Comprehensive and Detailed Explanation From Exact Extract:

Agonal respirations are not effective breathing and can mimic gasping or snorting. They often occur in cardiac arrest. However, before initiating chest compressions, the EMT must confirm pulselessness by checking a carotid pulse for no more than 10 seconds (AHA 2020 BLS Guidelines).

Only after pulse confirmation (or absence) should compressions begin. Suctioning or ventilating is premature unless a pulse is found.