The most important and erroneously reported vital sign in medicine


What if I told you that the most important vital sign of the COVID-19 pandemic is likely being incorrectly reported in almost every doctor’s office, urgent care center, and hospital around the country?

The everyday citizen probably believes that this is an exaggeration, but most physicians know that this is unfortunately, accurate. Let’s step back a minute. Years ago, terms like sepsis, septicemia, and bacteremia were frequently used in an interchangeable and haphazard fashion, with very little consistency within the medical field and in the medical literature.  In the quest to more thoroughly define these terms, a campaign of critical care physicians was summoned, and multiple markers were identified as being important to diagnose disease: temperature, heart rate, white blood cell count, and respiratory rate. These four markers came to be known as SIRS criteria. SIRS, as we know, is an acronym that stands for severe inflammatory response syndrome. As a refresher, SIRS is defined by the satisfaction of any two of the following criteria:

  • Body temperature >38 or < 36 degrees Celsius.
  • Heart rate greater than 90 beats per minute
  • Respiratory rate greater than 20 breaths per minute or partial pressure of CO2 less than 32 mmHg
  • Leucocyte count greater than 12,000 or less than 4000 per microliter or over 10 percent immature bands

It follows that sepsis became defined as having any 2 SIRS criteria plus a documented or strong suspicion for the presence of a pathogen. From there, the terms severe sepsis, septic shock, and eventually, multiple organ dysfunction syndrome (MODS) were defined to describe worsening degrees of infection.

But there are caveats to the use of SIRS criteria to diagnose pathology. In the daily practice of medicine, many of us have observed that a patient can be sick and not meet SIRS criteria, or a patient can be healthy and meet multiple criteria. This has also been pointed out in the literature on the subject. In fact, a huge blow to the use of SIRS criteria as a means to define sepsis came by way of a study in 2015, which showed that out of 130,000 patients reviewed, over 12.5 percent (1 in 8) did not have 2 SIRS criteria.

So now we say OK, SIRS criteria is useful but not perfect. I mean let’s face it, what in medicine is ever perfect? These darn diseases refuse to read the textbooks, right? So from there, the search continued to identify useful markers of disease and disease severity. In 2016, the European Society of Intensive Care Medicine (ESICM) and the Society of Critical Care Medicine (SCCM) created a task force to try and identify a set of criteria with a higher predictive value for sepsis than SIRS. From this task force came qSOFA, which is defined as sequential organ failure assessment.

The 3 component assessment system of qSOFA  involves:

  • systolic blood pressure below 100 mmHg
  • highest respiratory rate exceeding 21
  • lowest Glasgow coma score under 15

Due to the use of vasopressors, ventilation machines, and medically induced comas,  it is obvious that qSOFA has little benefit in the ICU setting. However, where qSOFA appears to have the highest predictive value for sepsis, is in the non-ICU hospitalized setting, emergency room, and urgent care center.

Between SIRS criteria and qSOFA criteria, there is only one vital sign or marker that is shared between the two: respiratory rate. But the fact of the matter is, in most settings across the country, respiratory rate is a guess, an afterthought. It is almost always 14, 16, or 18. I can count on multiple hands how many times during residency, I was called to a patient’s room, and they were in respiratory distress, tachypneic to the 30s or 40s, and yet every documented vital sign input by the nurse was between 14 and 18. I doubt that any hospital is going to admit this because that would mean admitting that they have known inaccuracies in patient charts. But as physicians and nurses, we all know that this is what is happening.

So my ask to the entire medical community is that we all pay a little bit more attention to this seemingly insignificant, yet clearly important vital sign. In the setting of SARS-CoV-2, a virus that causes an upper respiratory infection that has led to a once in a generation global pandemic, one of the ways that patients are likely to present is with shortness of breath, which reflexively leads to an increased respiratory rate.  One of the simple ways that we as a community can make a difference during this pandemic is to enact policies in the primary care, urgent care, and hospital setting that mandate accurate documentation of this very important vital sign.

Robert Drummond is an urgent care physician.

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