Teaching Capnography: Sequence instruction from pathophysiology to advanced waveform interpretation

Students need to know that capnography is part of the standard of care and is one of the most important diagnostic tools at their disposal


By Chris Cebollero 

Since the introduction of the 12-Lead EKG to EMS in the late 90’s has there been a more important piece of equipment then capnography? Your cardiac monitor with capnography capability has all the tools you need to find out the patient’s problem, determine a course of treatment and more importantly determine if that treatment is working.

Just like teaching 12-Leads, teaching the finer points of capnography can be a challenge. As an instructor you need to develop content and prepare to be creative, dynamic and fluid in your teaching style for students to gain an understanding and working knowledge of this powerful tool.

Preparation

The secret to creating a positive learning environment is preparation. In EMS education, preparation is too often grossly ignored and pushed aside. Standing in front of a class and reading from a PowerPoint slide deck, with your back to the class, is a failure on many levels. Be the instructor you would want to teach you.

A great instructor:

  • Is always prepared and practices. Spend as much as three hours of prep and practice for every hour of instruction.
  • Considers their class to be a performance. Be dynamic, energetic and use your presentation skills as a prop to deliver an awesome program.
  • Always watches the audience, makes eye contact and assesses whether the students are connecting with the material.
  • Develops and uses multiple examples to teach the same point to the different types of adult learners in the class.

A Field Training Officer (FTO) is just as accountable as an instructor that delivers initial paramedic education or a training officer teaching refresher courses. Even though an FTO’s classroom is the ambulance, a patient’s residence or a hospital emergency room an FTO needs to deliver with the same energy.

Capnography lesson plan objectives

Whether you are teaching capnography in the classroom or in the back of an ambulance, you have to ensure all the objectives are met. When creating a lesson plan remember these objectives:

  • Explain what capnography is
  • Explore the pathophysiology for exhaled carbon dioxide
  • Describe the function of end tidal monitoring
  • Demonstrate the different types of ETCO2 detectors
  • Recognize the field uses for capnography

Capnography hands-on skills

Grasping an understanding of capnography in a single lecture is an impossible challenge. This is not a skill that gets mastered in one lesson. For this reason, you should spend more time on the basics as students prepare for and participate in hands-on activities:

  • Refresh knowledge of respiratory anatomy and physiology
  • Master reading of a normal capnogram waveform.
  • Connect the underlying pathophysiology of ventilation and metabolism to normal and abnormal waveforms

Throughout the training, use as many waveform examples with matching patient scenarios as possible. It is best to outline the patient’s presentation, condition, vital signs and history before introducing the waveform and 12-Lead. This will assist the student in developing a relationship between the patient’s presentation and what to expect from the diagnostic findings.

Test students’ knowledge retention by asking them to draw and label a waveform as you present the four phases of inhalation and exhalation. See if students comprehend by capnography giving them a patient presentation, such as asthma or sepsis, and having them draw the anticipated waveform.

Keep building knowledge and confidence

As students develop mastery of what normal looks like introduce abnormal waveforms, one at a time, with the corresponding conditions they represent. Remember there are three basic abnormal waveforms:

1. Hypoventilation which is related to a decreased respiratory rate and will display fewer waveforms per minute. Each waveform has an increased height.

2. Hyperventilation which is related to an increase in respiratory rate and will display a higher number of waveforms per minute. You will also see a decreased height of the waveforms due to the presence of less exhaled CO2 per breath. (Ask students other reasons a waveform might have a lower height.)

3. Bronchospastic waveforms are identified by the shark-fin shape instead of the rounder-box waveform. Bronchospasms cause a slower, more variable release of CO2 from the alveoli which results in a slower rise in the expiratory upstroke.

Throughout training emphasize the importance of this powerful tool. From the very beginning students need to understand capnography is the standard of care for every patient. Mastering the use and interpretation of capnography takes a combination of knowledge, skill, and experience, and changes the game in patient treatment and management.  

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