Patient-Specific Aortic Pressure-CSA Calibration for Stroke Volume
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pulse contour methods for determining stroke volume and cardiac output rely on population-based non-linear pressure/CSA relationships, which are not individually specific, leading to inaccuracies due to dispersion in parameter values, particularly in patient monitoring applications.
Innovation Solution
A method that corrects general population-related non-linear pressure/CSA relationships using real-time measurements of the aortic diameter to adapt them into patient-specific relationships, allowing for continuous monitoring of arterial pressure and improving pulse contour methods for stroke volume and cardiac output calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If population-based non-linear pressure/CSA relationships are used for stroke volume and cardiac output determination, then the method is simple and can be applied generally, but measurement precision deteriorates due to parameter dispersion of approximately 20%
Solution Approach 1:
The patent changes the parameters of the pressure/CSA relationship by introducing patient-specific calibration factors. Instead of using fixed population-based parameters, the system adjusts the parameters (such as CSAmax, P0, P1) based on individual patient measurements, thereby reducing the 20% parameter dispersion and improving measurement precision while maintaining the simplicity of the overall method
Solution Approach 2:
The patent implements a feedback mechanism where initial stroke volume measurements obtained from population-based relationships are used to calibrate and refine subsequent measurements. The system uses feedback from actual patient data to adjust and personalize the pressure/CSA relationship parameters, improving precision over time while keeping the method applicable to general patient populations
2Measurement precision
If pulse contour methods rely on morphological features of blood pressure waveform (upstroke position, dicrotic notch position), then stroke volume can be determined, but detection difficulty increases because the dicrotic notch appears difficult to detect in patients
Solution Approach 1:
The patent introduces an intermediary approach by using the aortic cross-sectional area (CSA) as a mediator between pressure measurements and stroke volume calculation. Instead of directly detecting difficult morphological features like the dicrotic notch, the system uses CSA measurements (which can be obtained more reliably) in combination with pressure data to determine stroke volume, thereby bypassing the detection difficulty while maintaining measurement precision
3Adaptability or versatility
If standard deviation of approximately 20% is accepted in parameter values, then population-based relationships can be used, but reliability deteriorates in patient monitoring applications where absolute determination is required
Solution Approach 1:
The patent transforms the fixed population-based parameters into variable patient-specific parameters through calibration. By changing the parameters from standardized values to individually adjusted values based on patient measurements, the system maintains the adaptability and broad applicability of population-based methods while achieving the reliability and absolute determination required for clinical patient monitoring applications
Data Source
AI summary
A method is described for determining at least one patient-related parameter for monitoring a patient. A general population-related non-linear pressure/CSA relationship of the arterial vascular bed is used and the arterial pressure of the patient is measured to obtain a prediction of the cross sectional area (CSA) of the thoracic part of the aorta. The cross sectional area is measured, wherein at least one parameter of the general population-related non-linear pressure/CSA relationship is corrected by means of the measured cross sectional area to determine a patient-related non-linear pressure/CSA relationship such that the cross sectional area obtained with this patient-related pressure/CSA relationship is equal to the measured cross sectional area.