A Staten Island nurse recently saved the life of an off-duty NYPD detective after he went into cardiac arrest on the shoulder of the highway.

New Jersey resident Linda Messo, 26, who works as a neonatal intensive care unit (NICU) nurse at the Richmond University Medical Center, was on her way to work when she encountered the emergency on the side of the road.

Off-duty NYPD Detective Michael Caccioppoli was lying unconscious on the side of the road while his girlfriend called 9-1-1.

Messo knew she had to do something.

“I never drive in the far-right lane of 440 when I get off the bridge. I’m always in the left lane because I have to get on the expressway. I totally believe if I wasn’t in that far right lane that I wouldn’t have seen the car; I wouldn’t have seen him on the floor,” Messo explained.

Detective Caccioppoli was driving home from a New Jersey beach at the time when he began to feel sick and pulled over. He then began to vomit on the shoulder of the 440 when he suddenly passed out.

Messo immediately intervened and told the officer’s girlfriend she was a nurse. She knew right away that it was serious.

Not only had he aspirated some vomit into his lungs, but Messo could tell he was in cardiac arrest.

“I could tell based on my assessment that he was in full-blown cardiac arrest,” she said.

Messo then began to administer CPR — a skill she had just taken a training course on earlier that day for her two-year nursing recertification.

She believes her being there to save the day was an act of God.

“I truly believe God put me there and was with me that day. I’m a NICU nurse; I work with tiny babies — I’ve never performed CPR on an adult. I’ve only ever used my two fingers or my thumbs to do chest compressions. Everything lined up that day, even though this poor guy did suffer in that moment, everything that day happened for a reason,” she said.

Port Authority police arrived while Messo was performing CPR. Thankfully, they had an automated external defibrillator (AED) with them.

The AED shocked Caccioppoli three times before his sinus rhythm returned to normal. In total, Messo spent 20 minutes performing CPR.

The detective was then transported to Staten Island University Hospital (SIUH) in Princes Bay and then transferred to Glen Clove Hospital. He was intubated and placed on a ventilator for several weeks before making a full recovery.

Caccioppoli is set to return to active duty soon.

A neurologist at Staten Island University Hospital said Messo performed CPR so perfectly that Caccioppoli did not suffer any brain damage.

For her heroic deed, Messo was later presented with an award from Detectives Endowment Association President Paul DiGiacomo.