Key result
During general anesthesia, pNN50 was not correlated with high-frequency power (r = 0.096, P = 0.392), indicating it cannot reliably reflect cardiac vagal tone in anesthetized patients.
Why the study?
Relatively little was known about the validity of the pNN50 heart rate variability statistic during general anesthesia.
Does general anesthesia alter the validity of pNN50 as a measure of cardiac vagal activity in patients without autonomic nervous system diseases?
Observational (n=80)
No
Does general anesthesia alter the validity of pNN50 as a measure of cardiac vagal activity in patients without autonomic nervous system diseases?
The pNN50 statistic does not accurately reflect cardiac vagal tone during general anesthesia, suggesting alternative HRV parameters or thresholds (e.g., <47 ms) should be used in anesthetized patients.
Answers are grounded in this paper and cite their sources.
pNN50 loses correlation with HF power under anesthesia; leaves open whether alternative pNN thresholds better index vagal tone in this population.
Objectives 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). Results All HRV variables were significantly decreased during GA. HF power was not correlated with pNN50 during GA (r = 0.096, P = 0.392). Less than pNN47 was shown to have a correlation with other variables. Conclusions These data suggest that pNN50 can not reflect the level of vagal tone during GA.
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Lee et al. (2018) conducted an observational in General anesthesia (n=80). General anesthesia (sevoflurane) vs. Before anesthesia (awake state) was evaluated on Correlation between high frequency (HF) power and pNN50 during general anesthesia (r = 0.096, p=0.392). During general anesthesia, pNN50 was not correlated with high-frequency power (r = 0.096, P = 0.392), indicating it cannot reliably reflect cardiac vagal tone in anesthetized patients.
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