Author Question: A pulse oximeter differentiates oxyhemoglobin from deoxygenated hemoglobin by which of the following ... (Read 89 times)

shenderson6 · **on:** Jul 16, 2018

A pulse oximeter differentiates oxyhemoglobin from deoxygenated hemoglobin by which of the following methods?

a. Relating cyclical changes in light transmis-sion through the sampling site.
b. Shining and comparing two wavelengths of light through the sampling site.
c. Direct measurement by a heated polaro-graphic electrode applied to the skin.
d. Using a color sensing device that absorbs one wavelength of light through the skin.

Question 2

The term used to specify the flow, pressure, and volume waveforms that are graphed relative to time is called:

a. hysteresis.
b. loop.
c. waveform.
d. scalar.

allisonblackmore · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: B
A pulse oximeter uses spectrophotometry to differentiate between oxyhemoglobin and deoxy-genated hemoglobin. Two wavelengths of light (660 and 940 nm) are shined through a sample site. Oxyhemoglobin absorbs more light at 940 nm (infrared IR light) than does deoxygenated hemoglobin. Deoxyhemoglobin absorbs more light at 660 nm. The use of cyclical changes in light transmission measured at the sampling site is the method to determine the pulse rate with a pulse oximeter. A heated polarographic electrode is used for transcutaneous partial pressure of oxygen (PtcO2) measurements. A color sensing device is used to detect the amount of carbon dioxide in exhaled gas.

Answer to Question 2

ANS: D
Hysteresis can be thought of as a lagging of one of two associated phenomena; that is, two asso-ciated phenomena fail to coincide or occur simultaneously. The term scalar is used to specify the flow, pressure, and volume waveforms that are graphed relative to time (i.e., pressure, flow, and volume scalars). Basically, six shapes (waveforms) are produced with scalars during mechanical ventilation. The term loop is used to describe a graph of two variables plotted on the x and y co-ordinates, such as pressure-volume and flow-volume loops (these are discussed later in the chap-ter).