Forehead Oximetry Sensor Placement and Headband Pressure Control

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Solution Overview

Problem

The location of an oximetry sensor on a patient's body significantly affects the accuracy of physiological parameter measurements, with existing methods failing to ensure stable and reliable readings, particularly due to venous pulsations and vasoconstriction, which can lead to incorrect oxygen saturation and pulse rate determinations.

Innovation Solution

A forehead oximetry sensor placement method that involves positioning the sensor on the lower forehead, above the eyebrow, with the optics placed lateral to the iris and proximal the temple, and using a headband with an elastic and non-elastic segment to apply pressure within a specific range, reducing venous pulsations and minimizing vasoconstriction effects, while also employing temperature measurement to identify optimal placement areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the oximetry sensor is placed on various locations on the body, then oximetry measurements can be obtained, but the accuracy and stability of physiological parameter estimation deteriorates due to venous pulsations and vasoconstriction

Engineering Contradiction:

Improvestability of oximetry readingsVSAvoidaccuracy of physiological parameter estimation

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by selecting a specific location on the forehead (above the eyebrow, lateral to the iris, proximal to the temple) that has distinct physiological characteristics compared to other body locations. This specific site was chosen because it provides stable arterial blood flow with minimal venous pulsation interference, thereby improving measurement accuracy and reading stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The headband serves as an intermediary device that applies controlled pressure to the forehead sensor area. This pressure mediation stabilizes the sensor contact, reduces motion artifacts, and minimizes the impact of venous pulsations and vasoconstriction on the optical measurements, thereby improving both reliability and precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If pressure is applied to the forehead sensor area, then venous pulsations are reduced, but capillary pressure may be compromised if pressure is too high

Engineering Contradiction:

Improvereduction of venous pulsation interferenceVSAvoidpotential compromise of capillary pressure

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The headband is designed to apply pressure within a specific range that is higher than venous pressure but lower than capillary pressure. This parameter control allows the system to effectively reduce venous pulsation interference while avoiding compromise of capillary blood flow, thereby improving measurement reliability without introducing new harmful effects.

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

This approach provides stable and accurate physiological parameter measurements by minimizing the impact of venous pulsations and vasoconstriction, ensuring reliable oxygen saturation and pulse rate readings, even in varying environmental conditions.

Implementation Method 1

The headband includes an elastic segment sized to fit around a patient's head

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

oximetry sensors and in particular to forehead-type oximetry sensors

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS7899509B2Forehead sensor placement

Publication Date: 2011.03.01 COVIDIEN LP

AI summary

Forehead oximetry sensor devices and methods for determining physiological parameters using forehead oximetry sensors. One method includes placing an oximetry sensor on the forehead of a patient, such that the sensor is placed on the lower forehead region, above the eyebrow with the sensor optics placed lateral of the iris and proximal the temple; and operating the pulse oximeter to obtain the physiological parameter. In one aspect, the method also includes providing and placing a headband over the oximetry sensor, or alternately, the sensor is a headband-integrated sensor. The headband has an elastic segment sized to fit around the patient's head. The headband also includes a non-elastic segment that is smaller than and attached with the elastic segment. The non-elastic segment is sized to span a portion of the elastic segment when the elastic segment is stretched. In addition, the non-elastic segment is larger than the portion of the elastic segment it spans when the elastic segment is not stretched. When the headband or the headband-integrated sensor is sufficiently tight, it delivers a pressure in the range higher than the venous pressure and lower than the capillary pressure to the forehead of the patient.