After being drugged by Chloe's kiss, LaSalle's white hat falls into the street, a foot from the curb. When his back-ups arrive a few seconds later, the hat is clearly seen on the sidewalk several inches from the street.
When Pride and Gregorio are doing CPR on LaSalle, medical errors are made. Adequate CPR is 100 compressions per minute (about twice as fast as the rate they do CPR at) and adequate depth is 2 or more inches into the chest with each compression.
On top of this, Narcan takes time to take effect and CPR needs to be continued both during the administration of narcan and after, until a pulse is regained. The narcan won't reach the brain, where it's needed, if there's no circulation.