Method and device for predicting abnormal medical events and/or assisting in diagnosis and/or monitoring, particularly in order to determine depth of anesthesia
First Claim
1. A method for predicting abnormal medical events, assisting in diagnosis, or monitoring a patient, comprising detecting and simultaneously distinguishing between, continuously and in real time, a concomitant occurrence of a temporary inefficiency of the cardiac baro-reflex and an activation of the non-baro-reflex cardiovascular regulation, wherein the detecting and simultaneously distinguishing is carried out using a device comprising a computing unit;
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a) continuously measuring (beat-by-beat) time intervals determined from an ECG between two consecutive cardiac cycles (IT) and arterial pressure (AP); and
b) filtering by means of a low-pass filter the beat-by-beat series of the time intervals IT and the series of AP calculated at step a), the filtering giving rise to filtered series ITf and APf of IT and of AP respectively; and
c) monitoring for the occurrence of one or more of the following sequences;
(i) increase in APf/time period/reduced increase in ITf;
(ii) increase in APf/time period/delayed increase in ITf; and
(iii) increase in APf/time period/decrease in ITf;
wherein the occurrence of any one of (i)-(iii) is a predictive index that indicates (a) the concomitant occurrence of a temporary inefficiency of the cardiac baro-reflex and an activation of the non-baro-reflex cardiovascular regulation and (b) the cardiovascular depth of anesthesia.
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Abstract
The invention relates to the field of technological assistance for anaesthesia and intensive care practitioners, as well as to the field of simple, reliable medical monitoring for managing anaesthesia and/or predicting deleterious medical events. The invention aims to provide a system enabling prevention and anticipation of procedures necessary for patients and/or maintenance of patients in a suitable anaesthetic state for a surgical operation at a given time. For this purpose, the invention provides a method of predicting abnormal medical events and/or assisting in diagnosis and/or monitoring, comprising the continuous, real-time detection of a concomitant occurrence of a temporary inefficiency in cardiac baroreceptor reflex and an activation of non-baroreceptor reflex cardiovascular control. The invention also relates to the device used to implement said method.
32 Citations
16 Claims
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1. A method for predicting abnormal medical events, assisting in diagnosis, or monitoring a patient, comprising detecting and simultaneously distinguishing between, continuously and in real time, a concomitant occurrence of a temporary inefficiency of the cardiac baro-reflex and an activation of the non-baro-reflex cardiovascular regulation, wherein the detecting and simultaneously distinguishing is carried out using a device comprising a computing unit;
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wherein the detecting and simultaneous distinguishing comprises; a) continuously measuring (beat-by-beat) time intervals determined from an ECG between two consecutive cardiac cycles (IT) and arterial pressure (AP); and b) filtering by means of a low-pass filter the beat-by-beat series of the time intervals IT and the series of AP calculated at step a), the filtering giving rise to filtered series ITf and APf of IT and of AP respectively; and c) monitoring for the occurrence of one or more of the following sequences; (i) increase in APf/time period/reduced increase in ITf; (ii) increase in APf/time period/delayed increase in ITf; and (iii) increase in APf/time period/decrease in ITf; wherein the occurrence of any one of (i)-(iii) is a predictive index that indicates (a) the concomitant occurrence of a temporary inefficiency of the cardiac baro-reflex and an activation of the non-baro-reflex cardiovascular regulation and (b) the cardiovascular depth of anesthesia. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
is indicated by one or more of the following parameters: -
p1) a ratio between the area under the curve of a sequence of ITf called baro-reflex response of ITf and the area under the curve of the rise in APf which has caused said baro-reflex response of ITf, p2) an amplitude of the fall in ITf which has preceded the rise in ITf that follows said rise in APf, p3) a ratio between the amplitude of said baro-reflex response of ITf and the amplitude of said fall in ITf, p4) an algebraic difference Δ
IT between the value of ITf after a period of time referred to as estimation time starting from the beginning of said baro-reflex response of ITf and the value of ITf at the end of said baro-reflex response of ITf.
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9. The method of claim 8, wherein said baro-reflex response of ITf, caused by said rise in APf, is:
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either the rise in ITf that follows said rise in APf if said rise in ITf begins within an interval of time included between a lower limit equal to 0 s and an upper limit included between 10 s and 20 s with respect to the start of said rise in APf; or the sequence of ITf which begins after an interval of time included between 5 s and 15 s with respect to the start of said rise in APf, in the case where the rise in ITf that follows said rise in APf begins after said upper limit in the range between 10 s and 20 s with respect to the start of said rise in APf; in both cases, the duration of the baro-reflex response of ITf being equal to said estimation time;
the amplitude of said baro-reflex response of ITf being the difference between the maximum reached by the ITf in the course of its rise over the duration of said baro-reflex response of ITf and the level of ITf at the start of the rise in ITf that follows said rise in APf.
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10. The method of claim 9, wherein the only rises in APf taken into consideration are those whose amplitude is higher than a pressure threshold in the range between 1 mmHg and 5 mmHg.
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11. The method of claim 8, wherein the period called estimation period is equal to the duration of said rise in APf multiplied by a coefficient in the range between 0.5 and 2.
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12. The method of claim 8, wherein said areas under the curves of the baro-reflex response of ITf and of the rise of APf are calculated between a time called reference time and during said estimation time, by performing, for each sample of said curve in the course of said estimation time starting from said reference time, the sum of the algebraic differences between the value of the sample at a given moment and the value of the curve at said reference time.
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13. The method of claim 1, wherein at least one alarm is designed to predict any lightening, programmed or inopportune, of the anesthesia, comprising means for displaying the alarm designed to warn of the concomitant occurrence of a temporary inefficiency of the cardiac baro-reflex and an activation of the non-baro-reflex cardiovascular regulation, by continuously displaying in real time a predictive index expressing the cardiovascular depth of the anesthesia.
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14. The method of claim 8, wherein step c) of the surveillance for the concomitant occurrence of a temporary inefficiency of the cardiac baro-reflex and an activation of the non-baro-reflex cardiovascular regulation, together with the emission of an alarm according to step d), are alternately governed by at least one of the following sequences of steps:
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A1) the predictive index expressing the cardiovascular depth of the anesthesia indicates a lightening of the anesthesia and emits an alarm when at least the four following conditions are met; the ratio parameter p1 is below a value in the range between 0 and 4, the amplitude parameter p2 is above a value in the range between 30 ms and 300 ms, the ratio parameter p3 is below a value in the range between 0 and 1, and the algebraic difference parameter p4 is below a value in the range between −
100 and 25,A2) the predictive index, expressing the cardiovascular depth of the anesthesia and indicating a lightening of the anesthesia, is obtained by using a neural network having as input parameters the parameters of p1 to p4, and having learning conditions so as to obtain an optimal combination of sensitivity and specificity, by means of an ROC (Receiver Operator Characteristic) curve.
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15. A computer-readable medium having computer-executable instructions embodied therein for predicting abnormal medical events, assisting in diagnosis, or monitoring a patient, the computer-executable instructions implement the method of claim 8.
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16. A computer-readable medium having computer-executable instructions embodied therein for predicting abnormal medical events, assisting in diagnosis, or monitoring a patient, the computer-executable instructions implement the method of claim 14.
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Specification