A computer-implemented method of recording the times of events related to the medical care delivered to patient, and for integrating those times to provide a patient history, including recording a first time of occurrence of a first event, recording first clock information characterizing a first time source from which the first time of occurrence was obtained, recording a second time of occurrence of a second event, recording second clock information characterizing a second time source from which the second time of occurrence was obtained, wherein the first time source and the second time source are independent of one another and not synchronized with one another, transferring recorded data so that the first time of occurrence, first clock information, second time of occurrence, and second clock information are accessible at a computer; and producing a patient history using at least the first and second times of occurrence.