Sensor, apparatus and method for non-invasive measurement of oxygen saturation

#The present invention relates to a sensor, an apparatus and a method for performing non-invasive measurements of oxygen saturation based on the reflection technique.

#Oxygen saturation is a clinically very relevant parameter to assess the condition of a patient. Particularly in the operating room, the oxygen saturation of the blood gives an indication of the patient's condition, its supply with oxygen and other physiological factors.

#One possibility to obtain a very precise value of the patient's oxygen saturation is to take a blood sample and analyze it in a blood gas analyzer. Despite the high precision of this method, it is an invasive technique and this means that it cannot performed frequently, i.e. does not allow continuous monitoring. Therefore, significant changes in the oxygen saturation value may be missed. Last not least, it is understood that an invasive technique is not the preferred way to monitor a patient.

#Preferred embodiments of the invention will now be described--by way of a non-limiting example--with reference to the accompanying drawings in which:

#FIG. 1 depicts a cross-section through a simple reflection sensor in order to illustrate the basic concept;

#FIG. 2 depicts a second embodiment of such reflection sensor,

#FIG. 1 depicts a cross-section through an oximetry sensor of the reflectance type generally outlined as 1. This sensor comprises a carrier body 2 which is applied to a part of the human body generally designated as 3. Human body part 3 may be the chest, the stomach, a leg etc. of a patient. For centralized patients (i.e. patients in shock), the extremities such as arms or legs cannot be used due to a lack of pulsating blood. This is a particular application where reflection oximetry is required; as transillumination through the chest or the stomach is not possible, only a reflection sensor can be applied.

#Although the carrier body 2 is depicted as a one-component part here, it is understood that the carrier means may also consist of several connected or non-connected components. Carrier body 2 may be fixed to the human body in any convenient manner, e.g. using a surgical glue or a self-adhesive tape (not shown here).

#Carrier body 2 has three bores 4, 5 and 6. Bores 4 and 6 hold light-emitting diodes (LEDs) 7 and 9, whereas bore 5 houses a photoelectric receiver 8, e.g. a phototransistor or a photodiode. The electrical connection of the wires leading to these LEDs and the photoelectric receiver are not shown in detail here. These connections can be made in usual manner, e.g. they may lead to a connection cable for connection with an appropriate oximeter.