Point-of-Care Analysis of Neutrophil Phenotypes: A First Step Toward Immuno-Based Precision Medicine in the Trauma ICU.

Objectives: The amount of tissue damage and the amplitude of the immune response after trauma are related to the development of infectious complications later on. Changes in the neutrophil compartment can be used as read out of the amplitude of the immune response after trauma. The study aim was to test whether 24/7 point-of-care analysis of neutrophil marker expression by automated flow cytometry can be achieved after trauma.

Design: A prospective cohort study was performed. Polytrauma patients who developed infectious complications were compared with polytrauma patients who did not develop infectious complications.

Setting: The study was performed in a level 1 trauma center.

Patients: All trauma patients presented in the trauma bay were included.

Interventions: An extra blood tube was drawn from all patients. Thereafter, a member of the trauma team placed the blood tube in the fully automated flow cytometer, which was located in the corner of the trauma room. Next, a modified and tailored protocol for this study was automatically performed.

Main Results: The trauma team was able to successfully start the point-of-care automated flow cytometry analysis in 156 of 164 patients, resulting in a 95% success rate. Polytrauma patients who developed infectious complications had a significantly higher %CD16/CD62L neutrophils compared with polytrauma patients who did not develop infectious complications ( = 0.002). Area under the curve value for %CD16/CD62L neutrophils is 0.90 (0.83-0.97).

Conclusions: This study showed the feasibility of the implementation of a fully automated point-of-care flow cytometry system for the characterization of the cellular innate immune response in trauma patients. This study supports the concept that the assessment of CD16/CD62L neutrophils can be used for early detection of patients at risk for infectious complications. Furthermore, this can be used as first step toward immuno-based precision medicine of polytrauma patients at the ICU.