The patient had came to the emergency room because over the course of an afternoon he had become short of breath, unable to walk more than a few feet. Now admitted to the hospital, while he was talking to me, he had to stop and take a breath after every third word.
I was meeting this patient as part of a teaching activity. The doctor who was caring for this patient was watching me as I took his history, performed a physical exam, and tried to work through the diagnosis.
When I was finished, the doctor and I went to the conference room and I was given the patient's EKG. "What's on your differential?" the doctor asked me.
I reasoned my way through several classes of disease that would cause shortness of breath: infection, left-sided heart failure, asthma, chronic obstructive lung disease, and various types of lung disease. But none of these seemed to fit this patient's presentation.
"Keep going," he said. "You're missing something."
I racked my brain and came up with some esoteric diseases that were extremely unlikely.
"I'm thinking something big," he said.
I couldn't figure it out. "I give up," I said.
Shit! Pulmonary embolism is a common disease that can be life-threatening if unrecognized. And I hadn't recognized it, or even thought to look for signs of it on physical exam. This patient's presentation was classic, too.
As it turned out, the patient's lab results were inconsistent with pulmonary embolism, effectively ruling it out. But the awful feeling in my stomach remained. The obvious diagnosis hadn't made it onto my differential. This was the sort of mistake that could kill a patient.
Of course, I'm just a second-year medical student. I'm expected to make mistakes like this all the time. I will not be solely responsible for patients for quite a while. Even so, the teaching exercise was a rude reminder that there remains quite a lot for me to master.