The previous day, Williams, a 27-year-old refrigeration technician, had walked into Beth Israel Deaconess Medical Center weak and dizzy, suffering from excruciating abdominal pain. He had a bleeding ulcer, so severe that he lost almost half his blood.

“That’s your actual ulcer right there,’’ Feldman shows him on a picture, “the thing that sort of looks like a volcano, and what’s underneath that is a blood vessel.’’

He taps on the screen again, and a picture from Frank Netter’s “Atlas of Human Anatomy’’ comes up, showing the stomach and the blood vessels that feed it. He points out exactly where Williams’s ulcer is — “a bunch’’ of ulcers, actually.

Another few taps and Williams’s medical record pops up, so they can discuss discharge instructions. Williams eagerly takes in the information. He’s been through hell, he said, and it’s very important to him to stay healthy now.

ast month, at the launch of the iPad 2, Apple showed a video in which Dr. John Halamka, chief information officer at Beth Israel Deaconess, said the iPad “will change the way doctors practice medicine.’’

It was a bold statement, and not the first lofty claim made about technology. But this much is clear: Hospitals across the United States and as far as Israel and Australia are embracing iPads.

The reason is simple, Halamka said in a phone interview — iPads are a great fit for doctors.

“The secret for the ideal clinical device,’’ he said, “is it has to weigh a pound, it has to last 10 hours, because that’s their shift, you have to be able to disinfect it so there’s no risk of contamination, and you have to be able to drop it 5 feet onto carpet without damage.’’

Technically, iPads weigh about 1.3 pounds, and the wipe-downs they get constantly at Beth Israel Deaconess are strictly against Apple’s directions.

But what makes iPads ideal, doctors at Beth Israel Deaconess said, is that they combine mobility — the ability to do substantive work at the bedside, in a stairwell, anywhere — with interactive touchscreens they can use to share pictures and data with patients.

Other devices available at the hospital — computers on wheels, static workstations, laptops, tablet computers — fall short in critical ways, said Feldman and Dr. Larry Nathanson, an emergency physician and fellow iPad evangelist. Size, weight, and battery life get in the way, they said, and nothing can be flipped around and used at the bedside like an iPad.