Pneumonia is an infection in the lungs that cause the tiny air sacs called alveoli to become inflamed and fill up with fluid or pus. Pneumonia can result in mild symptoms that do not necessitate medical diagnosis or treatment, and can also be serious and life-threatening, especially if it is not timely diagnosed and treated.

Decades ago, doctors had few tools to treat pneumonia. Sir William Osler famously called it “the old man’s friend” because it was a relatively swift and painless way to die.

Today, however, doctors and other providers responsible for diagnosing and treating pneumonia have many more tools available, and as a result a patient’s prognosis is generally speaking much better than in Dr. Osler’s day.

With regard to diagnosis, clinicians have much more and better tools to avoid pneumonia misdiagnosis.

Identifying signs and symptoms before pneumonia is life threatening

Often, a patient with pneumonia has symptoms such as a productive cough, fever and/or chills, shortness of breath, pain when breathing, and fatigue.

When a patient’s complaints puts pneumonia on the doctor’s list of possible causes (called a “differential diagnosis”), she does not need to rely on her judgment or gestalt as to whether the patient is “sick” or not. Instead, she can obtain objective data to help her come to a diagnosis.

This can include vital signs, such as a patient’s oxygen saturation levels, respiratory rate, temperature and blood pressure.

It can also include physical exam findings, including checking to see if the patient has a running nose, and listening to the patient’s lungs to check for any abnormal sounds.

She can also order blood tests to look for evidence that the patient’s body is fighting an infection. And she can order imaging studies – typically x-rays – for a radiologist to interpret to determine whether there are findings suggestive of pneumonia.

Certainly, there are instances where patients present with unusual symptoms (or no symptoms suggestive of pneumonia), leading a reasonable doctor to not consider pneumonia even when the patient has it. And, it is possible that a patient’s objective data does not lead a reasonable doctor to conclude the patient has pneumonia when he or she in fact has it.

However, in the vast majority of situations, using the diagnosis process learned in medical school, along with all the tools a clinician now has within that process, patients with pneumonia should be diagnosed and appropriately treated to avoid serious injury and death.