1. A method for determining cardiac output from an arterial blood pressure curve measured at a peripheral region, comprising the steps of: measuring the arterial blood pressure curve at the peripheral region; arithmetically transforming the measured arterial blood pressure curve to an equivalent aortic pressure; and calculating the cardiac output from the equivalent aortic pressure, wherein the arithmetic transformation of the arterial blood pressure curve measured at the peripheral region into the equivalent aortic pressure is performed by the aid of an artificial neural network having weighting values that are determined by learning.