Objective: Oral anticoagulant (OAC) use increases the risk of death in conditions like hemorrhagic stroke, trauma, and traumatic brain injury. Early identification of OAC use is critical for timely interventions to mitigate hemorrhage risk and improve survival. We aimed to identify emergency medical services (EMS) care characteristics associated with patients using an OAC. Methods: We analyzed prehospital data (2018–2020) from the ESO Data Collaborative, focusing on adult (≥18 years) 911 EMS calls. The administered OACs were warfarin, dabigatran, rivaroxaban, and apixaban. We compared EMS call characteristics, patient demographics, response times, and interventions between OAC and non-OAC users. We used univariate logistic regression to identify independent predictors of OAC use. Results: Of 16,244,550 adult 911 EMS events, 906,575 involved OAC users (56 of 1,000 calls). Those using OAC were older (73.6 years vs. 56.9 years) and more often from nursing homes or long-term care facilities (17.0% vs. 9.2%) but less likely to have trauma (14.7% vs. 18.1%) or cardiac arrest (1.2% vs. 1.4%). The most common EMS primary clinical impressions for OAC users were chest pain (7.4%), altered mental status (7.3%), injury (6.5%), abdominal pain (4.3%), and brain injury (2.8%). Conclusion OAC users accounted for 1 in 18 adult EMS encounters. Specific patient and call characteristics were associated with OAC use. These findings should be incorporated into EMS training to facilitate recognition and appropriate management of OAC-related emergencies.

Objective To summarize the radiography ,CT and MRI findings of maxillary arteriovenous malformation (AVM ) . Methods Seventeen patients with maxillary AVM underwent panoramic radiography (3 patients) and enhanced MRI examination (6 patients) ,all the patient underwent enhanced CT examination .The clinical manifestation and imaging findings of maxillary AVM ,in‐cluding the location ,shape ,margin ,inner texture ,involvement of adjacent structures ,the density and signal intensity of the lesions , were analyzed .Results The lesions mainly located in molar areas (15/17) .The major clinical manifestation were repeated bleeding and acute bleeding .Other symptoms included swelling of the face ,pulsatile soft mass and anesthesia .The panoramic radiography only showed increased density .According to the change of the maxilla on enhanced CT images ,the lesions could be devided into two types :type Ⅰ ,showed intraosseous osteolytic destruction and cortical expansion (n=12);type Ⅱ ,showed“ground glass”appearance (n=5) .Bone destruction and soft tissue involvement ,widened feeding artery and draining veins ,elevated maxillary sinus were shown in all patients .External jugular vein enlargement and early enhancement (n=14) and root resorption (n= 6) were also detected . Flowing void on T1 and T2 weighted images (type Ⅰ) and hypo‐or isointense on T1WI ,hyperintense on T2WI and obvious enhance‐ment after injecting contrast material (type Ⅱ ) could observed .Conclusion Enhanced CT examination could be primarily recom‐mended and observe the extent of lesions and situation of vessels invaded of maxillary AVM .