Abstract
PURPOSE: The surgical operating room is a high-stakes environment where stress can impact performance and patient safety. While hormonal and neurophysiological markers are established stress indicators, integrative studies in real-world surgical settings are scarce. This study aimed to provide a comprehensive, multimodal characterization of stress in surgical teams during live operations, comparing neurophysiological, biological, and behavioral responses across different levels of expertise and surgical phases. The goal was to validate a multi-method approach and identify objective markers for monitoring stress in real-time. METHOD: Surgical teams, each composed of four members, were categorized as "Expert" or "Novice" based on the lead surgeon's experience. All teams performed a standardized inguinal hernia repair. Continuous electroencephalography (EEG) and electrodermal activity (EDA) were recorded throughout the procedure to derive stress indices. Blood samples were collected pre- and post-surgery to measure Adrenocorticotropic Hormone (ACTH) and cortisol levels. Subjective stress was assessed via questionnaires, and team performance was quantified using a Combined Behavioral Teamwork Index (CBTI) based on surgical time, materials used, and patient outcomes. FINDING: Neurophysiological data showed that the EEG-based stress index was significantly higher in Novice surgeons compared to Experts, particularly during the final and most demanding phase of the surgery (p = 0.008). This effect was most pronounced for the lead Novice surgeon (p = 0.01). Similarly, the EDA-based stress index was higher overall in Novices (p = 0.02). Post-surgery, ACTH levels increased significantly in Novices while decreasing in Experts (p = 0.008), indicating a sustained endocrine stress response in the less experienced group. Strong positive correlations were found between the EEG-stress index and both ACTH levels (R = 0.67) and subjective stress (R = 0.63), validating the multimodal assessment. CONCLUSION: This study demonstrates that a multimodal approach can effectively characterize stress dynamics in a real-world surgical environment. The EEG-derived metric emerged as the most sensitive indicator, capable of discriminating stress levels with high temporal and role-specific precision. Novice surgeons exhibit significantly greater neurophysiological and endocrine stress responses, underscoring the need for targeted support and advanced training protocols. These findings lay the groundwork for developing real-time, objective stress monitoring systems to enhance surgical performance, training, and patient safety.