The aim of this study was to analyse modification in the autonomic stress response of last year physiotherapy students in an OSCE composed of 12-scenario randomly assigned to students. The first hypothesis was confirmed because stress response varied regarding OSCE station complexity and demands. The second hypothesis was not fulfilled since higher sympathetic response was not found in higher emotional scenarios.
We found a large anticipatory stress response of students as the low values in PNN50, RMSSD, SD1, SD2, HF and high LF values showed. This result was related to an increased sympathetic nervous system modulation due to the OSCE was perceived as unknown, uncertain, uncontrollable, and even threatening for students. Then, the OSCE produced an increase in the sympathetic modulation that mobilize organic resources to prepare students to face the novel and uncontrollable situations of the OSCE. In the present study the OSCE is a mandatory event to their academic grades, what can act as a stressor for students. Moreover, it was the first OSCE experience for the students. The same autonomic response has been previously studied in other educational context, as final degree dissertation or clinical stays and in stressful environments like military combat training, parachute jumps or extreme sport events as ultra-endurance races [28,29,30,31]. In these eliciting environments an increased sympathetic response was also evaluated, highlighting the universal stress response of human body to face threats, independently of the nature of the stimuli [14, 32, 33].
As the three HRV domains used showed, a maintained sympathetic modulation was observed during the whole OSCE. The no reduction in the anxiogenic response could be explained because students had no experience in this type of clinical evaluation which is a novel, incontrollable and unpredictable environment for them. On this point, it is interesting to remark that the analysed OSCE had been only used once, in the previous academic year. There have not been new stations added or modified scenarios. Moreover, in contrast with other OSCE in physiotherapy in the world, in our study students face a higher number of stations and taps in every aspect of practice (musculoskeletal, respiratory, neuromuscular and obstetrics) . This lack of habituation response was also evaluated in other challenging education contexts as nursing students during an OSCE, pharmacy students in real chemistry laboratory practices and physiotherapy students in the defence of their final degree dissertation [15, 16, 35].
Although this sympathetic modulation is maintained, the HRV analysed showed a different autonomic stress response depending on the nature of the scenario and regardless the order of appearance in the OSCE. In our initial hypothesis students would present a higher sympathetic response in the scenarios that had a higher emotional impact: S7 (ICU patient), S8 (neurological patient) and S11 (urogynaecology patient with a companion). Contrary to our hypothesis results showed how the most stressful scenarios were S1 (red flags), S2 (physical examination) and S3 (modifying the treatment). In this regard, it is important to highlight that the sequence of scenarios is different for each student. The three of them have in common that students face simulated patients (actors), in contexts deeply linked to the basic underpinning physiotherapy profession in which the clinical reasoning and decision-making skills are essential. This could explain why the ICU station (S7) initially considered as high emotional impact scenario presented a lower sympathetic modulation as it uses a mannequin instead of an actor, what could decrease authenticity of setting and context . Even though in S8 and S11 students face patients, these scenarios demand communication and treatment skills over the clinical reasoning or decision making. This difference in difficulty and stress perception between students and teachers facing an OSCE evaluation have already been studied in previous studies .
The S1, the red flags station, was the most stressful situation evaluated in the OSCE. Specifically, PNN50 presented significantly lower values in S1, compared with S5, S6, S7, S8, S9, S10, S11 and S12. This scenario requires from the student to detect red flags what means being vigilant to signs and symptoms that can be medical emergency or are suggestive of sinister pathology. It requires dexterity in clinical reasoning, one of the most difficult skills to develop in the Physiotherapy curriculum. By contrary, the lower sympathetic response was found in S11 as show high values in every HRV parameters, even higher than in the resting scenarios (break). It is a communication station in which students interview an urogynaecology patient with a companion. The fact of interacting with 2 actors do not increase the stress response as expected, what could be justified by the fact that urogynaecology is a minority physiotherapy specialty that could be considered less useful in their future profession . Besides that, communication skills are trained in depth during the whole programme, through simulated scenarios and clinical practices what could also explain these results. The sympathetic modulation was maintained even in the resting scenarios, S6 and S11. As in previous research , the recovery scenarios were not enough to elicit a situation of calm and relaxation to decrease the anxiogenic response, increasing the sympathetic modulation and a new anticipatory anxiety response. Moreover, during these scenarios students sat waiting in a corridor surrounded by examiners what could increase the stress.
Interaction among examiners and students have been highlighted as stressor by previous studies [7, 19] using indirect tools (surveys) to examine stress. According to our HRV results, this could explain the high stress response in the non-interactive written scenarios (S4 and S9) in which students do not interact with patients but only with examiners. In addition, the demands in those scenarios requires higher level cognitive processes to access the information (analysing, evaluating, and creating) that could be negatively affected by the sympathetic modulation what could increase the anxiogenic response .
To summarize main findings, we can highlight that we found a large anticipatory stress response of undergraduate physiotherapy students and a maintained sympathetic modulation during the whole OSCE. Students undertook the OSCE for the first time what could explain the lack of habituation response.
The HRV analysed showed a different autonomic stress response depending on the nature and contents of the scenario and regardless their individual order of appearance in the OSCE:
The use of HRV to analyse autonomic stress response is a novel tool and it was applied to different stressful scenarios as sport, military, health and academics [22, 24, 25, 37, 38]. In this line, depending on the context and participants evaluated, different sensitivity to identify the autonomic response of the different HRV analysis domains were found. In the present research the HRV parameters sensitive to identify the autonomic modulation were related to the time domain (PNN50 and RMSSD) and nonlinear domain (SD1 and SD2). This result was in concordance with other studies conducted with physiotherapy students in their clinical practice . However, in other research with psychology students, it was found how the sensitive HRV parameters to identify the autonomic modulation were PNN50, RMSSD, SD1, SD2, and HF . In sport context, the sensitive parameters were the PNN50, RMSSD, and HF. It can be observed the impact on the context, the characteristics of the sample and the evaluation period on the HRV parameters´ sensitivity to identify autonomic modulation . More research is needed to better understand the HRV modifications in different contexts and populations.
The autonomic response is directly associated with variations in HRV parameters that are objectively measurable. The use of instruments to measure HRV in real time during OSCE could be a useful and valid tool to help teachers to understand and evaluate the complexity of the different scenarios designed in the OSCE evaluation. The stress response monitoring allows teachers to design OSCE scenarios more adapted to the students, limiting the effect of the stress response to allow a better performance. Patient interaction, authenticity of setting and professional contexts should be carefully monitored to vary the difficulty or complexity of stations. Students can benefit from the use of these instruments to obtain an objective measure of their stress level to use strategies to cope and reduce stress and improve cognitive functioning.
Limitations and future research lines
The principal limitation of the present study was the non-control of stress hormones such as cortisol and alpha amylase. Future research might seek to address these issues. It would be also interesting to analyse other variables that could modulate the stress response of students such as the psychological profile to develop coping strategies for those less adaptative profiles [40, 41].