Variable indication estimator
View Patent ↗A variable indication estimator which determines an output value representative of a set of input data. For example, the estimator can reduce input data to estimates of a desired signal, select a time, and determine an output value from the estimates and the time. In one embodiment, the time is selected using one or more adjustable signal confidence parameters determine where along the estimates the output value will be computed. By varying the parameters, the characteristics of the output value are variable. For example, when input signal confidence is low, the parameters are adjusted so that the output value is a smoothed representation of the input signal. When input signal confidence is high, the parameters are adjusted so that the output value has a faster and more accurate response to the input signal.
1. An apparatus for selecting output physiological parameter values based on signal confidence, the apparatus comprising:
one or more processors configured to:
receive an input physiological signal;
calculate physiological parameter values from the input physiological signal;
calculate a signal confidence based at least in part on the input physiological signal;
vary a mode parameter in real time based at least in part on the signal confidence;
apply a first filter to the physiological parameter values to produce output physiological parameter values in responsive to the mode parameter having a first value;
apply a second filter to the physiological parameter values to produce the output physiological parameter values in response to the mode parameter having a second value different from the first value; and
suppress at least one alarm responsive to the variation of the mode parameter.
2. The apparatus of claim 1 , wherein the first filter comprises a filter having a smoothing characteristic.
3. The apparatus of claim 2 , wherein the second filter comprises a filter having a tracking characteristic.
4. The apparatus of claim 1 , wherein the first filter comprises a filter having a constant mode averaging characteristic.
5. The apparatus of claim 1 , wherein the first filter comprises a filter having a linear mode averaging characteristic.
6. The apparatus of claim 1 , wherein the first and second filters are the same filter with different characteristics responsive to the signal confidence.
7. The apparatus of claim 1 , wherein the physiological parameter comprises oxygen saturation.
8. The apparatus of claim 1 , wherein the physiological parameter comprises blood pressure.
9. A method of selecting output physiological parameter values based on signal confidence, the method comprising:
under control of one or more processors:
receiving an input physiological signal;
calculating physiological parameter values from the input physiological signal;
calculating a signal confidence based at least in part on the input physiological signal;
varying a mode parameter in real time based at least in part on the signal confidence;
selecting a first filter characteristic as a selected filter characteristic in response to the mode parameter having a first value;
selecting a second filter characteristic as the selected filter characteristic in response to the mode parameter having a second value different from the first value; and
applying a filter having the selected filter characteristic to the physiological parameter values to produce output physiological parameter values.
10. The method of claim 9 , wherein the first filter characteristic comprises a smoothing characteristic.
11. The method of claim 10 , wherein the second filter characteristic comprises a tracking characteristic.
12. The method of claim 9 , wherein the first filter characteristic comprises a constant mode averaging characteristic.
13. The method of claim 12 , wherein the second filter characteristic comprises a linear mode averaging characteristic.
14. The method of claim 9 , wherein the physiological parameter comprises oxygen saturation.
15. The method of claim 9 , wherein the physiological parameter comprises blood pressure.