Traumatic brain injury (TBI) is one of the leading causes of death and disability worldwide, and it represents a global health concern and financial burden [1, 2]. The main causes of early death in trauma victims are acidosis, hypothermia and coagulopathy, which are related to each other and influence each other. Thus, this vicious circle is often referred to as the  trauma triangle of death  [3, 4]. Trauma-induced coagulopathy manifests as a state of hypercoagulopathy trending towards thrombosis [5] and a state of hypocoagulopathy with progressive intracranial hemorrhage and increased systemic bleeding [6, 7].~There are many studies continuously proving that trauma-induced coagulopathy is common in traumatic brain injury patients [8-10] and the incidence of coagulation disorders has great heterogeneity, ranging from 7% to 54% [11, 12]. Reasons that cause this variation include the different techniques and definitions used, the heterogeneity of the patients and the various testing times [13]. Secondary coagulopathy after traumatic brain injury represent an important factor for unfavorable prognosis [14, 15], resulting in a nine-fold higher risk of death and a 30-fold higher risk of poor prognosis than in TBI patients without secondary coagulation disorder [7, 9, 16]. Mortality in TBI patients with coagulopathy is also highly heterogeneous, ranging from 22% to 66% [17, 18]. TBI patients with coagulopathy tend to suffer from delayed or progressive intracranial hemorrhage, as well as from microvascular thrombosis [19, 20].~Many retrospective and observational studies have focused on coagulation upon admission or the presence of any coagulation disorders during the whole period of hospitalization [21, 22]. A multicenter study described the course of coagulopathy in patients with isolated TBI, and associated it with CT characteristics and outcomes [15]. The previous study mostly focused on the coagulopathy on admission, while the association between coagulopathy in perioperative period and long-term survival of TBI patients has not been explored. It is important to explore this relationship because many TBI patients require surgical treatment, and it has been well established that the surgical intervention have an impact on the coagulation functions. We therefore investigated for the first time whether coagulopathy during the perioperative period, with the use of coagulation function tests performed before the operation and on the first day after the operation, was related to the long-term survival of these patients. Furthermore, we investigated the predisposing risk factors that may cause coagulopathy in the perioperative period, to the extent that these risk factors could be controlled and managed for avoiding coagulopathy.
The purpose of this study was to identify the relationship between coagulopathy during the perioperative period (before the operation and on the first day after the operation) and the long-term survival of traumatic brain injury patients undergoing surgery, as well as to explore the predisposing risk factors that may cause perioperative coagulopathy.