Non-invasively monitoring blood parameters

Abstract

An apparatus for monitoring vital sign parameters in a biological entity is disclosed. In an embodiment, the apparatus includes at least one light source for transmitting light through the biological entity and at least one photodetector for receiving light transmitted through the biological entity. At least one light source and at least one photodetector are configured to be positioned proximate the biological entity in a manner that does not significantly impede blood flow through the biological entity. A signal is generated in response to the transmittance or reflectance of light through the biological entity. The signal corresponds to at least one characteristic of the generally unimpeded blood flow through the biological entity. The apparatus also includes a control system configured to analyze the signal to determine vital sign parameters in the biological entity. A method for monitoring vital sign parameters in a biological entity is also provided.

1 - 5 . (canceled) 
     
     
         6 . An oximetry monitoring system for monitoring a subject's tissue, comprising:
 an adhesive forehead sensor comprising a light source and a photodetector in a side-by-side position, the light source emitting light at first and second wavelengths, and the photodetector providing an electrical signal in response to exposure to the light after reflectance by the monitored tissue;   a control system in communication with the photodetector, and equipped to sample the electrical signal and calculate an area under the curve metric responsive to a blood oxygen status of the monitored tissue; and   a display operated by the control system to provide an indication of the blood oxygen status.   
     
     
         7 . The system of  claim 6 , wherein the light source and the photodetector are carried by a flexible support. 
     
     
         8 . The system of  claim 7 , wherein the flexible support comprises an adhesive patch. 
     
     
         9 . The system of  claim 6 , further comprising an alarm triggered by the control system based on the blood oxygen status. 
     
     
         10 . The system of  claim 9 , wherein the blood oxygen status comprises a measure of oxygen saturation in the monitored tissue. 
     
     
         11 . The system of  claim 6 , wherein the blood oxygen status comprises a measure of tissue perfusion in the monitored tissue. 
     
     
         12 . The system of  claim 6 , wherein the control system comprises an analog to digital converter for sampling the electrical signal, and a processor programmed to calculate the area under the curve metric. 
     
     
         13 . The system of  claim 12 , wherein the processor is further programmed to calculate a tissue perfusion index based on the blood oxygen status over time. 
     
     
         14 . The system of  claim 6 , further comprising a database of reference characteristics, and wherein the control system is further programmed to compare the pulse waveform signal to the reference characteristics. 
     
     
         15 . An oximetry system, comprising:
 a sensor input receiving first and second electrical signals representative of light emitted by first and second emitters, reflected by a subject's tissue, and detected at first and second detectors;   a control system programmed to:
 receive the first and second electrical signals and develop a pulse waveform signal representative of a blood parameter; 
 determine a value of the blood parameter based on the pulse waveform signal; 
 produce an area under the curve metric based on a pulse of the pulse waveform signal; and 
 determine a tissue perfusion index based on the area under the curve metric; 
   a display in communication with the control system; and   an alarm triggered by the control system based on a status of the pulse waveform signal.   
     
     
         16 . The system of  claim 15 , further comprising a database of reference characteristics, and wherein the control system is further programmed to compare the pulse waveform signal to the reference characteristics. 
     
     
         17 . The system of  claim 15 , further comprising an adhesive forehead sensor in communication with the sensor input, the adhesive forehead sensor comprising a light source and a photodetector in a side-by-side position, the light source emitting light at first and second wavelengths, and the photodetector providing the first and second electrical signals to the sensor input. 
     
     
         18 . A method for monitoring vital sign parameters of a subject, comprising:
 emitting light from first and second light emitters into a subject's forehead;   detecting the emitted light after reflectance by the subject's forehead, at first and second photodetectors;   generating first and second electrical signals representative of the detected light;   developing a pulse waveform signal based on the electrical signals;   analyzing the pulse waveform signal to produce an area under the curve metric;   monitoring the pulse waveform signal over time; and   displaying the pulse waveform signal.   
     
     
         19 . The method of  claim 18 , further comprising determining an oxygen saturation of the subject's tissue based on the first and second electrical signals. 
     
     
         20 . The method of  claim 18 , further comprising triggering an alarm based on a status of the pulse waveform signal.