Patent ID: 9591976
Date: 2017-03-14
CPC Classifications: A61B

Claim:
1. A blood volume measurement method for calculating a cardiac output (CO) from a pulse wave transit time, the method comprising the steps of: measuring respiratory variations of at least two types of parameters; measuring a pulse wave transit time (PWTT) in a respiratory cycle; measuring a heart rate (HR) in a predetermined time; and calculating and outputting, by a computer, a cardiac output (CO) by use of the respiratory variations of at least the two types of parameters, the pulse wave transit time, and the heart rate; and wherein patient's inherent coefficients α, β, and K are calculated by use of the respiratory variations of at least the two types of parameters and the pulse wave transit time, and the cardiac output is determined by an equation wherein the patient's inherent coefficient α is determined by an equation PAV is an amplitude of a pulse wave; PP1 is actually measured pulse pressure; PWTTavg is an average pulse wave transit time in a respiratory cycle; PWTT1 is an actually measured pulse wave transit time; PWTTmax is a maximum value of pulse wave transit time in the respiratory cycle; and PWTTmin is a minimum value of pulse wave transit time in the respiratory cycle.