Fig. 2.

Snapshots of the software. A : Data acquisition screen. The volume-pressure curve (white curve), numerical rating scores (red curve) and sound curve (green curve) are shown together. The slope of the white curve is steep while a contrast material is filling the needle (a). After checking the static opening pressure (*), the slope becomes more gentle (b). In this case, a patient screamed from back pain at the point of 0.7cc injected. At this point the green curve fluctuates (c) and the red curve increases by 5 levels (d). Other control buttons are arranged in right side of the screen. Pr : intradiscal pressure, V : injected volume, VAS : visual analog scale, Po : static opening pressure, dP : pressure difference, dP = Pr-Ps, Snd : sound intensity. B : Data access screen. Saved data can be retrieved for review or analysis. Raw data which are used for data analysis are presented in right lower side.