Nina Prommer / Patrick McMullan Co. via Tribune News ServiceRyan McGarry, who directs and stars in CBS’s “Code Black,” got the idea for the show after creating an award-winning documentary highlighting a situation in which a public hospital is overwhelmed by an influx of patients.

BEVERLY HILLS, Calif. — Go ahead, make comparisons between CBS’s new emergency room drama, “Code Black,” and the NBC classic “ER.”

“I’ll take them all,” said CBS Entertainment chairman Nina Tassler in August. “Are you kidding me? I’m thrilled.”

The “Code Black” title refers to when the influx of patients is so great it overwhelms the hospital’s staff. “Code Black” is based on a documentary about life in the ER at Los Angeles County Hospital that was directed by Ryan McGarry, a 2009 graduate of the University of Pittsburgh School of Medicine.

McGarry, who grew up in Chicago and graduated from Penn State in 2005, was always torn between becoming a doctor and a filmmaker. But when he was diagnosed with non-Hodgkin’s lymphoma at age 19, he opted to pursue medicine.

During his fourth year at Pitt, McGarry, who now has a clean bill of health, went on a rotation at Los Angeles County Hospital and was taken aback by the drama of an overwhelmed public hospital. He made a frantic call back to the University of Pittsburgh, asking for an extra four weeks on his monthlong rotation so he could start filming a documentary about L.A. County, which was closing down an old facility and reopening in a new state-of-the-art building.

“Without the University of Pittsburgh giving me that time, without their capacity and vision, the movie wouldn’t have happened,” McGarry said. “It was awesome because it led to an award-winning festival documentary, which led to this opportunity at CBS.”

Writer Michael Seitzman (“Intelligence”) serves as showrunner for “Code Black,” which is executive produced by McGarry, who hopes to eventually write and direct episodes once he learns the ropes of weekly TV drama production.

Marcia Gay Harden (“Trophy Wife”) stars as Angels Memorial residency director Dr. Leanne Rorish, whose high-risk procedures irk her more by-the-book colleague, Dr. Neal Hudson (Raza Jaffrey, “Smash”).

“We wanted to make a world that was not like any other medical show,” Seitzman said during a CBS press conference last month during the Television Critics Association summer press tour. “It’s not glossy. It doesn’t feel Hollywood. The world feels very handmade, made by people to serve people. In that was kind of the key to how to tell the story, to light it naturally, to not worry if somebody falls into darkness, to create a code black and then put three cameras in the middle of it and shoot it. We hired 30 real trauma nurses who work both off screen and on screen.”

McGarry said the goal of the show is to capture the transformative experience of an actual ER physician.

“You’re one person when you go to a shift as an ER physician, you leave as someone else,” he said, describing an experience he had of performing CPR on a patient. “I’m pushing and pushing and pushing, the cellphone falls out of this guy’s pocket. And on the cellphone you see, ‘Hey, are you there?’ Question mark. Question mark. And I’m pumping away. Question mark. Question mark. And I know in that moment I’m the only person on this planet who knows that this guy is in the act of dying, and we don’t know what’s going to happen. … It’s such an intimate moment. I don’t even know this man, and I’m touching his heart, pushing it hard, and seeing this relationship go on with this other person in front of him.”

After graduating from Pitt, McGarry returned to Los Angeles County for his residency, which ended in 2013. He’s now on faculty at Weill Cornell Medical College in Manhattan, commuting from Los Angeles to work two ER shifts a month at New York-Presbyterian Hospital.

He doesn’t rule out a return to Pittsburgh someday.

“I’m convinced, the happiest people in entertainment don’t live (in Los Angeles),” McGarry said, citing “Code Black” co-star Luis Guzman, who makes his home in Vermont. “They just come here when they have to. My issue now is I can’t find a girl — my plan would be to meet someone, get married and be like, ‘We’re moving to Pittsburgh.’ It’s a tough sell to someone who’s not from there.”