Robust fractional saturation determination
Inventors
Perea, Philip • Al-Ali, Ammar • Kiani, Massi Joe E.
Assignees
Publication Number
US-12226206-B2
Publication Date
2025-02-18
Expiration Date
2032-10-12
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
The present disclosure describes the derivation and measurement of a fractional oxygen saturation measurement. In one embodiment, a system includes an optical sensor and a processor. The optical sensor can emit light of multiple wavelengths directed at a measurement site of tissue of a patient, detect the light after attenuation by the tissue, and produce a signal representative of the detected light after attenuation. The processor can receive the signal representative of the detected light after attenuation and determine, using the signal, a fractional oxygen saturation measurement based on two or more different measures of fractional oxygen saturation.
Core Innovation
The invention concerns systems and methods for deriving and measuring fractional oxygen saturation in patients using non-invasive optical technologies. Traditional pulse oximeters provide functional oxygen saturation (SpO2), which measures the percentage of oxygenated hemoglobin relative only to oxygenated and deoxygenated hemoglobin, neglecting the presence of dishemoglobins like methemoglobin and carboxyhemoglobin. This omission can lead to inaccurate assessments of a patient's overall oxygen-carrying capacity, especially in cases where dishemoglobin levels are elevated.
The invention addresses this shortcoming by providing devices and algorithms that determine a more comprehensive fractional oxygen saturation value (SpFO2). The system uses an optical sensor to emit multiple wavelengths of light through tissue and detect the resulting signal after attenuation, which is then processed to measure not only functional oxygen saturation, but also dishemoglobin, methemoglobin, and carboxyhemoglobin levels. Calculations employ both direct measurements and derived relationships involving these various species to generate a robust fractional oxygen saturation measurement that better reflects the patient’s true physiological status.
The invention further introduces rule-based and confidence-weighted algorithms for combining multiple approaches to calculate fractional oxygen saturation. If measurements such as SpO2, SpMet, or SpCO are determined to lack reliability based on confidence values, the system may adjust the input weights, select among calculation methods, or use default or weighted values to produce the most accurate and robust output for clinical use. This approach helps to minimize errors caused by measurement anomalies or physiological complications affecting certain hemoglobin species.
Claims Coverage
There are two main independent inventive features in the patent claims pertaining to apparatus and method for robust fractional oxygen saturation determination.
Patient monitoring apparatus for robust fractional oxygen saturation measurement
The apparatus comprises: - A housing and a memory device storing signals from a noninvasive physiological sensor responsive to patient physiological conditions. - One or more hardware processors configured to: - Determine from the signal a functional oxygen saturation measurement, a methemoglobin measurement, and a carboxyhemoglobin measurement. - Determine a dishemoglobin measurement from the signal without using the methemoglobin and carboxyhemoglobin measurements. - Compute a first fractional oxygen saturation measurement using a first algorithm, with inputs of the functional oxygen saturation, methemoglobin, and carboxyhemoglobin measurements. - Compute a second fractional oxygen saturation measurement using a second algorithm, different from the first, with inputs of functional oxygen saturation and dishemoglobin measurement. - Determine an output fractional oxygen saturation measurement for presentation to a user from the first and second fractional oxygen saturation measurements.
Patient monitoring method for robust fractional oxygen saturation measurement
The method comprises: - Storing a signal generated by a noninvasive physiological sensor responsive to a patient's physiological condition. - Determining, from the signal, the functional oxygen saturation, methemoglobin, and carboxyhemoglobin measurements. - Determining a dishemoglobin measurement from the signal without using the methemoglobin or carboxyhemoglobin measurements. - Calculating a first fractional oxygen saturation measurement using a first algorithm with inputs from the functional oxygen saturation, methemoglobin, and carboxyhemoglobin measurements. - Calculating a second fractional oxygen saturation measurement using a second algorithm, different from the first, with inputs of the functional oxygen saturation and dishemoglobin measurement. - Determining an output fractional oxygen saturation measurement for presentation to a user from the first and second fractional oxygen saturation measurements.
The patent claims cover both apparatus and methods for concurrently deriving fractional oxygen saturation measurements using multiple algorithms and input hemoglobin measurements, and using combinations or selections of these measurements to determine a robust, clinically presentable output.
Stated Advantages
Provides a fractional oxygen saturation measurement that accounts for dishemoglobins, offering a more accurate assessment of the patient's blood analyte compared to functional oxygen saturation alone.
Improves reliability and accuracy by employing multiple algorithms and confidence-weighted or rule-based selection among different fractional oxygen saturation determinations.
Helps caregivers avoid clinical errors when high dishemoglobin levels would otherwise produce misleadingly high oxygen saturation readings, improving decision-making for patient oxygen therapy.
Documented Applications
Non-invasive clinical monitoring of patients’ fractional oxygen saturation to provide accurate assessment of oxygen-carrying capacity, including in cases where dishemoglobin levels are elevated due to conditions like methemoglobinemia or carboxyhemoglobinemia.
Interested in licensing this patent?