Assertion: carboxy hb | /r/HasProperty | cohb
Facets:
Source sentences:
text: The principal pathogenic mechanism of CO poisoning is the strong avidity of CO for Hb (240× greater than O2), forming carboxy-Hb (COHb), reducing the O2 carrying capacity of Hb and precipitating tissue hypoxemia.
text: Because oxyhemoglobin (O2Hb) and carboxy-Hb (COHb) absorb red light (660 nm) similarly and carboxy-Hb (COHb) absorbs very little near-infrared light (940 nm) (see Figure 5 below), the photodiode of standard pulse oximeters – that only emit red and near-infrared light – cannot differentiate between oxyhemoglobin (O2Hb) and carboxy-Hb (COHb).
text: Because oxyhemoglobin (O2Hb) and carboxy-Hb (COHb) absorb red light (660 nm) similarly and carboxy-Hb (COHb) absorbs very little near-infrared light (940 nm) (see Figure 5 below), the photodiode of standard pulse oximeters – that only emit red and near-infrared light – cannot differentiate between oxyhemoglobin (O2Hb) and carboxy-Hb (COHb).
text: Because oxyhemoglobin (O2Hb) and carboxy-Hb (COHb) absorb red light (660 nm) similarly and carboxy-Hb (COHb) absorbs very little near-infrared light (940 nm) (see Figure 5 below), the photodiode of standard pulse oximeters – that only emit red and near-infrared light – cannot differentiate between oxyhemoglobin (O2Hb) and carboxy-Hb (COHb).
text: The similar absorptive property of oxyhemoglobin (O2Hb) and carboxy-Hb (COHb) for red light is consistent with the clinical observation that patients with carboxyhemoglobinemia can appear bright red and not cyanotic.10
text: In the context of R, because carboxy-Hb (COHb) will decrease both deoxyhemoglobin (HHb) and O2Hb concentrations, the normally greater red light absorption by deoxyhemoglobin (HHb) will be decreased but the red light absorption of the combined oxyhemoglobin (O2Hb) and
text: carboxy-Hb (COHb) species will be maintained or slightly increased.
text: Semantically, it is important to emphasize that it is the fractional O2Hb content (FO2Hb) content and not the SaO2 that is decreased by carboxy-Hb (COHb).
text: For pulse oximeters to be able to detect carboxy-Hb (COHb) as well as oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb), an instrument with at least three light beams of different wavelengths would have to be employed10; while they exist, they are not widely available.
text: However, the authors note that while SpO2 may be used as an accurate representation of SaO2 in sickle cell disease, the fractional O2Hb content (FO2Hb) may be a more useful measurement, as some individuals with sickle cell disease may have elevated carboxy-Hb (COHb) (due to the metabolism of heme to bilirubin and carbon monoxide); in these instances, SpO2 overestimates the FO2Hb.