Determination of the clinical state of a subject

A method for providing a diagnostic index that is indicative of a clinical condition of a subject when the subject is in either of a pair of subject states and during a transition period following a change in the state of the subject from a first subject state to a second subject state, the changeable state of the subject being defined by different physiological characteristics of the subject than the clinical condition of the subject for which the diagnostic index is being provided, the method comprising the steps of:

• (a) obtaining a first signal using one or more sensors coupled to the subject, said first signal being responsive to the physiological functioning of an organ or organs of a first anatomical system of the subject, said first signal being capable of indicating the state of the subject;
• (b) acquiring at least one second signal from one or more sensors coupled to the subject to provide at least one clinical condition indicating signal, the second signal being responsive to the physiological functioning of an organ or organs of a second anatomical system of the subject different than the first anatomical system, the clinical condition indicating signal having at least one property that can be altered by a change in the state of the subject;
• (c) providing at least one adaptive transform in a computer unit for transforming an input signal applied thereto an outputted, transformed signal in accordance with an alterable, signal transforming characteristic of the adaptive transform;
• (d) with the subject in a first state, obtaining clinical condition indicating signal history data from the subject;
• (e) extracting statistical feature data from the clinical condition indicating signal history data;
• (f) using the statistical feature data to establish the signal transforming characteristic of the adaptive transform to one that transforms an input signal to an outputted, transformed signal having desired value range and distribution characteristics for the first state of the subject;
• (g) applying the clinical condition indicating signal as the input signal to the adaptive transform to provide a transformed signal for the first state of the subject from the adaptive transform;
• (h) forming, from the transformed signal, a diagnostic index in a form capable of perception to provide an indication of the clinical condition of the subject for the first state of the subject;
• (i) obtaining statistical feature data characterizing clinical condition indicating signal data for a second state of the subject;
• (j) determining a change in the state of the subject using the first signal;
• (k) upon the occurrence of a change in the state of the subject to a second state, replacing at least a portion of the statistical feature data for the first state used to establish the signal transforming characteristic of the adaptive transform with statistical feature data obtained in step (i) to alter the signal transforming characteristic of the adaptive transform to one that transforms the clinical condition indicating input signal to an outputted, transformed signal having desired value range and distribution characteristics for forming the diagnostic index as an indication of the clinical condition of the subject in a transition period following change of the subject from the first state to the second state;
• (l) with the subject in the second state, extracting statistical feature data from clinical condition indicating signal history data obtained from the subject in the second state;
• and
• (m) replacing at least a portion of the statistical feature data obtained in step (i) with statistical feature data extracted in step (l) to further alter the signal transforming characteristic of the adaptive transform so that the diagnostic index formed from the transformed signal continues as a indication of the clinical condition of the subject in the second state.