Utilization of Brain Tissue Oxygenation Monitoring and Association with Mortality Following Severe Traumatic Brain Injury.

BACKGROUND: The aim of this study was to describe the utilization patterns of brain tissue oxygen (PbtO2) monitoring following severe traumatic brain injury (TBI) and determine associations with mortality, health care use, and pulmonary toxicity. METHODS: We conducted a retrospective cohort study of patients from United States trauma centers participating in the American College of Surgeons National Trauma Databank between 2008 and 2016. We examined patients with severe TBI (defined by admission Glasgow Coma Scale score ≤ 8) over the age of 18 years who survived more than 24 h from admission and required intracranial pressure (ICP) monitoring. The primary exposure was PbtO2 monitor placement. The primary outcome was hospital mortality, defined as death during the hospitalization or discharge to hospice. Secondary outcomes were examined to determine the association of PbtO2 monitoring with health care use and pulmonary toxicity and included the following: (1) intensive care unit length of stay, (2) hospital length of stay, and (3) development of acute respiratory distress syndrome (ARDS). Regression analysis was used to assess differences in outcomes between patients exposed to PbtO2 monitor placement and those without exposure by using propensity weighting to address selection bias due to the nonrandom allocation of treatment groups and patient dropout. RESULTS: A total of 35,501 patients underwent placement of an ICP monitor. There were 1,346 (3.8%) patients who also underwent PbtO2 monitor placement, with significant variation regarding calendar year and hospital. Patients who underwent placement of a PbtO2 monitor had a crude in-hospital mortality of 31.1%, compared with 33.5% in patients who only underwent placement of an ICP monitor (adjusted risk ratio 0.84, 95% confidence interval 0.76-0.93). The development of the ARDS was comparable between patients who underwent placement of a PbtO2 monitor and patients who only underwent placement of an ICP monitor (9.2% vs. 9.8%, adjusted risk ratio 0.89, 95% confidence interval 0.73-1.09). CONCLUSIONS: PbtO2 monitor utilization varied widely throughout the study period by calendar year and hospital. PbtO2 monitoring in addition to ICP monitoring, compared with ICP monitoring alone, was associated with a decreased in-hospital mortality, a longer length of stay, and a similar risk of ARDS. These findings provide further guidance for clinicians caring for patients with severe TBI while awaiting completion of further randomized controlled trials.

Surfactants influence polymer nanoparticle fate within the brain.

Drug delivery to the brain is limited by poor penetration of pharmaceutical agents across the blood-brain barrier (BBB), within the brain parenchyma, and into specific cells of interest. Nanotechnology can overcome these barriers, but its ability to do so is dependent on nanoparticle physicochemical properties including surface chemistry. Surface chemistry can be determined by a number of factors, including by the presence of stabilizing surfactant molecules introduced during the formulation process. Nanoparticles coated with poloxamer 188 (F68), poloxamer 407 (F127), and polysorbate 80 (P80) have demonstrated uptake in BBB endothelial cells and enhanced accumulation within the brain. However, the impact of surfactants on nanoparticle fate, and specifically on brain extracellular diffusion or intracellular targeting, must be better understood to design nanotherapeutics to efficiently overcome drug delivery barriers in the brain. Here, we evaluated the effect of the biocompatible and commonly used surfactants cholic acid (CHA), F68, F127, P80, and poly (vinyl alcohol) (PVA) on poly (lactic-co-glycolic acid)-poly (ethylene glycol) (PLGA-PEG) nanoparticle transport to and within the brain. The inclusion of these surfactant molecules decreases diffusive ability through brain tissue, reflecting the surfactant's role in encouraging cellular interaction at short length and time scales. After in vivo administration, PLGA-PEG/P80 nanoparticles demonstrated enhanced penetration across the BBB and subsequent internalization within neurons and microglia. Surfactants incorporated into the formulation of PLGA-PEG nanoparticles therefore represent an important design parameter for controlling nanoparticle fate within the brain.