilaterally
During the debrief, make sure students are able to recognize the difference in shape in the capnography waveform from the normal patient. Discuss why shape of the waveform has changed in addition to highlighting why in this case hypercarbia has occurred in the presence of tachypnea.
Scenario 5: Tube displacement
Brief students on this patient presentation. They are assisting a paramedic who hasjust intubated a 60-year-old male using rapid sequence induction. The patient has signs and symptoms of a major stroke. Program the simulator with these parameters:
- Heart rate 72
- B/P 180/94
- Respiratory rate assisted
- SpO2 100%
- ETCO2 of 45 mm HG
Within 60 seconds of starting the scenario, the tube should be partially dislodged from the airway with a corresponding elimination of capnography waveform while maintaining an oxygen saturation of 100 percent. The students should immediately recognize the absence of the capnography waveform and identify a possible dislodged endotracheal tube as the cause. During debrief, discuss the time difference between oxygen saturation and capnography when monitoring appropriate tube placement.
When implementing simulation-based scenarios that utilize capnography, be aware that most high-fidelity simulators do not have the capability of providing actual carbon dioxide. While the simulation software can display capnography waveforms and values, participants will more than likely be unable to get actual readings on their specific patient care monitors when connected to the simulator. Facilitators should be knowledgeable of the limitations of their simulators and use the patient monitor screens that come with the simulator when necessary.
In conclusion, capnography can be used as a component of an EMT’s assessment and help provide additional support when determining the need for ALS. For example, by utilizing capnography, the EMT can learn to distinguish between hyperventilation, which is best treated with verbal coaching, and bronchoconstriction, which requires activation of ALS for medication administration.
About the author
Aaron Dix is the operations director for the Greenville Healthcare Simulation Center. He has a MBA in health care management, is a nationally certified EMS educator, and has 20 years of EMS experience. Previously he was the training coordinator for the largest and busiest EMS system in South Carolina, managing the education of over 500 EMTs, paramedics and firefighters. In addition to his duties at the simulation center, he remains a practicing paramedic with Anderson County EMS, Clear Spring Fire Rescue, and is an active member of the Emergency Medical Services for Children Advisory Council in South Carolina.