Fig. 1

Measuring the trace gradient between 4 and 6 s. The gradient of the VOP trace was measured at two time points, 4–6 and 6–8 s following occlusion. Above illustrates measuring the gradient between 4 and 6 s only, however the same process is used for the 6–8 s time point. It should be noted that the first 4 s on this axis are excluded, as full cuff inflation requires 2.5 s after which a non-specific jump in blood flow is observed. The gradients obtained are an expression of the percentage increase in flow per minute rather than an actual volume of blood over time