Analysis of heart rate variability (HRV) has been used as a measure of cardiac autonomic function. According to the pNN50 statistic, the percentage of differences between successive normal RR intervals (RRI) that exceed 50 ms, has been known to reflect cardiac vagal modulation. Relatively little is known about the validity of pNN50 during general anesthesia (GA). Therefore, we evaluated the correlation of pNN50 with other variables such as HF, RMSSD, SD1 of HRV reflecting the vagal tone, and examined the validity of pNN50 in anesthetized patients. Methods: We assessed changes in RRI, pNN50, root mean square of successive differences of RRI (RMSSD), high frequency (HF) and standard deviation 1 (SD1) of Poincaré plots after GA using sevoflurane anesthesia. We also calculated the probability distributions for the family of pNNx statistics (x: 2-50 ms).
All HRV variables were significantly decreased during GA. HF power was not correlated with pNN50 during GA (r = 0.096,
These data suggest that pNN50 can not reflect the level of vagal tone during GA.
The irritable bowel syndrome(IBS) is a chronic functional gastrointestinal disorder, characterized by abdominal pain, bloating and bowel disturbance. The pathophysiology of IBS is very complicated. Recent studies indicate that the most important mechanisms include visceral hypersensitivity, abnormal gut motility, autonomic nervous system(ANS) dysfunction and disorder of regulation of the brain-gut axis. Patients with IBS frequently present impaired autonomic regulation. Heart rate variability(HRV) is an acknowledged tool for estimating autonomic function. We experienced two cases of increased parasympathetic nervous system by HRV in irritable bowel syndrome with diarrhea as a predominant symptom