Veterans Affairs

Heated pulse oximeter

Specialized pulse oximetry probe with external heat pack will help obtain more accurate pulse oximetry readings consistent with values obtained with an arterial blood gas

Medical & Biotechnology

Pulse oximetry is a procedure used to monitor blood arterial oxygen saturation (SaO2) levels and pulse rates noninvasively. It is routinely used in operating rooms, Intensive Care Unit, and during emergency transport. Changes in SaO2 and pulse rate are important to monitor in order to be able to compensate for any decrease in patient oxygen saturation during hemodynamic monitoring.

Currently, there are two modes of pulse oximetry sensor configurations: the transmission mode and the reflectance mode. The transmission mode often is used when a pulse oximeter probe is placed on the finger, ear lobe or toe. In this case, an optical emitter and a detector are positioned on opposite sides of the tissue through which the measurement is to be made. The reflectance mode often is used on the forehead and the optical emitter and the detector are positioned side by side. In both types, the pulse oximeter probes transmit red and infrared light through blood-perfused tissue, for example, the arterial vascular bed. The detector measures the transmitted light as it passes through the vascular bed, thereby detecting the amount of colored light absorbed by the arterial blood, and from this, the arterial oxygen saturation level is calculated.

While pulse oximetry has become a standard for measuring oxygen saturation, there are a number of situations where it performs poorly. For example, variations in the tissue temperature in the region of the measurement site can affect the accuracy of the measurements by affecting blood perfusion. Low tissue temperatures result in vasoconstriction and low blood perfusion, which make it difficult to obtain valid SaO2 pulse rate values. This can lead to misdiagnosis and incorrect treatment.

Addressing the above deficiencies in pulse oximetry, researcher Catherine Abee at the Department of Veterans Affairs has developed a pulse oximeter probe integrated into a bandage-like harness, which contains a disposable chemical energy heating source. Heating is done by oxidation of a metal powder. An example of such a chemical heating source includes a mixture of iron powder, water, salt, activated charcoal, and vermiculite. Upon exposure to air, the iron powder begins to oxidize and release heat. The mechanism is similar to that in hand warmers commonly placed in ski gloves.

This invention is protected by US patent 9,795,332, which is related to US patent application 20170367629, plus two international patents that are pending approval.

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