1. A computer implemented method performed on a dispatch center computer to assist a dispatcher when responding to an emergency caller regarding a medical emergency of a patient, the method comprising: a dispatch center computer providing an emergency medical dispatch protocol to assist emergency dispatchers, the protocol including a plurality of interrogatories for a dispatcher to ask a caller to generate an emergency medical dispatch response by emergency responders; initiating a diagnostic tool on the dispatch center computer to determine a vital sign of a patient; the diagnostic tool providing a user interface on the dispatch center computer, the user interface configured to enable the dispatcher to initiate a timer indicative of a start time for a caller; in response to the timer initiation, the diagnostic tool running the timer; the diagnostic tool receiving vital sign related data which is input by the dispatcher corresponding to caller relayed information; the diagnostic tool stopping the timer; the diagnostic tool determining a rate or interval of the vital sign related data; and the diagnostic tool determining a patient diagnosis from the vital sign related data and the determined rate or interval of the vital sign.