Defibrillation Flashcards
What is defibrillation?
The passage of an electrical current of sufficient magnitude across the myocardium to depolarise a critical mass of cardiac muscles simultaneously
What does defibrillation do to the natural pacemaker?
enables it’s tissue to resume control
What three features do all defibrillators require?
- a power source capable of providing direct current
- a capacitator that can be charged to a predetermined energy level
- two electrodes which are placed on the patients chest across which the capacitor is charged
What is successful defibrillation defined as?
Absence of VF/pVT at 5s after shock delivery
What influences the delivered current?
Transthoracic impedence and electrode position
What can biphasic defibrillators do?
Measure the transthoracic impedence and adjust the energy to compensate
When is it sensible to consider increasing the shock energies?
If the first shock is not successful
when re-fibrillation occurs
When is synchronisation with the R wave required?
When cardioversion is used to convert atrial or ventricular tachyarrhythmias
It miminises the risk of inducing VF
Do pVT and VF require synchronised shocks?
no
What can be used to disable an ICD?
A ring magnet
What should be done after cardiac arrest in a patient with a pacemaker or ICD?
Interrogation
What energy should be used for internal defibrillation?
10-20J for biphasic shocks
Monophasic= 40J
