Sepsis: Your Triage

This is part one in a three-part series regarding sepsis. Sepsis is one of the most common life-threatening diagnoses made in the emergency department. It's more common than (and causes more mortality than) STEMI or stroke, and yet, even with the intensive surviving sepsis campaign recommendations and core measures, we still have a lot of options when we consider the evaluation, diagnosis, and management of our septic patients.

Choices with evaluation:

Since 1992, sepsis has defined as "SIRS (> 2 positive) + evidence of infection." This has long been a slightly confusing definition because many of the features of SIRS are indicative of infection (temperature, elevated white blood cell count). Nonetheless, SIRS has long been held as the bastion of high sensitivity sepsis diagnosis (sensitivity 94.5%, specificity crap). Severe sepsis was thus appropriately defined as SIRS + infection + end organ dysfunction.

SIRS:

T > 38 or <36

HR > 90

RR > 20 or PaCO2 < 32

WBC > 12 or < 4

In 2016, these terms were redefined with "Sepsis 3." SIRS + infection was dropped as the definition of sepsis, and "severe sepsis" as a term was discarded completely. Based on these new criteria, infection + end organ dysfunction is now sepsis, and this is codified by an increase of 2 or more points on the SOFA score.

SOFA:

To have a SOFA score of zero, your patient must have:

Platelets > 150K

GCS = 15

Bilirubin < 1.2

MAP > 70

Creatinine < 1.2

PaO2/FiO2 > 400

A SOFA score increase of > 2 from baseline with a suspected infection indicates sepsis, and the points increase in a graded fashion for each of these lab values/physical exam findings.

But as you can see, these requirements are not helpful for emergency department or EMS screening. Labs can be either impossible (in the setting of field medicine) or laborious and take forever, so the QSOFA score was developed to use as a possible screening tool to help decide whether or not a patient is at risk for sepsis.

QSOFA:

GCS < 15

RR > 22

SBP < 100

As it turns out, SOFA > SIRS > qSOFA for identifying mortality. But QSOFA is not a good screening tool for sepsis. Its sensitivity is only 54%. So even though the current Sepsis 3 guidelines recommend QSOFA use, CMS and emergency departments in general are sticking to SIRS, as imperfect as it may be in terms of sensitivity.

When using these diagnostic criteria, regardless of which one you choose, don't forget that your measurements may be faulty. In tachypneic patients, triage nurses are 38% sensitive and 84% specific in the detection of tachypnea. Electronic measurement of respiratory rate is no better, about 40% sensitive and 86% specific in the measurement of tachypnea. Physicians are just as bad, unless measuring the respiratory rate over a minute. So don't use gestalt here, yours or anyone else's.

Temperature measurement is just as problematic. 20-30% of elderly patients won't mount a fever in the setting of sepsis. Even if truly febrile, a normal oral temperature might not catch it. Compared to central thermometers, the pooled specificity of peripheral thermometers is 96%. The bad news is that the sensitivity is only 64%. Of these, the axillary temperature is particularly insensitive (14-63%).

References:

Seymour CW, Rea TD, Kahn JM, et al. Severe sepsis in pre-hospital emergency care: Analysis of incidence, care, and outcome. Am J Respir Crit Care Med. 2012;186(12):1264–1271.

Benjamin EJ et al. Heart Disease and Stroke statistics-2017 Update: A report from the American Heart Association. Circulation. 2017 Mar 7;135(10).

Hayder S et al. Comparison of QSOFA and SIRS criteria screening mechanisms for emergency department sepsis. Am J Emerg Med. 2017 Nas ov;35(11):1730-1733

Philip KE et al. The accuracy of respiratory rate assessment by doctors in a London teaching hospital: a cross-sectional study. J Clin Monit Comput 2015 Aug;29(4):455-60.

Lovett PB et al. The vexatious vital: neither clinical measurements by nurses nor an electronic monitor provides accurate measurements of respiratory rate in triage. Ann Emerg Med. 2005 Jan;45(1):68-76

Niven DJ et al. Accuracy of Peripheral Thermometers for Estimating Temperature. A Systematic Review and Meta-analysis. Ann Intern Med. 2015 Nov 17;163(10)768-77.

DeWitt S, Chavez SA, Perkins J, Long B, Koyfman A. Evaluation of fever in the emergency department. Am J Emerg Med. 2017 Nov;35(11):1755-1758.