Respiratory Therapy Services: Oximetry
A. Single Testing
B. Exercise Testing
Pulse oximetry is a non-invasive method allowing the monitoring of the oxygenation 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 photo detector. The changing absorbance at each of the wavelengths is measured, allowing determination of the absorbance due to the pulsing arterial blood alone, excluding venous blood, skin, bone, muscle, fat, and (in most cases) fingernail polish. With NIRS it is possible to measure both oxygenated and deoxygenated hemoglobin on a periperhal 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.