Preoperative vagal activity predicts clinical outcomes after total knee replacement

Total knee replacement (TKR) surgery carries with it significant surgical trauma and activates complex inflammatory pathways, which initially assist healing. However, impaired regulation of inflammatory pathways can cause tissue damage and postoperative complications. The vagus nerve regulates inflammation, the activity of which is indexed by heart-rate variability (HRV), which predicts postoperative pain, longer hospitalization and improved recovery during the postoperative period. The present study examined the relationship between presurgical HRV, inflammation and complications after TKR. The present study assessed data from 41 patients undergoing TKR. A retrospective design was used, where preoperative electrocardiograms were scanned to determine HRV. Outcome measures included inflammation [C-reactive protein (CRP) levels] over four postoperative days, length of stay (LOS), and complications. Preoperative HRV predicted the trajectory of postoperative CRP levels. The low HRV group demonstrated higher overall postoperative CRP and a longer time to recover than patients with high HRV. Furthermore, the magnitude of inflammatory decline between postoperative days two and four was associated with LOS. However, HRV did not predict postoperative complications. In conclusion, patients with lower presurgical vagal activity had a worse postoperative inflammatory profile than those with high vagal tone. In the age of personalized medicine, such findings may have implications for identifying and preparing patients before surgery.