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AssigneeNellcor Puritan Bennett LLC
InventorFernando J. Isaza
Estimating the term…
A parameter of interest being measured by a sensor is estimated from output response data from the sensor and the known transfer function of the sensor, allowing fast and accurate sensor data from sensors having a dynamic characteristic otherwise precluding assessment of the sensor input. A parameter of breathing gas from a ventilator is determined based upon the known transfer function and a plurality of the sensor output signals at predetermined intervals of time, to provide an estimation of the parameter of interest.
A system for determining parameters of a patient respiratory system for a patient receiving breathing gas from a ventilator having a source of the breathing gas and a ventilation flow path for delivering the breathing gas in fluid communication with the patient, the system comprising:
A method for determining parameters of a patient airway for a patient receiving breathing gas from a ventilator having a source of the breathing gas, a ventilation flow path for delivering the breathing gas in fluid communication with the patient, and a sensor having a known transfer function for generating sensor output signals indicative of a parameter of interest of the breathing gas, the method comprising the steps of:
A system for determining parameters of a patient respiratory system for a patient receiving breathing gas from a ventilator, said ventilator having a source of said breathing gas and a ventilation flow path for delivering said breathing gas in fluid communication with the patient, comprising:
A method for determining parameters of a patient airway for a patient receiving breathing gas from a ventilator, said ventilator having a source of said breathing gas, a ventilation flow path for delivering said breathing gas in fluid communication with the patient, and a sensor for generating sensor output signals indicative of a parameter of said breathing gas in said ventilation flow path in said patient respiratory system, said sensor having a known transfer function, the steps of the method comprising:
Dependencies are inferred from the claim text.
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Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume: of flowmeters
Control means therefor: including calculation means, e.g. using a processor
Circuits therefor, e.g. constant-current flow meters: comprising means to store calibration data for flow signal calculation or correction
Electrical: in the inspiratory circuit
Term end not estimated
1. Field of the Invention
This invention relates generally to enhancement of accuracy of sensor devices with known transfer functions and the use of information about the response of a sensor to an input parameter to closely estimate the input parameter, and more particularly concerns a system and method for determining a parameter of breathing gas in a patient ventilator from a sensor for the parameter, based upon a known transfer function of the sensor.
2. Description of Related Art
FIG. 1 is a graph illustrating the response delay of a typical thermistor to a step change in temperature;
FIG. 2 is a block diagram of a typical thermistor transfer function;
FIG. 3 is a schematic diagram of a microprocessor controlled ventilator of a patient respiratory system implementing the system and method of the invention for determining parameters of the breathing gas of the patient respiratory system.
The dynamic characteristics of a sensor and a parameter or variable being measured by the sensor can interfere with an accurate sensor measurement, generally requiring that a stable condition of the parameter of interest and the sensor be reached before the sensor measurement becomes reliably accurate. Unfortunately, when fast and accurate sensor measurements are required, the period of time required for stabilization of sensor response and a parameter value can be unacceptable, particularly when parameter values are continuously changing, precluding the possibility of accurate sensor measurements.
As is illustrated in the drawings, the invention is embodied in a system and method for estimation of an input parameter from a plurality of output responses of a sensor having a known transfer function, allowing fast and accurate sensor data from sensors having a dynamic characteristic otherwise precluding assessment of the sensor input when the measured parameter is also subject to dynamic change.
A typical thermistor transfer function can be represented by the block diagram shown in FIG. 2, where U(s) represents the Laplace transformation of the input signal, H(s) represents the Laplace transformation of the transfer function, and Y(s) represents the Laplace transformation of the output signal. The representation in FIG. 2 is commonly used to describe continuous, real time systems.