Fluid Responsiveness Detection with Envelope Signals in Unstable Conditions
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Solution Overview
Problem
Existing fluid responsiveness parameters are unreliable and inaccurate in unstable heart or respiration conditions, particularly during short measurement durations, limiting their clinical utility in situations like surgery or spot checks.
Innovation Solution
A system and method that utilizes two fluid responsiveness parameter determination signals, one covering the whole spectral range up to the respiratory rate and the other up to the heart rate, combined with filters and characteristic value analysis, to efficiently determine fluid responsiveness and its reliability, even in unstable conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fluid responsiveness parameters are determined using conventional methods in unstable heart or respiration conditions, then the measurement can be performed in dynamic patient scenarios, but the accuracy and reliability of the parameter determination deteriorates
Solution Approach 1:
The patent segments the blood pressure signal into individual blood pressure pulses and analyzes characteristic values within specific time windows corresponding to respiratory cycles. This segmentation allows accurate parameter determination even when overall signal stability is compromised by unstable heart or respiration conditions.
Solution Approach 2:
The patent dynamically adjusts the analysis by identifying characteristic values within moving time windows and adapting to varying respiratory rates. The system continuously updates the fluid responsiveness parameter based on current signal characteristics rather than relying on fixed assumptions, enabling accurate measurement in dynamic patient scenarios.
2Reliability
If measurement duration is extended to improve reliability of fluid responsiveness parameter, then parameter accuracy improves, but the time required for clinical decision-making increases
Solution Approach 1:
The patent uses partial action by analyzing only the essential characteristic values within specific time windows rather than requiring complete signal sequences. This allows reliable parameter determination with shorter measurement durations by focusing on the most informative signal features.
Solution Approach 2:
The system performs preliminary identification of characteristic values and their correspondence between consecutive blood pressure pulses before final parameter calculation. This preliminary analysis enables rapid determination of fluid responsiveness with minimal measurement time while maintaining reliability.
3Measurement precision
If complex signal processing is applied to improve accuracy in unstable conditions, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent extracts and focuses on specific characteristic values from the blood pressure signal that are most informative for fluid responsiveness determination. By isolating these key features rather than processing the entire signal complexly, the system achieves high accuracy with relatively simple processing.
Solution Approach 2:
The patent introduces an intermediary analysis step that identifies correspondence between characteristic values in consecutive pulses and uses this intermediate information to calculate the fluid responsiveness parameter. This intermediary approach simplifies the overall processing while improving accuracy in unstable conditions.
Data Source
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AI summary
A system (100) for determining a fluid responsiveness parameter, FRP, for a patient is presented, wherein the determined fluid responsiveness parameter is a systolic pressure variation (SPV) or a pulse pressure variation (PPV) that comprises units (101, 102, 103) for providing a respiratory rate, a heart rate and a measured blood pulsation signal indicative of a series of blood pulses of a patient. The system further comprises a unit (104) for determining, a first processed signal (env_up) based on the blood pulsation signal, wherein the first processed signal is indicative of an upper envelope of the blood pulsation signal, and a second processed signal (env_down) based on the blood pulsation signal, wherein the second processed signal is indicative of a lower envelope of the blood pulsation signal, and a unit (105) for determining the FRP by a) identifying, based on the first and second processed signals, first FRP determination signals (baseline_up, baseline_down) corresponding to the first and second processed signals in a spectral range up to the respiratory rate, and second FRP determination signals (ripple_up, ripple_down) corresponding to the first and second processed signals at the respiratory rate and any of its harmonics up to the heart rate, and b) determining the FRP based on the first and the second FRP determination signals.