City medics are demanding the resignation of EMS boss Abdo Nahmod, claiming he mismanaged the response to Superstorm Sandy.

First responders say medical care devolved into chaos as the hurricane’s floodwaters swamped EMS stations and paralyzed ambulances — sometimes stranding medics on their roofs — all because the FDNY failed to follow its own hurricane plan.

The two unions representing EMTs/paramedics and EMS officers last week voted “no confidence” in Chief Nahmod and called for his immediate ouster, according to copies of the resolution found on the FDNY/EMS Rant Web site and the Facebook page of a Local 2507 executive.

Nahmod “jeopardized the safety of the public and his front line . . . by not ordering evacuation of personnel and equipment from flooded stations,” the resolution charges.

EMS workers say stations in flood zones weren’t ordered to relocate until they were already inundated, despite the FDNY’s own hurricane plan that requires crews to begin preparing 72 hours in advance.

In the Rockaways, medics stood on the roof of an ambulance for hours after their station flooded, and one EMT had to swim to safety after winds knocked him off the vehicle.

With ambulances under water and crews stretched thin, firefighters had to haul patients to hospitals in the beds of pickup trucks.

Rank-and-file critics say Nahmod also disregarded department policy to call in off-duty units during major emergencies.

“They should have recalled all members and put everyone on 12-hour shifts to get them in,” one FDNY source told The Post. “They didn’t even do that until the last minute.”

Stations also reported a lack of food, water and power, although the FDNY’s plan requires supplies to be ready well before hurricane season begins.

Weeks after the storm, medics are still fuming.

“Many personnel feel as if they were left to fend for themselves . . . nobody was steering the ship,” one EMT posted on the Rant message board. “People have questions. Hopefully, they will get some answers.”

Fire Commissioner Salvatore Cassano defended Nahmod and the FDNY’s response.

“I ordered all FDNY members — EMTs, paramedics and firefighters — to stay in service and in quarters during the storm for as long as possible,” Cassano said in a statement. “Our members, along with the Police Department, were the last line of defense for the people in the communities we serve,” he said.

“I have the utmost confidence in [Nahmod] and his performance before, during and after Hurricane Sandy.”

Nahmod, a 26-year veteran of EMS with an advanced degree in homeland security, was appointed last year.

He replaced former EMS Chief John Peruggia, who was demoted following the December 2010 blizzard that resulted in a 1,300-call backlog in the 911 system and at least three deaths due to ambulance delays.