#### Average Pressure Waveform

The image shows the pressure waveform obtained by the average of all recorded pressure waveforms.
Augmentation Index [AIx]:
The blue dot in the figure shows the inflection point, which represents the point where the backward wave starts superimposing onto the forward wave. The inflection point is very important in order to assess the Augmentation Index [AIx]. This parameter provides an indication of the incidence of reflected waves on the total pulse pressure. The 'weight' of the backward waves is related both to their early superimposition onto the forward wave and the magnitude and distribution of reflected waves. AIx is calculated as the ratio between the augmented pressure [AP) due to reflected waves and the pulse pressure [PP = Systolic blood pressure - Diastolic blood pressure]: AIx = AP / PP. By convention, this ratio assumes a negative value when the inflection point is after the peak systolic pressure. This convention allows having a 'continuum' of AIx values in relation to the timing of reflected waves.
This inflection point in most cases is easily recognizable on the systolic phase of the pressure curve, however, sometimes, it is not clearly detectable. WPulsePen software allows to verify and manually change the marker corresponding to the inflection point.
Select the magnifying lens on the right corner of the figure.
Place the mouser pointer on the blue dot.
Keeping the mouse left button pressed, change the position of the blue dot marker corresponding to the inflection point.
Select again the magnifying lens on the right corner of the figure
and confirm the change.
Quality Index [Q.I.]:
Quality Index value [Q.I., %] is shown on the right corner of the figure.
Q.I. shows the score referred to the ten recorded pulse waves (see the "Exam Quality Index") paragraph.