Extreme Medicine (16 page)

But Gomersall, along with other doctors and nurses on the intensive-care unit, was fast becoming fatigued. It was unheard of to have so many patients dependent on such high levels of artificial support for such a prolonged period of time. At this point, the outbreak had been raging for weeks, and there was no end in sight. What's more, SARS was threatening the lives of the very frontline medical professionals who were struggling to keep its victims alive.

Protecting the clinical team had become a priority, one that Gomersall's intensive-care unit had found itself initially ill prepared for. The high-filtration masks, so essential to prevent droplets laden with virus from penetrating into the health-care workers' respiratory tracts, were in short supply. They also had to be tested for a precision fit: a poorly fitting mask was worse than no mask at all. This procedure could take up to twenty minutes for each person—a frustrating delay in the middle of the frantic battle against death and disease.

There were other, unanticipated problems. It was the beginning of the Hong Kong summer. Ambient temperatures ran at close to 30°C. (86°F.) with humidity at nearly 80 percent. The personal protection equipment covered the ICU team members from head to toe, leaving only a few square inches of skin exposed. The heat stress was stifling, even with the unit's air-conditioning set to a usually bone-chilling 17°C. (63°F.). But despite fastidious attempts to avoid infection, the intensive-care staff found that even their cumbersome masks, gloves, and protective clothing couldn't keep them safe from SARS. In all, five of their team contracted the disease, and one was later admitted to the intensive-care unit. But despite the dangers to themselves and their families, the doctors and nurses of the Prince of Wales Intensive Care Unit continued to show up for work, week in, week out.

Gomersall got into a routine. As soon as the severity of the situation became clear, he moved out of the family home, away from his wife, Carolyn, and two young daughters. He rented an apartment nearer the hospital and traveled to work by car. The act of getting in and out of the protective garb, to eat, drink, or go to the toilet, was time-consuming and left him vulnerable to infection. Gomersall took to waking early in the morning to breakfast and take on a decent load of water to hydrate himself. He then worked through the day without having to get undressed or remove his mask. Only when safely back inside his own car did he finally take the mask from his face. Each day, when he got back to his flat and closed the door, he felt a sense of overwhelming relief to be away from the ward and in his own space again. There, alone, he was in no danger of infection. More important, he was at no risk of passing the virus on to anyone else.

Gomersall would work for five days in a row on the unit. Before he could go home, he had to make sure that he wasn't incubating SARS. To do this, he would spend ten days away from the ward, teaching and doing administrative tasks in his office—still staying at the apartment. At the end of that time, if he wasn't sick and hadn't developed a fever, it would be safe to go back to his family. Gomersall went through this cycle of work, self-imposed quarantine, and brief family reunion three times.

He got only four days at home between each shift. His family would studiously avoid talking about the elephant in the room. SARS dominated the news. Hong Kong had been paralyzed by it. But Charles didn't much want to talk about what he'd seen, and Carolyn didn't want to hear about it. Should he fall ill at work, Charles had told Carolyn that she should not come and visit. To lose one parent to SARS would be tragic; to lose two—as some families in China already had—would be insupportable.

Every day the teams faced the same set of problems: an intensive-care unit full of people ravaged by SARS, hopelessly unwell, propped up by a constellation of machines and drugs. These weren't much more than a way of buying time in the hope that the disease would abate. That is all intensive care ever is: an extraordinary effort on the part of medicine to stretch human physiology well beyond its survivable limits in the hope that the patient can stay alive until something changes for the better.

In mid-June 2003, something did change. For the first time since the SARS epidemic began, no new cases were being admitted from outside the hospital. The only infections now were happening on the wards, between patients and health-care staff. SARS, for all its ferocity, had a peculiar pattern of behavior that had limited its spread. Some viruses, influenza for example, are highly transmissible very early in the infection, long before the patient becomes incapacitated and unwell. This is why flu spreads so quickly and so widely. Many people infected with flu remain well enough to go about their business, shedding virus to the outside world all the while.

But in most cases of SARS, the peak of contagiousness occurs only once the victim has become critically unwell, usually in the second week after infection. By this time, most of the patients had already been admitted to a hospital. This was why health-care staff had been so badly affected. Though the virus was both highly transmissible and deadly at this point, this limited SARS's spread in the world outside the hospitals. By mid-July 2003, a little over four months after Carlo Urbani had first been called to the French Hospital in Hanoi, the SARS outbreak was firmly in decline, and the last of the travel restrictions to affected areas, recommended by the WHO, had been lifted. Worldwide, there had been more than 8,000 cases with 916 deaths among these. By the following May, no new cases were being reported to the World Health Organization. The chain of spread from human to human had finally been broken.

It could have been far worse. Carlo Urbani's heroic efforts in the early identification of the disease and his swift actions in notifying the World Health Organization's headquarters in Geneva led to a series of events that contained outbreaks and limited the overall spread of the disease.

Urbani first reported his concerns in early March 2003. After tracking rapid dissemination to three other countries, the World Health Organization issued its global warnings a fortnight later. Before the month was out, Malik Peiris's laboratory at the University of Hong Kong had identified a new coronavirus, SARS-CoV, as the probable causative agent, and within a month of that, a Canadian laboratory succeeded in sequencing its genome. This provided information vital to the development of diagnostic tests and vaccines. But with travel to affected areas restricted and quarantine measures in place, the virus burned itself out.

The fight against epidemics and global pandemics is won not by high-tech interventions but by public-health measures. In this context, the work of intensive-care units may appear as little more than a gesture: the symbolic fighting of brush fires in a world under threat of being engulfed by a massive conflagration.

Indeed, the polio epidemic, which gave birth to the specialty of intensive care, was defeated not by ventilators, adrenaline pumps, or dialysis machines but by a program of vaccination—a campaign so effective that today the polio virus stands on the brink of eradication from the world. Since then, intensive care has retooled and repurposed itself. But the question remains: What is the value of intensive-care medicine—a specialty that invests so many resources for such marginal gains in the face of critical disease?

We can reassure ourselves that it is more than just a futile gesture. Of the sickest patients admitted to intensive-care units during the SARS epidemic, three out of four survived. Without the battery of artificial support, none would have lived. Mortalities in the worst-afflicted patients of Copenhagen's polio epidemic of 1952 fell from 90 percent to less than 20 percent as soon as Ibsen's innovations were implemented.

Today intensive care is a branch of medicine that allows other specialties to undertake more ambitious surgeries and interventions than ever before, safe in the knowledge that intensivists have successfully redefined the limits of human life when challenged by disease and injury.

At times of great crisis, the polio and SARS outbreaks included, intensive care has provided medicine with a much needed bulwark against illness, a means of buying precious time. It also does this for any given patient, on any given day, in any intensive-care unit. Intensive care exists in the hope that time enough might be bought for a disease to abate or for clinicians to successfully intervene.

—

W
E ARRIVE IN THE OPERATING ROOM
and administer another shock before the surgeons begin. The ventilator is running. The patient's lungs, too, are now beginning to fail—becoming stiffer and demanding more oxygen. The acidosis in his bloodstream is worsening, and his kidneys are deteriorating. We increase the adrenaline and the noradrenaline. The doses are now so high that their side effects are becoming a real problem. The drugs make his heart more irritable, more prone to fatal arrhythmias. We can hold his blood pressure up, but we must defibrillate more often now. Each time the ECG flips into a shockable rhythm, the defibrillator spits out an inch-wide strip of paper on which the jagged trace is printed in hard copy, like a seismograph beating out the lines of an earthquake. Several feet of this strip have now collected on the floor. An alarm goes off. I nod at the surgeons. They step back from the table. We fire the defibrillator again.

This is absurd. Sooner or later the rhythm of his heart will degenerate into something we can't treat, something that electricity can't reset. Perhaps, realistically, that is all we're waiting for.

But then the surgeons call out. They've found a section of dead bowel, its arcade of vessels blocked by something—a blood clot perhaps. Deftly, the surgeons snip out the gangrenous tissue and join healthy ends of bowel together. Things do not change immediately, but with the diseased bowel gone and no longer leaking toxins into the circulation, my patient's physiology will get better rather than worse. Surviving the next few days will be no mean feat, but the surgeons have given us the means to turn the corner. They are the change that we have been hoping for. We are far from out of the woods, but at least the woods are no longer on fire.

Back on the intensive-care unit, in the hours after the operation, the support we need to provide steadily decreases. We still deliver shocks, but they are fewer in number and less frequent. Slowly the patient is weaned off the drugs and the artificial ventilator. Over the next few days, we gradually hand control back to the patient, shutting off our machines as his normal physiology reasserts itself. Precisely how his body is able to recover and knit itself back together after such an insult is unclear. But he is young, and the young are remarkably resilient.

Less than four weeks later, that eighteen-year-old walks out of the hospital.

B
race! Brace! Brace!” he shouts, running the words together as though they were one. I shove my head up against the wall of the helicopter, my crash helmet clunking against the bulkhead, and fold my arms over my chest, hooking my thumbs under the shoulder straps of the four-point harness. We hit the water in darkness and immediately begin to sink. The water is already at my ankles. I rest my right hand on my harness's quick release, and with my left I find the handle that will jettison the door. Once underwater, the helicopter will sink a meter every second.

I never used to understand how it could be difficult to escape from a sinking vehicle. Open the door, swim out and up to the surface. How much of a challenge could that be? On dry land, I can hold my breath for the best part of three minutes, and I'm an OK swimmer. How long could it conceivably take for me to get to the surface from, say, twenty meters down? But of course you have to factor in the harsh realities of the physics and physiology of your predicament. How long could it take? Very probably forever.

This is HUET (pronounced
hew-it
), the Royal Navy's Helicopter Underwater Escape Training facility in Yeovilton. It exists to provide helicopter crews with the training they need to escape a vehicle that has ditched in open water. The work they do is vital. In more than 80 percent of helicopter crashes over water, the time between warning and impact is less than fifteen seconds. Of these, more than 70 percent sink immediately, with over half of them inverting. The military's experience of helicopter accidents into water is also pretty sobering. Of those occurring in daylight, the survival rate is 88 percent. But for survivable helicopter crashes into water occurring at night, that number is as low as 53 percent.

But why is this happening? These are healthy people, trained military personnel, and in most cases strong swimmers. The answer lies in the very structure of our bodies.

—

W
E TAKE OUR NATURAL BUOYANCY
for granted—mainly because the vast majority of us never dive beyond the point at which we are more likely to sink than float. From the surface, for the first seven meters or so, it takes a bit of effort to dive below the waves. The air in your body, principally that in your lungs, serves as a kind of float to keep you buoyant. Here the upthrust you experience by virtue of the good old Archimedes principle is more than enough to return you to the surface.

But below those few meters, the relationship is reversed. Your tissues become compressed, the volume of air in your lungs decreases as the pressure mounts, and you eventually become denser than the water around you: an object that would rather descend into the depths than float upward.

This state is described as negative buoyancy. It's a strange term when you think about it—like referring to the state of being poor as being “negatively rich.” What we're really talking about is sinking as a probable prelude to drowning.

—

T
HE WATER IS RISING FAST NOW,
already up to my waist, and every fiber of my body is telling me that I should unclip that harness and punch through that window. But to do that would be fatal. Free of the seat, I'd be swilled around the cabin by the inrush of water; finding my way to the exit and then locating the metal bar that jettisons the window would be impossible. If I'm to survive this, I have to wait. The water continues to bubble into the cabin. It's at my chest now, and the whole vehicle is overbalancing, skewed by the weight of the engines and rotors above, turning upside down in the darkness. The water is up to my chin as the cabin starts to rotate. These are my last few breaths, and still I'm strapped into my seat, resisting the urge to get the hell out of there.

—

H
OLDING YOUR BREATH:
that's what your survival boils down to here. It is, on the face of it, a simple act of mind over matter, a discipline you should be able to find within yourself—especially if your life depends upon it.

Yet the desire to breathe is among our most primitive urges. We're designed to draw air into our lungs, to exchange fresh oxygen for the waste gas of carbon dioxide. Our lives depend upon this perpetual to and fro of gases, and it is worth taking a moment here to consider your respiratory system in all its glory.

When we describe the path that oxygen takes from the outside world to its final destination in our mitochondria, we do so as though it has agency of its own. We talk of molecules of oxygen moving into our bodies, diffusing across membranes, arriving at mitochondria, almost as though they know where they want to go. But of course oxygen has no free will of its own. In the act of living, your body must solve the problem of how to grab molecules of this gas from the atmosphere and bundle them into cells in sufficient concentration that they can do the stuff of life.

The first part of that performance is the act of breathing. Your ribs are attached to your breastbone at the front and the bony column that is your spine at the rear. At the end of each exhalation, they slope steeply downward toward the ground. Contracting the muscles in the chest wall that do the work of breathing lifts the ribs up, to a nearly horizontal position, increasing the volume of the chest. At the same time your diaphragm, the large dome-shaped muscle that separates the chest from the contents of your abdomen, contracts and drops down, further increasing the volume of the cavity inside your chest.

Your lungs sit inside the cage formed by your ribs, adherent to the chest wall. As the chest moves, your lungs move with them. As the volume in your chest cavity increases, so too does that inside your lungs. The increase in volume leads to a decrease in pressure in your chest. That in turn produces suction, in exactly the same way as separating the handles on a bellows does, and air begins to flow.

That air passes through your upper airways, the larynx, and the trachea, and then down into your bronchial tree. I always thought of that branching network of airways as inverted sprigs of broccoli rather than trees. In terms of morphology, that's not far off. There's a hollow central trunk that sprouts branches of ever decreasing caliber, at the very end of which are saclike structures called alveoli: the buds, if you like, at the end of that sprig of broccoli. The cadaveric lung, formalin-soaked in the medical school's dissecting rooms, is solid and heavy; its airspaces are occupied by pungent preservative fluid. But in life, air-filled lungs are lighter than sponge, light enough to float on water.

The anesthetist's perspective in the operating room, the chest laid open during cardiothoracic surgery, gives a much truer impression of those organs. Watching as they expand and collapse with the rhythmic grind of the ventilator, you are immediately aware of a structure whose volume is principally air: a delicate organ horribly vulnerable to injury.

That fine structure exists to provide a massive surface area over which air can be brought into contact with blood. The alveoli, those tiny air sacs at the end of the bronchial tree, are each no more than a fraction of a millimeter in diameter, but each lung holds one and a half million. If you were to unfurl them and lay them out flat, they would form a mat of tissue half the size of a tennis court at Wimbledon. That vast area is required to bring enough air into contact with enough blood to keep you alive.

Over the surfaces of those alveoli runs a spiderlike network of capillaries, vessels with walls a single cell thick, providing just enough structure to confine the blood cells squeezing through them, while offering the minimum obstruction to the molecules of oxygen diffusing through their walls.

This is the most delicate interface in your body. Nowhere else is the point of contact between your body and the material from the outside world more insubstantial or delicate. That is why it is buried deep in your chest and protected with a formidable cage of ribs. There is no choice other than to make it that way; it has to be that extensive, that fragile, or else gas would not flow and exchange.

In the act of drowning, volumes of water replace air, swamping the gossamer-thin tissues designed to allow gas to pass from the air into our bloodstream. For the average adult, a total of around a liter and a half of water drawn into the lungs is lethal.

This was all too vivid in my mind while I sat trapped in the sinking helicopter.

—

“
W
AIT UNTIL ALL
violent motion has ceased.” The words of my training instructor come back to me. What he really means is wait until you're under and upside down. Wait until you're really sinking.

I can feel the wetness creeping under my chin and the coldness of the water; I start to take deep, gasping breaths. I tell myself it's because I'm trying to drop my carbon dioxide, extending the time before my body senses its levels building in me and thereby lengthening the time for which I can hold my breath. But in truth there are other reasons for my hyperventilation here. The water is at my lips. I tilt my head back and take a last long breath. And then we're under.

It is quieter here, somehow immediately less stressful. When my head was above the surface, there was noise and uncertainty. At least now you know that your race to escape can begin. You can't be sure how long the thing took to invert, how far below the surface you might already be. This is part of the problem. With a sink rate of a meter a second, if it takes longer than seven seconds to get out of the vehicle then you'll be negatively buoyant on your exit. If it's night and you have no source of light to guide you, the question becomes: “Which way do I swim?”

From those who have escaped from sinking aircraft at night, there are stories of people swimming through inky blackness for what seems like an eternity, knowing that if they have it wrong, if they've headed the wrong way, they will swim for the rest of their lives.

Underwater now, the familiar burning desire to breathe is already upon me. But I'm following the instructions. I stretch out my right arm, and the short lever that ejects the window presses into my palm. The black and yellow stripes were the last thing I saw clearly before the wash of water covered my head. Frantically I pull the lever to open the window, and then hold the frame to make sure I'm ready to haul my body out from the watery coffin. Only then do I dare undo the seat belt, fiddling with the rotating catch, hoping that it won't jam.

The release comes apart nicely, and I pull on the window frame, remembering which way is up. I haul myself out of the helicopter and begin my ascent to the surface. I break the surface with a gasp. It has taken nearly thirty seconds to escape. That's fine in the comfort of this warm swimming pool and simulator. But out there in the chill of the Atlantic, even that's probably going to be too long to save my life. To understand why, we need to think about what makes us breathe.

—

T
HE ACT OF BREATHING IS ONE
of the few bodily functions whose control is part automatic and part voluntary. You might think that such a vital system would be better left under the permanent supervision of your autopilot.

The only other comparable rhythm in your life is that of your heartbeat, and that is almost exclusively under automatic control. Yes, you might be proud of your ability to chill yourself out and slow it down a little, but when was the last time you had a game of “who can stop their heart longest”?

You can choose the way you breathe; you can choose right now to breathe harder and faster. You can choose to stop breathing altogether. But your body knows what you're like, and it doesn't completely trust you. It allows you to take control of your breathing temporarily, but never long enough to do yourself any permanent harm. It's not possible to stop breathing long enough to kill yourself; in fact, on dry land, it's tricky to hold your breath to the point of unconsciousness.

Sooner or later your body and its automatic system of management wrests control from you. Detecting when enough's enough is a bit of an art. Your body is pretty conservative, with a set of early-warning systems that trigger breathing long before your biochemistry gets too upset.

To know that you're not breathing, the body has to detect the way that your physiology changes when gas exchange stops. Broadly speaking, there are two things you could detect. Although the falling level of oxygen in your blood would be the obvious thing to use as an indicator of danger, that's not what your body does.

That leaves carbon dioxide. When you stop breathing, the level of carbon dioxide in your blood rises faster than the level of oxygen falls. That means that a high concentration of carbon dioxide becomes a telltale sign that you need to take a breath.

So in part, the early-warning system functions by sensing the effect that rising CO
₂
levels have in the body. Carbon dioxide molecules dissolve in water and make it more acidic. It's this acidity that indirectly tells the body that the mechanics of breathing have been halted for too long.

But the system is more complicated than that. In fact, nobody is sure precisely what triggers the break point in our drive to breathe: the point at which the urge to take a breath becomes irresistible. We know that there is a constant central rhythm, beaten out by respiratory centers deep in the brain stem—clusters of cells that keep time in a dance that lasts throughout the whole of our lives and one from which we may only very briefly absent ourselves. This rhythm is like a perpetual biological metronome. When the performance of breathing halts, it keeps ticking away, urging you to restart.

Then there are environmental factors. In swimming-pool tests—with the water at 25°C. (77°F.)—experimental subjects simulating escape from a helicopter could hold their breath, on average, for no more than thirty-seven seconds. Away from the warmth of an indoor pool, the situation deteriorates further.

In water below 12°C. (53.6°F.), the cold-shock response is activated. This, a reflex triggered by the widespread activation of cold receptors in the skin, provokes an involuntary and uncontrollable gasp, forcing an individual to draw huge volumes into the lungs whether immersed or not. The drive to breathe it produces is so profound that the average breath-hold time in cold water conditions falls to just six seconds.