Abstract: A patient is monitored by establishing a current warning limit for a physiological characteristic of the patient, providing a sensor for the physiological characteristic, and measuring a measured value of the physiological characteristic of the patient using the sensor. A revised warning limit is selected responsive to at least one of the steps of providing and measuring. The revised warning limit is then typically substituted for the current warning limit. The current warning limit serves to trigger some action in the event that the measured value of the physiological characteristic is not within an acceptable range defined by the current warning limit.