A control module for a medical injection system generates an injection control signal based on sensed internal pressure of a user activated control device, for example, in response to an applied external force that causes the sensed internal pressure to increase from a baseline pressure, and continues to sense the internal pressure of the device, following release of the applied external force, so that, if the sensed internal pressure drops below the baseline pressure, the control module may generate a notification. Thus, an operator of the system may monitor internal pressure of the control device for a drop below the baseline pressure, and then, if such a drop is detected, inspect the control device for leaks and reconnect, replace or repair the control device, or simply reconnect or replace the control device.
