Two of Ten

Had the day off, spent the morning working on a document called "Ten Things Every Paramedic Should Know about Capnography," which I hope to post soon.

Here's the first 2 Things:

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1. Definitions

Capnography – the measurement of carbon dioxide (C02) in exhaled breath.

Capnometer – the numeric measurement of C02.

Capnograph – the wave form.

“End Tidal CO2 reading without a waveform is like a heart rate without an ECG recording.” – Bob Page “Riding the Waves”


2. Oxygenation versus Ventilation

Oxygenation is how we get oxygen to the tissue. Oxygen is inhaled through the lungs and transported through the blood. Pulse oximetry measures oxygenation.

At the cellular level, oxygen and glucose combine to produce energy. Carbon dioxide, a waste product of this process (The Krebs cycle), diffuses into the blood.

Ventilation is how we get rid of carbon dioxide. Carbon dioxide is carried back through the blood and exhaled by the lungs. Capnography measures ventilation.

Capnography provides an immediate picture of patient condition. Pulse oximetry is delayed. Hold your breath. Capnography will show immediate apnea, while pulse oximetry will show a high saturation for a couple minutes or more.

“Pulse oximetry may provide a false sense of security, even as C02 levels rise to dangerous levels.”

-Baruch Krauss, M.D.
Capnography in EMS
JEMS, January 2003