Introduction
Traumatic brain injury (TBI) remains a challenging issue in critical care medicine due to its contribution to the majority of trauma-related deaths (1-3). TBI refers to non-congenital brain injury, initiated with focal or diffuse lesions at the time of the primary injury and possibly prolonged and exacerbated by a set of complex systemic and local events that results in secondary brain injury (4). The secondary injury is found to be promoted by several diverse etiologies, including metabolic changes, inflammation, ischemia, oedema, and excitotoxicity (5).
In the last two decades, investigators have made great progress in understanding the main mechanistic pathways linking inflammation to secondary brain injury after trauma (6). Post-traumatic neuroinflammation, the neurogenic inflammation following TBI, is primarily developed by several extracellular and intracellular signalling pathways and is found to be a key contributor to secondary injuries (4, 7). TBI also initiates systemic inflammatory response syndrome (SIRS), which is found to be a potential factor in raising the risk of nosocomial infection or multiple organ dysfunction (MOD) (8). SIRS score potentially predicts the length of hospital stay (LOS) and patients’ mortality (9). In the Intensive Care Unit (ICU), critically ill patients receive some supportive care, including nutritional support and mobilization in order to restore or maintain organ function. In critically ill TBI patients, early nutritional support via enteral route is of particular interest due to the enhanced neurological recovery, shortened LOS, and reduced mortality (10, 11).
Multiple lines of evidence have illustrated a direct correlation between certain dietary agents and reduced levels of inflammatory markers (12, 13). More specifically, providing ICU patients with immune-modulating nutrients (e.g., antioxidants, omega-3 fatty acids, glutamine, and arginine) not only prevents malnutrition, but also results in favourable alterations in inflammatory components, lipid profiles, antioxidant levels, intestinal microbial balance, and their acquired immune function (14-16). However, there is a scarcity of clinical knowledge about assessing the effect of antioxidant-rich enteral formulas on the clinical and biochemical outcomes of ICU patients. The Dietary inflammatory index (DII®) is a literature-derived tool, specifically developed to evaluate the inflammatory potential of food components on inflammatory biomarkers, such as C-reactive protein (CRP) (17). To our knowledge, there is no intervention study based on the DII score in critically ill TBI patients. Given that and due to the paucity of data on the effect of the DII score on metabolic and inflammatory responses in critically ill patients, this pilot study aimed to assess the effects of a low DII score enteral formula on metabolic and inflammatory factors of TBI patients admitted to ICU.