Implantable Blood Pressure Sensor with Passive Internal Applanation
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Solution Overview
Problem
Current methods for blood pressure monitoring, such as external radial artery applanation tonometry, are inaccurate in patients with higher body mass indices and require calibration against brachial arterial pressure, while invasive methods like A-Lines pose risks.
Innovation Solution
An implantable BP sensing device that measures waveforms from a peripheral blood vessel using passive, internal applanation tonometry, calibrated against brachial arterial pressures, to provide continuous and autonomous central arterial pressure monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If external radial artery applanation tonometry is used, then noninvasive blood pressure measurement is achieved, but measurement precision deteriorates in patients with higher body mass indices
Solution Approach 1:
The patent replaces the external mechanical tonometry system with an implantable sensor system that uses a pressure-sensitive element (such as a piezoresistive or capacitive sensor) to directly measure blood pressure within the vessel wall, eliminating the need for external mechanical flattening and improving measurement accuracy independent of body mass index
Solution Approach 2:
The patent introduces an intermediary structure (the implantable sensor device positioned within the vessel wall) that mediates between the blood pressure and the measurement system, allowing direct measurement of the pressure waveform without relying on external tissue transmission properties that vary with body mass index
2Measurement precision
If invasive arterial line (A-Line) is used, then measurement precision of blood pressure is improved, but object-generated harmful factors worsen due to infection, thrombosis, and embolization risks
Solution Approach 1:
The implantable sensor device serves as an intermediary that is less invasive than an arterial line, positioned within the vessel wall rather than requiring catheter insertion into the arterial lumen, thereby maintaining measurement precision while reducing the risk of infection, thrombosis, and embolization
Solution Approach 2:
The patent describes an implantable device that can be removed after a limited monitoring period (e.g., 30 days), providing continuous monitoring capability without the long-term commitment and associated risks of permanent arterial line placement
3Object-affected harmful factors
If external radial artery applanation tonometry is used, then noninvasive measurement is achieved, but device complexity increases due to requirement for calibration against brachial arterial pressure
Solution Approach 1:
The implantable sensor device performs self-calibration by utilizing the patient's own physiological parameters (such as ECG R-wave timing and pulse wave characteristics) to establish the relationship between the measured pressure waveform and actual blood pressure, eliminating the need for external calibration equipment and procedures
4Productivity
If continuous blood pressure monitoring is implemented, then productivity of healthcare monitoring is improved, but use of energy by stationary object worsens due to implantable device power requirements
Solution Approach 1:
The patent describes an implantable device that can operate in continuous monitoring mode when needed, with the understanding that the device is removed after a limited period (e.g., 30 days), thereby achieving continuous monitoring productivity while limiting total energy consumption through temporary rather than permanent implantation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implantable device offers accurate and reliable blood pressure monitoring, improving cardiovascular event prediction and hypertension management by measuring central arterial pressure continuously and autonomously.
Implementation Method 1
a pressure-sensing element projecting from an outer surface of the substrate and configured to sense blood pressure within the blood vessel
Data Source
AI summary
An implantable pressure-sensing device can be used to measure blood pressure. It can include a substrate to secure the implantable pressure-sensing device within 0 mm to 10 mm from a blood vessel, a pressure-sensing element projecting from an outer surface of the substrate and configured to sense blood pressure within the blood vessel, circuitry disposed on the substrate and in electrical communication with the pressure-sensing element and configured to receive data from the pressure-sensing element, and a power management system. The pressure-sensing device may also include a structure disposed around the pressure-sensing element configured to transmit pressure waves from the blood vessel towards the pressure-sensing element. The pressure-sensing device may also include a multilayer ceramic/polymer coating.