Development and Internal Validation of a Multimodal Prediction Score for Early Hemodynamic Deterioration in Adult Polytrauma Patients

• Age 18 years or older.
• Acute traumatic injury involving at least two distinct predefined major anatomical body regions.
• Presentation to the Emergency Department within 6 hours of injury.
• Injuries requiring hospital-level trauma evaluation or management (operational definition of polytrauma).
• Ability to obtain baseline predictor assessments (heart rate and systolic blood pressure for Shock Index, initial serum lactate, initial base deficit, and attempted point-of-care inferior vena cava ultrasound) as early as clinically feasible after ED arrival.
• Informed consent obtained according to institutional and ethical requirements (from the patient or legally authorized representative).
• Note: Hemodynamic stability at ED arrival is not required; patients presenting with hypotension (SBP \<90 mmHg), elevated Shock Index, or clinical shock remain eligible provided baseline predictor measurements can be obtained.

Exclusion Criteria:

• Isolated trauma involving only one anatomical body region.
• Age younger than 18 years.
• Pregnancy.
• Invasive mechanical ventilation initiated prior to baseline inferior vena cava (IVC) assessment.
• Known severe pre-existing cardiac dysfunction likely to substantially alter IVC respiratory dynamics (e.g., severe right heart failure, significant tricuspid regurgitation).
• Significant chronic hepatic dysfunction likely to substantially interfere with baseline serum lactate clearance and interpretation.
• Traumatic obstructive shock identified before baseline assessment (e.g., tension pneumothorax, cardiac tamponade) and resolved prior to obtaining measurements.
• Transfer from an outside facility following substantial resuscitation (prior blood-product administration, vasopressor therapy, emergent surgery, or interventional radiology).
• Inability to obtain baseline predictor measurements within the initial assessment window due to immediate priority of life-saving resuscitative procedures.
• Missing baseline clinical or laboratory parameters preventing calculation of the primary prediction model.
• Note: Inability to obtain an adequate IVC acoustic window alone is recorded as an ultrasound feasibility failure and does not exclude the patient.