Investigating Occupational Stress in ICU Nurses: A Comparative Analysis of Mental and Physical Stress Using Heart Rate Variability and Wrist-Worn Accelerometer Data

Objective: This study examined a novel method to differentiate between mental and physical stress using Baevsky’s Enhanced Stress Technique. Background: Occupational stress events, whether mental or physical, are handled by the sympathetic and parasympathetic nervous systems, which have been shown to be associated with heart rate variability (HRV), but have not been previously differentiated. Method: Naturalistic HRV and accelerometer data were measured continuously using wrist-worn sensors during a typical 12-h direct-care nursing shift (28 ICU nurses). Physical and mental stress events were calculated using the Baevsky’s Stress Index, and Activity Index was used to investigate their differences between mental and combined mental and physical stress. Results: Root mean square of successive differences between heartbeats (RMSSD), which is associated with the parasympathetic nervous system activity as well as low-frequency power/high-frequency power (LF/HF ratio), and the alpha value of detrended fluctuation analysis (DFA a2), which are associated with the balance between sympathetic and parasympathetic nervous system activity, were the most predictive features of stress events (accounting for AUC of 85.46). Conclusion: Baevsky’s Enhanced Stress Technique shows promise in assessing occupational mental stress among ICU nurses. There were more persistent and significant physiological changes in HRV associated with combined mental and physical stress events. Application: Findings suggest a new stress measurement method for classifying occupational mental stress. Measurement using wrist-worn accelerometer and HRV data sources has pragmatic relevance to the design of real-time, noninvasive, and cost-efficient stress monitoring tools relevant to applications in high-stress work environments.