Biomedical Instrumentation Multiple Choice Questions on “Electroencephalograph (EEG)”.
1. Pulse oximetry is used to measure the oxygen level in blood & heart rate.
a) True
b) False
Answer: a
Clarification: Pulse oximetry is a technology used to measure the oxygen level in your blood and your heart rate. A finger pulse oximeter is equipped with technology to rapidly detect changes in your blood oxygen level.
2. How many wavelengths are used by Pulse Oximeter?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: Pulse oximetry is based on the concept that arterial oxygen saturation determinations can be made using two wavelengths, provided the measurements are made on the pulsatile part of the waveform.
3. Light passing through finger will be adsorbed by ___________
(i) Skin Pigments
(ii) Tissue
(iii) Arteries
(iv) Veins
a) (i) & (iii)
b) (ii) & (iv)
c) (i) & (ii)
d) (iii) & (iv)
Answer: c
Clarification: The two wavelengths assume that only two absorbers are present; namely oxyhaemoglobin (HbO2) and reduced haemoglobin (Hb).Light passing through the ear or finger will be absorbed by skin pigments, tissue, cartilage, bone, arterial blood, venous blood.
4. How is the blood flow in arteries and arterioles?
a) plug
b) laminar
c) parabolic
d) pulsatile
Answer: d
Clarification: Most of the absorbances are fixed and do not change with time. Even blood in the capillaries and veins under steady state metabolic circumstances is constant in composition and flow, at least over short periods of time.Only the blood flow in the arteries and arterioles is pulsatile.
5. Law obeyed by Pulse Oximeter is _______
a) Lambert-Bouguer law
b) Beer ‘s law
c) Beer-Lambert law
d) Lamber-Bouguer, Beer’s and Beer-Lambert Law
Answer: d
Clarification: Light passing through the ear or finger will be absorbed by skin pigments, tissue, cartilage, bone, arterial blood, venous blood. The absorbances are additive and obey the Beer-Lambert law. Beer-Lambert is combination of Lambert-Bouguer and Beer’s Law.
6. Which oximeter probe is in the picture?
a) Ear
b) Pulse
c) Skin Reflectance
d) Intravascular
Answer: b
Clarification: Components of pulse oximeter Probe.
7. How many LED’s are used in Pulse oximeter probe?
a) 1
b) 2
c) 3
d) 4
Answer: b
Clarification: This has two LEDs (light emitting diodes), one that transmits infrared light at a wavelength of approximately 940 nm and the other transmitting light at approximately 660 nm.
8. Oxygen saturation is estimated by _________
a) ratio (R) of pulse-added red absorbance at 660 nm to the pulse-added infrared absorbances at 940 nm
b) ratio (R) of pulse-added red absorbance at 940 nm to the pulse-added infrared absorbances at 660 nm
c) ratio (R) of pulse-added red absorbance at 330 nm to the pulse-added infrared absorbances at 940 nm
d) ratio (R) of pulse-added red absorbance at 940 nm to the pulse-added infrared absorbances at 330 nm
Answer: a
Clarification: Oxygen saturation is estimated from the ratio (R) of pulse-added red absorbance at 660 nm to the pulse-added infrared absorbances at 940 nm.
9. What gets affected by lower saturation?
a) blood flow
b) translucency
c) accuracy
d) low atmospheric pressure
Answer: c
Clarification: An accuracy of 1% or better has been reported for the saturation range of above 80% for most transmission type pulse oximeters. Usually, the accuracy is less at lower saturation because of non-linear effects of absorption.
10. What factors has no significant influence on the measurement?
a) skin pigmentation
b) thickness
c) tissue
d) skin pigmentation, thickness and tissue
Answer: d
Clarification: The instrument can be empirically calibrated. Subject variability (skin pigmentation, thickness, tissue, sensor location, etc.) has no significant influence on the measurement.