Which is false regarding pulse oximetry?
Anaemia does not affect the reading of pulse oximetry. Factors affecting its accuracy- 1. Dyshemoglobins For example Met Hb absorb red and infrared wavelengths of light in a 1:1 ratio corresponding to an SpO2 of approximately 85%. Therefore, increases in Met Hb produce an underestimation when SpO2> 70% and an overestimation when SpO2 <70%. 2. Dyes (Methylene blue, indocyamine green) 3. Nail polish 4. Ambient light 5. Hypotension 6. Hypothermia 7. electrocautery
Hemoglobin saturation can be monitored in real time
In heavy smokers it may show a false high value
False value in anaemia
Probe can be attached to ear lobe in children
Monitoring in Anesthesia