Core body temperature measurement

Inventors

Telfort, Valery G.Perea, PhilipNovak, Jerome

Assignees

Masimo Corp

Publication Number

US-12257183-B2

Publication Date

2025-03-25

Expiration Date

2039-08-21

Interested in licensing this patent?

MTEC can help explore whether this patent might be available for licensing for your application.


Abstract

Continuous core body temperature measurements are made during hypothermic operations, where the core body temperature of the patient is lowered to reduce swelling. Caregivers monitor the patient's core body temperature to prevent damage that can occur to the patient if the patient's core body temperature becomes too low. To accurately determine the core body temperature of the patient, a temperature monitoring system measures the temperature at or near the surface of the patient and through at least a portion of a thermal block at multiple locations.

Core Innovation

The invention provides a temperature monitoring system designed to accurately and continuously measure core body temperature during procedures in which core body temperature is intentionally reduced, such as hypothermic operations. The system includes multiple temperature monitoring devices, each comprising thermal blocks with known thermal conductivities and dimensions and at least two temperature measuring devices, which may be temperature sensors like thermistors, thermocouples, or other suitable sensors. These sensors are positioned at or near the surface of the patient and within or on opposing sides of the thermal block, allowing for temperature assessment at multiple sites.

The problem addressed is the inaccuracy of core body temperature measurements caused by relying on assumptions about the thermal conductivity of a patient's skin in conventional systems. When only a single temperature monitoring device is used, assumptions about skin resistance can result in erroneous core temperature determinations. The invention solves this by utilizing at least two temperature monitoring devices at different locations, enabling the simultaneous determination of both the core body temperature and the skin's thermal resistance without estimating the latter.

By measuring temperatures at several points and using known properties such as distances and thermal conductivities of the thermal blocks, the system determines heat transfer rates and calculates the core body temperature with improved accuracy. The system may also derive additional variables, such as ambient air temperature, and can display the calculated core body temperature for caregiver monitoring. Furthermore, variants include use of active components such as Peltier devices for perfusion information.

Claims Coverage

The patent includes two independent claims, each introducing inventive features for accurately determining core body temperature using multi-site sensing and materials with known and differing thermal conductivities.

Multi-site temperature monitoring system using materials with differing thermal conductivities

The system includes: - A first temperature sensor positioned at a first skin location and a second temperature sensor associated therewith. - A first material and a second material with different thermal conductivities placed between these sensors. - A third temperature sensor at a second skin location and a third material positioned between this and a fourth temperature sensor. - The use of measurements from all four temperature sensors to determine a core body temperature estimate. This structure prescribes varying material conductivity and spatial separation for enhanced measurement accuracy.

Method for monitoring core body temperature using multi-site sensors and materials with differing conductivities

The method comprises: - Positioning a first temperature sensor at a first skin location and thermally coupling a second temperature sensor through both a first and a second material, each with different thermal conductivities. - Positioning a third temperature sensor at a second skin location and thermally coupling a fourth temperature sensor through a third material. - Determining the core body temperature estimate using measurements from all four sensors. This approach emphasizes operational steps for system deployment and the calculation process using multiple sites and materials.

These inventive features define a multi-site core temperature monitoring approach utilizing combinations of sensors and materials with differing thermal properties to improve the accuracy of core temperature estimation.

Stated Advantages

Continuous and accurate core body temperature measurements can be provided during medical procedures involving intentional reduction of core temperature.

Assumptions about the thermal conductivity of a patient's skin are eliminated when at least two temperature monitoring devices are used, increasing measurement accuracy.

The system can determine other physiological variables, such as ambient air temperature, in addition to core body temperature.

Documented Applications

Continuous monitoring of core body temperature during hypothermic operations or medical procedures in which core body temperature is intentionally reduced to reduce swelling or aid recovery.

JOIN OUR MAILING LIST

Stay Connected with MTEC

Keep up with active and upcoming solicitations, MTEC news and other valuable information.