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, when such parameters are potentially affected by other concurrent events. In one exemplary embodiment, apparatus and methods for compensating for occlusive events (e.g., pressure cuff inflation) occurring ipsilateral to the location of parameter measurement are disclosed. Upon passive detection of signal degradation resulting from the event, the apparatus selectively enters a “wait state” wherein further processing of the hemodynamic data is suspended until the degrading event subsides. This behavior mitigates any adverse effects the event might have on the accuracy of the representation of the measured hemodynamic parameter generated by the system. In another exemplary embodiment, the measured data is analyzed in order to classify the type of event (e.g., occlusive or other), such classification allowing the system to appropriately tailor its response to the event.

What is claimed is: 
     
         1 .- 31 . (canceled) 
     
     
         32 . Hemodynamic parameter measurement apparatus, comprising:
 first apparatus configured to non-invasively measure a hemodynamic parameter at a first location on a living subject;   second apparatus configured to passively detect a degrading event which occurs within a blood vessel at a location ipsilateral to said first location of said subject; and   third apparatus configured to mitigate effects of said degrading event on said measurement.   
     
     
         33 . The apparatus of  claim 32 , wherein said degrading event comprises an externally induced change within said blood vessel. 
     
     
         34 . The apparatus of  claim 32 , wherein said degrading event comprises substantially short-term or non-chronic change within said blood vessel. 
     
     
         35 . The apparatus of  claim 32 , wherein said degrading event comprises degradation in a magnitude of a measured value of said hemodynamic parameter. 
     
     
         36 . The apparatus of  claim 32 , wherein said mitigation comprises movement of said first apparatus relative to said living subject via a fourth apparatus coupled to said hemodynamic parameter measurement apparatus. 
     
     
         37 . The apparatus of  claim 32 , wherein said mitigation comprises a delay to be applied prior to evaluation of said non-invasively measured hemodynamic parameter until said degrading event has substantially subsided. 
     
     
         38 . A method of mitigating an effect of a degrading event on a hemodynamic parameter obtained from a hemodynamic parameter measurement apparatus applied to a living subject, said method comprising:
 measuring said hemodynamic parameter at a first location on said living subject;   passively detecting an event occurring within a blood vessel at a location ipsilateral to said first location of said living subject; and   mitigating effects of said event on said act of measuring.   
     
     
         39 . The method of  claim 38 , wherein said event comprises an externally induced change within said blood vessel. 
     
     
         40 . The method of  claim 38 , wherein said event comprises substantially short-term or non-chronic change within said blood vessel. 
     
     
         41 . The method of  claim 38 , wherein said act of passively detecting said event comprises detecting an absence of one or more events in said hemodynamic parameter. 
     
     
         42 . The method of  claim 38 , wherein said act of passively detecting said event comprises detecting a reduction in a magnitude of a measure value of said hemodynamic parameter. 
     
     
         43 . The method of  claim 38 , wherein said event comprises a change in a measured flow characteristic of said blood vessel, resulting from an occlusion occurring at said location ipsilateral to said first location. 
     
     
         44 . The method of  claim 38 , wherein said hemodynamic parameter is obtained tonometrically from said subject, and said act of mitigating further comprises:
 suspending said act of measuring for a predetermined period;   after expiration of said predetermined period, determining whether said event has terminated; and   when said event has terminated, re-initiating said act of measuring.   
     
     
         45 . The method of  claim 44 , wherein said act of mitigating further comprises suspending previously scheduled changes in a level of compression applied to said subject during said act of tonometrically obtaining said hemodynamic parameter during said period. 
     
     
         46 . Computer readable apparatus comprising media comprising a computer program having a plurality of instructions, said plurality of instructions configured to, when executed, cause a hemodynamic parameter measurement apparatus to:
 measure a hemodynamic parameter at a first location on a living subject;   passively detect a blood-vessel event which causes a degradation of said measurement of said hemodynamic parameter, said event being localized within said blood vessel at a location ipsilateral to said first location of said living subject; and   mitigate effects of said blood-vessel event on said measurement of said hemodynamic parameter.   
     
     
         47 . The computer readable apparatus of  claim 46 , wherein said blood-vessel event comprises an externally induced change within said blood vessel. 
     
     
         48 . The computer readable apparatus of  claim 46 , wherein said blood-vessel event comprises substantially short-term or non-chronic change within said blood vessel. 
     
     
         49 . The computer readable apparatus of  claim 46 , wherein said mitigation comprises:
 suspension of said measurement of said hemodynamic parameter for a predetermined period;   after expiration of said predetermined period, determination of whether said blood-vessel event has terminated; and   when said blood-vessel event has terminated, re-initiation of said measurement of said hemodynamic parameter.   
     
     
         50 . The method of  claim 49 , wherein said mitigation comprises suspension of changes in a level of compression applied to said subject during said period. 
     
     
         51 . The method of  claim 37 , wherein said hemodynamic parameter is obtained tonometrically from said subject, and said passive detection comprises detection of a reduction in a difference between systolic and diastolic pressures present in said hemodynamic parameter.