baxter Colleague 3 CXE, Operator'S Manual

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9
How Trumpet Curve Graphs are Interpreted
9-8
COLLEAGUE CXE VOLUMETRIC INFUSION PUMP OPERATOR’S MANUAL 071960491
How Trumpet Curve Graphs are Interpreted
The trumpet curve (Figure 9-2) provides a graphical view of the
maximum deviation in flow rate from the programmed delivery rate for
specific segments of delivery time. The horizontal axis does
not
represent elapsed delivery time, but rather acts as a graphical reference
for selecting specific observation time intervals. The widest area of the
trumpet curve (greatest deviation) reflects the smallest sampling
intervals or observation windows. As the sizes of the sampling intervals
increase (in minutes), the deviations in flow from the programmed
delivery rate are reduced as the deviations are spread out over the longer
periods of time. This results in the narrowing of the trumpet curve
giving a more realistic representation of the pump’s average flow rate
accuracy over longer intervals of time.
For example, if you were to look at the maximum and minimum
percentage error points corresponding to the 5-minute interval point on
the Observation Interval axis, you would be looking at the average flow
variance for any 5-minute period throughout the infusion.
Similarly, if you were to look at the 60-minute interval point on the
Observation Interval axis, you would be looking at the average flow
variance for any 60-minute period throughout the infusion.
How Trumpet Curve Graphs are Created
The trumpet curve graphs were developed in accordance with data
collection and manipulation methods defined in IEC 60601-2-24.
The trumpet curve graphs were created in the following manner:
„
Fluid from the pump is collected at the set flow rates over
72 hours.
„
Every 30 seconds, the cumulative weight of the fluid is recorded.
„
The data from the collection period are divided into observation
or time windows and the flow rate accuracy is determined for
each window.
„
The maximum and minimum deviations from the set flow rate for
various window sizes (2, 5, 11, 19, and 31 minutes) are plotted on
a graph.
„
These plotted points are connected to form the trumpet-shaped
lines.
„
Lines are then drawn to connect the plotted points to create the
trumpet curve.
Figure 9-2 Trumpet Graph
Example