| Abstract |
In the line of their duty, Emergency Medical Services (EMS) personnel are inevitably exposed to recurrent psychotraumatic stress elicited by their close contact with intense human suffering and death, and they are also at high risk to become victims of attacks, violence, and serious injury. As a consequence of encountering a multitude of potentially traumatic experiences on duty, EMS personnel exhibit a considerably elevated prevalence of serious mental and physical health problems, and, eventually, heightened rates of health-related job turnover and early retirement. Taking this in account, there is a huge need to develop measures that foster resilience among EMS personnel and enable them to maintain their overall well-being, health, and work ability in the long-term. Therefore, it is a prerequisite to characterise the precise origin and nature of traumatic stress in the EMS, and to identify resilience and vulnerability factors that influence the individual risk to develop negative trauma sequelae. For this purpose, an employee survey was conducted among the employees of two regional German Red Cross ambulance stations in Southern Germany. Cross-sectional data were collected from 115 EMS personnel, including (i) exposure to traumatic stress at work, in private life, and during their childhood; (ii) perceived work-related stress; (iii) current mental and physical stress symptoms; as well as individual differences in (iv) emotion regulation and (v) sense of coherence. In addition, participants agreed to donate 1 cm hair strands to analyse markers of the endocrine stress regulation. Based on these data, this thesis characterised the nature of traumatic mission incidents (Study I) and investigated possible influences on the mental and physical health status of EMS personnel on multiple levels. These included the role of child maltreatment (CM) in lowering the resilience against traumatic stress in later life (Study II), endocrine factors that possibly mediate the development of trauma-related health problems (Study III), and individual differences among EMS personnel in coping with traumatic stress (Study IV and V). In detail, Study I scrutinised the nature of psychotraumatic stress in the EMS. Content-analytical and correlational methods revealed that traumatic rescue missions are constituted of a chain of critical circumstances, including (i) hazards and injuries for the EMS personnel's individual health and safety, and circumstances that increase the personnel's risk (ii) to lose their professional detachment from patients and (iii) intense emotional distress during and after missions. Based on this, Study I proposed a provisional measure to quantify the cumulative exposure to potentially traumatic mission event types in the EMS. From a biographic perspective, Study II investigated whether CM is associated with a lower resilience to occupational trauma exposure among EMS personnel. Assuming the same degree of occupational trauma exposure in their line of duty, linear moderation analyses indicated that the higher the severity of CM, the more mental and physical stress symptoms EMS personnel exhibited. This observation emphasises the need to consider CM as a lifetime vulnerability factor in occupational health promotion. Exposure to traumatic stress during childhood as well as in later life can exert persistent alterations on various biological levels. Those are considered to act as a pathway translating the negative sequelae of traumatic stress on the mental and physical health across lifetime. Study III was the first study examining hair-based markers of alterations in the co-regulation of the hypothalamic-pituitary-adrenal cortex axis along with the endocannabinoid system in a stress- and trauma-exposed cohort. A total of 72 hair samples from EMS personnel were analysed with respect to the glucocorticosteroid cortisol and the endocannabinoids anandamide (AEA), 2-arachidonoylglycerol (2-AG), N-oleoylethanolamide (OEA), N-stearoylethanolamide (SEA), and N-palmitoylethanolamide (PEA). In line with the established perspective of hair cortisol as a marker of ongoing stress and shift work, EMS personnel with higher quantitative workload exhibited higher cortisol concentrations. Moreover, higher endocannabinoid levels were linked to higher CM severity and more severe depressive and physical stress symptoms. These findings underpin previous results suggesting the endocannabinoid system to be involved in mediating CM-related lifetime vulnerability for trauma-related mental and physical health problems. In Study IV and V, this thesis investigated individual differences in handling traumatic experiences and related intense emotional distress among EMS personnel. Examining the emotion-regulation style, Study IV showed that EMS personnel used adaptive strategies (i.e. problem-solving, reappraisal, and acceptance) more often than maladaptive strategies (i.e. suppression, avoidance, and rumination). In accordance with meta-analytical findings, the maladaptive emotion-regulation strategies were consistently associated with more severe mental and physical health problems. Conversely, the two adaptive strategies, reappraisal and problem-solving, featured no beneficial associations with mental and physical health. Solely, higher habitual use of emotional acceptance went along with less posttraumatic, depressive, and physical stress symptoms among EMS personnel. Overall, the findings of Study IV underscore that future research and practice need to consider the context-specific adaptiveness of emotion regulation in occupational contexts with specific regulatory demands such as trauma-focused professions. Study V focussed on the revised sense of coherence as a potential resilience factor for the health of EMS personnel. The concept refers to an individual's conviction of being able to handle life's challenges coupled with the metacognitive inclination to recognise and experience the coexistence of positive and negative life experiences as balanced. Contrary to the expectation, the association of a stronger sense of coherence with better mental and physical health was only due to higher manageability convictions, but not due to the individual inclination to reflect on and experience the balance of positive and negative aspects in life. Taken together, the results of Study IV and V imply that enhancing EMS personnel's medical action and emotion-regulation competences could increase their mental preparedness to cope better with critical rescue missions, and, thus, their risk of traumatisation and compromised well-being, health, and work ability may be reduced. In conclusion, the present thesis contributed to advance the qualitative understanding of the nature of psychotraumatic stress in the EMS and provided further insights into the role of biographic, endocrine, and coping-related factors influencing the risk for negative trauma sequelae. Replication studies are needed to validate the thesis' findings in representative samples with longitudinal designs, and, furthermore, to fathom the physiological mechanisms underlying symptom development. Complementing its findings, this thesis summarised the current knowledge about trauma-focused occupational health promotion in the EMS with the aim to allocate future efforts in research and practice on promising prevention paradigms. Prospectively, future research needs to aim at developing and rigorously testing preventive interventions to enhance the EMS personnel's resilience against psychotraumatic stress in the line of their duty. - Contents: (1) https://doi.org/10.3389/fpsyg.2019.02305 (2) https://doi.org/10.1016/j.chiabu.2019.104248 (3) https://doi.org/10.1038/s41598-020-79859-x (4) https://doi.org/10.3389/fpsyg.2018.02744 (5) https://doi.org/10.1080/20008198.2019.1606628 .
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