Thoratec HeartMate III, Инструкция по эксплуатации

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System Monitor 4
HeartMate III Left Ventricular Assist System Instructions for Use 4-21
Use the buttons in the Select Low Speed Limit box to increase or decrease the Low Speed Limit
(
Figure 4.21
).
Figure 4.21 Select Low Speed Limit Box (Settings Screen)
Setting the Low Speed Limit is similar to setting the Fixed Speed. The Low Speed Limit is generally
set at a value slightly above the minimum speed determined during the speed ramp study.
Clinical judgment and consideration of all factors should be used when selecting the
Low Speed Limit.
The Low Speed Limit default setting is 5,000 rpm, but it can be adjusted between 4,000 rpm
and 6,000 rpm. If the operating speed drops below the value set for the Low Speed Limit, the
WARNING: Low Speed Advisory alarm message appears.
If the system detects a PI event, the Pump speed automatically drops to the Low Speed Limit and
slowly ramps back up at a rate of 100 rpm per second to the Fixed Speed setpoint. This drop in
speed is accompanied by a reduced Pump flow. If the Low Speed Limit is set at a value above or
the same as the Fixed Speed setpoint, the Pump speed does not change during a PI event.
There are no audible alarms with a PI event.
PI events are assumed by the system during cases when there are sudden and substantial
changes in the pulsatility index. These events are also referred to as PI events, and may be
initiated for reasons other than true PI events. Some reasons include sudden changes in a
patient’s volume status, arrhythmias, sudden changes in power, and sudden changes in Pump
speed. These types of PI events are more likely to be triggered in cases of low pulsatility.