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We’ve Had The Same Four Vital Signs For Centuries

You check in for a doctor’s visit and a nurse or physician’s assistant leads you back to the exam room. There, they check your vitals — blood pressure, temperature, pulse, breathing rate. Maybe height and weight too.

Most of us are so used to this routine that we don’t think twice about it. Some of the core vital signs are as old as the field of medicine itself. Centuries ago, nobody used medical equipment to check if someone was breathing or had a pulse; you could simply watch for breathing from the mouth or feel for a pulse in the wrist. And before mercury thermometers, body temperature could be approximated by feel.

More recently, there have been campaigns to expand the list of vital signs to include new health metrics. So far, these efforts haven’t broken through.  

We talked to experts about the origins of the vital signs, how they inform patient care, and which vital signs (if any) might show up on your chart in the near future. 

The core four

Whether you’re at the ER or your primary care doctor’s office, most providers check the four main vital signs: heart rate, temperature, pulse and breathing rate.

“Those are the things you can look at very quickly and tell right away is this person sick or not,” says Dr. Allison Ruff, a primary care general internist and clinical associate professor at the University of Michigan. “We don’t mean, Do they have a cold? We mean, Is this a life-threatening situation? Those four vital signs are the quickest way to figure that out.”

“There are definitely limitations, especially when it comes to blood pressure.”

We can trace three of the four vital signs, body temperature, pulse and respiration, back to the earliest days of medicine.

“Even hundreds of years ago, pulse was always used to measure the basic presence or absence of life,” Ruff says. “Respiration is the same. Is this person breathing or not?”

Blood pressure as a vital sign came later. By the early 20th century, doctors began using stethoscopes and cuffs to measure patients’ systolic and diastolic blood pressure.

Today, providers track the four core vital signs at most visits, including routine checkups, specialist appointments and emergency care.

Vital signs in practice today

In primary care, providers monitor vitals at every visit to identify trends, such as a patient’s pulse or blood pressure readings increasing or decreasing over time.

“Low heart rate in the outpatient setting often means someone has excellent exercise tolerance and their heart is able to pump more efficiently,” Ruff says. On the other hand, chronically high blood pressure could be a sign of a condition that requires treatment.

ER care teams rely on vital signs to get a snapshot of a patient’s condition at a given moment.

“We’re looking for abnormal patterns,” says Dr. Justin Johnson, an emergency medicine and critical care doctor at Mercy Medical Center in Baltimore. “When [your heart rate] gets to 40 or below, I don’t care if you’re an athlete or not, that’s a problem. In the emergency department, we’re looking for extremes that would make us concerned. In the primary care office, they’re looking for changes from baseline.”

An emergency care provider might also look at additional indicators, depending on your reason for showing up to the ER.

“Glucose is not a vital sign, but it’s something that we use like a vital sign in almost every patient that comes into the emergency department,” Johnson says.

Height and weight aren’t technically considered vital signs either. But most providers measure them over time as well, Ruff says, to come up with a patient’s body mass index (BMI). This calculation measures your weight relative to your height, and its clinical value has spurred debate in recent years. “Oftentimes [BMI] correlates to health markers, but we know it doesn’t always,” Ruff says.

Limits of the vital signs

Although the four core vital signs offer a reliable, quantifiable way to evaluate a patient’s health, they aren’t perfect.

“There are definitely limitations, especially when it comes to blood pressure,” Ruff says. 

Ideally, blood pressure is measured in a dim room when a patient is seated with feet flat on the floor after five minutes of rest, Ruff says. 

“We know that is totally not how it happens in the doctor’s office or hospital,” she says. “If you’re in the ER, chances are you’re lying on a stretcher, you’re super anxious, you’re in the exact opposite setting of a relaxed, calm situation.”

“The reason why vital signs are so vital is because they are not subjective. Your heart rate is your heart rate.”

Ultimately, it’s important to interpret the vital signs in context, Johnson says.

We often try to use tools or systems that give us easy answers: If your heart rate is this high, or your blood pressure is this, then you have to be worried,” he says. “But you still have to take each one on a case-by-case basis.” 

The signs of sepsis, for example, include elevated heart rate, respiratory rate and temperature. But those same signs could also indicate that you just got back from a jog. Vital signs have to “be applied appropriately in the correct setting,” Johnson says.

Efforts to add new vital signs

Pain
In the mid 1990s, the American Pain Society began advocating for the adoption of “pain as the fifth vital sign.” This campaign was positioned as a way to improve treatment for both chronic and acute pain. To assess pain, patients were asked to rank their levels of pain on a scale from one to 10.

The campaign backfired, partly because the pain scale is subjective and pain is difficult to evaluate at a glance, Johnson says.

“The reason why vital signs are so vital is because they are not subjective. Your heart rate is your heart rate,” he says.

But the biggest cloud over the campaign is its connection to the US opioid epidemic.

When the “pain as the fifth vital sign” campaign started, Purdue Pharmaceuticals was also launching its own marketing campaign for Oxycontin, which received FDA approval in 1995. These efforts coalesced with a Medicaid reimbursement structure that rewarded hospitals where patients reported high levels of satisfaction with pain management. 

The result: Doctors began prescribing more opioids to minimize patients’ pain levels while increasing patient satisfaction. Many providers didn’t hesitate to prescribe opioids that were initially marketed as non-habit-forming, Ruff says.

Had you read about it at the time, it seemed like a good idea,” Ruff said. “The problem is there was reimbursement tied to this, and we created this idea that people should have no pain … Pain as the fifth vital sign has been attributed partially to creating the opioid epidemic.”

The campaign ultimately “made medicine into a business,” Johnson says. “People have less pain, they’re happier, they come back, you make more money.”

By 2016, the American Medical Association urged healthcare providers to stop using pain as a vital sign, pointing to the botched vital sign campaign as one driver of the overprescription of opioids.

“Exercise is super important, but so are lots of things. Why isn’t smoking a vital sign? Unhealthy eating? It just becomes a slippery slope.”

Today, your doctor may still ask about your pain, but most medical professionals have abandoned pain as a vital sign, Ruff says (and multiple studies have found that opioids aren’t any more effective than non-opioid pain medications).

“We still ask patients about their pain all the time, but we know now that pain is not in fact a vital sign,” she says. “You can live and be a normal person and be healthy with some pain.”

Exercise
In 2009, the Kaiser Permanente healthcare system in southern California began monitoring exercise as a vital sign. At every visit, patients answer two questions: 1) How many days a week do you engage in moderate exercise. 2) On those days, how many minutes do you exercise, on average?

Moderate exercise “means you’re walking fast enough that you couldn’t sing, but not so fast you couldn’t talk,” says Dr. Robert Sallis, a family and sports medicine physician at Kaiser Permanente Fontana Medical Center and the founder of Exercise is Medicine, an initiative promoting physical activity assessment in clinical care.

“I would say that [exercise] is the most important of the vital signs because it takes into account virtually every organ system in the body,” Sallis says. “When people’s activity level is low, they’re at much higher risk.”

If a patient doesn’t meet the CDC-recommended 150 minutes of weekly exercise, they’re flagged for a follow-up visit with their physician. If they also present with an issue like high blood pressure, prediabetes or depression, starting an exercise regimen could be a first-line treatment before turning to medication.

“If a doctor notices your blood pressure is high and you’re doing zero minutes a week of exercise, they might say before we start you on a medication, why don’t we start you on a walking program?” Sallis says. “All of these chronic conditions call for regularly exercising. There’s no medical condition that isn’t helped by being more active.”

Research suggests that classifying physical activity as a vital sign could be useful for monitoring some health conditions and patient populations. But this approach has been slow to take off in healthcare systems around the country, Sallis says, and he attributes that in part to a lack of marketing and resources.

“There’s no big pharma for exercise,” he says. “There’s no one making a lot of money and driving that prescription of exercise.”

To some providers, however, exercise just doesn’t make sense as a vital sign.

“Exercise is super important, but so are lots of things,” Ruff says. “Why isn’t smoking a vital sign? Unhealthy eating? It just becomes a slippery slope.”

The subjective nature of self-reported exercise habits also gives some doctors pause.

“People can say I exercise every day, but what does that mean to you? It might mean I walk from my couch to my mailbox,” Johnson says. “You really need objective data points for the vital signs.”

To that, Sallis says self-reported data informs medical care in plenty of other situations — so why not use exercise as a vital sign?

“Patients self-report their smoking habits, drinking habits, sexual habits … certainly there’s some reporting error,” he says. “We know self-reported [data] is not perfect, but we have to rely on it.”

Other new vital signs on the horizon?

Pain has largely been ousted as a vital sign, and relatively few health systems have followed Kaiser Permanente’s lead and added exercise to the list. Should patients expect to see any new vital signs in their charts in the near future?

“I think a nutrition vital sign would be helpful,” Sallis says. “It’s just so hard to get your hands around. You can’t get five experts to agree on what’s a healthy diet.”

Technology could also lead to new vital signs in the emergency room, Johnson says, pointing to pulse oximetry — the oxygen content of a patient’s blood — as an important sign when monitoring for sepsis. Decreased oxygen in the blood can also be a sign of COVID-19, and some experts encourage patients to use an at-home pulse oximeter to monitor their levels at home (but take heed: research suggests home monitoring leaves room for error).

After the fallout from the pain as a vital sign campaign, some medical professionals, including Ruff, doubt that additional vital signs will be added to the core four anytime soon.

“I hesitate to include anything as a vital sign that is not something I can glance at quickly and understand the health of my patient,” she says. “At the end of the day, the vital signs are something that physicians have been using similarly for hundreds of years … I do think it’s a little bold to start adding things to it.” 

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