The patient was an elderly Chinese immigrant with a history of gastric cancer. She had come into the emergency room in New York City complaining of abdominal pain.

“Tung, tung?” I asked in my laughable Cantonese.

She pinwheeled a hand over her belly. “Pain everywhere.”

When I pressed on her abdomen, she grimaced. But she had no fever or evidence of peritonitis, an inflammation of the membrane that lines the abdominal cavity.

“How long?” I asked her English-speaking daughter.

“Two days.”

“Getting worse?”

“Yes.”

Her abdominal X-rays showed no obstruction. But the X-rays couldn’t tell the whole story. Older people can harbor abdominal catastrophes—appendicitis, abscesses, gangrenous gallbladders—without mounting a temperature or yielding the usual physical exam clues.

So, as happens 10 million times a year in this country, I ordered a contrast CT scan—an imaging technique that employs a spinning X-ray beam to take multiple images that create a portrait of internal organs. In a contrast CT scan, additional substances are given to the patient that allow radiologists to better tell one organ from another or detect signs of infection.

First, the patient drinks a quart of what we call an oral contrast—an iodine-based concoction (comes in a tasty lemon-vanilla flavor) whose high molecular density coats the intestines. Next, we inject six ounces of an intravenous material, also iodinated, to enhance the outline of the blood vessels. These materials weaken the passage of X-rays and make the treated regions appear white against the gray of surrounding tissues. The substances are usually excreted in a few hours.

Sometimes the injected material can be dangerous because of the processing burden it puts on the kidneys. And it can trigger a life-threatening allergic reaction. That occurs some 4,000 times a year in the United States. And what of the oral contrast? Usually, the worst that happens is a little diarrhea. It’s about as scary as a milk shake.

The results of the CT scan showed nothing dire. “We will admit you to the hospital,” I told her, “and do more tests.”

She neither changed her expression nor met my eye.

“The good news is, the tests show nothing seriously wrong,” I said.

No reaction.

“How do you feel?”

A slight nod.

“The admitting doctors will be down in a little while.”

The daughter formed a thin smile. “Thank you.”

An hour later, the patient’s nurse, Nina, grabbed me.

“She’s bad. She can’t breathe. Sounds like airway obstruction.”

“Nina, it’s her belly, not her lungs.”

“You’d better look at her.”

I hurried over.

“Hrahaahr, hrahaahr” came the noise out of her throat. Above the rattle was a high-pitched tone that sounded like stridor, the sound of air being forcibly inhaled through swollen vocal cords or throat membranes. But my patient was making noise as she exhaled. When I listened through the stethoscope, her lungs sounded clear. The trouble was in her throat, but her breathing didn’t make sense. A straw is supposed to collapse when you suck on it, not when you blow out.

Nina and I quickly moved her to a fully monitored bed. The pulse oximeter showed the level of blood oxygen to be 90 percent—terrible, no; marginal, yes. I considered the possibilities. One was an allergic reaction to the scanning material she was given intravenously, which could cause vocal cord and laryngeal tissues to swell. But that would trigger stridor, not this bizarre-sounding exhalation. Another scenario: If the oral scanning material gets into the bronchial tubes that lead into the lungs, it can absorb a large amount of water and clog the airway. But the patient had drunk the concoction hours ago.

The larynx, however, is a bit like a Rube Goldberg contraption. Made up of nine different cartilages, it lies behind the tongue, jutting up like a half-buried, trumpet-shaped pitcher plant. The vocal cords, deep within, stretch from top to bottom. With every swallow, the trapdoor of the epiglottis drops over the opening, shutting off the entrance to the larynx. During the swallow, the whole laryngeal apparatus moves up and forward under the tongue, which with a powerful back kick propels the contents of the mouth into the esophagus. It requires split-second coordination of muscle, nerve, and cartilage to catapult food, drink, and saliva over the voice box and into the gullet.

As it happens, a little trough runs between the epiglottis and the tongue, and several pits lie behind the laryngeal opening, where secretions or food particles can accumulate. When we clear our throats, that’s generally the stuff we’re bringing up. Despite vocal cords that slam shut at the least irritation and a cough reflex that can blast air out at 50 miles an hour, fully half of healthy people inhale some stomach contents during sleep. As we age, weakened muscles and sluggish reflexes aggravate the problem. Every year many thousands of pneumonia cases among older people result from misswallowed food and drink.

I wondered if some of the oral contrast had pooled around my patient’s larynx, setting off irritation and swelling. Maybe she had then coughed some up and inhaled it.

Nurses and medical residents stood at her bedside. The level of oxygen in her blood had sagged into the 80s—definitely not good. I leaned over her bed rail to listen closely. The hrahaahr, hrahaahr rattled my ribs. Beads of sweat broke out on her face as she fought harder to breathe.

Upper airway obstruction but not stridor? The question raced inside my mind.

As a treatment of last resort we could inject epinephrine, also known as adrenaline, which is the most potent of antiallergy drugs. But this woman was 75 years old: The adrenaline boost could easily jolt her heart into a lethal rhythm. Besides, she showed no signs of a bodywide allergic reaction. The more I listened, the more obvious it seemed that her problem lay in the throat.

Two surgery residents were passing by. “I may need you here in a minute,” I told them. “If we can’t turn her around, she could be too swollen to intubate. Might need a trach.”

If we couldn’t slip a breathing tube down her narrowed throat, we would need to cut a hole in the windpipe, or trachea, to create an airway. A tracheostomy is a bloody and usually panic-lit procedure. We needed to be ready.

“Hrahaahr, hrahaahr,” she brayed. Her oxygen level now read 85 percent. We were losing ground.

“Somebody call a doctor,” I muttered.

The residents chuckled. They thought I was kidding.

Then I remembered another way to administer epinephrine. When children have croup, a viral infection that causes swelling in the trachea below the vocal cords, we give a different type of epinephrine—called racemic epinephrine—that can be inhaled. The inhaled mist constricts blood vessels in the airway and reduces inflammation. But I’d never used it on an adult.

“Nina, how about some racemic epinephrine?” I said. “You know, the kind we use on croupy kids.”

She looked doubtful. “I’ll take a look.”

“It can’t really hurt,” I wheedled.

The vials came down. Nina read and reread the instructions. She poured the clear liquid into a pod-shaped container, attached it to a mask, hooked up oxygen delivery, and strapped the contraption around the patient’s face. With a sharp hiss, a cloud filled the face mask. She breathed in and out a dozen times.

Precisely 45 seconds later the noise ceased. We all looked at each other. I listened again to her chest. Air, sibilant and clean, whistled through it.

“I’ll be darned,” I said.

Nina wasn’t sure. “Could it act so fast?”

“Oh, epinephrine works fast,” I told her. “I’m just surprised it worked at all. Maybe some of the contrast stayed in her throat and made everything swell up, or maybe it gurgled into her airway.”

“Hours later?” Nina asked.

“The anatomy ain’t perfect, you know.”

Ten minutes later, the patient got a little noisy again.

“Let’s give her another,” I told Nina.

Forty-five seconds later, there was the same result—this time for good.

“You convinced?” I asked Nina.

“Sure. But what’s the diagnosis?”

“Beats me,” I confessed. “But I’ll take a good cure over a clear diagnosis any day.”

The woman’s belly pain went away on its own over the next two days. In retrospect, she probably hadn’t needed the CT scan. But at least there was no more trouble with her airway. My best guess was that the oral material must have been the culprit—and I tried not to wonder how many patients undergo unnecessary CT scans. One thing I was sure of, though: It would be good to always be so lucky.

Tony Dajer is assisant director of the emergency medicine department at

New York UniversityDowntown Hospital in lower Manhattan. The cases described in Vital Signs are true stories, but the authors have changed some details about the patients to protect their privacy.