Heart rate variability as a tool to follow the effect of music on stress-relieving in patients under anaesthesia: Data from a clinical study

The aim of the current study was to explore the effect of music on reducing stress during surgery under anesthesia, while utilizing heart rate variability (HRV) as a noninvasive measurement of stress-related physiological changes. HRV is related to the sympathetic and parasympathetic activity of the autonomic nervous system. The HRV data in our study was obtained from 10 patients who underwent an abdominal (n=5) or orthopedic fracture surgery (n=5) under general (n=5) or spinal anesthesia (n=5). Relaxation music was played to the patients during the anesthesia. Percentage of normalized high frequency (HF) of the HRV was calculated from the sum of HF and low frequency (LF). The music elicited an increase in the mean normalized HF during the music period compared to the period before the music was played, which was also statistically significant (P=0.035). A slight increase in the mean normalized HF was noted when it was measured during the whole anesthesia ± music” compared with the mean normalized HF before music (P=0.063). Thus, the data clearly demonstrate that music played during an operation induced an increase in the mean normalized HF data, thereby activating the parasympathetic nervous system and inactivating the sympathetic nervous system, resulting in relaxation.