Module 10 Flashcards
What percent of O2 is carried in the plasma
2%
How many mL of O2 in 100mL of blood
19mL
How much O2 is dissolved in 100mL of plasma
.3mL
Plasma dissolved oxygen doesn’t play a significant role in oxygen transport
Arterial oxygen concentration is proportional to
HGB saturation
What causes a left shift in the dissociation curve?
Decreased: temp
2,3 DPG
H+
CO
What causes a right shift in dissociation curve
Increased: temp
2,3 DPG
H+
REDUCED AFFINITY
Oxyhemoglobin dissociation curve is a representation of
The relationship between the amount of oxygen bound to the HGB and the partial pressure of oxygen in the blood
Vital tool for comprehending how blood transports & releases oxygen
Saturations greater than 90% are
Independent of PAO2
What is the bore effect?
Tissues have higher amounts of CO2 & therefore hydrogen, which causes a right shift of the curve & unloading of oxygen from the HGB molecule
Tissue light absorbance
Contain pulsations times with HR due to the normal variation in arterial blood volume during each heart beat
Pulse oximetry became standard in
1986
Beer Lambert law states
The concentration of solutes can be determined by the intensity of light transmitted though a substance
Intensity & absorbance are
Inversely related
Of incidence of light intensity & the distance transmitted through a solution is equal, then the
Concentration of solutes can be determined in the extinction coefficient for each solute is know
What are the 4 most common hemoglobin species
Meth
Oxy
Reduced
Carboxy
The pulse oximeter estimates arterial HGB saturation by
Measuring light transmission at 2 wavelengths through a pulsating vascular bed
Light absorbance in tissue can be a
Constant component
Pulsating component
The pulsating component is the result of
Arterial blood pulsations & therefore by comparing light absorbance of the 2 components, the absorbance of the arterial blood can be determined
Most pulse odometers use 2 wavelengths of light
660 (red)
940 (infrared)
The light absorbance of the pulsatilla wavelength is divided by the light absorbance of the non pulse stoke wavelength, yielding
The pulse added absorbance which are independent of intensity & incidence
The pulse added absorbance for both wavelengths are calculated & the ratio is related to
The arterial HGB saturation
What 3 assumptions are made for pulse oximetry to work?
2 light absorbers
Pulsations are all caused by fluctuations in blood volume
One curve is valid for everyone
What are the most common sources of errors with oximetry readings
Dyshemoglobins & IV dyes
Wavelength variability
Signal to noise ratio
Motion