/ ACLS Glossary

What is Quantitative Waveform Capnography?

AHA Guidelines for Advanced Cardiac Life Support (ACLS) now recommend the use of quantitative waveform capnography when intubating patients during CPR.

This practice enables health care providers to monitor the quality of resuscitation, optimize chest compressions and quickly and accurately identify ROSC (return of spontaneous circulation.)

Additionally, continuous waveform capnography, coupled with clinical assessment, is considered to be the most reliable technique for confirming and monitoring the proper placement of an ET tube.

But what, exactly, is this treatment method and why is it so important for you to know?

Let’s take a look.

What is Quantitative Waveform Capnography?


Quantitative waveform capnography involves the continuous, non-invasive measurement of end-tidal carbon dioxide / ETCO2, also known as PetCO2.

Capnography utilizes a sensor/sample chamber which is placed for the optimal evaluation of expired CO2.

The carbon dioxide that is inhaled and exhaled is then graphically displayed on the monitor as a waveform, along with its corresponding numerical measurement.

Used as an assessment tool while CPR is being performed, capnography can assist the ACLS provider in determining a variety of things, including a direct measurement of lung ventilation as well as indirect measurement of circulation and metabolism.

For instance, a drop in cardiac output (perfusion) will decrease the delivery of carbon dioxide to the lungs.

This, in turn, will cause a decrease in the ETCO2 (end-tidal CO2), something that will be visible on the waveform as well as through the numerical measurement.

Practical Applications of Quantitative Waveform Capnography


Two practical uses of quantitative waveform capnography in CPR are as follows:

1. Evaluation of the effectiveness of chest compressions
2. Identification of ROSC (return of spontaneous circulation)

Assessing the effectiveness of chest compressions during CPR can be accomplished through the measurement of ETCO2 value.

For instance, a low ETCO2 value (< 10 mmHg) during CPR on a patient who is intubated would indicate that the quality of chest compressions being performed needs to be improved.

High quality chest compressions are represented by a value of at least 10-20 mmHg.

When ROSC occurs, ETCO2 will increase significantly (35-45 mmHg.) This increase represents a dramatic improvement in blood flow.

Subsequently, more CO2 is being pushed into the lungs by the improved circulation.

For patients in cardiac arrest who are intubated, quantitative waveform capnography is now considered the preferred method for monitoring the quality of chest compressions and determining when the patient has achieved ROSC.

Quantitative waveform capnography is one of the many critical topics covered in online ACLS certification coursework.

Study materials, quizzes and online tests will ensure that students gain an in-depth understanding of the concepts involved in capnography.