Alarm setting derived from the variability in signal characteristics
A method for creating alarm signals based on time-series signal behavior determined from real-time discrete data obtained from a medical device. In one embodiment the method includes identifying patterns in preceding time-series measurement threshold breaches in clinical readings obtained from said medical device when associated with a particular patient, and initiating an alarm signal to a front-line clinician based on the preceding quantity of threshold breaches.
1. A method for creating alarm signals based on time-series signal behavior of real-time discrete clinical data obtained from a medical device continuously monitoring a patient, the method comprising:
setting upper and lower thresholds in the patient's real-time discrete clinical data;
identifying breaches of upper and lower thresholds in the patient's real-time discrete clinical data;
calculating a moving average over a defined time interval in the real-time discrete clinical data;
setting new upper and lower thresholds within the defined time interval in response to the moving average;
determining each new breach of the new upper and lower thresholds in subsequent defined time intervals; and
calculating subsequent changes in the upper and lower thresholds if the number of breaches of the upper and lower thresholds exceeds a predetermined amount.
2. The method of claim 1 , further including the step of issuing an alarm in response to the subsequent number of threshold breaches.
3. The method of claim 1 wherein the new upper and lower thresholds in subsequent defined time intervals is in response to a percentage of the moving average, representative of a normal range of variability associated with the typical measurements of a specific patient.
4. The method of claim 3 wherein the percentage is between 10% and 30% inclusive.
5. The method of claim 1 further comprising the step of normalizing the count of the breaches of the upper and lower threshold to generate an instability index.
6. The method of claim 5 further comprising generating a weighting value for each breach of the upper and lower threshold.
7. The method of claim 6 wherein the weighting value is a function of the magnitude of the difference between the measurement resulting in the breach of the upper and lower threshold and the current value of the moving average.
8. The method of claim 6 comprising generating an alarm in response to the number of threshold breaches having a weighting value greater than a specified threshold value.