Non-invasively measuring arterial oxygen tension

Abstract

Oxygen tension is measured in the palpebral conjuctiva and is converted to arterial oxygen tension by applying a conversion factor thereto. A polarographic oxygen sensor on the outer surface of a scleral contact member is employed, and the current passed is read and converted, or read in terms of a special calibration.

I claim: 
     
       1. A method for non-invasively determining continuous arterial oxygen tension of a patient, comprising the steps of a. non-invasively measuring the palpebral conjunctival oxygen tension,   b. multiplying said tension by a constant dependent upon the relationship between the oxygen tension of the palpebral conjunctiva and the arterial oxygen tension of the patient, and   c. subtracting a second constant also dependent upon said relationship.   
     
     
       2. The method of claim 1 wherein said measuring, multiplying and subtracting are carried out substantially simultaneously and continuously. 
     
     
       3. A method for non-invasively and continuously determining continuous arterial oxygen tension of a patient, comprising the steps of a. continuously non-invasively measuring the palpebral conjunctival oxygen to provide readings thereof; and   b. continuously converting the readings to values in terms of the relation of palpebral conjunctival readings to arterial conditions.   
     
     
       4. The method of claim 3 wherein the measurements are continuously recorded. 
     
     
       5. A method for non-invasively determining continuous arterial oxygen tension of a patient, comprising the steps of 1. securing an oxygen-sensing electrode assembly to the outer surface of a scleral contact lens member,   2. emplacing said contact lens member between the cornea of the patient's eye and the palpebral conjunctiva of his eyelid,   3. applying voltage to said electrode assembly,   4. reading the current passed, and   5. calibrating said current in terms of the oxygen tension modified by factors corresponding to the relation between the slope and origin of the arterial oxygen tension to palpebral conjunctival oxygen tension.   
     
     
       6. The method of claim 5 wherein steps (3) and (4) are done continuously. 
     
     
       7. The method of claim 6 wherein the calibrated reading is continuously recorded. 
     
     
       8. Apparatus for non-invasively determining arterial oxygen tension of a patient, comprising a. means to abut the surface of palpebral conjunctiva for detecting the oxygen tension thereof,   b. means for reading the value of the detected tension while multiplying this value by a constant dependent upon the type of patient and upon the relationship between oxygen tension of the palpebral conjunctiva and the arterial tension of the type of patient while subtracting a second constant also dependent on said relationship.   
     
     
       9. The apparatus of claim 8 wherein said means (a) comprise a membrane polarographic oxygen sensor. 
     
     
       10. Apparatus for non-invasively determining continuous arterial oxygen tension of a patient, comprising a. means to abut the surface of palpebral conjunctiva for continuously detecting the oxygen tension thereof,   b. means for continuously indicating the value of the detected tension while multiplying this value by a first constant dependent upon the relationship between the oxygen tension of the palpebral conjunctiva and the arterial oxygen tension of the patient, and while continuously subtracting therefrom a second constant also dependent on said relationship, and   c. means for continuously displaying the results of (b).   
     
     
       11. Apparatus for non-invasively determining continuous arterial oxygen tension of a patient, comprising 1. a scleral contact lens member having an oxygen-sensing electrode assembly secured to said lens member and sensing at the outer surface thereof, so that said contact lens member can be placed between the cornea of the patient's eye and his eyelid,   2. means for applying voltage to said electrode,   3. means for reading the current passed, and   4. means calibrating said reading in terms of the oxygen tension as modified by factors corresponding to the relation between the slope and origin of the arterial oxygen tension to palpebral conjunctival oxygen tension.   
     
     
       12. The apparatus of claim 11 wherein said gas-sensing electrode assembly is a membrane polarographic electrode assembly. .Iadd. 13. Apparatus for non-invasively indicating continuous arterial oxygen tension of a patient, comprising 1. a scleral contact lens member having an oxygen-sensing electrode assembly secured to said lens member and sensing at the outer surface thereof, so that said contact lens member can be placed between the cornea of the patient's eye and his eyelid,   2. means for applying voltage to said electrode,   3. means for sensing the current passed, and   4. means indicating said sensed current in relation to the oxygen tension as modified by factors corresponding to the relation between the slope and origin of the arterial oxygen tension to palpebral conjunctival oxygen tension. .Iaddend..Iadd. 14. A method for non-invasively indicating continuous arterial oxygen tension of a patient, comprising the steps of   1. securing an oxygen-sensing electrode assembly to the outer surface of a scleral contact lens member,   2. emplacing said contact lens member between the cornea of the patient's eye and the palpebral conjunctiva of his eyelid,   3. applying voltage to said electrode assembly,   4. sensing the current passed, and   5. indicating said sensed current in terms of the oxygen tension modified by factors corresponding to the relation between the slope and origin of the arterial oxygen tension to palpebral conjunctival oxygen tension. .Iaddend.