Shock is the leading cause of death in multi-trauma patients and must be detected at an early stage to improve prognosis. Many parameters are used to predict clinical condition and outcome in trauma. Computed tomography (CT) signs of hypovolemic shock in trauma patients are not clear yet, requiring further research. The flatness index of inferior vena cava (IVC) is a helpful method for this purpose.

This is a prospective, cross-sectional study which included adult multi-trauma patients (>18 years) who were admitted to the emergency department (ED) and underwent a thoraco-abdominal CT from 2017 through 2018. The main objective of this study was to investigate whether the flatness index of IVC can be used to determine the hypovolemic shock at an early stage in multi-trauma patients, and to establish its relations with shock parameters. The patients’ demographic features, trauma mechanisms, vitals, laboratory values, shock parameters, and clinical outcome within 24 hours of admission were recorded.

Total of 327 (229 males with an average age of 40.9 [SD = 7.93]) patients were included in the study. There was no significant difference in the flatness index of IVC within genders (P = .134) and trauma mechanisms (P = .701); however, the flatness index of IVC was significantly higher in hypotensive (systolic blood pressure [SBP] ≤90 mmHg and/or diastolic blood pressure [DBP] ≤60 mmHg; P = .015 and P = .019), tachycardic (P = .049), and hypoxic (SpO2 ≤%94; P <.001) patients. The flatness index of IVC was also higher in patients with lactate ≥ 2mmol/l (P = .043) and patients with Class III hemorrhage (P = .003). A positive correlation was determined between lactate level and the flatness index of IVC; a negative correlation was found between Glasgow Coma Scale (GCS) and Revised Trauma Score (RTS) with the flatness index of IVC (for each of them, P <.05).

The flatness index of IVC may be a useful method to determine the hypovolemic shock at an early stage in multi-trauma patients.