<prompt> Which is false regarding pulse oximetry?Hemoglobin saturation can be monitored in real timeIn heavy smokers it may show a false high valueFalse value in anaemiaProbe can be attached to ear lobe in children  <response>: 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 