Medical Probe Calibration for Pulsatile Volume Detection

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Solution Overview

Problem

Existing non-invasive medical probes for detecting conditions like myocardial ischemia and endothelial dysfunction lack accurate calibration, leading to inconsistent and less reliable measurements due to variations in patient-specific body part characteristics.

Innovation Solution

Calibrating probes for specific physical characteristics of the monitored body part, such as tissue volume, to accurately quantify arterial pulsatile volume changes, thereby improving diagnostic performance and reproducibility of measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If probes are used without calibration for different patients, then the device complexity is reduced and ease of operation is improved, but measurement precision and reliability deteriorate due to patient-specific variations

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements calibration procedures that are performed in advance before actual measurements are taken. The system pre-determines calibration factors based on patient-specific characteristics (such as body mass index, body surface area, or anthropometric measurements) and stores these factors for use during subsequent measurements. This preliminary calibration action ensures measurement precision is maintained without adding complexity to the actual measurement process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent adjusts measurement parameters and calibration factors based on patient-specific parameters such as body mass index, body surface area, age, and gender. By changing the calibration parameters according to individual patient characteristics, the system achieves accurate measurements across different patients without requiring complex adaptive hardware. The calibration factors are mathematically adjusted based on these patient parameters.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If probes are calibrated for each patient's body part characteristics, then measurement precision and reliability are improved, but ease of operation and time consumption worsen

Engineering Contradiction:
ImprovereliabilityVSAvoidtime consumption
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system performs calibration calculations in advance using patient demographic and anthropometric data that are typically already collected during patient intake. By determining calibration factors before the actual measurement procedure, the system ensures reliable measurements without requiring additional time during the critical measurement phase. The calibration is integrated into the patient registration process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements automated calibration procedures where the system automatically calculates calibration factors based on input patient data without requiring manual intervention or complex user operations. The processor automatically retrieves patient characteristics, computes the appropriate calibration factors, and applies them to the measurement process. This self-calibrating capability maintains reliability while minimizing time loss and operational complexity.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If relative volume changes are measured without calibration, then ease of operation is maintained, but measurement precision deteriorates due to inability to quantify absolute pulsatile volume

Engineering Contradiction:
Improvemeasurement precisionVSAvoidease of operation
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent transforms the measurement system from providing only relative volume changes to providing absolute pulsatile volume measurements by introducing calibration factors that convert raw sensor signals into clinically meaningful absolute values. These calibration factors are derived from patient-specific parameters and allow the system to output absolute volume measurements (e.g., in milliliters) rather than arbitrary relative units. This parameter transformation maintains ease of operation while dramatically improving measurement precision and clinical utility.

Inventive Principle:
Principle #35Parameter changes

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

Enhances the accuracy and consistency of medical condition detection by accounting for individual patient variations, allowing for better comparison of test results over time and improved measurement of pulsatile volume changes relative to tissue mass.

Implementation Method 1

pressure sensors, which sense pressure changes in a compressible fluid system to which the patient's body part (e.g., finger, toe or a distal portion of a limb) is subjected, which pressure changes are convertible to volume changes in the body part due to pulsatile arterial blood volume changes therein

Methodology Applied
Scientific EffectPressure sensing:

Implementation Method 2

optical sensors, which sense optical density or transmissivity changes in the body part, which changes are also convertible to volume changes due to pulsatile arterial blood volume changes in the body part

Methodology Applied
Scientific EffectOptical density sensing: Absorption Spectroscopy

Data Source

PatentUS7819811B2Detecting medical conditions with noninvasive body probes
Publication Date: 2010.10.26 ITAMAR MEDICAL LTD
  • US7819811B2 patent drawing
  • US7819811B2 patent drawing
  • US7819811B2 patent drawing

AI summary

A method and apparatus for improving the diagnostic performance of a probe system (30) for detecting a medical condition in a patient by sensing volume changes in a monitored body part due to pulsatile arterial blood flow in the body part, characterized in calibrating the probe system (30) for the respective measurement site according to a predetermined characteristic of the monitored body part of the patient and quantifying the arterial pulsatile volume thereat. Such calibration is described with respect to probes including: (1) a pressure sensor (63), which senses pressure changes in a compressible fluid system to which the patient's body part (e.g., finger, toe or a distal portion of a limb) is subjected, which pressure changes are convertible to volume changes in the body part due to pulsatile arterial blood volume changes therein; and (2) an optical sensor (140), which senses optical density or transmissivity changes in the body part, which changes are also convertible to volume changes due to pulsatile arterial blood volume changes in the body part.