SAN DIEGO – The product of compared with the quick Sequential Organ Failure Assessment prompt, a small, single-center study showed.
“We know a lot about the pathophysiology of sepsis, but we don’t have great ways of identifying septic patients at an early stage,” lead study author David Lynch, MD, said in an interview at an international conference of the American Thoracic Society.
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Dr. David Lynch
He noted that screening tools such as the quick Sequential Organ Failure Assessment and Systemic Inflammatory Response Syndrome criteria have a sensitivity of about 70% in detecting sepsis. “Over the last 10-15 years we’ve been able to find ways of improving outcomes in patients whom we confirm are septic with early antibiotics and fluids,” said Dr. Lynch, a second-year resident in the division of pulmonary and critical care medicine within the department of medicine at the University of North Carolina at Chapel Hill. “We know that in sepsis, systemic vascular resistance is decreased and cardiac output is increased. We tried to come up with a way of estimating cardiac output at the bedside by multiplying heart rate with pulse pressure, with the pulse pressure being the surrogate for stroke volume, which you can measure easily.”
In a cross-sectional, observational study, Dr. Lynch, senior author Thomas Bice, MD, and their associates reviewed the records of 116 patients who were admitted directly to the University of North Carolina’s medical ICU (MICU) from the UNC ED between Jan. 5, 2016, and June 30, 2017. The primary outcome of interest was culture-positive sepsis, and the primary exposure was the product of pulse pressure and heart rate. Patients were determined to be positive for sepsis if an infection was suspected (such as if blood cultures were drawn and antibiotics were started), the admitting physician suspected sepsis, and cultures were subsequently positive.
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The average age of all patients was 53 years, 51% were female, the mortality rate was 12%, and the median length of stay was 4 days. A total of 25 of the 116 patients (22%) were positive for sepsis. The researchers observed that the pulse pressure multiplied by the heart rate was significantly higher in the culture-positive sepsis group, compared with controls (6,710 vs. 3,741, respectively; P less than .001).
Dr. Lynch and his associates found that, as a continuous variable, pulse pressure multiplied by the heart rate accurately classified 90% of sepsis cases (area under the receiver operator curve, 0.96; P less than .001). When using 5,000 as a cutoff, pulse pressure multiplied by the heart rate had a sensitivity of 100% and a specificity of 89% in detecting culture-positive sepsis. “We were surprised by how high the sensitivity was,” Dr. Lynch said. “The question is, will this translate to a larger cohort? And, would this be transferable to all patients in the ED, as opposed to the sicker patients who are going to the MICU?”
He and his associates plan to confirm the study’s results in a broader population of patients. “We don’t yet understand at what point in time this would be most applicable,” he added. “We looked at the first set of vitals when they came into the ED. We’d like to know if that applies to the second, third and fourth set of vitals, and whether it would be most useful to have an average of those.”
The study was supported in part by a grant from the National Institutes of Health. Dr. Lynch reported having no financial disclosures.
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