"If there are any doctors on this flight, could they please identify themselves by ringing the flight attendant call light?"
"I'm an ER doctor," I told the flightattendant.
"Well," she said, "she's back here."In the last pair of seats sat a pleasant-looking young man and woman. She was sobbing loudly.
"Hey," I said. "I'm a doctor. What's going on?"
The young man looked up at me in bewilderment. "She's crying. I don't know why."
"You're traveling from Miami?"
"We're on our honeymoon," the man said, a little shyly. His wife nodded.
"Did you have a fight?" I asked.
"No," she said, "it was the most wonderful trip I ever had. I just feel like I want to die . . . "
The husband had an expression that read, "Would you fix this, please?"
"Has your wife ever seen a psychiatrist? Does she have any history of depression?"
"No," her husband said. "She's really, really healthy."
I looked at the woman. "Tell me what's going on now."
"I'm just so sad."
"Because you are going home?"
She shook her head. "I want to go home," she said, sobbing. "I miss my d-d-d-dogs."
"Have you ever been on anything for depression before, any drugs?"
"Never," she wailed, pounding the seat in front of her.
"When did you start feeling sad?"
Sad wasn't the right word. She was close to hysterical.
"When did this start?" I asked her husband.
"Just after we took off."
What produces psychiatric symptoms at cruising altitude in a plane? Hypoxia?
A subtle stroke? I began to free-associate on "sadness." Maybe something nonorganicÑnot a physical illness. Maybe she was having an existential crisis, realizing, for the first time in her life, and at the altitude of 30,000 feet, how meaningless life can be.
I focused on Miami. "So you're coming from Miami?" I asked again.
"Bimini," he said. "The Bahamas. We flew in from there to Miami."
"How did you feel then?"
"When, on the plane? Not very good," she said. "I don't know . . . I just
think this whole marriage thing was a big mistake."
"What did you do in Bimini?" I asked.
"We were scuba diving," the husband said.
"The whole week?"
"Yeah, we took a course at a resort."
"I'm a diver too," I told him. "How were you certified? PADI and NAUI?"
He looked at me, a little bewildered. "I don't know."Resort course. Diving is not a sport to take lightly. Many resort courses provide only a minimal amount of real training. When I dive, I usually travel with doctors, who are, of course, safety-conscious. Once, though, I had gone alone for a brief vacation to a dive resort in the Caribbean. It was the worst vacation of my life. That week the resort was filled with friends of the owner. Anyone was allowed to dive whether certified or not. No one used U.S. Navy Dive Tables, created to minimize the risk of the bends, or dive computers, or even much common sense. People would dive down 220 feet— an insane depth— to take pictures of a plastic chicken tied to a stake to prove they "dove with the chicken."
Now I looked at the weeping wife. "What's five times seven?" I asked.
"I don't know."
Her husband leaned over, even more alarmed.
"I forget," she said. "I can't think." Then she tried for a moment.
I turned to the husband. "Did you keep a diving log?"
"Oh, yes," he replied, pulling a notebook out of his carry-on bag. At least the resort had him do that much.
Diving logs record the depth and length of a dive. They help you figure out how close you are to the safety limits. The two major medical catastrophes that can occur with diving are air embolism and diver's decompression sickness, or the bends. Air embolism occurs when a bubble of air is trapped in the bloodstream; although it can develop at any depth, it most frequently happens toward the surface. The bends (so called because the victims are sometimes bent over by pain) can result from a diver staying in deep water too long. Nitrogen is key. When a diver goes underwater, the ambient pressure increases dramatically. Ambient pressure doubles at 33 feet under the surface and, at 100 feet below, it's four times atmospheric pressure. This pressure drives oxygen and, more important, nitrogen, from the air the diver breathes into the tissue. The extra nitrogen sits, inert, until the diver returns to the surface. If a diver rises slowly enough, the nitrogen gradually exits the tissue without problems. But if the diver rises too quickly, the sudden difference in ambient pressure forces nitrogen to pass out of the tissue into the gaseous state again, forming bubbles. The bubbles can form anywhere: muscles, where they can cause severe pain as they deform and disrupt muscle fibers; joints, where they can inflict even more pain; blood, where they can initiate blood clots; the heart, where they can precipitate a heart attack and other nasty things; and the brain, where they can cause anything from subtle memory loss to severe, irreversible stroke damage.
I looked at the weeping woman, then looked down at the logbook.Divers work out their exposure to nitrogen under pressure using dive tables, a set of calculations developed in part by observing how long divers could stay underwater without getting bent. And that's the problem: The Navy assumed that the user would always be a healthy young male Navy diver, not a middle-aged, overweight vacationer. And the tables are complicated, especially for multiple dives. That's because there's some residual nitrogen in tissues when you start a new dive. Diving computers can simplify the calculations, but you still need to understand what the calculations mean to use the dive tables correctly.I opened up the dive log. There were 10 days of dives. The first dive was 25 feet, and the second and third dive bottomed out at 33 feet. After that, though, the dives went deeper and deeper, for longer and longer periods, until at the end, even without the tables handy, I could see that the couple had been very close to bends territory.
"Did you use the dive tables?" I asked the young man.
"Every day," he said and added, "exactly."
Exactly. "Did you dive yesterday?"
"Of course," he said. "It was our last day."
The rule in diving is never to dive the day before you fly. The dive tables are created for sea level, and when you fly you reach an atmospheric pressure considerably lower than sea level. Therefore, more rapid nitrogen release can occur, and more nitrogen bubbles can form. Even if you don't have the bends before you get on a plane, you can still experience symptoms when you reach cruising altitude.
One sign of the bends, I remembered, are subtle cognitive deficits. Could that involve a crying jag? Probably.
The treatment for the bends calls for a spell in a pressurized unit called a hyperbaric chamber, as well as supportive care with oxygen and fluids. In the chamber increased pressure drives the nitrogen back into the tissue, where it can dissipate under controlled circumstances and in the presence of lifesaving oxygen. If this young woman was actually suffering from the bends, she needed to spend time in a hyperbaric chamber— soon. We were stopping over in Louisville, Kentucky, which I was certain would have one.I headed up to the cockpit.
"Does she need an ambulance?" the pilot asked.
"Anything with oxygen on it."
When we landed in Louisville, the paramedics met us at the gate. When the young woman saw them she wailed even more. "I'm so embarrassed . . . " I watched them leave. They had "pushed the tables," as divers put it, but somehow only she had been affected. That would end her diving career. Because decompression illness can cause subtle but lasting changes in the circulatory system, doctors recommend that someone who has suffered the bends never dive again.
For a detailed explanation of the physiological effects of decompression sickness, visit www.mtsinai.org/pulmonary/books/scuba/sectiong.htm.