“What I want you to do,” I said, “is breathe in deep, then blow it all out like you’re blowing out birthday candles.”
He focused his eyes in concentration and blinked a few times, then did as I’d said, aiming for the finger I held in front of him.
I listened to his back with my stethoscope. “Again,” I said. “Again. Again. Good job! Again.”
His mother sat forward in her seat and breathed in sync with her boy, her face softened from the suspicious glare she’d trained on me a moment before. After I’d listened to every part of the kid’s chest, I put my hand up for a high five, which he gave me without prompting. His mother frowned and looked at me. “Well?”
I understood her frustration. It was the fifth time in a month that they’d been in the clinic for the boy’s wheezing. He was now on four asthma medications, and yet according to his mom, his coughing and wheezing were worse than ever. Indeed, I could hear the boy breathe from across the room. But with my stethoscope, I just heard some mild coarseness–no wheezing at all. I had the boy cough, then listened again, and heard the same thing.
I told the mother I heard very little wheezing on my exam, and that perhaps asthma alone was not sufficient explanation for the boy’s problems. I then stepped out to discuss the boy’s case with a supervising clinician, Dr. Mallet.
Dr. Mallet knew the boy well–he had seen this patient for every previous complaint of wheezing and had initiated all of the treatments the boy was taking. I like Dr. Mallet a lot, and think he is a bright and caring physician and an excellent teacher.
But Dr. Mallet heard wheezing. “Yeah, he doesn’t sound great,” he said after listening to the boy’s back. He suggested we start steroids and order a chest x-ray, then left me in the room to complete the paperwork. A moment later, he popped his head back in. “You know, let’s also do a course of antibiotics. This has been going on for an awfully long time.”
Before I gave the mother her stack of requisitions and prescriptions, I asked if I could listen to her boy one more time. Again, I heard no wheezing.
“Huh,” I said.
The following day, Dr. Mallet called me into the x-ray reading room. As it happened, the film showed traces of a pneumonia. The most likely pathophysiological scenario is that the boy had severe asthma that was incompletely controlled for long enough that he eventually developed a post-obstructive bacterial pneumonia. The noisy breathing was probably due in part to off-and-on wheezing and in part to upper respiratory congestion. But what interested me about this interaction wasn’t the pathophysiology.
I’m not an expert clinician, but I know what wheezing sounds like, and I have great hearing. By my three exams, this kid wasn’t wheezing. Sure, it’s possible that my lung exam stinks. But presuming it doesn’t, how is it possible that Dr. Mallet heard such different breath sounds than I did?
A great clinician I worked with in medical school used to say, “When you’re a hammer, everything looks like a nail.” He was talking about something called confirmation bias, which occurs when we selectively look for or “find” information that confirms what we believe to be true. It’s human nature to approach problems with this kind of bias, and even very good doctors have stories about mistakes made because of it.
If my exam really was right, Dr. Mallet “heard” findings of asthma because he had diagnosed the kid with asthma. Still, something made him come back to the room after continuing down his expected diagnostic path.
Even if Dr. Mallet’s findings were guided by his expectations, his plan was not. Although some part of him might have been trying to make this patient fit into a familiar pattern, it was overpowered by his sense that something didn’t fit. His attention to that sense–even in the face of a formidable and noisy bias–helped him make the right decision for this patient. In medicine, human nature demands constant questioning.
I refer you to Jerome Groopman’s excellent book, How Doctors Think, for more on the kinds of errors doctors make, and on ways to avoid them.