An excerpt from What Doctors Feel: How Emotions Affect the Practice of Medicine. Excerpted with permission by Beacon Press.

The stat cardiac-arrest page came through on my beeper at exactly the same moment as the hospital-wide PA system announced, “Code 411, cardiac arrest, MICU.” The operator chanted the mantra over and over with studied deliberativeness, as though there were even a snowball’s chance in hell that I hadn’t heard it. The repetitive droning of her voice echoing throughout the twenty-three floors of the hospital and the persistent buzzing of the beeper at my waist were like rising tides of terror pressing in on both sides of me.

This was it—the first code I was in charge of. After two years of racing to codes as a first- and second-year resident, buoyed by the excitement of dramatic action, thrilled to be part of a team, grateful to be assigned one of the many minute tasks required to save a life, secure in the knowledge that the medical consult would be directing the show—now suddenly, the code was mine. I was the medical consult. I was the one to call the shots, to direct the care, to assign the jobs, to make the decisions.

I had been on the medical-consult service for less than a week. I’d been privately counting on thirty days elapsing with every last coronary artery in the hospital capaciously wide open, every lung alveolus buoyant with oxygen, every blood clot obediently self-dissolving, but this strategy was evidently not working as I’d hoped. Here it was: my first code.

Shit!

I slapped my hands against the overloaded pockets of my white coat to keep the tools and cards and pocket guides from spilling out while I raced to the medical intensive care unit. I burst into the MICU breathless, throat parched to Saharan levels, pulse pounding powerfully enough to detonate the collar of my shirt, and glanced wildly about the unit.

There was the crowd, huddled around bed, I loped over and pressed through the bodies, angling toward the head of the bed. “I’m med consult,” I announced, gamely smoothing out the jitteriness in my voice.

And then my brain splintered into complete and utter blackness.

A resident began feeding me the facts—seventy-two-year-old guy, diabetes, coronary disease, stroke last year, admitted with pneumonia, developed allergic reaction to his antibiotics, subsequent renal insufficiency, transferred to the MICU three days ago for congestive heart failure, spiked a fever last night, a bit delirious but still talking, now unresponsive, BP 70 over palp, thready pulse.

Or something like that. The truth was, I couldn’t have told you the details twenty seconds after he finished relaying them to me, much less twenty years later. Everything he said sloshed into the primordial neuronal soup that was now the condition of my gray matter.

Say something, I implored myself. Anything. “Chest compressions,” I forced out. “Keep bagging the oxygen. Get a line in. EKG.”

Any idiot knows the basics for keeping someone alive! But what next?

My brain remained jammed up with panic. I couldn’t seem to remember a damn thing from those ACLS training courses. All the protocols had seemed so logical then, so ridiculously simple on those ever-forgiving mannequins.

But now there was someone real, someone alive—though perhaps not for much longer with me at the helm—and I couldn’t unknot a single protocol.

Did you shock first or give epinephrine first? Or was epi only for the asystole algorithm? Should I be following the pulseless electrical activity algorithm? Or the pulseless ventricular tachycardia algorithm?

Someone pressed an EKG into my hand. The presence of something actual in my hands brought a brief mollifying reprieve of emotion. These would be my tablets handed down from the Mount; the talismanic markings would allow me to divine the answer and jumpstart my fear-stricken brain.

I stared at the electrocardiogram. And stared. And stared. I squinted at the zigs and the zags, but they seemed to melt into a Sanskrit-like jumble. Think, I demanded. Think! All those exhortations from my teachers about approaching the EKG methodically, about systematically examining the rhythm, the rate, the axis, the P waves, the QRS complexes, the T waves—these lessons evaporated in the cold shudder of reality.

Think, I screamed to myself.

Okay, the T waves. Maybe they looked a little peaked. Peaked T waves were indicative of elevated potassium levels, except when they weren’t. And except when they looked peaked but weren’t actually peaked.

They did look sort of peaked, I thought to myself, but maybe they were just hyperacute T waves, or maybe they were enlarged from early repolarization. Or maybe they were just big. I was too terrified to trust myself on anything. I could order the treatment for hyperkalemia— if those peaked T waves were real—but I was too scared that I might be wrong. What if I injected intravenous calcium for hyperkalemia that wasn’t actually there, then really fucked things up?

“Who’s in charge here, anyway?” barked a new voice. My body seized up tighter, if that was even possible. A cardiology fellow blustered his way into the crowd, clearly seeing the mess for what it was. I looked up and made a vague indication that I was running the code.

There was an embarrassing moment as the fellow and I instantly recognized each other—Mitchell had been in my medical-school class. We’d spent the first two years of school together, even traveled in the same circle of friends. But because of the years I’d taken to do my PhD, he’d completed his training before me and was now a senior cardiology fellow while I was a third-year medical resident. It was evident that if he hadn’t known me from med-school days he would have dressed down the medical consult for not running the code more aggressively. He bit back his comment, sidled over to me, and leaned in to look at the EKG. “Peaked T waves, hyperkalemia,” he announced clearly, though not derisively—an act of humanity that allowed me a modicum of dignity. “Let’s get some calcium,” he said, “an amp of bicarb, D50 and insulin.”

The patient did all right in the end, or at least survived the code, which was pretty much what we considered success in the MICU. I slunk off after the patient stabilized, hoping to disappear myself in the sea of white coats shuffling off to conference or rounds or the ER. I was furious at myself for getting so paralyzed by fear that I could barely run the code. What had happened to all my training? All the codes I’d participated in? All the lectures and books I’d been learning from?

What made me the angriest at myself, though, was that I’d actually gotten it right. It was hyperkalemia. The T waves absolutely had been peaked. I could have called it on the spot and been the model of a take-charge resident, as a medical consult running a code is supposed to be. But I couldn’t get beyond my gripping fear—of the situation, of getting it wrong, of killing the patient, of looking like an idiot.

The amygdala is ground zero for the processing of fear in human beings. I remember the first time I laid eyes on an actual amygdala, after slicing through a brain with a repurposed kitchen knife in neuroanatomy class. That’s it? I thought. That nickel-size splotch tucked below the temporal lobes was the seat of my fears? It was monumentally underwhelming and even lacked the poetic almond shape that its Latin name connotes.

The amygdala acts as the ringleader of the limbic system—the emotional guts of our brain. Weaving together the hippocampus, thalamus, amygdala, and some ancient parts of the cerebral cortex, the limbic system calibrates the nitty-gritty of who we are—our fears, our attractions, our memories, not to mention the cornerstone imperatives of food, sex, and anger. If psychoanalysis had a neuroanatomical substrate, it would be the limbic system. And if it wanted a laser-like focus, especially when it comes to fear, it would train its sights on the amygdala.

I read of a patient with a rare condition that damaged the amygdala on both sides of her brain. Though her other emotions appeared normal, she neither felt nor expressed fear. Researchers did what they could to frighten her—brought in live snakes, set spiders loose, showed scary movies. They even took her on a haunted-house tour. She didn’t so much as flinch. It wasn’t that she had nerves of steel; she simply did not experience fear.

As a medical student and intern, I longed to be her. I desperately desired an emotional shield that would block out the paralyzing fear that seemed to track my every step. If I could only corral my amygdala and limbic system, being a doctor would be effortless.

Fear is a primal emotion in medicine. Every doctor can tell you of times when she or he was terrified; most can list more episodes than you might wish to hear. This fear of making a mistake and causing harm never goes away, even with decades of experience. It may be most palpable and expressible in neophyte students and interns, but that is merely the first link in a chain that wends its way throughout the life of a doctor. It may be sublimated at times, it may wax and wane, but the fear of harming your patients never departs; it is inextricably linked to the practice of medicine.

I sometimes compare career notes with friends who are in the business world, and I’ve asked what their worst fear is. It’s usually something along the lines of making a financial blunder, screwing up a major project, having an investment fall apart, losing a job, disappointing the boss or family, losing money. I have to restrain myself from saying, That’s it? That’s all you are afraid of?

That, of course, is the basic fear in medicine, that we will kill someone, or cause palpable bodily harm. I vividly remember my first reading of Ernest Becker’s classic existential treatise The Denial of Death. Becker posited that humans are terrified of their own mortality, and that every action we take, on an individual or societal level, is directed (usually unconsciously) by the necessary denial of imminent death.

This precisely captured my fear as a doctor-in-training, except that the fear was entirely conscious. I was terrified of causing death, and every action I took was an obeisance to that fear. Medical students, for all of their competence and competitiveness, are a pretty fearful bunch, more so than the general population and even more than their age-matched peers pursuing other professions. Some of this is not surprising. You really should possess some fear as you begin to jab sharp objects into other people’s bodies, prescribe potentially lethal medicines, or initiate treatments that put lives at risk. Any medical student without fear is a cavalier cowboy better suited to a desk job.

But the fears can easily spiral out of control and overwhelm students and interns. If this happened only rarely, to only those few who entered the medical field with their own preexisting mental-health conditions, that would be one thing. But the truth is that the fear overwhelms even the most psychologically sound and well-adjusted trainee. At some point it happens to nearly every single person who travels through the medical training process. If you don’t believe me, just ask any doctor you know.

Danielle Ofri is an internal medicine physician and author of What Doctors Feel: How Emotions Affect the Practice of Medicine.