Method and apparatus for control of non-invasive parameter measurements

• US 7,976,471 B2
• Filed: 11/05/2007
• Issued: 07/12/2011
• Est. Priority Date: 08/01/2002
• Status: Active Grant

• Current Assignee: United States GTM Medical Devices
• Original Assignee: Tensys Medical Inc. (Recorders & Medicare Systems Pvt Ltd.)
• Inventors: Craycroft, Warren, Voss, Gregory I., Gallant, Stuart L., Martin, Gregory J., Goharlaee, Manouchehr
• Primary Examiner(s): Mallari; Patricia C
• Application Number:
  US11/982,975
• Publication Number:
  US 20080064968A1
• Time in Patent Office: 1,345 Days
• Field of Search: 600/490
• US Class Current: 600/490
• CPC Class Codes: A61B 5/0048 Detecting, measuring or recording by applying mechanical forces or stimuli A61B5/021, A61B5/4884 and A61B9/00 take precedence
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/0225 the pressure being controlled by electric signals, e.g. derived from Korotkoff sounds
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence

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.

Claims

1. Blood pressure measurement apparatus, said apparatus comprising:

first apparatus adapted to tonometrically measure blood pressure at a first location;

second apparatus adapted to passively detect an occlusive event occurring at a location ipsilateral to said first location; and

third apparatus adapted to mitigate the effects of said occlusive event on said measuring.

2. Tonometric blood pressure measurement apparatus adapted to mitigate the effects of an occlusion of a blood vessel at a second location disposed ipsilateral to a first measurement location, the apparatus comprising:

a pressure sensor adapted to sense pressure and generate signals relating thereto;

a processor operatively coupled to said sensor, including a computer program running thereon, said processor and program cooperating to process said signals to generate a representation of said blood pressure; and

applanation apparatus coupled to said pressure sensor and operatively controlled at least in part by said processor and said computer program, said applanation apparatus adapted to variably compress said blood vessel;

wherein said processing of said signals comprises;

(i) passively detecting an occlusive event occurring at said second location;

(ii) suspending movement of said applanation apparatus for at least a first period; and

(iii) waiting for at least said first period until the effects of said occlusive event on said signals has substantially subsided.

3. Apparatus adapted to mitigate the effects of a blood vessel occlusion during non-invasive measurement of blood pressure using a pressure sensor, the apparatus comprising:

a processor to receive a signal generated by said pressure sensor; and

a computer program operative to run on said processor, said computer program adapted to process said signal to produce a representation of said blood pressure;

wherein said computer program is further adapted to;

(i) passively detect a change within said signal relating to an occlusive event affecting a first blood vessel; and

(ii) adjust said processing substantially in response to said detection of said change, said adjustment comprising compensation for degradation of a signal at a different blood vessel than said first blood vessel being measured using said sensor.

4. Blood pressure measuring apparatus adapted to mitigate the effects of a blood vessel occlusion, the apparatus comprising:

a non-invasive pressure sensor adapted for sensing the pressure applied thereto by a blood vessel at a first location on the body of a subject and generating a signal relating thereto;

a processor operatively coupled to said sensor; and

a computer program running on said processor, said computer program adapted to process said signal to produce a representation of said blood pressure;

wherein said computer program is further adapted to;

(i) passively detect a change within said signal; and

(ii) adjust said processing based on at least said change;

wherein said computer program further comprises;

a beat detector; and

a no-beat process; and

wherein said beat detector advises said no-beat process as to detected beats within said signal, said no beat process suspending said act of processing if no beats are detected within a first time interval.

5. The apparatus of claim 4, further comprising an applanation mechanism coupled to said pressure sensor, wherein said sensor and mechanism cooperate to selectively compress said blood vessel during said act of sensing.

6. The apparatus of claim 5, wherein said adjustment of said act of processing comprises delaying processing of said signal until said change has substantially subsided.

7. The apparatus of claim 5, wherein said computer program is further adapted to modulate the level of compression applied to said blood vessel via said mechanism, said act of processing further comprising correcting the sensed pressure.

8. Apparatus adapted to generate a representation of the blood pressure the blood vessel of a living subject and mitigate the effects of an occlusive event on said representation, said generating comprising:

tonometrically sensing pressure at a first location using at least one sensor and generating signals relating thereto;

passively detecting a degradation of said signals;

classifying said degradation based at least in part on said signals, said classifying comprising at least determining whether said degradation is the result of said occlusive event occurring ipsilateral to said first location; and

compensating for the effects of said degradation on said representation, said compensating substantially mitigating said effects.

9. The apparatus of claim 8, wherein said compensating comprises entering a wait state, the duration of said wait state being substantially related to the estimated duration of said occlusive event.

10. Apparatus adapted to mitigate the effects of a blood vessel occlusion during non-invasive hemodynamic parameter assessment, the apparatus comprising:

a processor to receive a signal generated by a hemodynamic parameter sensor; and

a computer program operative to run on said processor, said computer program adapted to, when executed, process said signal to produce a representation of said hemodynamic parameter;

wherein said computer program is further adapted to, when executed;

(i) passively detect a change within said signal relating to an occlusive event affecting a first blood vessel; and

(ii) adjust said processing substantially in response to said detection of said change, said adjustment comprising compensation for degradation of a signal at a different blood vessel than said first blood vessel being assessed by said sensor.