(1459) Sepsis-Induced Immunosuppression: Evaluation of PCT and Delta SOFA After a Second Septic Hit Event

Introduction: Sepsis is characterized by an initial exaggerated inflammatory response, followed by a compensatory anti-inflammatory response syndrome. This phenomenon results in a reduced pro-inflammatory response upon a second infectious exposure (second hit). This study investigates the impact of the anti-inflammatory effect during the second hit, compared to the first hit, on procalcitonin (PCT) and Sequential Organ Failure Assessment (SOFA) score.

Methods: Retrospective cohort study on adult septic patients who experienced two septic events within 1 to 30 days in the ICU. Patients with fewer than 3 PCT determinations, and chronic infections (e.g., endocarditis), were excluded. Baseline and sepsis onset SOFA scores, as well as PCT values, were recorded. The primary outcome was to compare the peak and reduction over time of PCT in the first and second hits. Secondly, we compared delta SOFA (between the previous onset of infection and the day of diagnosis) in both infections. We performed a multilevel mixed effects model, adjusting for the site of infection, bacterial rescue, and creatinine clearance.

Results: During the fist hit 47% of patients had abdominal infections, and 40% had gram-negative rescues in biological samples. During the second hit, 30% had pneumonia, and 43% had gram-negative. The first hit exhibited a PCT peak of 42.12 pg/ml, while the second hit showed a significantly lower PCT peak in the adjusted model (coeff. -9.66 [95%CI -15/-4] pg/ml; p< 0.01). The daily PCT decrease during the first hit was -5 (95%CI -5.9/-4 pg/ml; p>0.01), whereas, during the second hit, it was -3.55 pg/ml per day (interaction term Second Hit*Days 1.45 [95%CI 5/2.8]; p=0.04). The delta SOFA for the first hit was 5 (SD 3), while for the second hit, it was 2.5 (SD 2.1) (coeff. second hit -2.53 [95% CI -2.75/-2.3]; p< 0.01).

Conclusions: The second infectious hit exhibits lower peak PCT and a slower decrease, and lower delta SOFA independently of the site of infection, bacterial rescue, and creatinine clearance. This minour inflammatory response may be due to the effect of immunosuppression during the second hit.