Abstract
Purpose: The High Frequency Variability Index (HFVI) is purported to assess the balance between nociception and analgesia in patients under general anesthesia. This prospective observational study investigated whether intraoperative HFVI correlates with postoperative pain in patients performed with nerve block under general anesthesia in video/robotic-assisted thoracoscopic surgery (VATS/RATS).
Methods: We investigated whether maximum postoperative pain at rest and postoperative morphine consumption are associated with HFVI just before extubation, mean HFVI during anesthesia, the difference in HFVI between before and 5 min after the start of surgery, and the difference in HFVI between before and 5 min after the nerve block.
Results: Data obtained from 48 patients were analyzed. We found no significant association between HFVI just before extubation and postoperative Numerical Rating Scale (NRS) score. Receiver operating characteristic curve analysis revealed that moderate (NRS > 3) or severe (NRS > 7) postoperative pain could not be predicted by HFVI just before extubation. In addition, there were no associations between postoperative morphine consumption and HFVI at any time points.
Conclusions: The present study demonstrated that it is difficult to predict the degree of postoperative pain in patients undergoing VATS/RATS under general anesthesia combined with peripheral nerve block, by using HFVI obtained at multiple time points during general anesthesia.