A computer-implemented method for detecting a dicrotic notch for an individual heart beat cycle in a cardiac output related waveform comprising: providing cardiac output related waveform data; calculating a first derivative function for the waveform data and reversing the original time order of the data; comparing the amplitude of the first derivative function to a threshold value, the threshold value being a percentage of the maximum amplitude in the first derivative function; determining a starting time point of an individual heart beat cycle, the starting time point indicating the beginning of the individual heart beat cycle and being the first time the first derivative function equals zero immediately after the point at which the amplitude of the first derivative function is greater than the threshold value in the reversed time order data; determining a first time point in the first derivative function, the first time point occurring at the starting time point; determining a second time point from the first derivative function, the second time point being the second zero crossing after the starting time point for the first derivative function in the original time order of the data; calculating a second derivative function for the waveform data; determining a third time point and a fourth time point from the second derivative function, the third time point being the first zero crossing after the second time point for the second derivative function and the fourth time point being the second zero crossing after the second time point for the second derivative function; and searching the portion of the second derivative function between the third time point and the fourth time point for a local maximum, the local maximum occurring at a fifth time point, wherein the fifth time point corresponds to the time point at which the dicrotic notch is located in the cardiac output related waveform data for the individual heart beat cycle. providing cardiac output related waveform data; calculating a first derivative function for the waveform data and reversing the original time order of the data; comparing the amplitude of the first derivative function to a threshold value, the threshold value being a percentage of the maximum amplitude in the first derivative function; determining a starting time point of an individual heart beat cycle, the starting time point indicating the beginning of the individual heart beat cycle and being the first time the first derivative function equals zero immediately after the point at which the amplitude of the first derivative function is greater than the threshold value in the reversed time order data; determining a first time point in the first derivative function, the first time point occurring at the starting time point; determining a second time point from the first derivative function, the second time point being the second zero crossing after the starting time point for the first derivative function in the original time order of the data; calculating a second derivative function for the waveform data; determining a third time point and a fourth time point from the second derivative function, the third time point being the first zero crossing after the second time point for the second derivative function and the fourth time point being the second zero crossing after the second time point for the second derivative function; and searching the portion of the second derivative function between the third time point and the fourth time point for a local maximum, the local maximum occurring at a fifth time point, wherein the fifth time point corresponds to the time point at which the dicrotic notch is located in the cardiac output related waveform data for the individual heart beat cycle.