Pulse oximetry is a non-invasive method allowing the monitoring of the saturation of a patient's hemoglobin.
A sensor is placed on a thin part of the patient's body, usually a fingertip or earlobe, or in the case of an infant, across a foot. Light of two different wavelengths is passed through the patient to a photodetector. The changing absorbance at each of the wavelengths is measured, allowing determination of the absorbances due to the pulsing arterial blood alone, excluding venous blood, skin, bone, muscle, fat, and (in most cases) nail polish. With NIRS it is possible to measure both oxygenated and deoxygenated hemoglobin on a peripheral scale (possible on both brain and muscle).
Reflectance pulse oximetry may be used as an alternative to transmissive pulse oximetery described above. This method does not require a thin section of the patient's body and is therefore well suited to more universal application such as the feet, forehead and chest, but it also has some limitations. Vasodilation and pooling of venous blood in the head due to compromised venous return to the heart, as occurs with congenital cyanotic heart disease patients, or in patients in the Trendelenburg position, can cause a combination of arterial and venous pulsations in the forehead region and lead to spurious SpO2 (Saturation of peripheral oxygen) results.
... pulse oximetry monitoring market for equipment and sensors was over $700 million in 2011 ... equipment manufacturers in China were producers of pulse oximeters ... an upcoming peripheral for the Wii console, dubbed the "Vitality Sensor", which consists of a pulse oximeter ...
... sleep therefore, noninvasive methods are preferred such as pulse oximetry, transcutaneous oxygen monitoring, transcutaneous carbon dioxide, and pulse ... Pulse oximetry measures the oxygenation in peripheral capillaries (such as the fingers) however, an article written by Bohning states that pulse oximetry may not be that useful, such as diagnosing obstructive sleep-apn ... and carbon dioxide tension on the skin surface respectively, and the pulse transit time measures the transmission time of an arterial pulse transit wave ...
... Conventional pulse oximetry assumes that arterial blood is the only blood moving (pulsating) in the measurement site ... However, during patient motion, the venous blood also moves, which can cause conventional pulse oximetry to under-read arterial oxygen saturation levels because it cannot distinguish between ... accurate arterial oxygen saturation and pulse rate ...
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