12 Mode of operation
The remOVE DC Impulse is designed to send an electrical direct current pulse of
typically I
S
= 155 A for the duration of 60 ms through the bipolar, endoscopic
instrument remOVE DC Cutter.
This DC pulse flows through the clip segment the remOVE DC Cutter is estab-
lishing contact with, resulting in localized melting of the clip material.
Figure 11: Left: Establishment of contact between clip segment and remOVE DC
Cutter. Right: Cross-section of clip segment to be cut (b) and marking of current
path I
S
between electrodes (a)
The remOVE DC Impulse is equipped with internal energy storage, allowing the
device to generate a DC pulse without additional load on the power supply. This
internal energy storage is charged before the remOVE DC Impulse generates the
DC pulse.
The remOVE DC Impulse is designed to ensure that a direct current pulse can
only be generated when sufficient contact with a segment of the clip is estab-
lished. Sufficient contact is indicated through an acoustic signal.
Should contact break off between the remOVE DC Cutter and the clip during the
application of a DC pulse, the output of the remOVE DC Impulse will be deac-
tivated within less than 500 µs. Breaking-off of contact might occur, for example,
if one or both electrodes lose contact with the clip due to successful clip fragmen-
tation.
During a DC pulse, the voltage drop between the electrodes of the remOVE DC
Cutter is between 1.3 V and 2.0 V. During loss of contact, short-term (max. 500
µs) voltage spikes max. 22 V may occur. These spikes might be transferred into
the tissue if both electrodes of the remOVE DC Cutter are in contact with tissue.
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