**5.1.4 Pulse oximeters**

Usually two oximeters are placed , one in the upper limb and other in the lower extremity. Pulse oximeter uses two light emitting diodes and one photodiode for detection of red and infra red lights.

Accuracy of pulse oximeter is affected by

	- a. Thick skin
	- b. Dark color
	- c. Bright outside light
	- d. Presence of dyes like indocyanine green and methylene blue
	- a. Met Hb
	- b. Carboxy Hb

Not affected by fetal hemoglobin.
