Pulse oximetry: understanding its basic principles facilitates appreciation of its limitations.
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Cites background from "Pulse oximetry: understanding its b..."
...Oxy-hemoglobin (O2Hb) and deoxy-hemoglobin (HHb) differentially absorb red and near-infrared (IR) light.[108]...
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References
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"Pulse oximetry: understanding its b..." refers background in this paper
...The degree to which HbF affects FO2Hb readings depends on the specific co-oximeter used as different co-oximetermodels often utilize different sets of wavelengths; in addition, HbA and HbF differ in light absorbance (for both O2Hb and HHb) primarily in the 450e650 nm spectral rangeewhich coincides with the wavelengths used by most co-oximeters.(52,53) Although simply adding the fictitious COHb level to O2Hb in an attempt to correct the FO2Hb (provided there is no evidence of hemolysis or CO poisoning that can cause a true increase in COHb) may work for some systems, some cooximeters can correct the readings in the presence of HbF....
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"Pulse oximetry: understanding its b..." refers background in this paper
...Complications of sickle cell disease, such as vasoocclusive crisis and acute chest syndrome, are often precipitated or exacerbated by hypoxemia, and can result in a vicious cycle of additional sickling and vasoocclusive crises.(11) Thus, accurate detection of hypoxemia in these patients plays an important role in mitigating further red blood cell sickling....
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"Pulse oximetry: understanding its b..." refers background in this paper
...For example, in hypotensive, vasoconstricted patients, ear and forehead probes may be more reliable as these areas are less likely to vasoconstrict than the fingers in response to endogenous and exogenous catecholamines.(3,7) In hypothermia, where there is secondary vasoconstriction, the forehead probe has been shown to be more reliable than the finger probe....
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...It is fortuitous that O2Hb and HHb have significant differences in absorption at red and near-IR light because these two wavelengths penetrate tissues well whereas blue, green, yellow, and far-IR light are significantly absorbed by nonvascular tissues and water.(3) O2Hb absorbs greater amounts of IR light and lower amounts of red light than does HHb; this is consistent with experience e welloxygenated blood with its higher concentrations of O2Hb appears bright red to the eye because it scatters more red light than does HHb....
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"Pulse oximetry: understanding its b..." refers background in this paper
...Co-oximeter reports ell as FO2Hb (meaning fractional SaO2 although the term oth functional SaO2 and SpO2 are minimally affected by experimental animals, a SpO2 level of 90% was recorded ation was 30%.(55) Thus, even in significant CO poisoning, ication of oxygenation whereas the O2 carrying capacity is distinction between SaO2 and FO2Hb is illustrated ncluding that because a severely anemic patient has a e blood is adequate....
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