Changes in novel haematological parameters following thermal injury: A prospective observational cohort study

The mortality caused by sepsis is high following thermal injury. Diagnosis is difficult due to the ongoing systemic inflammatory response. Previous studies suggest that cellular parameters may show promise as diagnostic markers of sepsis. The aim of this study was to evaluate the effect of thermal injury on novel haematological parameters and to study their association with clinical outcomes. Haematological analysis was performed using a Sysmex XN-1000 analyser on blood samples acquired on the day of the thermal injury to 12 months post-injury in 39 patients (15-95% TBSA). Platelet counts had a nadir at day 3 followed by a rebound thrombocytosis at day 21, with nadir values significantly lower in septic patients. Measurements of extended neutrophil parameters (NEUT-Y and NEUT-RI) demonstrated that septic patients had significantly higher levels of neutrophil nucleic acid content. A combination of platelet impedance count (PLT-I) and NEUT-Y at day 3 post-injury exhibited good discriminatory power for the identifying septic patients (AUROC = 0.915, 95% CI [0.827, 1.000]). Importantly, the model had improved performance when adjusted for mortality with an AUROC of 0.974 (0.931, 1.000). A combination of PLT-I and NEUT-Y show potential for the early diagnosis of sepsis post-burn injury. Importantly, these tests can be performed rapidly and require a small volume of whole blood highlighting their potential utility in clinical practice.