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How to Understand Capnography?

Knowing a patient's oxygen levels can provide important information about their breathing status. But, did you know that measuring their exhaled carbon dioxide is often just as important? You can read this vital sign with a device called a capnography, which produces a waveform that closely resembles an electrocardiogram.

1. Understanding capnography information 

Understanding capnography can tell you anything from whether your airway placement was successful to whether the patient suffered respiratory impairment. Therefore, these devices are equally valuable for triage and long-term monitoring. A capnogram measures ventilation by a measure called end-tidal carbon dioxide. The normal range for patients regardless of age, sex, race or size is between 35-45 mm Hg or about 5% CO2. When you look at the capnogram, you will notice that the vertical axis measures the EtCo2 value. The horizontal axis represents elapsed time.

Understand that capnograms show real-time scrolling and are usually not marked. In this case the exact EtCO2 value will be displayed elsewhere on the screen. You will use wave shapes to explain general ventilation patterns. Standard of care for end-tidal capnography will vary depending on your setting and circumstances – for example, field nurses may use slightly different methods than an anesthetist in an operating room. Even so, you can read waveforms displayed on capnography equipment in the same way, regardless of the machine used or the condition of the patient. Ekingst portable capnography device is one great option for you.

2. How to understand the capnography information?

How to have an understanding of a capnogram can give you a superficial understanding of a patient's ventilation status. However, learning how to interpret the data you read can also tell you about their perfusion, metabolic status, and any abnormal respiratory status. You can use ekingst waveform capnography device to help you know more about the data.

Hypoventilation: Slow breathing and/or hypoventilation can lead to a build-up of carbon dioxide in the body. A hypoventilated person will have an end-tidal carbon dioxide value above 45 mm Hg. You'll also notice that their wave rectangles appear elongated due to the longer time between breaths.

Hyperventilation: If your patient is breathing more than 20 breaths per minute, they are eliminating far more carbon dioxide than average. This excess elimination results in a decrease in the concentration of carbon dioxide in the body.

A typical capnographic waveform for hyperventilation will still have a near normal shape. Outstanding feature is EtCO2 well below the typical 35 mm Hg. You'll also notice that the rectangle is smaller than normal due to the shorter time between breaths. Potential reasons you might see this waveform include metabolic acidosis, anxiety or panic attacks, or even rapid manual ventilation with an artificial airway or bag-valve mask.