4.2. Measurements
            4.2.3. Gas analysis
                4.2.3.3. Other techniques
4.2.3.3.1. Capnograph

Capnograph

... graphical measurement of CO2 versus time

Measurement options

Most common: infrared absorption spectroscopy

Disadvantage

Interference

Response time

Consists of transit time and rise time

Transit time (lag time)

... is time for gas to reach sensor

Depends on

Rise time

... time for analyzer to respond to an input signal

Others

4 phases of capnograph

  1. Inspiratory - baseline
  2. Expiratory upstroke - consists of dead space gas and early CO2 output
    * slope is an indication of dead space volume
  3. Alveolar plateau - exhalation of alveolar gas
  4. Inspiratory downslope - beginning of next inspiration

End-tidal CO2

Keywords:  Capnograph ; End-tidal pCO2
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Created20050602
Reviewed20050602


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