A New Marker of Sepsis Post Burn Injury?

Abstract

Objectives: Accurate diagnosis of sepsis is difficult in patients post burn due to the large inflammatory response produced by the major insult. We aimed to estimate the values of serum N-terminal pro-B-type natriuretic peptide and procalcitonin and the changes in hemodynamic variables as markers of sepsis in critically ill burn patients. Design: Prospective, observational study. Setting: A quaternary-level university-affiliated ICU. Patients: Fifty-four patients with burns to total body surface area of greater than or equal to 15%, intubated with no previous cardiovascular comorbidities, were enrolled. Interventions: At admission, a FloTrac/Vigileo system was attached and daily blood samples taken from the arterial catheter. Infection surveillance was carried out daily with patients classified as septic/nonseptic according to American Burns Consensus criteria. Measurements and Main Results: N-terminal pro-B-type natriuretic peptide, procalcitonin, and waveform analysis of changes in stroke volume index and systemic vascular resistance index were measured within the first 24 hours after burn and daily thereafter for the length of the ICU stay or until their first episode of sepsis. Prevalences of stroke volume variation less than 12% (normovolemia) with hypotension (systolic blood pressure < 90?mm Hg) were recorded. Patients with sepsis differed significantly from "no sepsis" for N-terminal pro-B-type natriuretic peptide, systemic vascular resistance index, and stroke volume index on days 3-7. Procalcitonin did not differ between sepsis and "no sepsis" except for day 3. Area under the receiver operating characteristic curves showed excellent discriminative power for B-type natriuretic peptide (p = 0.001; 95% CI, 0.99-1.00), systemic vascular resistance index (p < 0.001; 95% CI, 0.97-0.99), and stroke volume index (p < 0.01; 95% CI, 0.96-0.99) in predicting sepsis but not for procalcitonin (not significant; 95% CI, 0.29-0.46). A chi-square crosstab found that there was no relationship between hypotension with normovolemia (stroke volume variation < 12%) and sepsis. Conclusions: Serum N-terminal pro-B-type natriuretic peptide levels and certain hemodynamic changes can be used as an early indicator of sepsis in patients with burn injury. Procalcitonin did not assist in the early diagnosis of sepsis.