Endovascular heat exchange systems and methods wherein a heat exchange catheter is positionable within the vasculature of a patent to exchange heat with the patient's flowing blood. The rate at which heat is being exchanged is determined and quantitative blood flow determinations may be made based on the rate of heat exchange. The system provides notification(s) to personnel when one or more blood flow-related events occur(s), such as a) resumption or continuation of effective spontaneous circulation; b) cessation of absence of effective spontaneous circulation, c) the occurrence of spontaneous or cardiac-compression-generated circulation that is below a minimum effective blood flow rate and e) the occurrence of spontaneous or cardiac-compression-generated circulation that is at or above a minimum effective blood flow rate.