Operation of the pulse oximeter (see previous problem).The transmission of light energy as it passes througha solution of light - absorbing molecules is described by theBeer–Lambert law I = I010-εCL or log10 (I/I0) = -εCL which gives the decrease in intensity I in terms of the distance Lthe light has traveled through a fluid with a concentration Cof the light - absorbing molecule. The quantity ε is called theextinction coefficient, and its value depends on the frequencyof the light. (It has units of m2/mol.) Assume the extinctioncoefficient for 660 - nm light passing through a solutionof oxygenated hemoglobin is identical to the coefficient for940 - nm light passing through deoxygenated hemoglobin.Also assume 940 - nm light has zero absorption (ε = 0) inoxygenated hemoglobin and 660 - nm light has zero absorptionin deoxygenated hemoglobin. If 33% of the energy ofthe red source and 76% of the infrared energy is transmittedthrough the blood, what is the fraction of hemoglobin that isoxygenated?
Operation of the pulse oximeter (see previous problem).
The transmission of light energy as it passes through
a solution of light - absorbing molecules is described by the
Beer–Lambert law
I = I010-εCL or log10 (I/I0) = -εCL
which gives the decrease in intensity I in terms of the distance L
the light has traveled through a fluid with a concentration C
of the light - absorbing molecule. The quantity ε is called the
extinction coefficient, and its value depends on the
of the light.
coefficient for 660 - nm light passing through a solution
of oxygenated hemoglobin is identical to the coefficient for
940 - nm light passing through deoxygenated hemoglobin.
Also assume 940 - nm light has zero absorption (ε = 0) in
oxygenated hemoglobin and 660 - nm light has zero absorption
in deoxygenated hemoglobin. If 33% of the energy of
the red source and 76% of the infrared energy is transmitted
through the blood, what is the fraction of hemoglobin that is
oxygenated?
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