Platelet morphological indices on Intensive Care Unit admission predict mortality in septic but not in non-septic patients.

BACKGROUND: Thrombocytopenia is associated with worse outcomes in critically ill patients. The clinical relevance of other platelets indices is less studied. We investigated the ability of the platelets distribution width (PDW) and the mean platelet volume (MPV) to predict mortality in critically ill patients. We hypothesized that the prognostic values of PDW and MPV could be different in septic and non-septic patients. METHODS: We prospectively analyzed patients with an expected ICU length of stay ≥48 hours. Repeated measurements of PDW and MPV were considered (on ICU admission and up to day 5 thereafter). The primary outcome was to investigate the ability of PDW and MPV to predict 90-day mortality in septic and non-septic patients. RESULTS: We included in the study 234 patients of which 31% patients were septic. 90-day mortality was 39% in septic and 27% non-septic patients. PDW and MPV values on admission were 12.5±2.5% and 10.7±1.1 fL, respectively. The AUROC of PDW values on admission to predict 90-day mortality in septic patients was 0.813, being higher than those in non-septic patients (0.550, P<0.001). Similarly, the AUROC for MPV in septic patients was higher than non-septic patients (0.55, P<0.001). The combined analysis of platelets morphological indices and lactate improved the predictive accuracy (PDW and lactate AUROC=0.870; MPV and lactate AUROC=0.867). CONCLUSIONS: Platelet morphological indices are independent predictor of 90-day mortality in septic patients but not in non-septic patients. A combined analysis of platelets morphological indices and lactate in septic patients resulted in improved prediction of mortality.

Using arterial-venous oxygen difference to guide red blood cell transfusion strategy.

BACKGROUND: Guidelines recommend a restrictive red blood cell transfusion strategy based on hemoglobin (Hb) concentrations in critically ill patients. We hypothesized that the arterial-venous oxygen difference (A-V O2diff), a surrogate for the oxygen delivery to consumption ratio, could provide a more personalized approach to identify patients who may benefit from transfusion. METHODS: A prospective observational study including 177 non-bleeding adult patients with a Hb concentration of 7.0-10.0 g/dL within 72 h after ICU admission. The A-V O2diff, central venous oxygen saturation (ScvO2), and oxygen extraction ratio (O2ER) were noted when a patient's Hb was first within this range. Transfusion decisions were made by the treating physician according to institutional policy. We used the median A-V O2diff value in the study cohort (3.7 mL) to classify the transfusion strategy in each patient as "appropriate" (patient transfused when the A-V O2diff > 3.7 mL or not transfused when the A-V O2diff ≤ 3.7 mL) or "inappropriate" (patient transfused when the A-V O2diff ≤ 3.7 mL or not transfused when the A-V O2diff > 3.7 mL). The primary outcome was 90-day mortality. RESULTS: Patients managed with an "appropriate" strategy had lower mortality rates (23/96 [24%] vs. 36/81 [44%]; p = 0.004), and an "appropriate" strategy was independently associated with reduced mortality (hazard ratio [HR] 0.51 [95% CI 0.30-0.89], p = 0.01). There was a trend to less acute kidney injury with the "appropriate" than with the "inappropriate" strategy (13% vs. 26%, p = 0.06), and the Sequential Organ Failure Assessment (SOFA) score decreased more rapidly (p = 0.01). The A-V O2diff, but not the ScvO2, predicted 90-day mortality in transfused (AUROC = 0.656) and non-transfused (AUROC = 0.630) patients with moderate accuracy. Using the ROC curve analysis, the best A-V O2diff cutoffs for predicting mortality were 3.6 mL in transfused and 3.5 mL in non-transfused patients. CONCLUSIONS: In anemic, non-bleeding critically ill patients, transfusion may be associated with lower 90-day mortality and morbidity in patients with higher A-V O2diff. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03767127. Retrospectively registered on 6 December 2018.