Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (27 page)

On the sea floor, I held on to a rock outcropping with one hand while a sensor in my other hand measured the temperature and salinity of the upwelling water. Divers around me were placing concrete blocks in a circle, and divers above me were deploying the collecting bell—a blue canvas sheath that looked like a closed umbrella with dangling ropes. One by one each rope was attached to a ring in one of the concrete blocks; then a long supple tube, a chimney with a wide opening at the bottom, was placed over the mouth of the spring. The water rose naturally through the tube, snapping it straight before exiting through the opening at the top, directly under the dome of the bell. The fresh water was trapped inside and filled the bell like a hot air balloon. The bell expanded into a gossamer dome 8 feet across and 3 feet high, pale blue against the deep-blue dimensionless background. As the fresh water bubbled in at its center and the salt water that it replaced spilled out around its edges, I found it hard not to imagine that the bell was a breathing organism: a giant blue jellyfish with rope tentacles, hovering just above me. I was mesmerized. The longer I watched, the more I believed it was alive. I knew I had to move, but not because I thought it would attack. It wasn’t frightening—after all, the jellyfish’s tentacles were tied into concrete blocks—but the image was too real. I had been too deep too long. I needed to ascend a few
dozen feet to clear my head and reverse the early symptoms of nitrogen narcosis—rapture of the deep.

Breathing at depth is possible only because compressed air is delivered at the same pressure as the surrounding water. The scuba regulator senses the outside pressure and opens the air valve to match it exactly so that a diver’s lungs inflate with no resistance. The simple system has allowed divers to adapt to otherwise inhuman depths. However, forcing air into the body under pressure creates its own unnatural and very strange problems. The first human bodies to react to the effects of breathing air under high pressure belonged not to divers but to tunnel and bridge workers. To keep water out of their workplace, compressed air was pumped into partially completed tunnels, or into wooden tubes, called caissons, lowered into rivers where workers were constructing bridge pilings. Often, by the end of the day, the mood of the entire crew turned euphoric, with workers singing and laughing spontaneously. The cause of the strange behavior remained a mystery for many years because the guilty agent had been almost above suspicion. Nitrogen is an inert gas that makes up nearly 80 percent of the air in our atmosphere. Humans have been breathing it as long as they have been human—but always at atmospheric pressure. When nitrogen is inhaled under increased pressure, it becomes a narcotic.

Humans have no use for nitrogen gas, which passes in and out of the lungs during respiration without the body even noticing. None is absorbed, because gases, like nitrogen, do not mix readily with liquids, like body tissues. Gases and liquids can be made to mix under pressure, however, as is done when adding carbon dioxide to beverages. Breathing compressed air is like getting carbonated. Nitrogen gas is forced into the blood, then picked up by the liquid in individual cells, especially in the brain. Once inside, it interferes with the transmission of electrical impulses, although how this happens is only poorly understood. The effect is predictable enough, however, for doctors to rely on certain compounds of nitrogen to provide anesthesia. Nitrogen also blocks inhibitory pathways that moderate behavior, in much the same way alcohol does, which is why divers who have gone too deep begin to feel drunk or hallucinate.

Before the giant blue jellyfish could grab me, I ascended about 30 feet, to a depth that would depressurize the nitrogen I was breathing. Within a few minutes the gigantic sea creature had turned back into a canvas bell. The scene was nonetheless captivating. The system was working. Suspended in the sea, we were collecting water from a spring that once flowed on dry land 300 feet above sea level. Men of the Ice Age must have come here to drink from this powerful source of fresh water. Less powerful flows would have dried up, leaving behind tunnels that led to caves deep inside the cliffs. Caves that Henri Cosquer’s ancestors could have walked into.

The NympheaWater team was ready to celebrate the success of its pilot project, but had we left the water quickly, we would all most likely have been dead in a few hours. This environment, which requires such meticulous planning to enter, demands even greater care and caution to leave. A quick exit would bring on the bends, the other disease brought on by breathing air under pressure. It too was first described in tunnel workers, and was originally called caisson’s disease, but unlike nitrogen narcosis, whose onset occurs when a diver goes down, the bends doesn’t strike until a diver tries to come up. Depth, time, and exertion all contribute to the amount of gas that is forced into the tissues. This dive had a lot of all three—more than enough to turn the liquid portions of our bodies into carbonated beverages. Had we surfaced abruptly, the sudden release of pressure on us would have the same effect as popping the cap off a soda bottle. We would have fizzed up.

Dissolved gases that come rapidly out of solution form bubbles. When it happens inside the body, the dissolved nitrogen that has entered quietly bursts into a rampaging enemy that is everywhere at once. Blood vessels that had unwittingly transported hazardous material are suddenly filled with tiny air bubbles rapidly coalescing into large ones. The pale yellow lubricating fluid in joints now looks like sparkling champagne. Inside individual cells all over the body, pressure rises as bubbles form within their liquid milieu and expand against their cell membranes. The alien invader is not like anything the body has ever confronted in its entire history of evolution, and consequently it has
never developed any defense for it. Its response is as chaotic as earth’s would be to an invasion from Mars.

Having gained access to the body’s internal transportation system, the bubbles are carried by circulating blood deep into organs and tissues, stopped only when vessels become too small for them to pass through. At that point they occlude the channel, preventing any further flow of blood. Without their supply of oxygen and nutrients, tissues and organs downstream of the blockage starve. Within the blood itself there is mass confusion. White cells, which travel in the blood patrolling for infection, encounter the invader and interpret it as a new form of bacteria. They react by creating an inflammatory response, as if fighting an infection. Platelets, traveling blood cells that institute clotting, sense the presence of air. For them, that means that the blood vessel has been cut and there is a breach from outside. They activate the clotting mechanism to stop bleeding that isn’t occurring, forming blood clots that have nowhere to go. Outside the blood, things are no better. Bubbles squeeze the contents of individual cells beyond the cell membrane’s ability to contain them—cells throughout the body randomly burst.

The only way to prevent this anatomic catastrophe is to let the pressure dissipate very gradually. A soda bottle can be opened without much fizz if the cap is released gently and a little at a time. A diver can emerge unscathed from the depths if he ascends slowly and stops at prescribed intervals. That’s why our team members were moving toward the surface little by little, stopping at various points along the anchor line or along safety lines dropped from buoys. Air tanks had been tied to the lines at specific depths to provide decompression stations where we would have the extra oxygen we needed to extend our time underwater. The number of stops required, the depth at which to make them, and the length of time at each one has been worked out in decompression tables drawn up by the U.S. Navy. The schedule depends on the diver’s maximum depth and time underwater. Each of us was following his or her individual prescription to avoid the bends.

Whenever I’m tempted to take a shortcut to the surface, I think
about my longtime friend and dive buddy Bernie Chowdhury, who got severely bent a few years ago, but lived to tell about it. Bernie is the publisher of
Immersed, a
high-end scuba magazine, whom I met when he invited me to write an article. He’s also a consummate diver. One day when he was exploring the wreck of an ocean liner off the coast of Delaware, however, he was pushed to the human limit. He recounts the story as a part of his book,
The Last Dive,
and I’ve heard him retell it many times. Each time I hear it, I can’t help wondering whether Bernie didn’t actually exceed the human limit—and still make it back.

The wreck in question, the
Northern Pacific,
was stuck bow-down in the sand at a depth of 150 feet. It was Bernie’s third dive to it. He wasn’t feeling well that morning, and being a cautious diver he would ordinarily have followed his instincts by not diving. However, he had already gone down twice and decided there wouldn’t be much risk in diving it again. When he arrived at the upended stern he tied off the extra air tank he would need later for his decompression. Then he swam down the 500-foot length of the ship and entered the bow section, looking for portholes, dishes, and other artifacts, or at least some lobsters. He didn’t find any souvenirs, and after bagging his second lobster, his dive time was up. He exited the bow, intending to swim back to his decompression tank tied to the ascent line at the stern. The current had picked up, though, forcing Bernie to kick harder and harder to make headway. To get out of the current, he dropped below the ship, to the sandy bottom, where he made better progress. But the increase in depth, combined with all the exertion, was enough to give him a dose of nitrogen narcosis. Bernie says he felt as if he had instantly gulped a martini. His head wasn’t clear—and neither was the water so close to the seafloor. When he reached the stern he couldn’t find the anchor line. He kept swimming around, looking frantically for his spare air tank, until he recognized with a shock that he was back at the bow of the ship. He had somehow swum underneath the raised stern and circled completely around the boat. Bernie weighed the odds of making it back to the stern and finding the spare tank before his dwindling air supply ran out. He still had enough air to ascend, but only if he didn’t stop to decompress.
He was physically and mentally exhausted. The stern was 500 feet away, and he couldn’t see more than 30 feet through the cloudy water. The odds against finding the spare tank were too high. Bernie decided to go straight to the surface.

The pain started while he was bobbing in the water, his friends trying to pull him into the dive boat. There was some thought of taking Bernie back down with fresh tanks and then bringing him back up slowly—an in-water recompression—but his pain became so intense so quickly that he would have drowned had he stayed in the water any longer. He was hauled out, placed on the gear table, and given oxygen. He was having trouble breathing, and the pain was everywhere; he began seeing in triplicate; he lost hearing in both ears; strength and feeling were slowly leaving his arms and legs; his pulse was steadily weakening. He realized he was facing death.

Bernie writes, “The pain eased and a feeling of well-being washed over me. A bright white light appeared . . . my body drifted upward . . . I could see everyone aboard and my sorry self lying on the table. I went into a white tunnel. I had only to float to the end and all my problems would be over. I drifted closer to the end of the tunnel and the light got even brighter.” Then Bernie remembered his wife and son and how much they needed him. “I stopped my drift and struggled to turn around. I had to get back. The white light dimmed and then went away completely. I opened my eyes. Searing pain racked my body again.”

The impression of floating over the scene, the out-of-body experience, has often been described by people who have seemingly died and then come back to life. It’s reminiscent of Pablo Valencia lost in the desert and Beck Weathers, an Everest climber whom I treated after he collapsed in the snow. It’s also reminiscent of my jungle friend Antonio describing the effect of his hallucinogenic drug. What these experiences have in common appears to be that when body function shuts down, the highest cerebral centers remain active and, dissociated from any outside input, create from within a vibrant image free of any space-time underpinning. The image has electrical power and if intense enough can restart activity in the rest of the body.

Bernie willed himself back to the dive boat. He focused on surviving
one step at a time. First he had to last until the evacuation helicopter arrived. Then he had to endure the flight to the recompression chamber. Maybe he would start to feel better after recompression, but maybe not. He didn’t know how much of his body had been permanently destroyed. He was having difficulty breathing because bubbles had lodged in the small capillaries surrounding his lungs, blocking air exchange. He couldn’t walk, because bubbles had entered his joint spaces. He couldn’t hear, because both inner ears had taken direct hits. Most ominous were the nerve problems. Parts of the fine plexus of blood vessels around the spinal cord had been occluded, damaging the nerves they supply by depriving them of oxygen. With signal transmission pathways interrupted, Bernie was losing control of his voluntary muscles and losing awareness of his skin sensation. Nerve cells in various parts of his brain were malfunctioning, leaving him unable to balance or focus both eyes simultaneously. He was somewhat confused, but his mind was still clear enough to comprehend his predicament and to fear death, a healthy fear that no doubt reinforced his determination to stay among the living.

Forty-five minutes after he surfaced, Bernie was lifted into a Coast Guard helicopter and flown to a recompression chamber at the Hospital of the University of Pennsylvania. The principle of recompression is to reapply the maximum pressure to which the body was subjected, so that the gas bubbles go back into solution, then to reduce the pressure gradually enough to prevent them from reforming. Bernie spent six hours in the chamber. When he came out he was in less pain, and his vision and hearing had improved, but he still had no balance, couldn’t walk, and had difficulty concentrating. Some of his nerve tissue had been permanently destroyed, and his brain and body had to adapt to new ways of doing things. It took over a year, yet somehow—incredibly—Bernie made a full recovery. He is even diving again.