Light Flashcards
Regarding pulse oximetry (true or false):
Beer’s Law governs absorption in substances of differing densities
True. The Bouguer-Lambert law also plays a role.
Regarding pulse oximetry (true or false):
Red light is absorbed at 910 nm
False. Red light is absorbed at 660 nm. Infrared light is absorbed at 910 nm.
Regarding pulse oximetry (true or false):
An isobestic point is found at 805 nm
True. This is the isobestic point for oxyhaemoglobin and deoxyhaemoglobin.
Regarding pulse oximetry (true or false):
Carboxyhaemoglobin may interfere with pulse oximetry
True. The pulse oximeter tends to read 97% saturation due to the absorption of light by carboxyhaemoglobin.
Regarding pulse oximetry (true or false):
Fetal haemoglobin may interfere with pulse oximetry
False. Fetal haemoglobin has no effect on pulse oximetry readings.
Regarding pulse oximetry (true or false):
Infrared gas analysis relies on similar principles to the pulse oximeter
True
Regarding the physical principles of light (true or false):
The angle at which light hits a surface is the angle of reflection
False. It is the angle of incidence.
Regarding the physical principles of light (true or false):
The angle of reflection equals the angle of incidence
True
Regarding the physical principles of light (true or false):
Fibreoptic bundles use total external reflection
False. Fibreoptic bundles rely upon total internal reflection.
Regarding the physical principles of light (true or false):
The speed of light is constant in all substances
False. The speed of light varies in different substances. Comparison of a particular substance to the speed of light in a vacuum leads to the index of refraction.
Regarding the physical principles of light (true or false):
Cladding glass has a lower index of refraction than core glass
True
Regarding the physical principles of light (true or false):
Refraction is demonstrated by objects appearing to bend when placed in water
True
Regarding infrared gas analysis, match the substance to the following statement:
Carbon Dioxide
Nitrous Oxide
Oxygen
Volatile Agents
Water
Maximally absorbs light at 4.26 μm
Carbon Dioxide
Regarding infrared gas analysis, match the substance to the following statement:
Carbon Dioxide
Nitrous Oxide
Oxygen
Volatile Agents
Water
Can cause falsely high CO2 readings
Water
Regarding infrared gas analysis, match the substance to the following statement:
Carbon Dioxide
Nitrous Oxide
Oxygen
Volatile Agents
Water
Is compensated for by modern analyzers
Nitrous Oxide