The dose–response effects of terbutaline on the variability, approximate entropy and fractal dimension of heart rate and blood pressure
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To study the dose-response effects of intravenous terbutaline on the cardiovascular and respiratory autonomic nervous regulation.The study followed a randomized, placebo-controlled crossover design in six healthy adult volunteers. The terbutaline dose ranged from 10 to 30 microg min(-1) We continuously measured electrocardiogram, finger systolic arterial pressure (SAP) and flow-volume spirometry in supine and upright positions at baseline and during 3 h drug infusion. The periodic variability components of R-R intervals (time between successive heart beats) and SAP in relation to respiration were assessed using spectral analysis techniques. The regularity of the time series was assessed by approximate entropy (ApEn) and the convolutedness by fractal dimension (FD).Terbutaline dose-dependently decreased total variability of R-R intervals, low frequency (LF) variability of R-R intervals (10 s waves), high frequency (HF) variability of R-R intervals (respiratory variability), total variability of SAP, HF variability of SAP, baroreflex sensitivity, plasma potassium concentration, approximate entropy of R-R interval and of SAP as well as fractal dimension of R-R interval. Terbutaline dose-dependently increased heart rate, LF/HF ratios of R-R intervals and of SAP, LF variability of SAP, minute ventilation and plasma terbutaline concentration.Terbutaline infusion decreases parasympathetic cardiovascular reactivity, baroreflex sensitivity, dimensionality of heart rate and plasma potassium concentration; it increases sympathetic dominance in cardiovascular autonomic balance, minute ventilation, and the regularity of heart rate and blood pressure time series.Keywords:
Terbutaline
Approximate entropy
Supine position
Abstract. The correlation between cyclic AMP (cAMP) production in myometrial tissue and that in leukocytes was studied in 21 women delivered by cesarean section for obstetrical reasons. After in vitro β‐adrenoceptor stimulation, cAMP production in myometrial tissue was found to be closely correlated with that in leukocytes (r = 0.96). Using cAMP production in leukocytes as an indicator of the state of the β receptor function in myometrium, 18 women treated with terbutaline for preterm labor were studied. Repeat analyses of cAMP production were made in leukocytes before, during and after treatment. The results showed a significant reduction in cAMP production 3‐5 hours and 1‐2 days after terbutaline infusion. The cAMP values remained low during infusion. In women orally treated with terbutaline, a slight reduction in cAMP production was found after the first dose, but there was no significant reduction after 1‐14 days of treatment. After cessation of terbutaline treatment, cAMP production remained low during the following 3 days, but after 5‐8 days an increase was found in 7 out of 9 patients. It is suggested that a desensiti‐zation of the β‐adrenoceptor system in leukocytes appears after β‐adrenoceptor agonist treatment in high doses and that measurement of cAMP production reflects the state of desensitization of the β‐adrenoceptors in myometrial cells too.
Terbutaline
Myometrium
Tocolytic
Tocolytic agent
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To explore the Civil Aviation Pilots hypertensive patients cardiovascular autonomic nervous regulation of the changes to provide a reasonable basis for hypertension control. Methods: To use conventional AR spectral analysis methods on 14 cases of civil aviation pilots hypertensive patients and 14 healthy pilots Short-term heart rate variability (HRV) signal analysis, sequential analysis at the same time using its baroreflex sensitivity (BRS). Results: Compared with the control group, the HRV hypertensive patients decreased significantly, the difference was significant (P Conclusions: Pilots hypertensive patients regulatory function of the cardiovascular autonomic nervous obvious anomaly, a relatively sympathetic regulatory activities increased, vagus nerve regulatory activities be curbed. flight personnel in the control of hypertension, should strengthen its regulatory function of the autonomic nervous analysis.
Sympathetic nervous system
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Beta 2-agonists are known to cause a range of unwanted biochemical and cardiovascular responses. The present study was designed to investigate the effect of chronic exposure to beta 2-stimulation on the magnitude of these responses produced by an acute challenge with a beta 2-agonist. In this single blind placebo controlled study in six healthy male volunteers, we have compared the effects of chronic dosing with either oral terbutaline (5 mg three times daily for two weeks) or placebo on a number of these responses produced by an intravenous infusion of terbutaline (6 micrograms per kilogram over 1 hour). The infusion was given twenty-four hours after the last dose of oral terbutaline or placebo. The rise in pulse rate, systolic blood pressure and plasma glucose and the fall in serum potassium during terbutaline infusion, although still demonstrable, were significantly reduced following treatment with oral terbutaline compared to placebo. This suggests downgrading of beta-receptor function after chronic beta 2-stimulation.
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Terbutaline
Aminophylline
BETA (programming language)
Chronic bronchitis
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Objective: Heart rate variability (HRV) and baroreflex sensitivity (BRS) are influenced by various internal and external factors, making it necessary to establish universal reference values. We aimed to identify independent factors affecting short-term HRV parameters and BRS, as well as determine appropriate reference ranges, which are lacking in Asian populations. Materials and Methods: A total of 117 healthy Thai participants (aged 20-72 years; final n=117) were recruited based on strict criteria, including normal medical history, physical examination (ascertained by a physician), and normal blood profile. Spontaneous 5-minute HRV parameters (time and frequency domains) and spontaneous cross-correlation BRS were measured. Results: Age and resting heart rate (HR) are independently and inversely correlated with BRS and all HRV parameters, except LFnu (normalized low-frequency component) and LF/HF ratio (ratio of low- to high-frequency component). Sex differences were observed only in LF, which was higher in men. However, multiple regression analysis showed that sex did not significantly contribute as an independent variable to either HRV or BRS. Remarkably, BRS exhibited moderate to strong correlations with all HRV values, indicating its prominent role in influencing HRV and surpassing the impact of age. Conclusion: Age and resting HR were identified as independent factors influencing 5-minute HRV and BRS. Our findings suggest that decreased baroreflex function associated with aging may contribute to reduced HRV among the elderly. Furthermore, we established reference ranges for each 5-minute HRV parameter and BRS, categorized by age group (20-39, 40-59, and ≥60 years old). These reference values offer valuable clinical insights, particularly for Asian populations where such normative ranges were previously unavailable.
Autonomic function
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A new β 2 ‐adrenoceptor agonist D2343 has been shown in a human i.v. study to be less potent than terbutaline. Animal experiments showed an increased affinity to lung tissue and a longer bronchodilating effect than terbutaline when inhaled. In a randomized single‐blind, crossover comparison, 2.5 and 5 mg D2343 and 5 mg terbutaline were inhaled by eight asthma patients. We found that 5 mg of D2343 was equipotent to 5 mg terbutaline in bronchodilatory effect measured with FEV 1 . The duration was longer with an increased bronchodilation ( P < 0.01) 6 h after D2343 inhalation compared with terbutaline. The mean fall in FEV 1 3–6 h after inhalation was significantly greater with terbutaline than with D2343 ( P < 0.05). Thus, this study shows that inhaled D2343 has a longer bronchodilating effect than terbutaline.
Terbutaline
Bronchodilation
Crossover study
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Background: Several factors are associated with successful treatment of mild to moderate OSA with a mandibular advancement device (MAD). Data about the predictive value of supine-dependent OSA are conflicting. Very little literature is available about the predictive value of the AHI in supine position. Here, we investigate supine dependent OSA and AHI in supine position as predictors of successful treatment with MAD. Methods: From January 1, 2015 until December 31, 2017, patients with OSA with an AHI >5 and <30 receiving an MAD were included. Successful treatment was defined as a decrease of AHI with MAD of at least 50% and AHI <10/hour. Results: 118 patients were included, 78.8% had supine dependent OSA, 21.2% had non-supine dependent OSA. Successful treatment was achieved in 44% of the patients with supine dependent OSA, versus 28% of patients with non-supine dependent OSA, p=0.12. With linear regression, the only independent predictor of success was BMI. No relations were found between success and supine dependent OSA or AHI in supine position. Conclusion: In our cohort, supine dependent and AHI in supine position were not predicting factors for successful treatment of mild to moderate OSA with MAD.
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Forty-eight patients with severe chronic airways obstruction were given 5 mg terbutaline or placebo from a nebulizer twice daily for 2 + 2 weeks. Twenty three patients preferred terbutaline, 9 placebo and 16 had no preference. The baseline lung function and the 6 minute walking distance were not increased after the terbutaline period. The patients who preferred terbutaline indicated less dyspnoea after the terbutaline period as compared to the placebo period, but did not differ with regard to lung function or walking distance after the terbutaline treatment. The physiology behind the subjective relief from the terbutaline inhalations remains unexplained.
Terbutaline
Nebulizer
Bronchodilator Agents
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Heart rate variability (HRV) has been widely used as indices for autonomic regulation, including linear analyses, entropy and multi-scale entropy based nonlinear analyses, and however, it is strongly influenced by the conditions under which the signal is being recorded. To investigate the variability of healthy HRV under different settings, we recorded electrocardiograph (ECG) signals from 56 healthy young college students (20 h for each participant) at campus using wearable single-lead ECG device. Accurate R peak to R peak (RR) intervals were extracted by combing the advantages of five commonly used R-peak detection algorithms to eliminate data quality influence. Thorough and detailed linear and nonlinear HRV analyses were performed. Variability of HRV metrics were evaluated from five categories: (1) different states of daily activities; (2) different recording time period in the same day during free-running daily activities; (3) body postures of sitting and lying; (4) lying on the left, right and back; and (5) gender influence. For most of the analyzed HRV metrics, significant differences (p < 0.05) were found among different recording conditions within the five categories except lying on different positions. Results suggested that the standardization of ECG data collection and HRV analysis should be implemented in HRV related studies, especially for entropy and multi-scale entropy based analyses. Furthermore, this preliminary study provides reference values of HRV indices under various recording conditions of healthy young subjects that could be useful information for different applications (e.g., health monitoring and management).
Approximate entropy
Sample entropy
Sitting
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Heart Rate Variability (HRV) has been established as a vital index for diagnostics and prognosis of a number of pathological conditions. Moreover, HRV is a proven indicator of autonomic balance. As HRV is a result of multiple responses acting at various time scales, these interactions need to be quantified. In this paper, a complexity measure called ApEn is utilized to quantify the complexity of HRV. This method is tested on age stratified standard Fantasia database from Physionet. It is observed that young subjects show higher HRV complexity than the older ones. The effect of tolerance threshold ‘r’ is also evaluated on the HRV complexity estimation of young and old subjects. Further, for r≥0.10, the complexity of HRV is higher for young subjects but the trend is reverse for r<0.10. Therefore, it is concluded that the tolerance threshold ‘r’ should be carefully selected for the complexity analysis of HRV. Keywords: Approximate Entropy, Autonomic Nervous System, Complexity, Heart Rate Variability
Approximate entropy
Complexity index
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