A medical system includes a medical device and a controller. The medical device is controlled according to a control protocol. The controller is configured to receive a measured data set containing a current value at a current time and past values at past times of a physiologic signal measured on a recipient, calculate a difference signal at the current time based on the measured data set, and predict a difference value using the difference signal and a prediction algorithm. The difference value is a difference between a predicted future value of the physiologic signal at a future time and the current value. The controller is further configured to calculate the predicted future value based on the difference value and the current value and update the control protocol according to the predicted future value.