Biomedical Instrumentation Questions and Answers – Vectorcardiography (VCG)

This set of Biomedical Instrumentation Multiple Choice Questions & Answers (MCQs) focuses on “Vectorcardiography (VCG)”.

1. Which gas saturation is of great importance in clinical practice?
a) oxygen
b) carbon dioxide
c) hydrogen
d) nitrogen
View Answer

Answer: a
Explanation: In clinical practice, the percentage of oxygen saturation in the blood is of great importance. This saturation being a bio-constant is an indication of the performance of the most important cardio-respiratory functions. It is maintained at a fairly constant value to within a few percents in a healthy organism.

2. Liquid part of blood is __________
a) Platelets
b) Red Blood Cells
c) White Blood Cells
d) Plasma
View Answer

Answer: d
Explanation: The plasma (liquid part of the blood) is a very poor carrier of oxygen. At the pressures available, only 0.3 ml of oxygen can dissolve in 100 ml of plasma, which is quite insufficient for the needs of the body.

3. What does red blood cells contain for combining with a large volume of oxygen?
a) Proteins
b) Haemoglobin
c) Lipids
d) Platelets
View Answer

Answer: b
Explanation: The red blood cells contain haemoglobin which can combine with a large volume of oxygen so quickly that in the lungs it may become 97% saturated forming a compound called oxyhaemoglobin.
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4. How much quantity of oxygen bound with haemoglobin in the normal arterial blood?
a) 20.3ml %
b) 21.5ml %
c) 19.4ml %
d) 20.1ml %
View Answer

Answer: c
Explanation: The total quantity of oxygen bound with haemoglobin in the normal arterial blood is approximately 19.4 ml percent at a pO2 of 95 mmHg. On passing through the tissue capillaries this amount is reduced to 14.4 ml percent at a pO2 of 40 mmHg.

5. When blood is withdrawn from the subject under anaerobic conditions and measurement for oxygen saturation is made at a later time in the laboratory, the procedure is referred to as _________ oximetry.
a) in vitro
b) in vivo
c) transmission
d) reflection
View Answer

Answer: a
Explanation: When blood is withdrawn from the subject under anaerobic conditions and measurement for oxygen saturation is made at a later time in the laboratory, the procedure is referred to as in vitro oximetry.

6. For discrete blood samples, a spectrophotometric measurement of oxygen saturation can be made by which method?
a) in vitro
b) in vivo
c) transmission
d) cannot be determined
View Answer

Answer: c
Explanation: For discrete blood samples, a spectrophotometric measurement of oxygen saturation can be made by either a transmission method or a reflection method.

7. Which principle is used by ear oximeter usually?
a) in vivo
b) transmission
c) reflection
d) in vitro
View Answer

Answer: b
Explanation: Ear oximeters usually make use of the transmission principle to measure arterial oxygen saturation. In this case, the pinna of the ear acts as a cuvette. Blood in the ear must be made similar to arterial blood in composition.
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8. Blood in _________ must be made similar to arterial Blood in composition.
a) heart
b) brain
c) ear
d) eyes
View Answer

Answer: c
Explanation: Blood in the ear must be made similar to arterial blood in composition. This is done by increasing the flow through the ear without appreciably increasing the metabolism. Maximum vasodilatation is achieved by keeping the ear warm.

9. By keeping the ear warm, maximum vasodilatation is achieved.
a) True
b) False
View Answer

Answer: a
Explanation: Yes, maximum vasodilatation is achieved by keeping the ear warm. It takes about 5 or 10 min for the ear to become fully dilated after the ear unit has been put up in place and the lamp turned on.
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10. What is time taken for the ear to become fully dilated after ear unit has been placed?
a) 5-10 min
b) 10-15 min
c) 15-20 min
d) 20-25 min
View Answer

Answer: a
Explanation: Maximum vasodilatation is achieved by keeping the ear warm. It takes about 5 or 10 min for the ear to become fully dilated after the ear unit has been put up in place and the lamp turned on.

11. Merrick and Hayes (1976) describe details of a _________ oximeter which enables the measurement of oxygen saturation of blood.
a) Pulse
b) Ear
c) Skin Reflactance
d) Intravascular
View Answer

Answer: b
Explanation: Merrick and Hayes (1976) describe details of an ear oximeter which enables the measurement of oxygen saturation of the blood. This measurement is independent of a wide range of encountered variables and is made without involving patients in any calibration or standardization procedure.

12. This technique involves measuring the optical transmittance of the ear at how many wavelengths?
a) 12
b) 6
c) 8
d) 10
View Answer

Answer: c
Explanation: In brief, the technique involves measuring the optical transmittance of the ear at 8 wavelengths in the 650 to 1050 nm range. A 2.5 m long flexible fibre ear probe connects the patient to the instrument.

13. Ear probe which connects the patient to instrument is ___________ m long.
a) 1.5
b) 2.0
c) 2.5
d) 3.0
View Answer

Answer: c
Explanation: A 2.5 m long flexible fibre ear probe connects the patient to the instrument. The ear probe can be either held in position for discrete measurements or can be conveniently mounted to a headband for continuous display.

14. Ear oximeter instrument is based on Beer-Lambert law.
a) True
b) False
View Answer

Answer: a
Explanation: The instrument is based on the Beer-Lambert law. However, it is assumed that the optical absorbers act independently and additively and that the effects of light scattering by the ear tissue can be minimized by a proper source and detector geometry.

Sanfoundry Global Education & Learning Series – Biomedical Instrumentation.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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