Clinical relevance of heart rate variability in anaesthesia

Heart Rate Variability (HRV) reflects the response of the heart to a variet y of influences and provides informations about sympathetic and parasympath etic influences affecting the cardiovascular system in the perioperative pe riod. However, because of the complexity of the autonomic control of the ca rdiovascular system the interpretation of HRV measurements needs caution. T he knowledge of the pathophysiology underlying HRV is critical in order to understand the state of the autonomic nervous system and its relevance for patient management. HRV seems to be a useful tool for preoperative cardiova scular risk stratification. Confounding effects of multiple factors influen cing HRV in the perioperative setting limit this methodology for example as a depth-of-anaesthesia monitor. Lack of standardization renders the comparison of results of different inve stigations difficult. Of major concern in this context is the quality of th e electrocardiogram recording when assessing HRV. Because of the ongoing pr ogress in monitoring with regard to acquisition and computer-based analysis of HRV data it seems at least possible to measure HRV routinely in the per ioperative setting. However, large prospective and standardized trials are necessary. Depending on the results the clinical relevance of HRV as a rela tively simple and noninvasive perioperative monitoring should be reevaluate d.