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Pacemaker
6
User guide
Pacemaker Function
6.1
A
rt.
no.
: 0-48-
0227
Rev.:
g
DEFIGARD/PHYSIOGARD Touch 7
6 Pacemaker
6.1 Pacemaker Function
6.1.1
Fixed-rate mode (Fix)
In this operating mode, the module delivers pacing impulses with the user-defined
current at a user-defined rate. The selected rate remains constant and is not affected
by intrinsic actions of the patient's heart. This mode is mainly used in the case of
asystoles.
6.1.2
Demand mode
In demand mode, the pacemaker does not deliver pacing pulses as long as the
patient's intrinsic heart rate exceeds the set pacing rate. When the heart rate drops
below the pacing rate, the pacemaker starts emitting stimulation pulses. This can only
be ensured by continued monitoring of the ECG with a 4- or 10 -lead patient cable.
The pacemaker reads the necessary ECG signal via the pads. If the module is not
able to reliably identify QRS complexes, it will stimulate the heart permanently in
demand mode.
The demand mode is the recommended pacing mode when the patient is at risk of
developing bradycardia or even asystole as a result of a critical event. As the
pacemaker function is controlled by the patient's ECG, the harmful competition
between intrinsic and external stimulation, which could induce ventricular fibrillation,
is excluded.
The pacemaker is the module for external transcutaneous stimulation of the heart.
The pacemaker offers two modes of operation, demand and fixed-rate pacing. In
demand mode, the pacemaker requires an ECG signal for synchronisation.
The same, large adhesive electrodes used for defibrillation are also employed for
pacing. They ensure good electrical contact with the skin. These electrodes and a 20
ms square-wave pulse reduce painful muscle contractions provoked by excessive
current density.
Pacer rate, pulse width and current are checked when the device is turned on and
during operation; therefore, a functional test of the pacemaker module is not
necessary.
