Pulse Oximetry Flashcards
How does pulse oximetry work?
What about the wavelengths?
LED in pulse ox do what?
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
Causes of inaccuracy for pulse oximetry:
Nail polish (greatest effect with blue)
Motion artifact
Electrocautery
Loss of signal with hypo-perfusion
Errors in pulse oximetry:
Carboxyhemoglobin: overestimates the fraction of hemoglobin available for oxygen support
Methemoglobin: at high levels, spo2=85%
Transient decrease with indocyanine green and methylene blue