What are the indications of First aid Cardiopulmonary resuscitation?

CARDIOPULMONARY ARREST, NO PULSE 

Not responding, no breathing, no pulse

1. Person is unresponsive.

2. Not breathing.

3. No or very weak pulse

These are indications for CPR

Unresponsive person and not breathing are indications for CPR,

This is the simple answer to the question.

Whenever you found a person unresponsive we should start the BLS protocol

CPR HAS BEEN STARTED ONCE THERE IS NO SIGNS OF LIFE.FOR EXAMPLE WHEN THER IS NP PULSE AND NO BREATHING OF THE PATIENT.THERE ARE 4 RHYTHMS WE CAN SEE ON THE MONITOR.2 OF THEM ARE SHOCKABLE AND 2 ARE NON-SHOCKABLE.MULTIPLE DRUGS HAVE BEEN USED DURING THE RESUSCITATION OF THE PATIENT AND WE HAVE TO RULE OUT ANY REVERSIBLE CAUSES.

We immediately perform CPR if the patient has no pulse and breathing pattern to prevent irreversible brain damage. 

If an unconscious individual has no heartbeat and breathing, you must immediately perform the Cardiopulmonary Resuscitation. Irreversible brain damage can occur if the blood circulation to the brain stops within 8-10mins.