Heart rate variability analysis as a possible predictor of perioperative risk in patients undergoing general surgery

In spite of all advances made in medicine, the perioperative environment remains a high-risk environment for patients. Perioperative organ injury, including mainly cardiovascular complications, is a major threat and often only detected at a later stage. Cardiovascular risk assessment, executed before surgery, translates into the need for advanced monitoring in high-risk patients. Evidence reveals that a comprised autonomic nervous system (ANS) has a strong correlation with cardiovascular events. Therefore it could be useful to assess ANS activity in the perioperative period as a risk indicator. The purpose of the present study was to observe if patients in high-risk groups (with American Society of Anesthesiologists (ASA) score above 1) show different patterns in their perioperative ANS activity, accessed by heart rate variability (HRV) analysis, than patients with low risk (ASA score of 1). Results show that the general course was the same for all risk groups, with a HRV decrease during anesthesia followed by an increase in the recovery period. However, the high frequency power of patients with ASA=1 seemed to be elevated in the post-anesthesia care unit, suggesting a higher parasympathetic activity during recovery than in patients with ASA > 1. Although a difference in HRV could be observed between low-risk and high-risk patients, the HRV was not sufficient as input for a classification algorithm. For a more detailed evaluation in the future, more patients need to be studied with the aim to identify if ANS monitoring may suit a novel surrogate marker for risk-assessment inthe perioperative period.