Medical Emergency in the Dental Practice 2025 – Defibrillator and Heart Rhythm
Is the defibrillator the answer to a perceived cardiac arrest?
No, doing continual chest compressions is the answer.
Remember, the brain restarts the heart so we need to keep it alive.
The defibrillator is a great device but its only role is to detect if a heart rhythm is shockable and that’s it!
Yes, there are unshockable heart rhythms whose prognosis for survival is poor. The defibrillator needs some electrical activity in the heart to shock it. The shock stops the heart rhythm, which stimulates the brain to send a signal to restart the heart with a normal heart rhythm, all going well.
Once the shock is delivered, chest compressions continue straight way!
Don’t Stop!
Shockable vs. Non-shockable Rhythms in Cardiac Arrest
Shockable rhythms
The two shockable rhythms in cardiac arrest are pulseless ventricular tachycardia (pVT) and ventricular fibrillation (VF).
Shockable rhythms are associated with the best prognosis in cardiac arrest.
Ventricular fibrillation
Ventricular fibrillation is chaotic and disorganised electrical activity with no identifiable normal activity also known as QRS complexes. VF activity is all over the place, but then activity reduces to eventually asystole (no activity) if prompt defibrillation is not performed.
Pulseless Ventricular tachycardia
This shockable heart rhythm appears on the monitor as a regular broad complex tachycardia, typically between 100-300 beats per minute.
Non Shockable
Pulseless electrical activity (PEA)
This is defined as the absence of a pulse in a patient with electrical activity
Causes of PEA include severe fluid depletion or blood loss, cardiac tamponade, massive pulmonary embolism and tension pneumothorax.
There is hardly any electrical activity for the defibrillator to identify. So, the unit will “no shock needed, continue chest compressions”.
Don’t stop!
Asystole
This is the absence of electrical activity and is Non Shockable.
This is rarely a completely flat line, as slight undulations are usually seen with additional interference from ventilation and chest compressions.
If a completely flat line is seen, ensure the monitoring is attached correctly.
However there is a heart rhythm that a defibrillator it will deem as “no shock required”.
Yes, the gold standard heart rhythm- and that is a normal heart rhythm or a QRS complex. (Lup, Dup). The beat of atrial and ventricle chambers of the heart working together as a team keeping the person alive!
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