Sensing gas bubbles in a living body

Abstract

A method of detecting gas bubbles in a living body, comprising transmitting at least one original electromagnetic signal to a body portion; detecting a signal modulated by a flow of blood in said body portion; and analyzing a perturbation in said signal to determine at least one of an existence and a property of a bubble in said blood flow.

1 . A method of detecting gas bubbles in a living body, comprising:
 transmitting at least one original electromagnetic signal to a body portion;   detecting a signal modulated by a flow of blood in said body portion; and   analyzing a perturbation in said signal to determine at least one of an existence and a property of a bubble in said blood flow.   
     
     
         2 . A method according to  claim 1 , comprising performing AM on said detected signal. 
     
     
         3 . A method according to  claim 2 , wherein said AM analysis comprises estimating an unperturbated signal and counting zero crossings relative to said estimation. 
     
     
         4 . A method according to  claim 3 , wherein said estimation is selected to preclude the detection of perturbations below a certain threshold. 
     
     
         5 . A method according to  claim 3 , wherein said estimation comprises an adaptive threshold. 
     
     
         6 . A method according to  claim 3 , wherein said estimation reduces the effect of systolic-caused changes in said signal. 
     
     
         7 . A method according to  claim 2 , comprising performing FM on said detected signal. 
     
     
         8 . A method according to  claim 7 , comprising combining said AM analysis and said FM analysis. 
     
     
         9 . A method according to  claim 1 , comprising performing FM on said detected signal. 
     
     
         10 . A method according to  claim 9 , wherein said FM analysis comprises applying a frequency transform to said detected signal. 
     
     
         11 . A method according to  claim 9 , wherein said FM analysis comprises detecting changes in a delay time of a said detected signal relative to said original signal. 
     
     
         12 . A method according to  claim 9 , wherein said FM analysis comprises detecting a change in amplitude of a frequency component. 
     
     
         13 . A method according to  claim 1 , comprising analyzing said received signal to determine a value or a change in a physiological parameter other than bubbles. 
     
     
         14 . A method according to  claim 13 , wherein said physiological parameter comprises a heart rate. 
     
     
         15 . A method according to  claim 13 , wherein said physiological parameter comprises oxygen saturation. 
     
     
         16 . A method according to  claim 13 , wherein said physiological parameter comprises one or both of a respiration rate and a respiratory capacity. 
     
     
         17 . A method according to  claim 16 , wherein the physiological parameter comprises a respiration rate, and determining the value or change in the physiological parameter comprises determining the respiration rate from a measured systolic wave. 
     
     
         18 . A method according to  claim 13 , wherein said physiological parameter comprises one or more of a wave form, pulse form, a cardiac output, a blood flow rate, a blood volume, a blood pressure, and a systemic vascular resistance. 
     
     
         19 . A method according to  claim 18 , wherein the physiological parameter comprises a local blood flow rate to an organ, and the method also comprises using a change in the local blood flow rate to estimate a change in a physiological condition of the body as a whole. 
     
     
         20 . A method according to  claim 13 , wherein a user selects one or more such physiological parameters. 
     
     
         21 . A method according to  claim 20 , also comprising displaying one or more such physiological parameters selected by the user. 
     
     
         22 . A method according to  claim 21 , comprising using a change in the physiological state to predict problems during a dive, and to indicate where certain action should be taken or is imminent. 
     
     
         23 . A method according to  claim 22 , wherein the change in the physiological state comprises one or more of appearance of bubbles, reduction in cardiac output, and increase in stress. 
     
     
         24 . A method according to  claim 22 , wherein using the change in the physiological state to predict problems comprises adapting the prediction to a person doing the diving based on a real-time response of the person. 
     
     
         25 . A method according to  claim 1 , wherein said analyzing comprises estimating a number of bubbles. 
     
     
         26 . A method according to  claim 1 , wherein said analyzing comprises estimating a volume of bubbles. 
     
     
         27 . A method according to  claim 1 , wherein said analyzing comprises tracking the formation of at least one bubble. 
     
     
         28 . A method according to  claim 1 , wherein said analyzing estimating a diameter of at least one bubble. 
     
     
         29 . A method according to  claim 1 , comprising estimating a physiological state for diving purposes based on said analysis. 
     
     
         30 . A method according to  claim 1 , wherein transmitting comprises transmitting when in contact with a skin surface. 
     
     
         31 . A method according to  claim 1 , wherein analyzing comprises estimating a growth rate of bubbles. 
     
     
         32 . A method according to  claim 1 , comprising estimating a physiological state based on said analysis, in air or in outer space. 
     
     
         33 . A method according to  claim 1 , comprising estimating a physiological state using multiple measured parameters, taking into account the interaction of the parameters. 
     
     
         34 . A method according to  claim 33  wherein a change in one or more physiological parameters in said measured parameters affects one or more other parameters in said measured parameters. 
     
     
         35 . A method according to  claim 33  comprising verifying the integrity of said estimating based on said interaction of the parameters. 
     
     
         36 . A method according to  claim 1 , wherein transmitting comprises transmitting through clothes. 
     
     
         37 . A method according to  claim 1 , wherein transmitting comprises transmitting through an optical transparent material. 
     
     
         38 . A method according to  claim 1  comprising identifying a change of stress level in a user by identifying any one of, or combination of, a change in pulse rate, a change in respiratory rate, a change in systolic rate, or a change in cardiac output. 
     
     
         39 . A method of detecting gas bubbles in a living body, comprising:
 transmitting at least one original optical signal to a body portion;   
       detecting a signal modulated by a flow of blood in said body portion; and
 analyzing, using AM analysis, a perturbation in said signal to determine at least one of an existence and a property of a bubble in said blood flow. 
 
     
     
         40 . A method according to  claim 39 , comprising applying an FM analysis. 
     
     
         41 . Apparatus according to  claim 39 , wherein said wave is optical and wherein said device is adapted to be worn on a human body. 
     
     
         42 . Apparatus according to  claim 39 , wherein said wave is optical and wherein said device is adapted for underwater use during diving. 
     
     
         43 . A wearable apparatus for physiological tracking bubble detection, comprising:
 at least one electromagnetic signal source adapted to transmit an optical light wave into a body;   at least one sensor adapted to receive said signal after modulation by a flow in said body; and   circuitry adapted to analyze said received signal and detect at least changes in at least two physiological parameters of said body.   
     
     
         44 . Apparatus according to  claim 43 , wherein said at least two physiological parameters are selected from a group comprising, existence of bubbles, heart rate, respiration rate, blood pressure, oxygen saturation and vascular response.