Beta-adrenergic agonists. A problem

Use of a Wearable Biosensor to Study Heart Rate Variability in Chronic Obstructive Pulmonary Disease and Its Relationship to Disease Severity

The purpose of this study was to explore the relationships between heart rate variability (HRV) and various phenotypic measures that relate to health and functional status in chronic obstructive pulmonary disease (COPD), and secondly, to demonstrate the feasibility of ascertaining HRV via a chest-worn wearable biosensor in COPD patients. HRV analysis was performed using SDNN (standard deviation of the mean of all normal R-R intervals), low frequency (LF), high frequency (HF), and LF/HF ratio. We evaluated the associations between HRV and COPD severity, class of bronchodilator therapy prescribed, and patient reported outcomes. Seventy-nine participants with COPD were enrolled. There were no differences in SDNN, HF, and LF/HF ratio according to COPD severity. The SDNN in participants treated with concurrent beta-agonists and muscarinic antagonists was lower than that in other participants after adjusting heart rate (beta coefficient −3.980, p = 0.019). The SDNN was positively correlated with Veterans Specific Activity Questionnaire (VSAQ) score (r = 0.308, p = 0.006) and handgrip strength (r = 0.285, p = 0.011), and negatively correlated with dyspnea by modified Medical Research Council (mMRC) questionnaire (r = −0.234, p = 0.039), health status by Saint George’s Respiratory Questionnaire (SGRQ) (r = −0.298, p = 0.008), symptoms by COPD Assessment Test (CAT) (r = −0.280, p = 0.012), and BODE index (r = −0.269, p = 0.020). When measured by a chest-worn wearable device, reduced HRV was observed in COPD participants receiving inhaled beta-sympathomimetic agonist and muscarinic antagonists. HRV was also correlated with various health status and performance measures.

Increased sympathetic modulation and decreased response of the heart rate variability in controlled asthma

OBJECTIVE

To compare the autonomic modulation of heart rate (HR) in asthmatic and healthy volunteers to correlate it with the forced expiratory volume in the first second (FEV1).

METHODS

Ten healthy and 14 asthmatic volunteers were included in this cross-sectional study. The volunteers underwent a cardiopulmonary exercise test, spirometry and a register of both resting heart rate variability (HRV) in the supine and seated positions along with HRV during the respiratory sinus arrhythmia maneuver (M-RSA).

RESULTS

At rest in supine, asthmatic volunteers presented a higher HR (77.1 ± 9.9 vs. 68.7 ± 8.7 bpm), shorter interval between two R waves (R-Ri) (807.5 ± 107.2 vs. 887.5 ± 112.7 ms) when compared with the healthy volunteers, respectively. Moreover, in the frequency domain of HRV, there was increased low frequency (LF) index (50.4 ± 17.1 vs. 29.2 ± 11.1 n.u.) and decreased high frequency (HF) index (49.4 ± 17.1 vs. 70.7 ± 11.1 n.u.). During the M-RSA, the asthmatic presented higher HR (82.6 ± 10.0 vs. 72.4 ± 7.6 bpm) and lower values of R-Ri (746.4 ± 92.1 vs. 846.4 ± 81.4 ms) and approximate entropy (ApEn) (0.7 ± 0.0 vs. 0.8 ± 0.1). FEV1 was strongly correlated with the change of the continuous beat-to-beat variability of HR (SD2) index from the seated to the supine position (r = 0.78).

CONCLUSION

Controlled asthma in adults appears to induce an increased sympathetic modulation and attenuated response to the postural changes and the M-RSA. Furthermore, there is a correlation between the airways' obstruction and HRV, especially during postural changes.

The effects of inhaled formoterol on the autonomic nervous system in adolescents with asthma

BACKGROUND

The safety of long-acting beta-2-adrenergic agonists is increasingly questioned by physicians. Although formoterol is frequently used in childhood, its effects on the autonomic cardiovascular system have not been studied.

OBJECTIVE

To investigate the effects of inhaled formoterol on autonomic nervous system using heart rate variability in adolescents with persistent asthma.

METHODS

Electrocardiography of 20 asthmatic adolescents (12-20 years) was monitored for 5 specific days. The first day served as basal measurement, and the 2nd and 3rd days reflected the effects of a single and 2 doses of formoterol, respectively. From days 4 to 29, patients received regular treatment with formoterol/budesonide and were monitored on days 30 and 31 to evaluate the development of cardiac and respiratory tolerance after single-dose and 2 doses of formoterol, respectively. Electrocardiographs were analyzed for heart rate, heart rate variability (both time and frequency domain parameters), and spirometry tests were performed.

RESULTS

Inhalation of single-dose formoterol increased heart rate and decreased heart rate variability parameters (ratio of the normal-to-normal [NN] interals changing in excess of 50 ms to total of NN intervals [pNN50], total power [TP][ms], TP[ln]) compared with the corresponding baseline values during the first 12 hours of the day. The heart rate variability parameters (pNN50, TP[ms], TP[ln], root mean square of differences between adjacent NN intervals) during the first 12 hours were increased on the 30th day compared with the 2nd day and decreased on the 31st day compared with the 30th day.

CONCLUSION

Single-dose formoterol inhalation decreases cardiovagal responsiveness and increases the sympathetic tone in cardiac autonomous control, and regular use of formoterol causes development of tolerance to these effects. However, additive doses of formoterol cause loss of this tolerance.

Comparison of the acute effects of salbutamol and terbutaline on heart rate variability in adult asthmatic patients

This study investigated the effects of beta2-adrenergic agonist therapy on heart rate variability (HRV) in adult asthmatic patients by using frequency domain measures of HRV. A randomized crossover design was used. Twenty adult patients with asthma were studied. All patients showed a mild-to-moderate decrease in baseline forced expiratory volume in one second. Any diseases that might have influenced the autonomic function were excluded. All patients had a complete physical examination and medical history that revealed no cardiovascular disease or medication. The study used 200 microg inhaled salbutamol and 500 microg inhaled terbutaline. HRV analysis was performed for each 5-min segment, 5 min before inhalation of the study drug and 5, 10, 15, 20, 25 and 30 min after inhalation. Total power (TP: <0.40 Hz), high-frequency power (HF: 0.15-0.40 Hz), low-frequency power (LF: 0.04-0.15 Hz) and LF/HF ratio were calculated. The LF and LF/HF ratio increased and TP decreased at 5, 10, 15 and 20 min after the salbutamol and the terbutaline inhalation, HF did not change significantly after the salbutamol and terbutaline inhalation. Acute salbutamol and terbutaline inhalation produce similar effects on heart rate variability and increase sympathetic modulation in the cardiac autonomic activity.

Is delayed introduction of inhaled corticosteroids harmful in patients with obstructive airways disease (asthma and COPD)? The Dutch CNSLD Study Group. The Dutch Chronic Nonspecific Lung Disease Study Groups

BACKGROUND

The institution of inhaled corticosteroids is generally advocated for effective treatment of patients with asthma. It is yet unknown what is the best time to start inhaled corticosteroid therapy and especially whether delayed introduction is harmful. PHASE 1: In a previous study in patients with asthma and COPD, we found that 2.5 years of treatment with a beta 2-agonist plus inhaled corticosteroid (BA + CS) was more effective in improving the FEV1 and the provocative concentration of histamine causing a 20% reduction in FEV1 (PC20) than treatment with a beta 2-agonist plus anticholinergic (BA + AC) or placebo (BA + PL). PHASE 2: We extended this study with 6 months to investigate whether delayed introduction of inhaled CS therapy (800 micrograms beclomethasone dipropionate) in the groups previously not treated with inhaled CS (BA +/- AC) could also improve FEV1 and PC20 to the same degree. A distinction was made between patients with predominantly asthma (high baseline reversibility, delta FEV1 > or = 9% of predicted), and predominantly COPD (low baseline reversibility, delta FEV1 < 9% of predicted).

RESULTS

Improvement of FEV1 percent predicted by inhaled CS was comparable both in the asthmatics between phase 1 (13.8% predicted) and phase 2 (8.5% predicted; p = 0.31) as well as in the patients with COPD (2.5% and 1.5% predicted, respectively). PC20, however, increased significantly more in the asthmatics in phase 1 (1.77 doubling concentration [DC]) than in phase 2 (0.79 DC; p = 0.03). Improvement of PC20 in the patients with COPD was not significantly higher in phase 1 (0.74 DC) than in phase 2 (0.00 DC; p = 0.19).

CONCLUSIONS

Our study indicates that although delayed introduction of inhaled CS in asthmatics leads to similar improvements in FEV1, improvements in PC20 are significantly less. These findings in patients with longer-existing asthma concur with other findings in newly detected asthma. We suggest that institution of inhaled CS therapy should not be postponed in asthmatics with documented airways obstruction and reversibility.

Asthma in the pregnant adolescent: a review

Adolescent pregnancy has increased in the past decade (1-5), often in association with poverty, poor education, and inadequate prenatal care. While it has been suggested that adverse pregnancy outcomes are more common among adolescents in the inner city, recent data show that in a white, middle-class population teenaged mothers are more likely to have adverse pregnancy outcomes (5). Asthma is also becoming more common, with an incidence of at least 6.6% in 15-16 year old girls (6,7). Poverty and living in the inner city are associated with increased morbidity and mortality from asthma (8-11). Adolescents with asthma who become pregnant provide an added challenge to the physician who must consider the impact of the pregnancy on the asthma and vice versa. The physician must understand the effects of both the asthma medication and/or poorly controlled disease on the fetus. The physician must also be able to convey this information to the adolescent in a developmentally appropriate manner to enable the patient to make informed health care decisions (12).

High-dose MDI salbutamol treatment of asthma in the ED

Beta-adrenergics have long been under special scrutiny because of their potential for cardiotoxicity. To assess the safety of high doses of salbutamol delivered by metered dose inhaler (MDI) with spacer in the emergency department (ED) setting, 11 patients (mean age 33 +/- 12.2 years) with severe acute asthma were studied. All patients were treated with 400 micrograms of salbutamol at 10-minute intervals for 3 hours (1,200 micrograms each 30 minutes or 7,200 micrograms at 180 minutes. There were dose-related significant increases in forced expiratory volume in the first second (FEV1) and peak expiratory flow (PEF) (P < .01), with a net mean increase of 90.4% and 80.1%, respectively. A significant (P < .01) reduction of heart rate was observed with treatment. At the end of protocol, reductions ranged from 7 beats/min to 35 beats/min (mean decrease 10.6 +/- 10.5 beats/min). There was no prolongation in the QTc interval. Mean baseline serum potassium was 4.23 +/- 0.53 mmol/L and decreased nonsignificantly after treatment to 3.99 +/- 0.62 mmol/L. Only 4 patients showed net decreases. There were no significant changes in oxygen saturation and plasma glucose. The mean end-treatment salbutamol level was 10.0 +/- 1.67 ng/mL. These data support the notion that treatment of acute asthma patients in the ED with 2.4 mg salbutamol per hour delivered by MDI and spacer produce satisfactory bronchodilation, low serum concentration, and minimal extrapulmonary effects.

The effects of sympathomimetics on the cardiovascular system of sheep

1. Sheep hearts have been used to study the effects of beta-adrenoceptor (beta-AR) agonists in order to better understand the effects of common asthma treatment drugs on heart rate, cardiac power output and cardiac pathology. Hearts have been examined both in vivo and in vitro. 2. In whole anaesthetized sheep, isoprenaline, fenoterol and salbutamol induced dose-dependent increases in heart rate. Hypokalaemia in response to salbutamol was accentuated in hypoxia. Many of these hearts showed significant myocardial lesions. Hypoxia alone caused no significant cardiac response. 3. As expected, the beta 1-AR agonist dobutamine caused dose-dependent increases in heart performance (heart rate and cardiac power output). Both responses were blocked by metoprolol and propranolol. The beta 2-AR agonist salbutamol caused dose-dependent increases in heart rate and although cardiac output increased, cardiac power output remained unchanged as a consequence of the fall in peripheral resistance. The heart rate changes were blocked by metoprolol. Importantly, propranolol blocked both the heart rate response and the fall in peripheral resistance. 4. Isolated atrial strips showed a right shift of their dose-response curve to isoprenaline in the presence of the highly selective beta 2-AR antagonist ICI 118,551 at concentrations above 1 x 10(-8) mol/L. 5. We conclude that the sheep heart shows many pharmacological characteristics of the human heart which makes it a good pharmacological model in addition to its being amenable to many common techniques available for humans.