This is the first study to describe the extent of staffing variety of trauma teams. We found a very high variation in trauma team staffing at our level one trauma center, which is incorporated in an academic teaching hospital. All 32 trauma teams demonstrated an unique composition and 101 unique members were identified of a trauma team. Thereby, we found that on average, two-thirds of the trauma team staffing rotated during the successive resuscitation. Within most academic hospitals, education of (para) medic personnel is common and rotation of residents, fellows and nurses is routine and occurs frequently. As many level one trauma centers are incorporated within academic teaching hospitals variation in trauma teams is likely to be common within trauma resuscitation in the emergency department. In the United States, approximately 75 percent of all level one trauma centers are incorporated in academic teaching hospitals .
Some recent studies found positive effects of familiarity of team members on teamwork, processes or patient care, which supports the reasoning that less variation in trauma team staffing may improve trauma care. First of all, Joshi et al.  investigated familiarity of team members on teamwork and clinical effectiveness during three simulated trauma scenarios. Teams whose staffing remained constant across the scenarios (stable teams) were compared to team whose staffing fluctuated with each scenario (dynamic teams). 46 trainees (23 General Surgery; 23 Emergency Medicine) were allocated into stable- or dynamic teams. The teamwork in both groups enhanced significantly, but the teamwork was more enhanced in the stable teams (stable: 9%, p < 0.04; dynamic = 4.9%, p < 0.03). Thereby, significant increased improvements in clinical effectiveness was only seen in the stable team. (stable: 15.2%; p = 0.03; dynamic 8.7% p = 0.19). A study of Powezka et al.  performed a retrospective analysis of 326 vascular procedures. They introduced the Familiarity Score, which yields the total of numbers of times each team member (vascular consultant, vascular registrar, scrub nurse, anesthetic consultant) had worked together, in the previous six months, divided by the number of possible combinations of pairs in the team. They found that the Familiarity Score was significantly associated with the length of the procedure (Bayes Factor= 37). Moreover, Krumann et al,  performed a retrospectively analysis on the effect of familiarity among team members on complication rates after elective open abdominal surgery. During a 6- month period a senior and junior surgeon performed all surgical interventions. The first and last month of this period where compared. A significant higher percentage of complications were found during the first period compared to the last period (54.2% vs. 34.5 %; P = 0.04), demonstrating familiarity may improve team performance and patient safety. Finally, Obermair and colleagues  evaluated impact of team familiarity in elective gynecological surgery on complications among 6,707 medical records. After surgery, the lead surgeon scored familiarity of the team using a five–point Likert scale which was documented at the operation report. In their analyses, after adjustment for ASA score and BMI, the likelihood of an adverse event was doubled in non-familiar teams compared to familiar teams (OR 2.06, 95%CI 1.20 to 3.55 p < 0.01). Moreover, in contrast to predictable circumstances during elective surgery or simulated environments, the circumstances during the resuscitations of severely injured patients are more stressful and less predictable, requiring highly adaptive teams. Therefore, extrapolating the findings of the discussed recent studies to actual trauma resuscitations, familiarity may enhance teamwork and team performance even more.
Although this study did not investigate the direct effects of familiarity within trauma teams on patient’s outcome, our findings emphasize the importance of non-technical abilities among team members and clear role assignments of the team members. Nontechnical skills such as communication, leadership, and teamwork are examples of nontechnical skills that are increasingly being recognized as key components of emergency resource management . Thereby, a clear task delineation is required as it is hard to collaborating together without fully understanding each other necessitates. Trauma team simulation training has been proven to increase nontechnical skill development . Furthermore, during simulation training, understanding of role assignment within trauma teams might be a trainable aspect. Therefore, regular trauma team training might reduce the negative effects of unfamiliarity of team members.
More research is required to gain insights into the nature and extend of trauma team staffing variations and the impact on patient care and patient outcomes. First of all, to obtain a general overview and to increase generalizability of our study results, our study should be replicated in multiple trauma centers. Second, there is evidence of previous studies that teamwork leads to improved performance . Therefore, we suggest investigating the impact of high variance in team staffing on teamwork. Future research projects, should an may further improve our understanding of the impact of the trauma team variation including clinical outcomes. The overall theory is that considerable variance in trauma team staffing leads to impaired teamwork, which in turn is thought to lead to deteriorated performance. In simplest form, the impact of team variance on teamwork could be assessed during simulation sessions to compare teams with no or little variance to high variance. There are reliable and validated tools available to assess the teamwork, such as the T-NOTECHS tool [22,23,24]. Third, interventions to effectively reduce team variation could be developed, tested and implemented into practice. We suggest two types of interventions to be investigated. First interventions that reduce team staffing variance and second, interventions that reduce negative effects of team staffing variance. An example how team variance could be reduced is by advanced scheduling systems. Coordination of having the similar staff occupation within teams is extremely challenging, as multiple (para)medical specialties are involved in the trauma team. A possible approach could be scheduling using advanced methods, such as deep learning techniques, as described by Rosemarin . Their supposed deep-learning scheduling system was able to schedule based on hospital’s data and specific goals, which among other goals, could be the reduction of trauma team staffing variance.
Strengths and limitations
The strength of this study was the use of video recordings of trauma resuscitations to analyze trauma team composition, which provides an unbiased, indisputable and accurate documentation of the trauma resuscitation. However, our study also has limitations that should be considered. This was a single-site study in a level one trauma center in an academic institution. The practices and policies at our institution may differ from other academic medical centers and even more from smaller non-academic hospitals. As such, the generalizability of our findings may be limited. Furthermore, we analyzed 32 trauma team activations, within a relative short time. Thereby, most of the trauma resuscitations were during day and evening time, and very few during the night. Therefore, our study populations was too small to perform additional analysis. Therefore, results should be considered as a rough estimation of the extent of staffing variation of trauma teams at our hospital. Nevertheless, we believe that our key finding, that there is a high variance team staffing, will not change with an larger study population. Thereby, theoretically, there shall even be more variations over longer periods, because of rotations of residents, vacations and new personnel during the year.