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
2
Q
Causes of inaccuracy for pulse oximetry:
A
Nail polish (greatest effect with blue)
Motion artifact
Electrocautery
Loss of signal with hypo-perfusion
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
