Pulse Oximetry Flashcards

1
Q

How does pulse oximetry work?
What about the wavelengths?
LED in pulse ox do what?

A

Light absorbance measurements of pulsatile blood are used to determine the concentration of various species of hemoglobin.
2 wavelengths of light are used to distinguish oxyhemoglobin from reduced hemoglobin.
LEDs in pulse sensor emit red 660 nm and near infrared 940 mm light

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2
Q

Causes of inaccuracy for pulse oximetry:

A

Nail polish (greatest effect with blue)
Motion artifact
Electrocautery
Loss of signal with hypo-perfusion

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3
Q

Errors in pulse oximetry:

A

Carboxyhemoglobin: overestimates the fraction of hemoglobin available for oxygen support
Methemoglobin: at high levels, spo2=85%
Transient decrease with indocyanine green and methylene blue

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