A device and a method thereof for determining a haemodynamic state of an individual from a magnitude of a perfusion signal, wherein the control device is configured to receive a perfusion signal and a heart rate signal, divide the perfusion signal into frames, wherein a frame length is determined from an oscillation period of the heart rate signal, and determine a magnitude of the perfusion signal from at least two frames, so as to obtain a more reliable magnitude of the perfusion signal. In an embodiment the frame length may be determined based on an average oscillation period of the heart signal. The device may reduce noise as any noise in the signal or any peak or trough may be discounted as a result of the summation of the divided perfusion signal frames, as the peak and the trough that have been caused by the heart beat will correspond in time in every frame.
