Patent ID: 8423108

Claim:
A computer-assisted method for identifying a volume status of a patient, the method comprising: administering a cardiovascular preload to the patient; continuously recording, prior to, during, and after the step of administering the cardiovascular preload to the patient, a pulse density signal from a non-invasive transducer transmitting data from the patient; applying, using a processor, a first filter to the pulse density signal to identify a first respiration sampling period recorded prior to the step of administering the cardiovascular preload and a second respiration sampling period recorded after the step of administering the cardiovascular preload; applying, using the processor, a second filter to the pulse density signal to identify a first plurality of cardiac cycles occurring during the first respiration sampling period and a second plurality of cardiac cycles occurring during the second respiration sampling period; and calculating, using the processor, a variation of the pulse density signal before and after the step of administering the cardiovascular preload, wherein the variation is used as an index of the volume status of the patient, wherein the variation is a quotient of a difference between a mean pulse density signal between the second and the first respiration sampling periods to a sum of the mean pulse density signal of the second and the first respiration sampling periods, wherein the mean pulse density signal for each respiration sampling period is a quotient of a sum of a difference between a maximum point on the pulse density signal and a minimum point on the pulse density signal for each cardiac cycle occurring during such respiration sampling period to a total number of cardiac cycles occurring during such respiration sampling period.