Extreme Medicine (2 page)

R
obert Falcon Scott is dying, slowly succumbing to hypothermia in a tent pitched on the wastelands of the Ross Ice Shelf, full of the weary knowledge that he was not the first explorer to reach the South Pole—only the first to have lost an entire expeditionary party doing so. It is 1912. Antarctica is as inaccessible as it is fraught with risk; and that, of course, is its attraction, leading men to pit themselves and their lives against its challenges.

Having been beaten to the pole by Roald Amundsen's Norwegian expedition, Scott is now embarking on a race of a different kind: the scramble to write his letters to the next of kin of his expedition team, telling of their brilliance and honor and taking responsibility for having led them to their deaths. Time is against him.

Scott's life is a property distributed across the many trillions of cells that comprise his body. Like all human beings, he exists in a state of tension. By that I mean simply that nature seeks equipoise: It would like, as far as possible, for all things to be as equal as they can be.

The default state for an atom or molecule is electrical neutrality. Here the number of positively charged protons, in their composite nuclei, and negatively charged electrons, in orbit around them, is equal. But with a little effort, atoms and molecules can be made to lose or gain one or more electrons, and in so doing lose their neutrality. This is achieved by imparting a little energy—through chemical reaction, radiation, or electrical discharge. Energy transforms molecules and atoms into ions. It changes their nature. They become more dynamic, capable of being influenced by and generating electrical or magnetic fields. In the body, ions can flow across porous barriers—of the type that comprise the walls of our cells—because a negative charge seeks to neutralize a positive charge.

The machinery of our cells is designed to separate charged ions across cell membranes. That process of separation, of creating inequality, leaves a system out of step with the simple arrangement that physics would prefer. It creates the potential for something far more dynamic: a person.

Imagine a budget airline operating a plane that is only half full. Say that it's a long-haul flight and that the airline chooses to expend a little energy in getting its cabin crew to cram all of those passengers like sardines into the front half of the plane, leaving the rear of the aircraft entirely empty. (This, I think you'll agree, is a situation with the potential for the release of a lot of pent-up energy.) Now imagine that the chief executive of the airline decides people can sit where they like, just so long as they pay him another $10 for the privilege. The passengers shout and swear a bit, but eventually most of them decide that being crammed into the front of the plane is worse than paying the money and being able to spread themselves out evenly in all those lovely empty seats. The result is a plane whose passengers are distributed more evenly and an unscrupulous airline executive with some extra cash in his pocket.

What the airline does with the passengers and cash is what the body does with ions and energy. By expending energy in creating artificial inequality—in the case of the body, by pumping ions to where they don't want to be—and then harvesting and storing energy as the system attempts to return to equilibrium, you can save energy for later use. This energy can be stored in the form of chemical intermediates within cells and used to drive growth, repair, replacement, and reproduction.

We see this all around us in nature. In weather systems, for example, winds blow from areas of high pressure to those of lower pressure. The winds are a manifestation of inequalities in pressure and the system's natural tendency to smooth those differences out. In the same way that this difference allows turbines to harvest energy from wind, the body can exploit the flow of ions across cell membranes.

The flow of ions, along with the beautifully elegant machinery that exploits it, makes complex life possible. It keeps the whole that is greater than the sum of its parts—the whole that is ultimately Scott—going.

It has taken me most of my medical career to finally appreciate the tiny processes that enable biological systems to store and release energy. These biochemical events individually appear to bear little relation to the wonder of life, when in fact collectively they
are
life; they are everything we do, everything we are.

The privilege of the human body's complexity is bought at a price: It must expend energy pumping ions where they don't want to be in order to keep the body going. When that price is no longer affordable, simplicity reigns once again. And here simplicity is synonymous with death.

—

T
HE ENVIRONMENT OUTSIDE
the tent abhors Scott's complexity. There is more at work here than temperatures that can freeze exposed flesh in seconds. First, there is Antarctica's aridity. The continent's great sheets of ice hold water locked away, and less than a single inch of rain falls there each year. So the Ross Ice Shelf is considered a desert, and it will attempt to dehydrate and desiccate Scott's body. With much of the continent thrust two miles above sea level, Scott is high enough to make heavy exertion uncomfortable, even for the acclimatized. That's not to mention the scouring Antarctic winds, which will carry heat away from his body, driving his temperature down. All told, Antarctica is a continent of fierce extremes: the coldest, the highest, the most parched. Its climate has made it uninhabitable for all but the last hundred years of human history.

Bleak though Antarctica may be, it's important to consider how Scott's body reacts to his plummeting temperature, because that process is the key to an extraordinary advance in future medical technology.

As Scott's core temperature drops, the pumps that move ions across his cell membranes are grinding slowly but surely to a halt. The process is inexorable. In the absence of energy, borrowed from the fuel of food and burned in the fire of the oxygen that we breathe, the pumps wind down and eventually stop. The ions begin to assume equal concentrations on either side of the cell membranes. This simple symmetry is how death begins.

Scott isn't yet ready to die. His physiology, ignorant of his predicament, is designed to battle for him, to buy him every moment that it can, to give him his best chance of survival. As Scott writes, he feels the heat draining out of his hand. The blood vessels that run in his body's periphery, carrying hot blood to his skin's surface and losing that heat uselessly to the outside world, are constricting. His body hair stands on end in an effort to trap more air close to his skin. Both of these measures are an effort to reduce conductive heat losses. In the context of the Antarctic environment, however, this physiological strategy is next to useless.

Next, Scott will begin to shiver uncontrollably, generating enough heat to slow the drop in his temperature. This shivering is more than the casual tremor we might experience at a bus stop in midwinter; Scott's muscles will shake themselves as hard as they can, consuming fat and carbohydrates ravenously. This type of shivering, a last desperate attempt at staving off death, becomes an act of physical endurance in itself. It can account for fully 40 percent of the body's maximum exercise capacity and it will continue while there is fuel enough to do so. But shivering, no matter how athletically, is merely a holding measure, the body's method of buying time in the hope that something in its external environment will change for the better, not a solution in its own right.

As it proceeds, the deep hypothermia will go on to alter Scott's mind, making him irritable and possibly irrational. When his body's reserves of fuel run out, the shivering will stop—a respite that will only accelerate the rate at which he cools. Like a marathon runner hitting the wall, Scott is at the end of all of his reserves. There is nothing left to draw upon. Mercifully, something that looks like sleep will follow as the electrical activity in his brain begins to fail. He will slip into a coma well before the channels in the cell membranes of his heart muscle, the gatekeepers of electrical stability in that organ, are compromised. Frenzied anarchic rhythms may follow, the heart writhing uselessly like a bag of worms before finally coming to a standstill.

With his heart no longer beating, his body will be starved of its fresh supply of oxygen. But at such low temperatures, the rate at which Scott's cells fail and die will be dragged out in time. Death results from the failure of the chemical processes that drive our cellular machinery. In the deep cold those processes, too, become sluggish. The normal window of a few hundred seconds when his brain is dying yet his circulation might still be reestablished will instead stretch to many minutes. This window, elongated by cold temperatures, will become crucial to medical practitioners in the years ahead.

But for Scott there is no rescue. The seconds become minutes, the minutes hours. Scott, once a blazing furnace of life on the subzero wasteland of Antarctica, is finally no more energetic than the ice and snow that surround him.

—

L
IKE ALL LIVING BEINGS,
we fight against the laws that govern inanimate objects in an effort to avoid equilibrium with the physical world. Through the act of living, we maintain a level of complexity otherwise unknown in the universe: the ability to grow, to adapt, to reproduce, and as humans, the capacity for sentience and self-awareness. As fascinating and enigmatic as neutron stars and supernovas might seem, your brain is more complicated and more impenetrable to science than either. What makes us different, what sets us apart from the inanimate matter about us, is our ability to defy entropy, to avoid the thermodynamic reorganization, that would see us reduced to a simpler, lifeless state. As the decades pass, we—the human race—become better at it and expand the envelope in which life is possible.

For all its personal tragedy, Scott's death also contains some hints about the directions in which the envelope expanded in the century that followed his doomed expedition. Trying to conquer Antarctica forced us to confront the world's most extreme physical conditions and understand the havoc that they wreak upon the human body. Deepening that understanding of the body allowed us to continue our explorations there. Our frail physiology, left unprotected in these hostile environments, stood little chance.

The challenge of exploration became less about the spirit and determination of our plodding expeditionary teams and more about the challenge of how—through science and technology—we might protect them against challenges that had been fatal throughout all of human history. As the decades passed and our knowledge grew, we were able to overcome hypothermia. The answer lay in understanding our narrow limits and what our body might tolerate. With better clothing, habitats, and systems of transport, we could go further.

But today that understanding allows us to do far more than persist in these environments: Hypothermia has become an asset to medicine, a tool for cheating death.

—

N
EARLY A CENTURY
after Scott's expedition, a twenty-nine-year-old woman skiing in the mountains of Norway suffered an accident and went through the same sequence of physiological events. She was as lifeless as Scott, hundreds of miles from help, trapped by ice, her heart at a standstill as seconds became minutes and minutes became hours. But she survived.

In May 1999, three junior doctors, Anna Bågenholm, Torvind Næsheim, and Marie Falkenberg, were out skiing off-trail in the Kjølen Mountains of northern Norway, near the town of Narvik. It was a beautiful evening, one of the first days of eternal sunshine at the start of the Arctic summer, and the skiing had been good. They found themselves descending into a shaded gully called the Morkhala, a place they knew well, which had a good covering of snow even late in the season. All three were expert skiers and Anna began her run confidently.

But during the descent, Anna unexpectedly lost control. Torvind and Marie watched from afar as she tumbled headlong onto a thick layer of ice covering a mountain stream. Anna slid across it on her back and then fell through a hole into the water. Her head and chest became trapped beneath the frozen surface. Her clothes began to soak, their extra weight carrying her deeper, dragging her downstream with the current and farther beneath the ice.

Torvind and Marie arrived at the spot just in time to grab her ski boots, stopping her from vanishing under the lip of the ice. Anna was lying face up with her mouth and nose out of the water in an air pocket. She continued to struggle, freezing, in the Arctic stream.

None of the three could have been in any doubt about the seriousness of the situation. Anna was trapped, her clothes soaked with ice-cold water, the stream carrying heat away from her body. Even in those first minutes, her core temperature was beginning to plunge. Torvind called for help on his mobile phone, explaining the life-and-death predicament to the dispatcher. As doctors, Torvind, Anna, and Marie had many friends and colleagues in the rescue services—the dispatcher among them. Firm in the faith that they would make every effort to expedite an emergency rescue helicopter or a mountain rescue team, Torvind returned to help keep Anna from slipping under the ice.

But after what seemed to Torvind like an interminable age of waiting, he rang the dispatcher again, this time demanding to know why nobody had yet arrived. “Yes, Torvind,” came the reply, “we are trying as hard as we can, but you must understand it takes more than three minutes to make these things happen.” To Torvind, fighting for Anna's life, three minutes had seemed like eternity enough.

Two rescue teams were sent; one from the top of the mountain, on skis, and another from the town of Narvik at its base. The ski team, led by Ketil Singstad, was the first to arrive, but they were lightly equipped, and their snow shovel wasn't enough to break through the thick covering of ice. All they could do was lash a rope around Anna's feet to help Marie and Torvind stop her from slipping farther beneath the ice.