QUIZ answers:

Answers & Explanations to the quiz questions

All can give inaccurate reading with pulse oximeter except: [CEE 2077]

   a. Jaundice

   b. Methemoglobinemia

   c. Henna

   d. Nail paint

Ans: a

Ref: Morgan & Mikhail’s Clinical Anesthesiology, 5th Edition, Page No: 125

Ref: The effect of nail polish on pulse oximetry by C J Coté in Anesth Analg; 1988 Jul;67(7):683-6.

Ref: Effect of henna (mehndi) on pulse oximetry reading; Nazia Uzma.

Ref: Hyperbilirubinemia does not interfere with hemoglobin saturation measured by pulse oximetry; Anesthesiology; 1989 Jan;70(1):118-22

Ref: Henna dye: A cause of erroneous pulse oximetry readings by Mustapha Bensghir; Saudi J Anaesth. 2013 Oct-Dec; 7(4): 474–475.

Hyperbilirubinemia does not interfere with hemoglobin saturation measured by pulse oximetry.

Henna, when newly applied, causes a black discolouration of the skin. During this initial phase, it absorbs all wavelengths of visible light, allowing only infrared rays to pass through. This results in the failure to monitor oxygen saturation using pulse oximeters.

Black, blue, and green nail polish significantly lowered oximeter readings of oxygen saturation. Blue and green produced greater decreases than purple and red; black produced an intermediate decrease.

Methemoglobinemia causes a falsely low saturation reading when Sa o 2 is actually greater than 85% and a falsely high reading if SaO2 is actually less than 85%.

Most pulse oximeters are inaccurate at low SpO2, and all demonstrate a delay between changes in SaO2 and SpO2. Other causes of pulse oximetry artifact include excessive ambient light, motion, methylene blue dye, venous pulsations in a dependent limb, low perfusion (eg, low cardiac output, profound anemia, hypothermia, increased systemic vascular resistance), malpositioned sensor, and leakage of light from the light-emitting diode to the photodiode, bypassing the arterial bed (optical shunting).