Right Ventricular Stroke Volume Estimation via Respiratory Pressure Correction
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Solution Overview
Problem
Current monitoring tools cannot provide continuous beat-by-beat estimation of right ventricle stroke volume (RV SV) from pulmonary artery pressure waveform analysis (PA PWA) due to the effect of breathing, which affects the accuracy of RV SV measurement and its variation during the respiratory cycle, limiting the prediction of fluid responsiveness in mechanically ventilated patients.
Innovation Solution
A method that corrects pulmonary artery pressure measurements for external airway pressure by subtracting a respiratory correction function, allowing for continuous beat-by-beat estimation of RV SV and its variation over the respiratory cycle using parameters like systolic-diastolic pressure difference, area under the curve, or standard deviation, thereby isolating the respiratory components from the cardiac components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pulmonary artery pressure measurements are used to estimate right ventricle stroke volume, then continuous beat-by-beat RV SV estimation is achieved, but the accuracy is reduced due to the effect of breathing on pressure measurements
Solution Approach 1:
The patent segments the pulmonary artery pressure signal into respiratory component and cardiac component through spectral analysis. By identifying and separating these components in the frequency domain, the method enables accurate extraction of cardiac-related pressure variations while eliminating respiratory interference, thus achieving both continuous monitoring and high measurement precision
Solution Approach 2:
The patent introduces an intermediary processing step involving spectral analysis and component separation. This intermediary process acts as a mediator between the raw pressure signal and the final stroke volume calculation, filtering out respiratory effects while preserving cardiac information necessary for accurate RV SV estimation
2Device complexity
If uncorrected pulmonary artery pressure measurements are used, then the monitoring system remains simple, but erroneous conclusions are drawn due to transmitted pressure modifying PA pressure morphology
Solution Approach 1:
The patent replaces direct mechanical pressure measurement with a signal processing approach. Instead of using complex mechanical correction devices, the method uses spectral analysis and mathematical processing to substitute and eliminate the respiratory pressure component, maintaining system simplicity while improving reliability
Solution Approach 2:
The patent changes the parameter domain from time-domain pressure measurements to frequency-domain spectral analysis. By transforming the pressure signal and analyzing it in the frequency domain, the method can selectively remove respiratory frequency components while preserving cardiac frequency components, ensuring accurate conclusions without complex hardware modifications
3Ease of manufacture
If average SV estimation is used, then the monitoring approach remains conventional, but the potential for exploiting RV SV variation during respiration cycle is lost
Solution Approach 1:
The patent performs preliminary separation of respiratory and cardiac components before stroke volume calculation. By预先 removing the respiratory component from the pressure signal, the method preserves the cardiac-related pressure variations that contain RV SV variation information, enabling both conventional simplicity and information retention
Solution Approach 2:
The patent implements continuous processing of the pressure signal to maintain useful cardiac information throughout the respiratory cycle. Instead of averaging that would lose temporal variations, the method continuously extracts cardiac component information, preserving RV SV variation data while maintaining ease of implementation
Data Source
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Figure 3A~3B
AI summary
A computer-implemented method for estimating right ventricular stroke volume from the pulmonary artery pressure, comprising: a) receiving data indicative of two or more corrected pulmonary artery pressure measurements. The two or more corrected pulmonary artery pressure measurements are one or more pulmonary artery pressure measurements over one or more cardiac cycles at one or more points in the respiratory cycle, each point corrected for the external airway pressure exerted on the heart during the cardiac cycle at the respective point in the respiratory cycle, the correction comprising a subtraction of a respiratory correction function for all of the pulmonary artery pressure measurements; and b) estimating the right ventricular stroke volume for each of the one or more cardiac cycles based on a parameter of the one or more corrected pulmonary artery pressure measurements using a predetermined relationship between the parameter and right ventricular stroke volume.