What can capnography tell you?

The capnograph is the waveform that shows how much CO2 is present at each phase of the respiratory cycle, and it normally has a rectangular shape. Capnography also measures and displays the respiratory rate. Changes in respiratory rate and tidal volume are displayed immediately as changes in the waveform and ETCO2.

Why is capnography important?

Capnography is an effective method to diagnose early respiratory depression and airway disorders, especially during sedation, leading to a reduction in serious complications (23, 24). Capnography provided more safety in monitoring patients during sedation.

What does a Capnometer measure?

Capnometers measure carbon dioxide (CO2) in expired air and provide clinicians with a noninvasive measure of systemic metabolism, circulation, and ventilation. If two of these systems are held relatively constant, changes in CO2 excretion will reflect the third.

What is the capnography waveform a representation of?

of CO2 exhaled
Waveform capnography is a graphical representation of the concentration of CO2 exhaled, used as an indirect indicator of the actual concentration, or partial pressure, of CO2 in arterial blood.

What are the phases of capnography?

The normal capnography waveform Phase I is the inspiratory baseline, which is due to inspired gas with low levels of CO2. Phase II is the beginning of expiration which occurs when the anatomic dead space and alveolar gas from the alveoli/bronchioles transition. a. The transition from phase II to III is the alpha angle.

How is capnography done?

Capnography uses infrared waves to measure CO2. Infrared waves are waves that are invisible to the eye and have a lower frequency than visible light. The frequency is below red light, which is why it is called “infra” red. Infrared is absorbed by gases that have “two or more different atoms.

Which factor can affect the result of capnography?

The presence of high airway resistance, respiratory rate, or inspiratory-to-expiratory ratio may decrease the accuracy of the measurement obtained from a sidestream capnograph, compared to a mainstream capnograph. In addition, a breathing frequency > 10 breaths/min affects different capnographs differently.

What is Capnometry and capnography?

Capnography is the continuous analysis and recording of the CO2 concentration in respiratory gas. Although the terms capnography and capnometry are sometimes considered synonymous, capnometry means only the measurement of CO2 in respiratory gas (ie, analysis alone), without a continuous written record or waveform.

What should capnography read?

Capnography measures ventilation through a metric known as end-tidal carbon dioxide (EtCO2). EtCO2 values are recorded in mm Hg (millimeters of mercury), a unit of pressure. The normal values for patients regardless of age, sex, race, or size range between 35-45 mm Hg, or about 5% CO2.

How does capnography change during inspiration?

How does capnography waveform change during inspiration?

During inspiration, CO2 is essentially zero and thus inspiration is displayed at the zero baseline. Phase 1 occurs as exhalation begins, which is shown as A to B on the capnogram. The first gas to appear at the sampling point is the last gas that was inhaled into the conducting airways.