Postoperative stress assessment using PPG-based heart rate variability and exploratory ECG analysis in colorectal surgery

Heart rate variability (HRV) reflects autonomic nervous system (ANS) activity. HRV has been shown to be associated with physiological stress response to surgery. This study aimed to evaluate perioperative changes in PPG- and ECG-based derived HRV following colorectal surgery, with a primary focus on postsurgical stress and an exploratory assessment of postoperative complications. Patients undergoing minimally invasive colorectal surgery for colorectal malignancy or benign disease were recruited. In the final analysis, pre- and postoperative HRV measurements were obtained using PPG in 20 patients. Furthermore, 36 patients were monitored using a Holter ECG device for 2 postoperative days. HRV parameters from linear and nonlinear domains were extracted and analyzed for each patient. Some HRV parameters derived from PPG reflected the impact of surgery on ANS function, showing significant differences between pre- and postoperative measurements (e.g. SDNN, SampEn, SNS index). While postoperative complications were not consistently captured by ECG-derived HRV measures due to the small sample size and short follow-up, some parameters demonstrated modestly different recovery patterns between patients with and without complications (e.g. HF power, DFA α2). PPG-based HRV is sensitive to postsurgical stress following colorectal surgery and can capture surgery-induced autonomic changes across multiple HRV parameters. However, the ability of ECG-based HRV to detect postoperative complications was found to be limited in this exploratory study. The study was not powered to evaluate the ability of HRV to detect postoperative complications, and larger studies with extended monitoring are required to confirm these findings.ClinicalTrials.gov Identifier NCT04996511