Abstract: An intravascular blood flow sensing system is provided. The system includes an intravascular catheter or guidewire with a flow sensor that obtains flow data of blood flow within a blood vessel. The system includes a processor circuit that communicates with the intravascular catheter or guidewire. The processor circuit receives the flow data from the intravascular catheter or guidewire, determine a plurality of values based on the flow data, and outputs a plot of the plurality of values to a display. The plot includes peak associated with coronary reactivity testing (CRT). The processor circuit can also automatically change between a louder volume and a softer volume for audio output of the flow data. The processor circuit can additional communicate with a device other than the flow sensor (e.g., ECG, pressure sensor, etc.), and graphical representations of the flow data and the data received from the other device can be independent scaled.