Purpose A sentinel event is an unexpected occurrence resulting in death or serious physical or psychological injury or the risk thereof. The purpose of this paper is to investigate the influencing factors of sentinel events in the emergency department of a military hospital in Tehran to find out some of the effective solutions. Design/methodology/approach In this qualitative study with content analysis approach, 20 hospital healthcare personnel participated as participants from the fields of medicine and nursing. Purposive random sampling and semi-structured interviews were used for data collection. Atlas.ti software version 5.2 was used for data analysis. Findings Four themes and 32 subthemes were identified by numerous revisions and combining the codes. The four main themes of sentinel events were: causes, incidence barriers, cause prevention solutions, and barriers' improvement solutions. Moreover, these main factors were related to these issues: staff and patients' education, communication, assessment, patients and their companions, employee rights, leadership, care continuum, human factors, physical environment, information management and medication use. Some solutions were also suggested according to these factors and a policy was recommended. Practical implications Hospital managers and authorities should try to find the main causes of sentinel events by periodical analysis to find ways to prevent them in the future, using logical and reasonable solutions. Originality/value This study confirms that strategies to reduce the sentinel events in emergency departments should focus on empowerment of all staff.

<p><strong>INTRODUCTION: </strong>Increasing car accidents in young group and head-stroke mechanisms in developing countryis are the main cause of brain lesions and injuries related to trauma, so that traumatic severe brain lesions and injuries and uncontrollable hemorrhage are the major cause of mortality and morbidity due to trauma. Statistical analysis and factors along with main injuries can give us useful information in the field of injury management, patient dispatching management, proper scheduling, and patients dispatching to appropriate centers.</p><p><strong>MATERIALS &amp; METHODS: </strong>This research is a retrospective descriptive study with trend method in which data such as age, sex, mechanism of injury, severity of injuries, the kind of lesion, dispatching indications, patient accepting hospital, dispatching physician were extracted and analyzed by SPSS software in a five-year period from 2009-2013 using the files of patients referred to emergency department of Shahid Rajayi hospital of Gachsaran due to brain trauma.</p><p><strong>RESULTS: </strong>From total 760 patients, 455 People (9.67%) were male, and 215 (1.32%) were female. The highest rate of dispatching has been related to the year 2012 with 213 (3.18%) People. The most prevalent age group was 20 to 45 years old with 308 people dispatched. The most common type of traumatic mechanisms was due to bikes and cars injuries (79.7%) and then other various factors such as: falling from height (16.9%) and dispute and contention (3.4%). 66.9 percents of these injuries were slight. There was significant relationship between distribution of lesions severity resulted from trauma and the kind of injury mechanism (p&lt;0.0001).</p><p><strong>CONCLUSION: </strong>according to the fact that  brain trauma injuries are more prevalent in patients within young age group and these injuries may be duplicated due to patients transmission and dispatching on a long and high-risk way, so some measures should be taken to provide required medical facilities and equipments and human forces for urban area hospitals, in order to reduce injuries due to brain trauma which involves mostly the young people who consist the most active potential forces of are our society.</p>