Capnography – So Easy And Effective

Capnography can detect early phases of respiratory depression which can allow more precise and safe use of medications. Monitoring of exhaled carbon dioxide should be considered for all patients receiving medications that will potentially experience decreased respiratory rates.
The comparison between capnography and pulse oximetry:


  • Carbon Dioxide Reflects ventilation
  • Hypoventilation/apnea detected immediately
  • Reflects ventilation changes within 10 seconds
  • Should be used with pulse Oximetry

Pulse Oximetry:

  • Oxygen saturation Reflects oxygenation
  • SpO2 changes lag when patient is hypoventilation or apneic
  • Reflects changes in oxygenation with 5 minutes
  • Should be used with capnography

History of Capnography

Capnography used by anesthesiologists since the 1970's and has been the standard of care in the operating rooms since 1991. Recommendations and standards set by Joint Commission are expanding the utilization of Capnography. It has value for the transport teams and is utilized with intubated and non-intubated patients. Hospital uses include: patient receiving moderate sedation, patients on PCA, and intubated patients. Capnography can also be used in the neonatal and pediatric population.

What is Capnography?

It is a noninvasive method of measuring the exhaled carbon dioxide (EtCO2) concentration over a period of time. The value is displayed digitally on the monitor screen. There is also a distinct waveform (tracing) for each respiratory cycle. Detection of obstructive apnea requires the evaluation of oral or nasal airflow. Accurate information about the rhythm and rate of respirations can be obtained by monitoring capnography. Early signs and symptoms of high levels of carbon dioxide over 45mmHg include flushed skin, rapid respiratory rate, dyspnea and reduced neural activity. In severe increased levels other signs may include confusion, lethargy, arrhythmias, convulsions, unconsciousness and potentially death.

The advanced capnography is very user friendly- it just plugs into the monitor adaptor, requires no zeroing or calibration, uses laser technology, and is not affected by other gases. It can be used on non-intubated patients through a nasal cannula.

Patients who are hypo ventilating will have a lower respiratory rate resulting in an increased CO2. Example of patients benefiting from this monitoring system include sedated patients or those receiving pain management. These patients many times experience decreased respiratory rates related to pain medication. Capnography can assist in the decision regarding the continued use of sedative or pain medications or determining patients sedation levels.

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