Low central venous saturation predicts poor outcome in patients with brain injury after major trauma: A prospective observational study

Background. Continuous monitoring of central venous oxygen saturation (ScvO2) has been proposed as a prognostic indicator in several pathological conditions, including cardiac diseases, sepsis, trauma. To our knowledge, no studies have evaluated ScvO2 in polytraumatized patients with brain injury so far. Thus, the aim of the present study was to assess the prognostic role of ScvO2 monitoring during first 24 hours after trauma in this patients' population. Methods. This prospective, non-controlled study, carried out between April 2006 and March 2008, was performed in a higher level Trauma Center in Florence (Italy). In the study period, 121 patients affected by major brain injury after major trauma were recruited. Inclusion criteria were: 1. Glasgow Coma Scale (GCS) score 13; 2. an Injury Severity Score (ISS) 15. Exclusion criteria included: 1. pregnancy; 2. age <14 years; 3. isolated head trauma; 4. death within the first 24 hours from the event; 5. the lack of ScvO2 monitoring within 2 hours from the trauma. Demographic and clinical data were collected, including Abbreviated Injury Scale (AIS), Injury Severity Score (ISS), Simplified Acute Physiologic Score II (SAPS II), Marshall score. The worst values of lactate and ScvO2 within the first 24 hours from trauma, ICU length of stay (LOS), and 28-day mortality were recorded. Results. Patients who deceased within 28 days showed higher age (53 16.6 vs 43.8 19.6, P = 0.043), ISS core (39.3 14 vs 30.3 10.1, P <0.001), AIS score for head/neck (4.5 0.7 vs 3.4 1.2, P = 0.001), SAPS II score (51.3 14.1 vs 42.5 15, P = 0.014), Marshall Score (3.5 0.7 vs 2.3 0.7, P <0.001) and arterial lactate concentration (3.3 1.8 vs 6.7 4.2, P <0.001), than survived patients, whereas ScvO2 resulted significantly lower (66.7% 11.9 vs 70.1% 8.9 vs, respectively; P = 0.046). Patients with ScvO2 values 65% also showed higher 28-days mortality rate (31.3% vs 13.5%, P = 0.034), ICU LOS (28.5 15.2 vs 16.6 13.8, P <0.001), and total hospital LOS (45.1 20.8 vs 33.2 24, P = 0.046) than patients with ScvO2 > 65%. Conclusion. ScvO2 value less than 65%, measured in the first 24 hours after admission in patients with major trauma and head injury, was associated with higher mortality and prolonged hospitalization.