Method and apparatus for control of non-invasive parameter measurements

Abstract

Improved methods and apparatus for non-invasively assessing one or more parameters associated with fluidic systems such as the circulatory system of a living organism. In a first aspect, an improved method of continuously measuring pressure from a compressible vessel is disclosed, wherein a substantially optimal level of compression for the vessel is achieved and maintained using perturbations (e.g., modulation) of the compression level of the vessel. In one exemplary embodiment, the modulation is conducted according to a pseudo-random binary sequence (PBRS). In a second aspect, an improved apparatus for determining the blood pressure of a living subject is disclosed, the apparatus generally comprising a pressure sensor and associated processor with a computer program defining a plurality of operating states related to the sensed pressure data. Methods for pressure waveform correction and reacquisition, as well as treatment using the present invention, are also disclosed.

1 - 68 . (canceled) 
     
     
         69 . A method of operating a hemodynamic parameter measurement apparatus adapted for use on a living subject and comprising one or more sensors in contact with tissue overlying a blood vessel of said living subject, said method comprising:
 operating said apparatus in a first non-transient mode such that data relating to one or more hemodynamic parameters is obtained using said one or more sensors;   detecting at least one transient event via said obtained data; and   operating said apparatus in a second transient recovery mode subsequent to said act of detecting said transient event so as to compensate therefor.   
     
     
         70 . The method of  claim 69 , wherein said transient event changes said contact of at least one of said one or more sensors to said tissue, thereby potentially affecting an accuracy of said obtained data. 
     
     
         71 . The method of  claim 70 , wherein said act of detecting comprises detecting a reduction in a magnitude of one or more pressure values. 
     
     
         72 . The method of  claim 70 , wherein said act of detecting comprises detecting an absence of one or more cardiac beats in said obtained data. 
     
     
         73 . The method of  claim 70 , wherein said hemodynamic parameter comprises blood pressure, and at least one of said one or more sensors comprises a tonometric or non-invasive pressure sensor. 
     
     
         74 . The method of  claim 70 , wherein said second transient recovery mode comprises temporarily suspending use of said obtained data. 
     
     
         75 . The method of  claim 74 , wherein said second transient recovery mode further comprises adjusting a position of said at least one of said one or more sensors obtaining said data. 
     
     
         76 . The method of  claim 75 , wherein said blood vessel comprises a radial artery, and said act of adjusting said position of said at least one of said one or more sensors obtaining said data comprises adjusting at least one of a lateral and/or proximal position of said at least one sensor relative to said artery. 
     
     
         77 . The method of  claim 75 , wherein said blood vessel comprises a radial artery, and said act of adjusting said position of said at least one of said one or more sensors obtaining said data comprises adjusting an applanation or compression level of said at least one sensor relative to said tissue. 
     
     
         78 . The method of  claim 69 , wherein said act of detecting comprises detecting a reduction in a magnitude of a parameter represented by said data. 
     
     
         79 . The method of  claim 78 , wherein said act of detecting said reduction comprises detecting a reduction in a magnitude of a pulse pressure. 
     
     
         80 . The method of  claim 69 , wherein said act of detecting comprises detecting an absence of one or more cardiac beats in said data. 
     
     
         81 . An apparatus for use in transient event compensation during hemodynamic parameter measurement from a living subject, said apparatus comprising:
 first apparatus configured to establish an initial substantially optimal state of mechanical coupling to said living subject;   a sensor configured to obtain data relating to said hemodynamic parameter from said living subject; and   a processor apparatus configured to execute a computer program thereon, said computer program comprising a plurality of instructions configured to, when executed:
 cause said data to be received from said sensor; 
 detect an occurrence of said transient event by analyzing changes in said data, said transient event alters said mechanical coupling between said living subject and said sensor; 
 cease use of said data from said sensor; 
 identify a second substantially optimal state of mechanical coupling of said sensor to said living subject; and 
 resume using said data from said sensor after said second state has been achieved. 
   
     
     
         82 . The apparatus of  claim 81 , wherein said plurality of instructions are further configured to initiate a sweep through a plurality of different states to identify said second substantially optimal state of mechanical coupling. 
     
     
         83 . The apparatus of  claim 82 , wherein said plurality of instructions are further configured to cause said sweep to begin only after said transient event is determined to have substantially subsided. 
     
     
         84 . The apparatus of  claim 81 , wherein said plurality of instructions are further configured to control said first apparatus to establish said second substantially optimal state. 
     
     
         85 . The apparatus of  claim 81 , wherein said initial substantially optimal state and said second substantially optimal state each comprise states of compression of tissue overlying a blood vessel. 
     
     
         86 . The apparatus of  claim 81 , wherein said detection of said occurrence of said transient event comprises a comparison of at least one of (i) a measured pressure, (ii) a measured velocity and/or (iii) a measured acceleration, with one or more predetermined values. 
     
     
         87 . A non-invasive blood pressure measurement apparatus comprising:
 a pressure sensor;   a data storage medium configured to store pressure data in a non-transient mode from said pressure sensor; and   a processor configured to detect an occurrence of at least one transient event based at least in part on an evaluation of said data;   wherein said apparatus is placed in a transient recovery mode subsequent to said detection of said at least one transient event.   
     
     
         88 . The apparatus of  claim 87 , wherein said apparatus is configured to operate in a second non-transient mode when non-transient induced changes occur, said non-transient changes being detected by said processor via evaluation of a second set of non-transient pressure data, said second set of non-transient pressure data being obtained at least in part by a modulation of a compression level of a blood vessel with an applanation mechanism from which said non-transient data is obtained.