Methods and apparatus for visually representing a cardiac status of a patient

摘要

Method and apparatus are provided for computing signals related to cardiac output from physiologic input signals related to circulatory pressures or flows. Method and apparatus are provided for constructing a transforming filter and applying said filter to the physiologic input signals in order to obtain a signal proportional to phasic cardiac output or time-averaged cardiac output. This invention provides a means for real-time monitoring of cardiac output and stroke volume which is of great clinical importance but not otherwise feasible by present techniques.

主权项

1. A computer-facilitated method for visually representing to a medical practitioner a cardiac status of a patient so as to facilitate a determination by the medical practitioner of 1) a need for a cardiac-related intervention and/or 2) an effect of a prior cardiac-related, intervention, the method comprising:
A) measuring, via a sensing device coupled to the patient, a circulatory parameter of the patient so as to provide, as an output of the sensing device, a physiologic input signal related to a circulatory pressures of the patient; B) electronically converting the physiologic input signal from the sensing device, via an analog-to-digital converter coupled to the sensing device, to a plurality of digital samples of the physiologic input signal related to the circulatory pressure of the patient; C) electronically processing at least some of the plurality of digital samples of the physiologic input signal, via at least one computer coupled to the analog-to-digital converter, to construct a transforming filter to transform the plurality of digital samples of the physiologic input signal based at least in part on one or more periods of time corresponding to diastole of the heart of the patient during which the aortic valve or the pulmonary valve of the heart of the patient is closed; D) electronically applying the transforming filter, via the at least one computer, to at least some of the plurality of digital samples of the physiologic input signal to compute a cardiac output signal proportional to a phasic cardiac output of the patient, the phasic cardiac output corresponding to a flow across the aortic valve or the pulmonary valve of the heart of the patient, wherein:
the cardiac output signal has a sufficient time resolution to reflect variations in the flow across the aortic valve or the pulmonary valve within a single cardiac cycle; andin C), the transforming filter is constructed so that, when the transforming filter is applied in D) to the at least some of the plurality of digital samples of the physiologic input signal, the cardiac output signal is reduced during the one or more periods of time corresponding to diastole of the heart of the patient, subject to a normalization constraint on a gain of the transforming filter; and E) electronically displaying, on a display device coupled to the at least one computer, a visual representation of the cardiac output signal computed in D) to provide the cardiac status of the patient to the medical practitioner and thereby facilitate the determination by the medical practitioner of the need for the cardiac-related intervention and/or the effect of the prior cardiac-related intervention.