• Child Health Nursing Research
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• v.15 no.3
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• pp.299-305
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• 2009

Purpose: Multiple studies have documented that high resting levels of cardiac vagal tone suggest higher levels of self-regulation. The aim of this study was to evaluate cardiac vagal tone as an indicator of autonomic nervous function in healthy newborn and premature infants. Methods: This study was conducted using a descriptive comparison design and a convenience sampling strategy. The participants were 72 healthy and 62 premature infants delivered in a university hospital. Continuous heart rate data recordings from the infant's ECG were analyzed and Mxedit software was used to calculate mean heart period and an index of cardiac vagal tone. Results: The healthy infants had significantly higher cardiac vagal tone than the premature infants, when the influence of gestational age was removed using analysis of covariance. However, there were no significant differences in heart rate and heart period between the two groups when the influence of gestational age was removed using analysis of covariance. Conclusion: The results of this study show that cardiac vagal tone may be used as an index for determining infant's autonomic nervous function. Nursing staff in pediatric departments can use cardiac vagal tone with ease, as this index can be calculated in a noninvasive method from the ECG.

• Kosin Medical Journal
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• v.33 no.3
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• pp.369-379
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• 2018

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 $Poincar{\acute{e}}$ 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.

• Journal of Life Science
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• v.34 no.5
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• pp.320-332
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• 2024

The aims of this study were to compare the differences in hemodynamics between cigarette smoking and using heated tobacco products (HTPs) and to determine the acute effects of using HTPs on cardiac autonomic regulation. Another goal was to examine the acute cardiac autonomic responses when using different tobacco sticks in HTPs. Sixteen healthy male smokers completed an open-label, randomized, crossover trial consisting of non-smoking (NS), cigarette smoking, and the use of two different HTPs (IQOS with HEETS; lil SOLID with Fiit). Sub-trials, which included NS, lil SOLID with Fiit, and lil SOLID with HEET, were performed on eight smokers among the total subjects. Hemodynamic variables, such as systolic blood pressure (SBP) and diastolic blood pressure (DBP), and heart rate variability were measured before, during, and 30 minutes after using each tobacco product. Using HTPs resulted in a significant increase in both SBP and DBP, comparable to smoking cigarettes. Cardiac sympathetic activity significantly increased, and cardiac vagal tone (CVT) significantly decreased after acute exposure to HTP aerosol, similar to the effects of cigarette smoke exposure. Furthermore, differences in the withdrawal of CVT were observed when using different tobacco sticks in the same HTPs. The findings of this study indicate that acute exposure to HTP aerosol increases the hemodynamic burden and disrupts cardiac autonomic balance, similar to exposure to cigarette smoke. Moreover, depending on the type of tobacco stick inserted into the HTP device, acute withdrawal of CVT may have been enhanced.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.91-95
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• 2001

In this study, we estimated the behavior of the diversity of physiological responses under varied physical environmental factors by measuring variations of heart rate variability (HRV), an index of activity of cardiac autonomic control. Seven healthy young male adults consented and participated in the study. The environmental conditions consisted of thermal, lighting, and acoustic conditions. Two components of HRV were measured. one was the low frequency (LF) component of HRV, which provided a quantitative index of the sympathetic and parasympathetic (vagal) activities controlling the heart rate (HR). The other component measured was the high frequency (HF) component, which provided an index of the vagal tone. The percent contribution of physical environmental factors to the variations in HRV indices were calculated by ANOVA. The contribution of physical environmental factors to the variations in HR was higher than the contribution of HF and LF. However, the contribution of these factors was lower than the contribution related with individual difference in all indices. This result showed that the individual diversity of physiological responses is not a negligible quantity.

• Nutrition Research and Practice
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• v.14 no.6
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• pp.606-620
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• 2020

BACKGROUND/OBJECTIVES: Although some juices affect subjective sleep quality, there is a lack of information on the effect of a specific juice on objective sleep quality and heart rate variability (HRV) during sleep; thus the present study investigated whether a blended juice made from natural extracts influenced sleep quality and HRV during sleep in adults with disturbed sleep. SUBJECTS/METHODS: A randomized, crossover study was conducted on twenty-five adults (15/10, female/male) complaining of difficulty initiating or maintaining nighttime sleep (Pittsburgh sleep quality index [PSQI] ≥ 5). During feeding sessions (FS), subjects received sleep-inducing juice made of natural ingredients (250 mL/trial) twice a day for 8 weeks or non-FS (N-FS) for 8 weeks while maintaining normal activities. Sleep quality and parameters were recorded via wearable actigraph for 7 consecutive days, and PSQI scores were assessed before and after the intervention. HRV was also monitored at rest and during sleep. RESULTS: After receiving the sleep-inducing juice intervention (FS), PSQI scores were significantly decreased (P < 0.001) and correlated with a significant decline in fatigue severity scale and visual analogue scale levels (P < 0.05; both). HRV indices of vagal activity were significantly improved during FS (P < 0.05), and no significant differences in N-FS were observed. Sleep efficiency and total sleep time increased significantly (P < 0.05) and sleep latency, total counts, sleep fragmentation index, and movement index, decreased significantly (P < 0.05, all 4) during FS, with no significant differences-observed during N-FS. CONCLUSIONS: This study results demonstrated that an 8-week course of sleep-inducing juice has led to improve sleep quality, suggesting an enhanced cardiac vagal tone during sleep. Thus, it could be a well-tolerated option for adults with disturbed sleep.

• Korean Journal of Acupuncture
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• v.24 no.4
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• pp.25-36
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• 2007

Objectives : Acupuncture restores the flow of vital energy in the body by stimulating the organ-specific meridians and enhances cardiac vagal activity and suppresses sympathetic activity. The purpose of this review is to summarize and evaluate the acupuncture studies on autonomic nervous system (ANS). Methods : We conducted a PubMed search to obtain a fair sample of acupuncture studies related ANS published in English in 2007. Each article was reviewed for study objectives and outcomes, as well as acupuncture points, experimental and control interventions. Results : We reviewed a total of 15 studies published from 1997 to 2007. In normal states, acupuncture enhanced either vagal or sympathetic tone depending on the stimulated acupuncture point sites. On the other hand, most of studies demonstrated that acupuncture restored the autonomic dysfunctions in various kinds of stressful states. Conclusions : We reviewed studies that contributed to an understanding of the autonomic mechanisms of acupuncture with the hope that this review will be of benefit to the future studies. Although the relationship between acupuncture and ANS response is still uncertain, acupuncture would be a noteworthy modality for modulating autonomic dysfunction.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.994-996
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• 1999

In this paper, we proposed complex demodulation method(CDM) to visualize the instantaneous frequency change of LF component and HF component of HRV signals, which represent the dynamics of sympathetic and parasympathetic (vagal) tone, respectively. As we know the range of the center frequencies of each autonomic tones, we could apply complex demodulation method. To simulate the heart rate variability signal, the IFPM model was adopted for generation of simulated cardiac event series. Then, we can visualize and access the dynamic changes of LF and HF component of autonomic tones in the time-frequency domain.

• Journal of Life Science
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• v.33 no.8
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• pp.639-650
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• 2023

The levels of harmful components in aerosols from heated tobacco products (HTPs) have been reported to be significantly lower than in cigarette smoke. However, it remains unclear whether the use of HTPs can mitigate the cardiovascular risks associated with cigarette smoking (CS). The objective of this study was to investigate the effects of a short-term switch from CS to HTP use on cardiac autonomic regulation (CAR). Seven healthy male smokers completed an open-label, randomized, cross-over trial consisting of five days of CS, use of three different HTPs (IQOS use, IQ; lil SOLID use, LS; lil HYBRID use, LH), or non-smoking (NS). Each session was separated by a one-week washout period, and levels of exhaled carbon monoxide (CO) and carboxyhemoglobin (COHb), systolic (SBP) and diastolic blood pressure (DBP), and heart rate variability (HRV) reflecting CAR were assessed before use of the product assigned to each session and at 24, 48, 72, 96, and 120 hr after use. Levels of exhaled CO and COHb were statistically significantly reduced only during NS. There were no statistical changes in SBP and DBP within any session. However, in HRV spectral analysis, log-transformed high frequency (lnHF) increased statistically significantly in IQ, LS, and NS, respectively. Normalized HF (HFnu) was significantly increased in NS and LH, respectively. lnHF and HFnu showed significant interaction effects. The findings of this study suggest that a short-term switch to HTPs instead of CS may lead to different distribution patterns of CAR, primarily driven by enhanced cardiac vagal tone.

• Tuberculosis and Respiratory Diseases
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• v.41 no.4
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• pp.379-388
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• 1994

Background : In sleep apnea syndrome, arterial oxygen saturation($SaO_2$) decreases at a variable rate and to a variable degree for a given apneic period from patient to patient, and various kinds of cardiac arrythmia are known to occur. Factors supposed to affect arterial oxygen desaturation during apnea are duration of apnea, lung voulume at which apnea occurs, and oxygen consumption rate of the subject. The lung serves as preferential oxygen source during apnea, and there have been many reports related with the influence of lung volume on $SaO_2$ during apnea, but there are few, if any, studies about the influence of oxygen consumption rate of an individual on $SaO_2$ during breath holding or about the profile of arterial oxygen resaturation after breathing resumed. Methods : To investigate the changes of $SaO_2$ and heart rate(HR) during breath holding(BH) and rebreathing(RB) and to evaluate the physiologic factors responsible for the changes, lung volume measurements, and arterial blood gas analyses were performed in 17 healthy subjects. Nasal airflow by thermistor, $SaO_2$ by pulse oxymeter and ECG tracing were recorded on Polygraph(TA 4000, Gould, U.S.A.) during voluntary BH & RB at total lung capacity(TLC), at functional residual capacity(FRC) and at residual volume(RV), respectively, for the study subjects. Each subject's basal metabolic rate(BMR) was assumed on Harris-Benedict equation. Results: The time needed for $SaO_2$ to drop 2% from the basal level during breath holding(T2%) were $70.1{\pm}14.2$ sec(mean${\pm}$standard deviation) at TLC, $44.0{\pm}11.6$ sec at FRC, and $33.2{\pm}11.1$ sec at RV(TLC vs. FRC, p<0.05; FRC vs. RV, p<0.05). On rebreathing after $SaO_2$ decreased 2%, further decrement in $SaO_2$ was observed and it was significantly greater at RV($4.3{\pm}2.1%$) than at TLC($1.4{\pm}1.0%$)(p<0.05) or at FRC($1.9{\pm}1.4%$)(p<0.05). The time required for $SaO_2$ to return to the basal level after RB(Tr) at TLC was not significantly different from those at FRC or at RV. T2% had no significant correlation either with lung volumes or with BMR respectively. On the other hand, T2% had significant correlation with TLC/BMR(r=0.693, p<0.01) and FRC/BMR (r=0.615, p<0.025) but not with RV/BMR(r=0.227, p>0.05). The differences between maximal and minimal HR(${\Delta}HR$) during the BH-RB manuever were $27.5{\pm}9.2/min$ at TLC, $26.4{\pm}14.0/min$ at RV, and $19.1{\pm}6.0/min$ at FRC which was significantly smaller than those at TLC(p<0.05) or at RV(p<0.05). The mean difference of 5 p-p intervals before and after RB were $0.8{\pm}0.10$ sec and $0.72{\pm}0.09$ sec at TLC(p<0.001), $0.82{\pm}0.11$ sec and $0.73{\pm}0.09$ sec at FRC(p<0.025), and $0.77{\pm}0.09$ sec and $0.72{\pm}0.09$ sec at RV(p<0.05). Conclusion Healthy subjects showed arterial desaturation of various rates and extent during breath holding at different lung volumes. When breath held at lung volume greater than FRC, the rate of arterial desaturation significantly correlated with lung volume/basal metabolic rate, but when breath held at RV, the rate of arterial desaturation did not correlate linearly with RV/BMR. Sinus arrythmias occurred during breath holding and rebreathing manuever irrespective of the size of the lung volume at which breath holding started, and the amount of change was smallest when breath held at FRC and the change in vagal tone induced by alteration in respiratory movement might be the major responsible factor for the sinus arrythmia.