Deriving Blood Flow Contour from Pressure Waveform Landmarks
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Solution Overview
Problem
Current hemodynamic monitoring technologies struggle to accurately monitor blood flow chronically in ambulatory patients, as pressure measurements alone do not account for variations in vascular impedance, which affects forward arterial flow, and require frequent calibration.
Innovation Solution
A system and method that estimates a blood flow waveform contour from a pressure signal using a pressure sensor and microprocessor-based implantable cardiac monitoring device, identifying landmark points on the pressure signal to approximate the flow contour, allowing for estimation of cardiac output and other hemodynamic parameters without frequent calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct flow monitoring is implemented chronically in ambulatory patients, then measurement precision of blood flow would be improved, but device complexity and invasiveness would worsen
Solution Approach 1:
The patent uses pressure waveform as an intermediary parameter to indirectly estimate blood flow characteristics. Instead of directly measuring flow with complex sensors, the system measures pressure (which is easier to obtain chronically) and derives flow contour information from pressure waveform features, thus avoiding direct flow sensor complexity while maintaining measurement utility
Solution Approach 2:
The patent creates a simplified copy of the flow waveform by identifying landmark points on the pressure waveform that correspond to flow features (onset, peak, end of ejection). This pressure-based flow contour copy provides sufficient hemodynamic information without requiring actual flow measurement, resolving the contradiction between measurement precision and device complexity
2Ease of operation
If pressure measurements are used to estimate flow, then ease of operation would be improved, but measurement precision would worsen due to vascular impedance variations
Solution Approach 1:
The patent performs preliminary identification of landmark points on the pressure waveform that correspond to specific flow events (onset of flow, peak flow, end of ejection). By pre-establishing these correspondence relationships, the system compensates for vascular impedance variations and improves flow estimation precision while maintaining ease of operation
Solution Approach 2:
The patent transforms the pressure waveform parameter into flow contour information by identifying specific landmark points (onset, peak, end) that represent flow characteristics. This parameter transformation allows derivation of flow-like information from pressure measurements, improving measurement precision without sacrificing ease of operation
3Ease of operation
If traditional pressure contour methods are used, then ease of operation would be improved, but reliability would worsen due to frequent calibration requirements
Solution Approach 1:
The patent uses only the essential landmark points (onset, peak, end) of the pressure waveform to derive flow contour information, rather than requiring complete waveform calibration. This partial action approach provides sufficient reliability for continuous monitoring without the burden of frequent full calibration procedures
Solution Approach 2:
The patent changes the approach from calibrated pressure contour analysis to landmark point identification. By focusing on key waveform features (onset, peak, end points) rather than requiring full waveform calibration, the system achieves reliable continuous monitoring with minimal calibration requirements, resolving the contradiction between ease of operation and reliability
Data Source
AI summary
The present invention provides a system and method for estimating a blood flow waveform contour from a pressure signal. An arterial or ventricular pressure signal is acquired from a pressure sensor. Landmark points are identified on the pressure waveform that correspond to features of a flow waveform. In one embodiment, the landmark pressure waveform points correspond to the onset of flow, the peak flow, and the end of the systolic ejection phase. The landmark pressure waveform points define a contour that approximates the flow contour. Beat-by-beat flow contour estimation can be performed to allow computation of flow-related hemodynamic parameters such as stroke volume or cardiac output for use in patient monitoring and/or therapy management.