The primary purpose of our study was to evaluate the most common required surgical disciplines in trauma patients with indication for immediate surgery, and how this depends on hypotension on admission, in a German level 1 trauma centre.

Secondly, we wanted to assess the usage of damage control protocols in these selected trauma patients.

Thirdly, our aim was to analyse outcome (mortality) and possible differences between patients with no-shock (SBP > 90 mmHg) and shock (SBP < 90 mmHg) on admission.

We were able to show that abdominal surgery is the most common required discipline in patients with indication for immediate surgery, especially for haemorrhage in patients with shock. Other frequently needed surgical disciplines are neurosurgery (decreasing proportion in patients with hypotension on admission), thoracic surgery and vascular surgery.

To our knowledge, this is the first study with special focus on this topic. Our results, despite being obtained in a single centre with a relatively small patient cohort, may be relevant to optimize surgical staffing of level 1 trauma centres, particularly in the context of early subspecialisation in surgery. Since Germany and many other European countries do not have a trauma surgeon as a formal specialty, the treatment of severely injured patients is only possible as an interdisciplinary surgical approach. So which surgical disciplines do we really need for immediate interventions and potentially saving lives of those patients? And how is this affected by hypotension on admission as an indicator for shock? With this study, we presented an analysis to answer these important questions.

Abdominal, thoracic and vascular surgeons in Germany are mainly focused on elective and oncologic surgery. Based on the results of our study, the following implications arise: since these surgical disciplines most frequently perform immediate surgeries in trauma patients, they are encouraged to focus intensively on trauma, both theoretically and practically.

However, severe abdominal and thoracic trauma is relatively rare in absolute numbers in Germany. Thus, surgical skills from elective and oncologic surgery should be supplemented by trauma course formats to train specific procedures needed for trauma surgery.

In our cohort of trauma patients with immediate surgical interventions, the usage of damage control protocols was as high as 59%, even in patients with SBP > 90 mmHg on admission, and partially without any other triggers for damage control surgery (acidosis, coagulopathy, hypothermia). One possible reason for the very liberal usage may be that the surgical staff consists exclusively of military surgeons - and damage control principles are well known and trained with them. However, it was shown that overutilization of damage control surgery [28] and application of temporary abdominal closure [29] in patients without clear indications may be even harmful.

It should be noted that hypotension on admission is only a single parameter indicating shock in trauma patients. We did neither discriminate between volume responders and non-responders, nor did we take the use of catecholamines into account. However, hypotension on admission appears to be a parameter of high value in trauma patients, especially for rapid initial assessment of shock– as systolic blood pressure is very quick and easy to measure.

In our patients, hypotension on admission was associated with an increased mortality. Of note, there were further significant differences between the two groups, e.g., acidosis, coagulopathy and mass transfusion, each with a possible independent impact on mortality, as demonstrated before [8, 30].

Prolonged time to surgery may also influence mortality independently, especially in patients with shock. In stable trauma patients without shock, Harmsen et al. found no correlation between the on-site and prehospital time and the mortality rate [31].

Our study has several limitations. First, its retrospective nature has all known flaws and risks of bias. Secondly, the relatively small number of patients must be taken into account when the results are interpreted. For example, p values may not indicate differences that might have been found for a larger study cohort.

However, we focused exclusively on a very relevant subgroup of trauma patients with subsequent immediate surgery (with and without shock), and these patients are not very numerous, even in level 1 trauma centres.

Further studies are required to obtain more reliable results using multicentre data and a larger number of patients.