ICU Utilisation in Polytrauma and Traumatic Brain Injury Patients in Switzerland – Temporal and Seasonal Variation by Injury Severity and Affected Body Region

National retrospective registry study based on the SGI Minimal Dataset (MDSi) describing the incidence, injury pattern, ICU resource utilisation and outcomes of adult polytrauma and traumatic brain injury patients (AIS head ≥ 3) admitted to Swiss ICUs between 2005 and 2024. Outcomes include nursing workload (NEMS), ventilation days, ICU-based surgical interventions, ICU and hospital length of stay and ICU mortality. Pre-specified hypotheses examine the impact of the 2011 Highly Specialised Medicine (HSM) centralisation of trauma care, the 2012 introduction of SwissDRG flat-rate reimbursement and the COVID-19 pandemic on resource use, injury patterns and outcomes.