Table 1. Content Validation Index of the instrument developed to assess knowledge about Basic Cardiopulmonary Resuscitation in adolescents, obtained through the evaluation of specialist. Peru, 2021.

Questions	CVI-1
1 what is a heart arrest?	1
a) The heart stops beating and the person does not breathe.
b) The heart slowly stops beating.
c) Absence of breathing.
d) Sudden loss of consciousness.
2. What is the first step to be taken in front of a person with loss of consciousness?	1
a) Request help from the health service by calling 116*.
b) Extend the neck backwards so that the air enters.
c) Move the unconscious person to wake up.
d) Be by the person's side until the ambulance arrives.
3. What should I say when I telephone the emergency service, for example, the fire department 116?	1
a) I inform that the person does not respond, is not breathing and where I am.
b) I shout reporting my data asking for help and hang up immediately.
c) I ask another person to pass on the information about what is happening with the person.
d) I scream and ask someone else to pass the information to the health personnel.
4. While the ambulance arrives, how many compressions should I perform	1
a) 30 compressions per minute.
b) 15 compressions per minute.
c) 100-120 compressions per minute.
d) Those necessary until the ambulance arrives.
5. If after doing the compressions in the center of the person's chest I CHECK, HE (or SHE) IS BREATHING, what should I do?	0,92
a) I sit him down and give him water.
b) I put him on its side.
c) I tell him what happened.
d) I take him to a cooler place.	0,92
6. If after some time performing compressions in the center of the person's chest, I verify that he/she is still unconscious and not breathing, what should I do?
a) I will continue with compressions until help arrives.
b) I ask someone to help and I start filming.
c) I ask someone else to do the compressions while I rest.
d) I continue compressions, even if I feel very tired.
7. Why should compressions be given to the center of the chest in the person in cardiac arrest?	1
a) Because with each compression it stimulates the heart and blood reaches the entire body.
b) For him to wake up, walk and go home.
c) Because the air enters the lungs better.
d) Because the person may be choking and thus the foreign body may come out.
8. What should we do when the ambulance arrives?	1
a) I retire and go home.
b) I start filming with my cell phone.
c) Explain to him what has been done until his arrival.
d) Acompany he person to the hospital.

CVI-1=Content Validation Index applied to the questions. * Emergency phone number - Firefighters of Peru