The passenger in his 60s had a medical emergency related to his diabetes. Flight attendants called for a doctor.
Ruiz was in the right place at the right time Thursday morning after a passenger on board an American Airlines flight out of Washington, D.C. collapsed.
"I was in the back of the plane at the time, and so I walked up to the front and I saw the fireman who was there already taking care of him, and so we both teamed up and with the flight attendants, we did the best we could," said Ruiz, an experienced emergency room doctor.
Thirty minutes into the flight the freshman congressman put his medical skills to use.
"We put a defibrillator on his chest and I applied oxygen and made sure that he had a pulse and that he was getting his oxygen that he needed," said Ruiz.
On board the same flight was Texas Congressman Pete Gallego (D) who witnessed what Ruiz did. He tweeted: "Hope @CongressmanRuiz is on all my flights home! An emergency room dr by training, was impressive to see him in action. He saves lives!"
During the emergency their Dallas-bound flight was diverted to Raleigh, North Carolina. Once there the patient was transported to a hospital in unknown condition, and the flight resumed.
"If he's out there looking, I just want to tell him I prayed for him on the way home, and I'm just glad that he's going to be OK," said Ruiz.
The man may have been suffering a heart attack or a stroke. The patient appeared to be doing well.
Ruiz said this is not the first time he's been asked to put his medical skills to use while in flight. But he says this is the first time the patient was in such dire risk that it caused the plane to be diverted.
Ruiz campaigned in the lower desert as a novice politician and an experienced emergency room doctor.