BT17i
Blood Pressure User’s Guide
|
9
Method 2 – via derivative graph
14.
Right-click the
p-difference
vs.
p-trend
graph and select
Analyze/Process > Derivative.
15.
Select under Run the option
Run 5
.
16.
Select under Variable the variable
Fit of p_difference5
17.
Select under Order
First derivative
and under Method
Differences
.
18.
Click
Plot
.
19.
Accept with OK.
20.
Click a pane to place the Derivative graph.
21.
Use the
Scan
function to read out the blood pressure values.
-
The pressure value of the intersection of the derivative with the horizontal axis
corresponds to the MAP value.
-
The pressure value of the minimum of the derivative graph corresponds to the
systolic pressure.
-
The pressure value of the maximum of the derivative graph corresponds to the
diastolic pressure.
Figure 5:
A bell shaped “envelope curve” vs. the trend pressure. As blood pressure values are
usually rounded to 5 mmHg we find a blood pressure of 120/80. A best-fit bell-shape envelope is
drawn in the graph to find the maximum (MAP).