Continuous HRV analysis of HEMS emergency physicians to specify the work load over the different working days

Heart rate variability and perception of mental stress among medical students and residents at an emergency department

BACKGROUND

When Medical Residents (MR) and Medical Students (MS) are assigned to the demanding environment of an Emergency they inevitably encounter stress. The aims of this study are to measure short-term heart rate variability (HRV) before and after shifts, estimate perceived stress levels, and assess the recovery patterns after their shifts.

METHODS

We assessed HRV parameters in MS and MR using the wristband physiological monitor Polar® Verify Sense before and after day (DS) and night shifts (NS). Perceived stress levels were evaluated using the simplified State Trait Anxiety Inventory (STAI-S6) and the Subjective Units of Distress Scale.

RESULTS

This study included 60 participants of which 55% were female with a mean age of 26 years. MS presented significant reduction in sympathetic nervous system index after DS [0.68 (0.01-2.42) vs -0.22 (-0.75-1.13), p < 0.01] and NS [0.87 (-0.28-1.45) vs 0.06 (-0.70-1.04), p < 0.01], while MR maintained the same levels of sympathetic activity [DS: 1.17 (0.04 -2.88) vs 0.93 (0.50-1.41), p = 0.14; NS: 1.37 (0.76-2.21) vs 1.29 (0.35-2.18), p = 0.40]. Psychological data from STAI-S6 showed statistically significant differences when comparing before and after DS in both groups, with more perceived stress after than before DS (MS: 12 ± 4 vs 14 ± 4, p = 0.04; MR: 14 ± 4 vs 16 ± 4, p = 0.04), which was not observed at NS (MS: 12 ± 3 vs 12 ± 3, p = 0.84; MR: 15 ± 3 vs 15 ± 4, p = 0.40).

CONCLUSIONS

Short-term HRV recordings before and after day or night shifts among MR and MS revealed heightened sympathetic activity preceding each shift, with a more sustained increase observed in the MR population and more perceived stress after day shifts in both groups.

Heart Rate Variability: A Measure of Cardiovascular Health and Possible Therapeutic Target in Dysautonomic Mental and Neurological Disorders

Mental illness such as depression and anxiety as well as cerebrovascular disease are linked to impairment of neurocardiac function mediated by changes to the autonomic nervous system with increased sympathetic and decreased parasympathetic activity. Autonomic neurocardiac function can be evaluated by computing heart rate variability (HRV). Over the past decades, research has demonstrated the diagnostic value of HRV as independent predictor of cardiovascular mortality and as disease marker in progressive autonomic nervous system disorders such as Parkinson’s disease. Here we summarize our studies on HRV and its therapeutic modulation in the context of psychopharmacology as well as psychiatric and neurological disorders to honor the life of Professor Evgeny Vaschillo, the true pioneer of HRV research who sadly passed away on November 21st, 2020.

Continuous HRV analysis of HEMS emergency physicians to specify the work load over the different working days

INTRODUCTION

Up to date, there has been little research about the acute stress load of emergency physicians of the Helicopter Emergency Medical Service (HEMS). Therefore, this study investigates the physiological stress level between an air-rescue day, a clinic day, and a day off (control day). Furthermore, phases of activity and resting were compared to assess the activity of the autonomic nervous system (ANS).

METHODS

In this field study (within-subjects design), heart rate variability (HRV) and self-perceived stress levels were monitored on an air-rescue day, a clinic day, and a control day of 20 HEMS EPs [three females, 17 males; age: mean (M) = 44.95, standard deviation (SD) = 4.80].

RESULTS

When comparing the activity phases, significant differences were found for HR and HRV. The highest HR was found on the air-rescue day during the phase of landing at the operation site with M = 107.30 bpm (SD = 22.66 bpm), which was significantly higher than during activity phases of the clinic day (M = 88.28 bpm, SD = 11.81 bpm) and the control day (M = 83.28 bpm, SD = 14.83 bpm). The SDNN is significantly higher on the air-rescue day for the phase before the alarm (M = 72.23 ms, SD = 38.60 ms), the phase of the alarm (M = 77.52 ms, SD = 40.52 ms), and the average of all phases (M = 60.04 ms, SD = 34.07 ms) than on the clinic day (M = 38.42 ms, SD = 15.16 ms) and the control day, where the lowest value was reached (M = 39.11 ms, SD = 17.65 ms). The highest LF/HF was found during activity phases of the clinic day with M = 1281.84% (SD = 587.33%), which was significantly higher than the first five phases of the emergency operations and the average of all phases of the emergency operations of the air-rescue day, where a maximum of M = 896.57 ms (SD = 681.79 ms) during the phase before the alarm and a minimum of M = 764.69 ms (SD = 372.28 ms) during the phase of landing at the operation site. The lowest LF/HF for all testing days was found during the activity phases of the control day with M = 693.74% (SD = 404.73%). Overall, 60 observations were analyzed. In the psychological assessment, on average, the EPs shows lower values than the norm sample.

DISCUSSION

In the comparison of the activity phases, significant effects were found on the clinic day and during the phases of the emergency operations of the air-rescue day for the HR and HRV. Hereby, a significant activation of the EPs ANS and an outweigh of the sympathetic nervous system could be shown, whereby the subjective stress load was reported mainly as low. For the resting phases, no significant differences were found between all testing days. We interpret this as a good sign for the ability of regeneration between the phases of high stress load.