Flow Estimation
AssigneeMassachusetts Institute of Technology
InventorRichard J. Cohen
Life of this patent
Estimating the term…
Abstract
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.
Claims69
A method for computing a signal proportional to phasic cardiac output, comprising:
- measuring a physiologic input signal related to circulatory pressures or flows;
- constructing a transforming filter to transform the physiologic input signal into a signal proportional to phasic cardiac output;
- and
- applying the transforming filter to the physiologic input signal to compute a signal proportional to phasic cardiac output.
A method for computing a quantity related to systemic or pulmonary vascular resistance, comprising:
- measuring a physiologic input signal related to systemic or pulmonary circulatory pressures or flows;
- constructing a filter in which the quantity is a parameter;
- applying the filter to the physiologic input signal over one or more cardiac cycles;
- adjusting the quantity to reduce the width of the filtered output waveform or waveforms corresponding to the one or more cardiac cycles;
7 The method of claim 4 in which the filter's impulse-response function is the functional inverse of an exponentially decaying impulse-response function, whose time constant is a quantity which is proportional to the vascular resistance.
A method for computing a signal proportional to the time-averaged cardiac output, comprising:
- measuring a physiologic input signal related to circulatory pressures or flows;
- constructing a transforming filter to transform the physiologic input signal into a signal proportional to phasic cardiac output;
- time-averaging the physiologic input signal;
- applying the transforming filter, or applying a modified form of the transforming filter suitable for use with a time-averaged physiologic input signal, to the time-averaged physiologic input signal to compute a signal proportional to the time-averaged cardiac output.
29 The method of claims 24, 25, or 26 further comprising the step of normalizing the computed signal proportional to the time-averaged cardiac output by using one or more independent methods of measuring absolute cardiac output.
System for computing a signal proportional to phasic cardiac output, comprising:
- sensor means for measuring a physiologic input signal related to circulatory pressures or flows;
- computer means for constructing a transforming filter to transform the physiologic input signal into a signal proportional to phasic cardiac output;
- and
- computer means for applying the transforming filter to the physiologic input signal to compute a signal proportional to phasic cardiac output.
System for computing a quantity related to systemic or pulmonary vascular resistance, comprising:
- sensor means for measuring a physiologic input signal related to systemic or pulmonary circulatory pressure or flows:
- computer means for constructing a filter in which the quantity is a parameter;
- computer means for applying the filter to the physiologic input signal over one or more cardiac cycles;
- and
- computer means for adjusting the quantity to reduce the width of the filtered output waveform or waveforms corresponding to the one or more cardiac cycles.
System for computing a signal proportional to time-averaged cardiac output, comprising:
- sensor means for measuring a physiologic input signal related to circulatory pressure or flows;
- computer means for constructing a transforming filter to transform the physiologic input signal into a signal proportional to phasic cardiac output;
- computer means for time-averaging the physiologic input signal;
- and
- computer means for applying the transforming filter, or applying a modified form of the transforming filter suitable for use with a time-averaged physiologic input, to the time-averaged physiologic input signal to compute a signal proportional to the time-averaged cardiac output.
Dependencies are inferred from the claim text.