#### Distance Measurement

The Pulse Wave Velocity "PWV" is obtained as the ratio between the travel distance of the pressure wave and the time 'DeltaT' taken to cover such distance:
'DeltaT' is automatically calculated by the software, according to delay between feet of the pressure waves.
The distance can be estimated mainly in two ways, both of them supported by the PulsePen Software:
1) Direct Method:
A tape measure is used to quantify the direct distance between the Carotid - C and the peripheral Artery (F - Femoral in the example). The software automatically multiplies the result by 0.8, according to the accredited guidelines.
2) Subtractive Method:
This method relies on the fact that the initial pressure wave, once the bifurcation corresponding to the suprasternal notch (sSN in the figure) has been reached, moves in both directions, towards the Carotid and the Aorta. Assuming that propagation characteristics are similar in both paths when the ascending pressure wave has arrived at C (Carotid), the descending one will arrive at C', equidistant from sSN related to C. According to such considerations, the distance effectively traveled by the pressure wave corresponding to delay DeltaT in the figure, is equivalent to the path C' - F and therefore distance = (sSn - F) - (C' - sSN) that can be approximated as distance = (sSn - F) - (C - sSN).
Measurement of distances for Femoral, Tibial, Dorsalis Pedis Arteries :
A tape measure is used to quantify the distance between Carotid - C and peripheral Artery (F - Femoral in the example), between Carotid - C and suprasternal notch, and between suprasternal notch, and peripheral Artery.
Measurement of distances for Brachial, Radial Arteries:
With the arm at 45 degrees as shown in the figure, a tape measure is used to quantify the distance between Carotid and peripheral Artery (Radial in the example), between Carotid and suprasternal notch, and between suprasternal notch, and peripheral Artery.