Have you ever considered how difficult it is to measure pain? Probably not. But consider this: If you've got a fever, you grab a thermometer that gives you a temperature in degrees, and you can check blood pressure by slapping on a cuff and reading the millimeters of mercury (mmHg). But despite all the advances in modern medicine, there's no instrument to measure pain. That's where pain scales come in.
Pain scales are tools that doctors and nurses use to estimate the intensity of discomfort. Some rely on self-reporting, meaning patients are asked to assess their own pain. There are many ways to do this, but one familiar way is for a physician to ask those in their care to rate pain on a scale from 0 to 10. However, because such screenings are subjective and require communication, they aren't always reliable or even feasible. That's why doctors also use observation to make their own pain assessment. Some clues to a patient's discomfort level might be behavioral symptoms, like wincing and moaning, or physiological symptoms like increased heart rate and blood pressure.
So why measure pain? Whether determined through self-reporting or observation, pain levels are an important part of the medical diagnosis and treatment process. Say a patient comes in with chest pain, and they rate it at a 7 on the scale we mentioned above — that could indicate anything from a heart attack to a muscle strain. If the doctor then gives the patient some pain reliever and the pain goes down to a 2, that change in rating could help rule out the heart attack. Such measures can also aid doctors in tracking whether a patient's condition is improving or declining, as well as pinpointing the amount and type of pain medications needed to make the patient comfortable. In fact, measuring patient discomfort has become such an important part of medical practice that that the American Pain Society has declared pain "the fifth vital sign."
Despite their widespread use today, pain scales are a relatively new phenomenon. Read on to learn about their origins and one particularly misguided experiment conducted in an attempt to create the perfect pain scale.