Given that it is difficult to measure the RR accurately in the prehospital stage, the pulse oximeter has been used as an objective tool to measure hypoxic status in diverse clinical settings, oxygen saturation reflects the patient’s respiratory function more objectively and efficiently. Third, RR has been used as a physiologic indicator to assess the severity of trauma. Thus, assessing hypoxia and hypotension is essential during prehospital care to predict outcome. If combined, hypoxia and hypotension increased the risk of mortality by 6.1-fold. Prehospital hypotension in TBI patients causes a 2.5-fold increase in mortality, and hypoxia results in a 3.0-fold increase.

Hypotension before emergency department arrival has a linear correlation with mortality. Second, hypoxia or hypotension during prehospital transport was included in the models as they have been shown to cause worse clinical outcomes such as mortality in recent studies. Moreover, the logistic model showed a more linear relationship with the outcome. First, we replaced the GCS with the motor GCS, which has been shown to have a predictive power equivalent to that of total GCS in previous research. Thus, to improve ease of use and discriminative power, we developed an NTS-TBI. However, some variables in the RTS are not easily available in the field. RTS has been used to predict outcomes for trauma patients, and the components of RTS are included in the first step of assessment in the field triage scheme. Briefly, the GOS is a global scale used to assess functional outcome the score ranges from 1 to 5, with 1 indicating dead 2, vegetative state 3, severely disabled, dependent for daily support due to mental or physical disability, or both 4, moderately disabled, able to work in a sheltered environment, and travel by public transportation and 5, good recovery, resumption of normal life. The exclusion criteria were as follows: (1) severe disability before the accident (2) unknown or missing information on the variables in the NTS-TBI model, including SBP, RR, motor GCS, and age and (3) a Glasgow Outcome Scale (GOS) of 2 or 3 before the injury. We excluded patients who had prehospital traumatic arrest or those with non-traumatic injury.

The Abbreviated Injury Scale is a scoring system to measure the severity of injury for six body parts independently and is used for calculating Injury Severity Score. TBI was defined as a head injury according to the Abbreviated Injury Scale. Among those enrolled in the EMS-ST-DB in 20, patients older than 18 years with TBI were included in the study.

Glasgow coma scale score sheet