The present invention relates to an apparatus and a method for determining an indication of blood flow in a limb. According to an embodiment, the apparatus comprises an orientation sensor, a blood volume (BV) measuring device and a control unit. The orientation sensor is configured to determine an orientation of the limb and output an orientation signal indicative thereof. The blood volume measurement device is configured to measure an indication of blood volume (BV) in the limb and output a BV signal indicative thereof. The control unit is arranged to receive the orientation signal and the BV signal, determine a change in orientation of the limb in dependence on the orientation signal, and correlate the change in orientation with a change in blood volume of the limb determined in dependence on the BV signal.