Trajectories of early secondary insults correlate to outcomes of traumatic brain injury: results from a large, single centre, observational study

Background: Secondary insults (SI), such as hypotension, hypoxia, and intracranial hypertension frequently occur after traumatic brain injury (TBI), and have a strong impact on patients' clinical outcomes. The aim of this study is to examine the trajectories of SI from the early phase of injury in the prehospital setting to hospital admission in a cohort of TBI patients. Methods: This is a retrospective, observational, single centre study on consecutive patients admitted from 1997 to 2016 to the Neuro Intensive Care Unit (NICU) at San Gerardo Hospital, in Monza, Italy. Trajectories of SI from the prehospital to hospital settings were defined as "sustained", "resolved", "new event", and "none". Univariate and multivariate logistic regression analyses were performed to correlate SI trajectories to a 6-months outcome. Results: Nine hundred sixty-seven patients were enrolled in the final analysis. About 20% had hypoxic or hypotensive events and 30.7% of patients had pupillary abnormalities. Hypotension and hypoxia were associated with an unfavourable outcome when "sustained" and "resolved", while pupillary abnormalities were associated with a poor outcome when "sustained" and as "new events". After adjusting for confounding factors, 6-month mortality strongly correlated with "sustained" hypotension (OR 11.25, 95% CI, 3.52-35.99), "sustained" pupillary abnormalities (OR 2.8, 95% CI, 1.51-5.2) and "new event" pupillary abnormalities (OR 2.8, 95% CI, 1.16-6.76). Conclusions: After TBI, sustained hypotension and pupillary abnormalities are important determinants for patients' outcomes. Early trajectories define the dynamics of SI and contribute to a better understanding of how early recognition and treatments in emergency settings could impact on 6-month outcomes and mortality.