Section 10 • Delivery Rate Accuracy
59
Changes
Effect
Comments
Adding
microbore tubing
to the inlet or
outlet side of the
cassette
Volume
infused
decreases
This may result in an under-infusion due to the
tubing restricting flow into the pump, or creating
significant back pressure on the downstream side
of the pump. See comment about using a smaller
catheter.
The following graphs show the pump’s delivery accuracy for dose, bolus and basal flow
rate infusions. The dose and bolus accuracy is shown at different volumes over a number of
sequential bolus/dose events. The basal flow rate accuracy is shown as trumpet curves under
different conditions of flow rate and delivery pressures. These graphs are applicable for all
ambIT
®
pump cassettes.
The ambIT
®
PIB
v1.5
pumps use a rotary peristaltic mechanism to deliver fluid. Each rotation
of the peristaltic mechanism delivers 0.050 ml (50 μl) of fluid. During bolus/dose delivery, the
pump delivers a prescribed volume at a flow rate of 210 ml/hr accuracy. The accuracy is shown
as the percent error for the actual vs. prescribed bolus/dose volume. This error is measured
sequentially over a number of bolus/dose events at a minimum bolus/dose volume (0.1 ml) and
a bolus/dose volume (20 ml).
During basal delivery, the pump delivers fluid at a prescribed flow rate. The flow rate is
controlled by the time interval between rotations of the peristaltic mechanism. The trumpet
curves are used to describe the flow rate in basal mode. The trumpet curve defines, for a
programmed flow rate, the maximum and minimum percentage variation from the expected
flow rate for given time intervals measured from the start-up. Over short time intervals,
fluctuations in flow rate have a greater effect on accuracy as represented by the “bell” portion
of the trumpet curve. As the time interval increases, short term fluctuations have little effect on
accuracy as represented by the narrower portion of the trumpet curve.
The user is directed to these graphs in order to be aware of the delivery profile of the ambIT
®
pump and to ensure that the delivery profile is acceptable for the drug being infused, the drug’s
concentration, and the drug’s rate of delivery.
