Washington ? The Army is bracing for the release of a documentary film that promises a graphic and unflinching portrait of life in a U.S. military hospital in Iraq.

The film, “Baghdad ER,” focuses on the emergency room of the 86th Combat Support Hospital in Baghdad’s fortified Green Zone during a two-month period last year as doctors and nurses treated wounded troops fresh off the battlefield. It also looks at the day-to-day lives of doctors, nurses, chaplains and soldiers who work at the hospital, one of the busiest in Iraq. The film airs May 21 on HBO.

A memo dated Tuesday from Lt. Gen. Kevin Kiley, the Army’s chief surgeon, warned medical staff at Army posts across the country to prepare for a possible influx of soldiers and families seeking comfort and counseling after watching the documentary.

“This film highlights the heroic efforts of our medical personnel and the vital role of the (Combat Support Hospital) on the modern battlefield, but it also shows the ravages and anguish of war,” Kiley wrote. “Those who view this documentary may experience many emotions.”

He said soldiers who had served in Iraq might have flashbacks and nightmares, both symptoms of post-traumatic stress. Families who have loved ones in Iraq or Afghanistan may experience increased anxiety about their safety, and some viewers may have strong reactions to medical procedures in the film, which include amputations.

“It is an extremely graphic and moving look at how we care for severely wounded service members,” Kiley wrote.

The Army and the other military services have limited the release of photographs and video footage showing wounded and dead troops in Iraq and Afghanistan. Recently, however, those images are being shown more frequently as journalists and filmmakers are allowed greater access to medical evacuation crews and treatment facilities.

Col. Joe Curtin, an Army spokesman, said Defense Department policy allowed images of American casualties as long as they couldn’t be identified. All the wounded service members shown in “Baghdad ER” either signed waivers or have their faces blocked out, he said. The only images of dead troops are those in body bags.

One aspect of the Iraq war that’s highlighted in the film is that 90 percent of the wounded who make it to trauma centers such as the 86th Combat Support Hospital survive, the highest survival rate in any war in U.S. history.

“I think when the public sees this whole thing, it’s a gripping account of what America’s best generation of people is doing,” he said.