Does Pre-Operative Vagal Activity Predict Clinical Outcomes after Total Knee Replacement?
2Social Welfare and Health Studies, Haifa University, Israel
Background:
Total knee replacement surgery (TKR) is surgical procedure carries with it significant surgical trauma activating complex inflammatory pathways which assist post-surgical healing. However, impaired regulation of such inflammatory pathways may cause local tissue damage instead of healing, leading to complications such as: increased post-surgical pain, longer rehabilitation, delayed surgical wound healing, and increased risk of infection. Postoperative C-reactive protein (CRP) levels in serum show good correlation with surgical trauma and considered a parameter of postsurgical inflammatory response. Since inflammatory pathways are a delicate balance of pro and anti- inflammatory response, orchestrated by the cholinergic anti-inflammatory pathway of the vagus nerve, Synchronization between neurophysiological and peripheral disease markers has prognostic value. The vagus is the main branch of the parasympathetic nervous system innervating most internal organs. It is possible to induce its activity through the heart-rate variability (HRV), which is the change in normal cardiac inter-beat intervals and governed by vagal tone. Low HRV has shown to predict all-cause mortality with worse prognosis after myocardial infarctions, worse cancer prognosis and even some forms of psychopathology.
Methods:
In our department we developed a Matlab program to calculate HRV based on the R-R intervals in a 10 second E.C.G. Using the results we examined the relationships between pre-operative vagal activity and post-operative outcomes (complications, infections, inflammation indexed by C-reactive protein, monocytes and white blood cells levels and the post-surgery hospitalization) following TKR.
Results:
We show that higher pre-operative vagal tone (higher HRV) predicts better short-term recovery, reduced inflammation, indexed by C-reactive protein (CRP), shorter hospital stays and rehabilitation.
Conclusion:
We have shown that a patient`s pre-operative vagal tone can help predict short-term recovery, inflammatory response, hospital stays and rehabilitation. In the age of personalized medicine, the ability to predict such parameters can help guide a more personalized post-surgical plan.