To study the impact of prehospital management duration by SMUR teams in the Essonne department (91) on early patient mortality (within 24 hours) and to analyze the procedures performed on scene.

The study hypothesis is that all-cause in-hospital mortality may be associated with the duration of prehospital care, with either a beneficial impact related to the performance of life-saving interventions or a negative impact due to prolonged time to access definitive treatment.

Identifying potential factors associated with prolonged prehospital management times could help define possible areas for improvement and future interventions.

Trauma is the leading cause of mortality among individuals aged 25-34 years, regardless of the mechanism of injury (road traffic accidents, falls from height, defenestration, ballistic or stab wounds, etc.).

More than 50% of trauma-related deaths occur within the first hour following injury, and over 80% occur within the first 24 hours.

Since the 1970s, the principle that definitive treatment should be initiated within one hour of the beginning of medical care for any life-threatening condition has been introduced. This concept, known as the "Golden Hour," has been applied in many fields, including trauma care, with the assumption that any delay is associated with decreased patient survival.

In the literature, prehospital time intervals do not consistently demonstrate a clear impact on mortality, with study results often being contradictory (1-11). A French study conducted within a SMUR-type system by Tobias Gauss in 2019 reported a significant linear increase in mortality associated with longer prehospital time (1).

In contrast, other American and European studies (3,7) did not find a significant association between prehospital care time and short- or long-term mortality, in healthcare systems that are not always comparable to the French SMUR model.

Overall, studies on this topic have yielded heterogeneous and sometimes conflicting results.

Nevertheless, these time intervals appear to play a more critical role in patients with penetrating trauma or with initial arterial hypotension.

The major challenge in the prehospital setting is therefore to rapidly identify patients for whom prolonged on-scene management would have a detrimental impact on survival.

The physician must then determine the optimal amount of time to spend at the scene during SMUR intervention, based on the risk-benefit balance for the patient.

Some patients will require longer prehospital management in order to perform life-saving procedures, whereas for others, for whom definitive treatment is exclusively hospital-based, any delay will be unacceptable.

Inclusion Criteria:

• Age ≥ 15 years (upper age limit for the pediatric population)
• Severe trauma, defined as any road traffic accident, defenestration, fall from a height greater than 3 meters, stab wound, or ballistic injury requiring medically supervised transport to one of the Level 1 trauma centers in the Île-de-France region
• Prehospital management provided by one of the SMUR teams in the Essonne department (91)

Exclusion Criteria:

• Patients declared dead at initial medical contact, without resuscitation initiated, or with resuscitation attempted and subsequently discontinued (non-return of spontaneous circulation)
• Secondary inter-hospital transfer from another hospital to a Level 1 trauma center
• Transport to a hospital for local computed tomography imaging only (without direct admission to a Level 1 trauma center)
• Cases regulated (dispatched) by emergency coordination centers other than the Essonne (91) medical dispatch center

Patients managed prehospital by a SMUR team from the Essonne department (91) and transported to a Level 1 trauma center according to the predefined inclusion criteria