Heart Rate Variability and Disease Characteristics in Patients with COPD

Heart rate variability in horses with and without severe equine asthma

BACKGROUND

Equine asthma in severe form (severe equine asthma [sEA]) shares remarkable similarities with human asthma. Human studies detected changes in the autonomic nervous system function in asthmatic patients based on heart rate variability (HRV) analysis.

STUDY DESIGN

Observational study.

OBJECTIVES

To investigate the relationship between sEA and HRV in horses.

METHODS

Twenty horses diagnosed with sEA and 20 asymptomatic (non-sEA) horses were investigated. SEA horses showed clinical signs. The RR intervals of the ECG were recorded for 1 h at rest between 9 AM and 11 AM using a heart rate (HR) monitor. HRV data were calculated using Kubios software. Parameters recorded for the sEA and non-sEA groups were compared using one-way MANOVA model. The significance level was set at α = 0.05.

RESULTS

SD2 (mean 99.6 ± SD 25.3 vs. 42.5 ± 17.1), SDNN (82.7 ± 20.7 vs. 41.3 ± 14.3), TINN (398.1 ± 104.9 vs. 209.3 ± 71.9), SD2/SD1 ratio (1.7 ± 0.2 vs. 1.1 ± 0.3), Total power (4740.2 ± 1977.9 vs. 1503.0 ± 1179.3), LF (2415.3 ± 1072.4 vs. 707.4 ± 649.9), SD1 (60.9 ± 15.9 vs. 39.2 ± 14.1), RMSSD (86.0 ± 22.6 vs. 55.3 ± 19.8) and HF (1575.8 ± 902.5 vs. 578.1 ± 491.1) were lower in sEA horses compared with the non-sEA horses (p < 0.01 for each variable). SD2, SDNN, TNN, the SD2/SD1 ratio and Total power showed the greatest discriminatory power in differentiating the sEA and non-sEA groups.

MAIN LIMITATIONS

Small sample size.

CONCLUSION

Our findings indicate that like humans, asthmatic horses show an overall reduction in autonomic control. A relative increase of the parasympathetic modulation of the heart was also observed. After further investigations, HRV measurement might be a non-invasive approach to monitor autonomic nervous system responses of sEA horses.

Inter- and intrarater reliability of short-term measurement of heart rate variability on rest in chronic obstructive pulmonary disease (COPD)

BACKGROUND

Individuals with COPD have an imbalance of cardiac autonomic control. In this context, HRV is considered an important tool for assessing cardiac sympathetic and parasympathetic balance, however it is a dependent evaluator measure and subject to methodological biases that may compromise the interpretation of results.

OBJECTIVE

This study examines the inter- and intrarater reliability of HRV parameters derived from short-term recordings in individuals with COPD.

METHODOLOGY

Fifty-one individuals of both genders with COPD clinical diagnosis confirmed by the pulmonary function test and aged ≥50 years were included. The RR interval (RRi) were recorded during a 10 min period on supine position using a portable heart rate monitor (Polar® H10 model). The data were transferred into Kubios® HRV Standard analysis software and analyzed within the stable sessions containing 256 sequential RRi.

RESULTS

The intraclass correlation coefficient (ICC) ranged from 0.942 to 1.000 according to the intrarater analysis by Researcher 01 and 0.915 to 0.998 to the intrarater by Researcher 02. The interrater ICC ranged from 0.921 to 0.998. The coefficient of variation was up to 8.28 for Researcher 01 intrarater analysis, 9.06 for Researcher 02 intrarater analysis and 13.07 for interrater analysis.

CONCLUSION

The measurement of HRV using a portable heart rate device in individuals with COPD present acceptable values of intra- and interrater reliability, supporting the use of HRV in the clinical and scientific scenario. Furthermore, it is important that the data analysis be performed by the same experienced evaluator.

Heart Rate Variability for Outcome Prediction in Intracerebral and Subarachnoid Hemorrhage: A Systematic Review

This systematic review presents clinical evidence on the association of heart rate variability with outcome prediction in intracerebral and subarachnoid hemorrhages. The literature search led to the retrieval of 19 significant studies. Outcome prediction included functional outcome, cardiovascular complications, secondary brain injury, and mortality. Various aspects of heart rate recording and analysis, based on linear time and frequency domains and a non-linear entropy approach, are reviewed. Heart rate variability was consistently associated with poor functional outcome and mortality, while controversial results were found regarding the association between heart rate variability and secondary brain injury and cardiovascular complications.

Day-night patterns in heart rate variability and complexity: differences with age and cardiopulmonary disease

STUDY OBJECTIVES

Heart rate variability (HRV) measures provide valuable insights into physiology; however, gaps remain in understanding circadian patterns in heart rate dynamics. We aimed to explore day-night differences in heart rate dynamics in patients with chronic cardiopulmonary disease compared with healthy controls.

METHODS

Using 24-hour heart rate data from patients with chronic obstructive pulmonary disease (COPD) and/or heart failure (n = 16) and healthy adult controls (older group: ≥50 years, n = 42; younger group: 20-49 years, n = 136), we compared day-night differences in conventional time and frequency domain HRV indices and a multiscale-entropy-based complexity index (CI1-20) of HRV among the 3 groups.

RESULTS

Twenty-four-hour HRV showed significant day-night differences (marked with "△") among younger healthy (mean age: 34.5 years), older healthy (mean age: 61.6 years), and cardiopulmonary patients (mean age: 68.4 years), including change in percentage of adjacent intervals that differ > 50 ms (△pNN50), high frequency (△HF), normalized low frequency (△nLF), ratio (△LF/HF), and △CI1-20. Among these, △LF/HF (2.13 ± 2.35 vs 1.1 ± 2.47 vs -0.35 ± 1.25; P < .001) and △CI1-20 (0.15 ± 0.24 vs 0.02 ± 0.28 vs -0.21 ± 0.27; P < .001) were significant in each pairwise comparison following analysis of variance tests. Average CI1-20 was highest in younger healthy individuals and lowest in cardiopulmonary patients (1.37 ± 0.12 vs 1.01 ± 0.27; P < .001). Younger healthy patients showed a heart rate complexity dipping pattern (night < day), older healthy patients showed nondipping, and cardiopulmonary patients showed reverse dipping (night > day).

CONCLUSIONS

As measures of 24-hour variability, traditional and complexity-based metrics of HRV exhibit large day-night differences in healthy individuals; these differences are blunted, or even reversed, in individuals with cardiopulmonary pathology. Measures of diurnal dynamics may be useful indices of reduced adaptive capacity in patients with cardiopulmonary conditions.

CITATION

Ma Y, Chang M-C, Litrownik D, Wayne PM, Yeh GY. Day-night patterns in heart rate variability and complexity: differences with age and cardiopulmonary disease. J Clin Sleep Med. 2023;19(5):873-882.

A systematic review and meta-analysis of heart rate variability in COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with disruption in autonomic nervous control of the heart rhythm. We present here quantitative evidence of the reduction in HRV measures as well as the challenges to clinical application of HRV in COPD clinics.

METHOD

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we search in June 2022 Medline and Embase databases for studies reporting HRV in COPD patients using relevant medical subject headings (MeSH) terms. The quality of included studies was assessed using the modified version of the Newcastle-Ottawa Scale (NOS). Descriptive data were extracted, while standardized mean difference was computed for changes in HRV due to COPD. Leave-one-out sensitivity test was performed to assess exaggerated effect size and funnel plots to assess publication bias.

RESULTS

The databases search yielded 512 studies, of which we included 27 that met the inclusion criteria. The majority of the studies (73%) had a low risk of bias and included a total of 839 COPD patients. Although there were high between-studies heterogeneity, HRV time and frequency domains were significantly reduced in COPD patients compared with controls. Sensitivity test showed no exaggerated effect sizes and the funnel plot showed general low publication bias.

CONCLUSION

COPD is associated with autonomic nervous dysfunction as measured by HRV. Both sympathetic and parasympathetic cardiac modulation were decreased, but there is still a predominance of sympathetic activity. There is high variability in the HRV measurement methodology, which affects clinical applicability.

Oxidative stress associated with impaired autonomic control and severity of lung function in chronic obstructive pulmonary disease patients

Oxidative stress has been suggested to play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). This study aimed to investigate a link between malondialdehyde (MDA) levels, pulmonary function, and cardiac autonomic control in patients with COPD. Plasma levels of MDA, heart rate variability, and pulmonary function were measured in 50 clinically stable COPD patients and 50 normal male controls. COPD patients exhibited lower means of the standard deviations of all normal to normal (NN) intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD), and high frequency (HF). Nevertheless, they presented greater low frequency (LF) and low frequency/high frequency ratio (LF/HF ratio) in supine and head-up tilt positions than controls (P<0.001). More-over, a negative correlation between MDA levels with SDNN (P<0.001) and a positive correlation with LF (P<0.01) and LF/HF ratio (P<0.05) were observed in both positions. In COPD patients, plasma MDA levels were 2.3 times greater than controls (4.33±2.03 μM vs. 1.89±0.39 μM, P<0.001), and they were inversely correlated with forced vital capacity, forced expiratory volume in 1 sec, midexpiratory flow, and peak expiratory flow (P<0.001). Our findings suggest a potential role for oxidative stress in impaired cardiac autonomic control and clinical relevance of plasma MDA levels as a predictor of severity of COPD in COPD patients.

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.

A novel lung radiomics feature for characterizing resting heart rate and COPD stage evolution based on radiomics feature combination strategy

The resting HR is an upward trend with the development of chronic obstructive pulmonary disease (COPD) severity. Chest computed tomography (CT) has been regarded as the most effective modality for characterizing and quantifying COPD. Therefore, CT images should provide more information to analyze the lung and heart relationship. The relationship between HR variability and PFT or/and COPD has been fully revealed, but the relationship between resting HR variability and COPD radiomics features remains unclear. 231 sets of chest high-resolution CT (HRCT) images from "COPD patients" (at risk of COPD and stage I to IV) are segmented by the trained lung region segmentation model (ResU-Net). Based on the chest HRCT images and lung segmentation images, 231 sets of the original lung parenchyma images are obtained. 1316 COPD radiomics features of each subject are calculated by the original lung parenchyma images and its derived lung parenchyma images. The 13 selected COPD radiomics features related to the resting HR are generated from the Lasso model. A COPD radiomics features combination strategy is proposed to satisfy the significant change of the lung radiomics feature among the different COPD stages. Results show no significance between COPD stage Ⅰ and COPD stage Ⅱ of the 13 selected COPD radiomics features, and the lung radiomics feature Y1-Y4 (P > 0.05). The lung radiomics feature F2 with the dominant selected COPD radiomics features based on the proposed COPD radiomics features combination significantly increases with the development of COPD stages (P < 0.05). It is concluded that the lung radiomics feature F2 with the dominant selected COPD radiomics features not only can characterize the resting HR but also can characterize the COPD stage evolution.

The Indices of Instantaneous Pulse Rate Variability Are Indicators for Daily Life Quality Assessment in Patients with COPD

Chronic obstructive pulmonary disease (COPD) is a progressive respiratory illness. Questionnaires such as modified Medical Research Council (mMRC) dyspnea scale and COPD assessment test (CAT) are useful for COPD condition and life quality assessment. These questionnaires reflect how respiratory disorder affects daily life. Breathing and autonomic nervous system (ANS) usually regulate each other. Few studies discussed the ANS activity and daily life quality in patients with COPD. Therefore, this study aimed to find the relationship between daily life quality assessed by mMRC or CAT and ANS assessed by a novel method, instantaneous pulse rate variability (iPRV), a method indicating not only the ANS activity but also the peripheral response. The result showed that the change in mMRC and the change in low frequency power to high frequency power ratio, which usually represents the sympathetic activity in conventional heart rate variability analysis, had significant correlation (r = 0.63; p < 0.05). The change in CAT and the change in high frequency power (regulated by vagal nervous and respiratory system) or very high frequency power (new frequency band can be indicated in iPRV spectrum) had significant negative correlation (r = -0.64 and -0.55, respectively; p < 0.05 for both). This study showed the change in iPRV indices when the condition of COPD was improvement or exacerbation. This study presents a possible way to show how cardiovascular activity affects daily life quality in patients with COPD. Increase in LF or decrease in HF and VHF would cause poorer quality of daily life in patients with COPD. The result can also be a reference for patients with COPD to choose the breathing type to adjust rehabilitation and therapy program for ANS regulation to indicate or improve their daily life quality.

Heart Rate Variability in Adults with Sickle Cell Anemia During a Multitasking Field Test

Background: The integrity of the autonomic nervous system (ANS) is essential for keeping physiological processes stable, even under stress. Since there is growing interest in heart rate variability (HRV) analysis for the noninvasive assessment of the ANS in sickle cell anemia (SCA) patients, we studied the behavior of the ANS in the presence of a stressor that simulates daily-life multitasking, the Glittre ADL test (GA-T). Objectives: To evaluate the involvement of the ANS using HRV in adults with SCA during the GA-T and to quantify the strength of the correlation of HRV with lung and muscle functions. Methods: In this cross-sectional study, 16 adults with SCA and 12 healthy controls without sickle cell disease underwent HRV assessment during the GA-T, pulmonary function tests (spirometry, diffusing capacity for carbon monoxide (DLCO), and respiratory muscle testing). Peripheral muscle function [handgrip strength (HGS) and quadriceps strength (QS)] were also measured. Results: Compared to the healthy controls, adults with SCA showed lower HRV, with worse parasympathetic modulation due to reductions in the following indices: the root-mean-square difference of successive normal iRRs (iRR) (RMSSD); the percentage of pairs of consecutive iRRs whose difference is > 50 m (pNN50); the high-frequency component of heart rate variability (HF); and the standard deviation of instantaneous beat-to-beat variability (SD1) (P < 0.001 for all). Compared to healthy controls, individuals with SCA showed greater sympathovagal imbalance (higher ratio between low-frequency and HF components) and lower complexity of the ANS (lower approximate entropy). The GA-T time was correlated with parasympathetic activity indices: RMSSD (rs = -0.650, P < 0.01); pNN50 (rs = -0.932, P < 0.0001), HF (rs = -0.579, P < 0.01), and SD1 (rs = -0.814, P < 0.0001). Correlations between parasympathetic activity indices and DLCO, HGS, and QS measures were also significant. Conclusions: Adults with SCA have low HRV, with low parasympathetic activity, sympathovagal imbalance, and abnormal ANS complexity. In addition, lower HRV is associated with longer GA-T time, greater impairment of pulmonary diffusion, and greater muscle strength dysfunction.

Brain-heart autonomic axis across different clinical status and severity of chronic obstructive pulmonary disease

PURPOSE

Impairment of cardiac autonomic integrity is common in chronic obstructive pulmonary disease (COPD) patients. The influence of the interaction between clinical and severity status on brain-heart autonomic axis (BHAA) is not well known. We aimed to investigate the BHAA function across different clinical status and severity of COPD.

METHODS

Cross-sectional study involving 77 COPD patients allocated into four groups according to clinical status [acute exacerbation (GAE) or stable (GST)] and severity [less (-) or more (+)]: 1) GAE-, n = 13; 2) GAE+, n = 20; 3) GST-, n = 23; and 4) GST+, n = 21. Heart rate variability (HRV) at rest and heart rate recovery (HRR) after 6-min walk test were markers of BHAA. Mean R-R, STDRR, RMSSD, RRtri, HF, LF, SD1, SD2, ApEn and SampEn were the HRV indexes and, HRR was obtained as: HR at 1st min of recovery minus peak HR.

RESULTS

A main effect of clinical status (p < 0.001) was found to vagal modulation in GAE-vs. GST- (RMSSD: 25.0 ± 14.8 vs. 12.6 ± 5.5 ms; SD1: 18.0 ± 10.6 vs. 8.9 ± 3.9 ms) and to GAE + vs. GST+ (RMSSD: 26.4 ± 15.2 vs. 15.4 ± 6.3 ms; SD1: 18.3 ± 11.2 vs. 10.9 ± 4.5 ms). An effect of clinical status (p = 0.032) and severity (p = 0.030) were found to HF (vagal) in GAE + compared to GAE- and GST+ (264.7 ± 239.0 vs. 134.7 ± 169.7 and 135.8 ± 139.7 ms2). Lower HRR was found in GAE-compared to GST- (8.0 ± 2.4 vs. 19.6 ± 2.4 bpm), p = 0.002.

CONCLUSION

In COPD patients, clinical status (AECOPD or stable) was more dominant than the severity on BHAA function. A more pronounced parasympathetic modulation was found in AECOPD patients with a lower HRR to exercise.

[Evaluation of respiratory parameters in patients with chronic obstructive lung disease during physical exercises]

AIM

To study the relationship between the indicators of dynamic capnography and pulse oximetry with the indicators of the 6-minute walk test (6MWT) in patients with chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS

67 patients of both sexes were examined: 45 patients with COPD (age 60.02.74 years) and 25 patients of the control group (age 47.603.46 years). The study of the functional capabilities of the patients respiratory system was carried out before, during and after the 6MWT on the equipment LifeSense LS1-9R capnograph-pulse oximeter (MedAir AB).

RESULTS AND DISCUSSION

In the comparison group, the parameters of dyspnea at rest were higher than the control group (p0.05), the spirometry indices were significantly lower (p0.05). Shortness of breath as a reason for stopping/slowing down the pace during the 6MWT was noted by patients of both groups (p0.05). When analyzing the PETCO2 trend graphs, periodic breathing (PВ) was revealed. In the group of patients with COPD, signs of PВ in the analysis of the PETCO2 trend were found in 80.95% (p0.05). Regression analysis of Cox proportional risks of mortality in patients with COPD revealed the prognostic value of the following parameters of a comprehensive assessment of the patient: body mass index (BMI), BODE index, dyspnea index on the mMRS scale, Borg, forced expiratory volume in 1 second (FEV1), index Tiffno, signs of PВ, distance 6MWT, signs of PВ and desaturation during 6MWT. At the same time, the total contribution of these indicators to the risk of a lethal event was assessed (p=0.003).

CONCLUSION

When analyzing the correlation dependence, it was revealed that the presence of PВ was a prognostically unfavorable sign in patients with COPD. Predictors of an unfavorable course of COPD were BMI (23.0 kg/m2), BODE index, dyspnea indices on the mMRS, Borg, FEV1 scales, Tiffnos index, signs of PH, distance 6MST, signs of PD and desaturation during 6MST (reliability of the model coefficient p=0.003) in terms of forecast.

Physical activity and cardiac autonomic dysfunction in patients with chronic obstructive pulmonary disease: a cross-sectional analysis

BACKGROUND

The cardiac autonomic function in patients with chronic obstructive pulmonary disease (COPD) has been poorly studied.

OBJECTIVES

We aimed to 1) describe the cardiac autonomic function assessed by heart rate recovery (HRR) and chronotropic response (CR) during a 6-min walk test (6MWT) and afterward and 2) estimate the association of physical activity with HRR and CR in COPD patients.

METHODS

This cross-sectional analysis included 320 patients with mild to very severe COPD. Physical activity (steps, time in any/moderate-to-vigorous/vigorous physical activity, intensity and sedentary time) was measured during 1 week by accelerometer. CR and HRR were measured during a 6MWT and 5 min after, respectively, and their association with physical activity parameters was estimated by multivariable linear regression models.

RESULTS

Patients were 82% male and had a mean (SD) age 68 (8) years, post-bronchodilator FEV1 57 (18) % predicted, and walked a mean of 7716 (4139) steps/day. HRR was slow until 5 min after the 6MWT; the mean (SD) was 15 (10), 22 (11), 25 (12), 25 (12) and 27 (12) bpm after 1, 2, 3, 4 and 5 min, respectively). The mean CR was 35% (16). After adjusting for relevant confounders, time in vigorous physical activity was significantly associated with a fast decrease in HRR (p=0.044) and an increase in CR (p=0.021). We found no independent association for other physical activity parameters.

CONCLUSION

A cardiac autonomic dysfunction is present in patients with mild to very severe COPD and is inversely related to the practice of vigorous physical activity.

Immediate Effects of Rib Mobilization and Diaphragm Release Techniques on Cardiac Autonomic Control in Patients With Chronic Obstructive Pulmonary Disease: A Pilot Study

Objective

The purpose of this pilot study was to evaluate the feasibility of testing an intervention protocol and measuring the immediate effects of a rib mobilization technique (RMT) and a diaphragm release technique (DRT) on the autonomic nervous system of patients with chronic obstructive pulmonary disease (COPD).

Methods

This was a pilot study of a randomized controlled trial. Fourteen individuals were evaluated. Eligibility criteria were being a sedentary person with a diagnosis of COPD, age between 50 and 72 years, and being clinically stable. Exclusion criteria were heart disease, other respiratory comorbidities, and body mass index above 30kg/m². Participants first underwent cardiorespiratory evaluation and were then allocated into 2 groups: the RMT + DRT group and the DRT group. Clinical assessments were performed immediately before and after the intervention. Statistical analysis was carried out through a paired-sample Wilcoxon test, and the comparison between groups was performed using the Mann-Whitney test.

Results

All randomized participants completed the assessment and intervention protocol. Sample size was estimated at 24 individuals per group. The DRT group decreased resting heart rate by 5 bpm (P = .03) and increased variance (P = .04) and mean R-R interval (P = .03). The RMT + DRT group decreased mean R-R interval (P = .02).

Conclusion

The design for this study appears to be feasible for evaluating manual-therapy intervention in the nonmusculoskeletal function of patients with COPD. It was possible to determine the sample size for future studies. Preliminary data show that the diaphragm release technique may reduce mean resting heart rate and increase heart-rate variability immediately after the intervention.

Resistance exercise training improves mucociliary clearance in subjects with COPD: A randomized clinical trial

INTRODUCTION

Elastic tubing was recently investigated as an alternative to the conventional resistance training (RT) in chronic obstructive pulmonary disease (COPD). The effects of RT on the mucociliary system have not yet been reported in the literature.

OBJECTIVE

The aim of this study was to evaluate the effects of two RT programs on mucociliary clearance in subjects with COPD.

METHODS

Twentyeight subjects with COPD were randomly allocated by strata, according to individual strength of lower limbs, to defined groups: conventional resistance training (GCT) or resistance training using elastic tubing (GET). Nineteen subjects (GET: n=9; GCT: n=10) completed the study and were included in the analysis. The measurement of vital signs (blood pressure, heart rate and respiratory rate), lung function (spirometry) and the primary outcome mucociliary clearance analysis (saccharin transit time test (STT)) were performed before and after the 12 weeks of RT.

RESULTS

In relation to the mucociliary transportability analysis, no differences were observed between the baseline evaluations of the training groups (p=0.05). There was a significant reduction in the STT values in both training groups, GET (10.64±5.06 to 6.01±4.91) and GCT (12.07±5.10 to 7.36±2.54) with p=0.03. However, no differences between groups were observed on the magnitude of SST changes after interventions (GET: -43.51%; GCT: -38.94%; p=0.97).

CONCLUSION

The present study demonstrated that both RT with elastic tubing and conventional training with weights promoted similar gains in the mucociliary transportability of subjects with COPD.

Effects of Water-Based Aerobic Interval Training in Patients With COPD: A RANDOMIZED CONTROLLED TRIAL

PURPOSE

Chronic obstructive pulmonary disease promotes systemic repercussions, which can be minimized with physical exercise. This study investigated the effects of a water-based aerobic interval training program on the autonomic modulation of heart rate (HR), quality of life (QoL), and functional capacity (FC) of patients with chronic obstructive pulmonary disease.

METHODS

Nineteen patients with chronic obstructive pulmonary disease were enrolled in this randomized clinical trial and allocated to either the usual care group (n = 9) or training group (n = 10). Before and after 24 sessions of water-based physical training, the patients underwent evaluation of autonomic modulation of HR by analyzing the HR variability, QoL using the St George's Respiratory Questionnaire, and FC using 6-min walk test distance.

RESULTS

The results showed significant improvement when comparing the variables of HR variability, QoL, and FC in the training group in the pre- and post-training conditions (P < .05). In the usual care group, there was no significant difference for any of the variables. Negative correlations were found between HR variability and QoL (r =-0. 55; P = .01) and 6-min walk test distance and QoL (r =-0.49; P = .02).

CONCLUSION

Water-based physical training promoted beneficial adaptations in the autonomic modulation of HR, QoL, and FC of patients with chronic obstructive pulmonary disease.

Analysis of Autonomic Modulation in Response to a Session of Aerobic Exercise at Different Intensities in Patients With Moderate and Severe COPD

Despite the many benefits of performing physical exercise in patients with chronic obstructive pulmonary disease (COPD), information on the response of acute cardiac autonomic modulation in subjects with moderate and severe COPD during and after an aerobic exercise session at different intensities is unknown. The aim of this study was to evaluate the response of cardiac autonomic modulation in patients with moderate and severe COPD during and after an aerobic exercise session at different intensities. Twenty-seven patients with COPD, divided into: Moderate Group and Severe Group, underwent an aerobic exercise sessions with intensities equivalent to 60% and 90% of velocity corresponding to peak oxygen consumption. The heart rate variability (HRV) indices were analyzed in the time and frequency domains at the following times: at rest, during exercise, immediately after, and 5, 10, and 15 minutes after exercise. In the comparison analysis between the two groups, no differences were observed in any of the HRV indices at different intensities applied. However, it was observed that the exercise caused autonomic changes when the groups were analyzed separately. Sessions of aerobic exercise influence the autonomic modulation in patients with COPD. However, COPD severity did not influence the autonomic nervous system response to exercise and recovery moments; and there was no difference between the exercise intensities.

Two Days of Measurement Provides Reliable Estimates of Physical Activity Poststroke: An Observational Study

OBJECTIVE

The aim of this study was to determine the duration of physical activity (PA) monitoring required for reliable measurements following stroke.

DESIGN

Single-center, prospective, observational study.

SETTING

PA was measured in a community setting.

PARTICIPANTS

Adults (N=70) poststroke.

MAIN OUTCOME MEASURES

The SenseWear armband was used to monitor PA for 5 days (≥10 hours wear per day).

DATA ANALYSIS

Variance among 2, 3, 4, and 5 days of consecutive measurements for PA variables was examined using intraclass correlation coefficients (ICCs). The minimum number of days to achieve acceptable reliability (ICC ≥0.8) was calculated. Differences between weekdays and weekend days were investigated using paired t tests and Wilcoxon signed rank tests.

RESULTS

Two days of measurement was sufficient to achieve an ICC ≥0.8 for daily averages of total energy expenditure, step count, and time spent sedentary (≤1.5 metabolic equivalent tasks [METs]) and in light (1.5-3 METs) and moderate- to vigorous-intensity (>3 METs) PA. At least 3 days were required to achieve an ICC ≥0.8 when investigating the number of and time spent in bouts (≥10 minutes) of moderate to vigorous PA and sedentary behavior. Participants took significantly more steps (P=.03) and spent more time in light PA (P=.03) on weekdays than weekends.

CONCLUSION

Following stroke, 2 days of measurement appears sufficient to represent habitual PA for many simple variables. Three or more days may be necessary for reliable estimates of bouts of PA and sedentary behavior. Consistent inclusion or exclusion of a weekend day is recommended for measuring step count and light PA. Short periods of monitoring provide reliable PA information and may make PA measurement more feasible in the clinical setting.

Plasma Leptin Concentration and Sympathetic Nervous Activity in Older Adults With Physical Dysfunction

Context

Previous research has shown a positive relationship between plasma leptin and sympathetic nervous activity. High plasma leptin activate inflammatory cytokines and lead to muscle wasting. However, studies have detected low sympathetic nervous activity and high plasma leptin in older adults with muscle wasting, sarcopenia, and frailty. High plasma leptin do not seem to correlate with high sympathetic nervous activity. However, their relationship in older adults remains unclear.

Objective

We investigated the relationship between plasma leptin and sympathetic nervous activity in older adults.

Design, Setting, and Participants

We conducted a cross-sectional study and analyzed the results from 69 participants aged ≥75 years. Sympathetic nervous activity was measured by heart rate variability, obtained from 24-hour Holter monitoring. A functional independence measure (FIM) and Barthel index were used to assess physical function.

Results

The plasma leptin was higher in women (men, 3.4 ± 2.8 ng/mL; women, 6.6 ± 6.5 ng/mL; P = 0.024). Plasma leptin was negatively and substantially related to the FIM (β = −0.233; P = 0.049) and Barthel index (β = −0.298, P = 0.018) after adjustment for covariates. However, the data showed no relationship between the plasma leptin and sympathetic nervous activity.

Conclusions

We could not detect an association between sympathetic nervous activity and plasma leptin in older adults. This might suggest a failure of the feedback system of the sympathetic nervous system, leading to muscle wasting in older adults.

The effects of home oxygen therapy on energy metabolism in patients with COPD

Background

COPD is preventable and treatable and is characterized by completely nonreversible airflow obstruction. In this study, we aimed to investigate the effect of long-term oxygen therapy on patients with stage 4 COPD who were followed up and treated at the polyclinic or clinic service. We evaluated the effects of oxygen therapy on energy metabolism and physical activity in patients with COPD.

Methods

Nineteen patients with COPD (16 male/3 female), treated with oxygen therapy for the first time, were included in this study. Analysis of arterial blood gases and pulmonary function test was performed. Metabolic Holter device (SenseWear^® Armband) was placed pre- and post-oxygen therapy on the patients’ arm for at least 3 days. This device captures Holter data in a digitized electronic system, and the daily average value was calculated from the data.

Results

Post-oxygen treatment showed a significant increase in energy expenditure by patients with COPD (pretreatment, 1,497±596 joule; posttreatment, 2,977±5,985 joule; P=0.044). Moreover, number of steps during walking (pretreatment, 2,056±256; posttreatment, 2,120±195; P=0.03), resting (pretreatment, 6.36±3.31 hours; posttreatment, 3.47±2.19 hours; P<0.03), and sleeping (pretreatment, 4.23±2.13 hours; posttreatment, 2.33±1.42 hours; P<0.00) showed significant differences. Increased daily energy expenditure in patients with respiratory failure was detected with long-term oxygen therapy. In addition, the immobility of patients decreased and duration of physical activity increased in patients with COPD.

Conclusion

In this study, positive effects of long-term oxygen therapy have been demonstrated with respect to energy metabolism and physical activity of patients with COPD. Thus, we recommend that medication adherence and long-term oxygen therapy should begin early in patients with COPD.

What is the relationship between physical activity and cardiovascular risk factors in stroke survivors post completion of rehabilitation? Protocol for a longitudinal study

INTRODUCTION

Physical activity (PA) can modify cardiovascular and other health risks in people with stroke, but we know little about long-term PA in this group. This study aims to describe PA levels and investigate relationships between PA, cardiovascular risk factors, mobility and participant characteristics (eg, age, mood and fatigue) in the 2 years following rehabilitation discharge after first stroke.

METHODS AND ANALYSIS

This is a longitudinal observational study with follow-up at 6, 12 and 24 months after rehabilitation discharge. Inclusion criteria are broad; excluding only those with previous stroke, palliative diagnosis, living more than 2 hours from the centre or admitted less than 5 days.The primary outcome of interest is duration of moderate to vigorous PA (min/day) measured by the Sensewear MF Armband (SWAB). Secondary outcomes include other PA measures measured with the SWAB; cardiovascular risk factors (eg, systolic blood pressure, fasting lipid profile and smoking status), mobility (10 m walk test), the Hospital Anxiety and Depression Scale and the Fatigue Severity Scale. All outcomes, except blood tests, are gathered at each time point.The target sample size is 77. We will explore associations between PA levels, cardiovascular risk factors, mobility and participant characteristics at baseline compared with 6, 12 and 24 months using random-effects regression modelling.The long-term PA of stroke survivors is largely unknown. We hope to identify factors that influence PA and cardiovascular risk in this population, which may help health professionals target the stroke survivors most at risk and implement appropriate treatment, preventative strategies and education.

ETHICS AND DISSEMINATION

Approval was granted from Alfred Hospital and La Trobe University Research Ethics Committees. The study results will be disseminated in a number of ways including journal publication and international conference presentations.

TRIAL REGISTRATION NUMBER

ACTRN12613000196741.

Effect of respiratory rehabilitation techniques on the autonomic function in patients with chronic obstructive pulmonary disease: A systematic review

Patients with chronic obstructive pulmonary disease (COPD) show several extrapulmonary abnormalities such as impairment in the autonomic function (AF). Similarly, the use of respiratory training techniques such as controlled breathing techniques, noninvasive mechanical ventilation (NIMV), and oxygen supplementation for AF modulation in patients with COPD is popular in existing literature. However, the evidence to support their use is nonexistent. A systematic search of studies reporting on the effect of controlled breathing techniques, NIMV, and/or oxygen supplementation techniques on AF outcome parameters was conducted in three online databases: PubMed, Embase, and Web of Science. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement, relevant studies were retained and qualitatively analyzed for evidence synthesis. The methodological quality in these studies was evaluated using the evidence based guideline development (EBRO) checklists per designs provided by the Dutch Cochrane Centre. Eighteen studies met the inclusion criteria of the review and were included and discussed. The evidence synthesis revealed that a strong and moderate level evidence supported oxygen supplementation and slow breathing techniques, respectively, in significantly enhancing the baroreceptor sensitivity (BRS) values in patients with COPD. The effect of the examined techniques on the heart rate variability and muscle sympathetic nerve activity was of a limited or inconsistent evidence. The findings from this review suggest that oxygen supplementation and controlled breathing techniques have profound positive influence on the BRS in patients with COPD. However, it is not fully clear whether these influence translates to any therapeutic benefit on the general AF of patients with COPD in the long term.

Increased parasympathetic cardiac modulation in patients with acute exacerbation of COPD: how should we interpret it?

Background

Cardiac autonomic modulation (CAM) is impaired in patients with stable COPD. Exacerbation aggravates the patients’ health status and functional capacity. While the clinical and functional effects of exacerbation are known, no studies investigated CAM during exacerbation and whether there is a relationship between CAM and functional capacity and dyspnea.

Methods

Thirty-two patients with moderate to severe COPD were enrolled into two groups: stable COPD (GSta, n=16) and acute exacerbation of COPD (GAE, n=16). The GAE patients were evaluated 24–48 hours after starting standard therapy for COPD exacerbation during hospitalization; the GSta patients were evaluated in an outpatient clinic and included in the study if no decompensation episodes had occurred during the previous month. The heart rate (HR) and R-wave peak detection intervals in ms (RRi) were registered using a heart rate monitor (Polar^® system) at rest in seated position during 10 minutes. CAM was assessed by heart rate variability (HRV) linear and non-linear analysis. Functional capacity was evaluated by handgrip strength test, performed by Jamar^® dynamometer, and dyspnea was scored using the modified scale of the Medical Research Council.

Results

GAE presented higher parasympathetic CAM values compared with GSta for square root of the mean squared differences of successive RRi (RMSSD; 17.8±5.6 ms vs 11.7±9.5 ms); high frequency (HF; 111.3±74.9 ms² vs 45.6±80.7 ms²) and standard deviation measuring the dispersion of points in the plot perpendicular to the line of identity (SD1; 12.7±3.9 ms vs 8.3±6.7 ms) and higher CAM values for standard deviation of the mean of all of RRi (STD RRi; 19.3±6.5 ms vs 14.3±12.5 ms); RRi tri (5.2±1.7 ms vs 4.0±3.0 ms); triangular interpolation of NN interval histogram (TINN; 88.7±26.9 ms vs 70.6±62.2 ms); low frequency (LF; 203±210.7 ms² vs 101.8±169.7 ms²) and standard deviation measuring the dispersion of points along the line of identity (SD2; 30.4±14.8 ms vs 16.2±12.54 ms). Lower values were observed for the complexity indices: approximate entropy (ApEn; 0.9±0.07 vs 1.06±0.06) and sample entropy (SampEn; 1.4±0.3 vs 1.7±0.3). Significant and moderate associations were observed between HF (nu) and handgrip strength (r=−0.58; P=0.01) and between LF (ms²) and subjective perception of dyspnea (r=−0.53; P=0.03).

Conclusion

COPD exacerbated patients have higher parasympathetic CAM than stable patients. This should be interpreted with caution since vagal influence on the airways determines a narrowing and not a better clinical condition. Additionally, functional capacity was negatively associated with parasympathetic CAM in COPD exacerbation.

Are heart rate dynamics in the transition from rest to submaximal exercise related to maximal cardiorespiratory responses in COPD?

BACKGROUND

Poor exercise capacity is an important negative prognostic marker in patients with chronic obstructive pulmonary disease (COPD). Heart rate variability (HRV) responses can indicate alterations in cardiac autonomic control. Nevertheless, it remains unclear whether these abnormalities are related to cardiorespiratory responses to exercise in these patients.

OBJECTIVE

To evaluate whether HRV at rest and submaximal exercise are related to impaired cardiopulmonary responses to exercise in COPD patients.

METHODS

Fifteen men (66.2±8.7 years) with COPD (FEV1: 55.1±19.2%) were assessed. The R-R interval (RRi) data collection was performed at rest (stand position) and during the six-minute walk test (6MWT). All patients performed a symptom-limited cardiopulmonary exercise test on a cycle ergometer. The HRV changes from rest to submaximal exercise (Δ rest-6MWT) were calculated.

RESULTS

We found significant correlations between low frequency (LF) and high frequency (HF) Δ rest-6MWT with Δ oxyhemoglobin saturation by pulse oximetry (r=-0.64 and r=0.65, respectively; p<0.05), minute ventilation/carbon dioxide output relationship from beginning to peak exercise (r=-0.52 and r=0.53, p<0.05), and exercise ventilatory power (r=0.52 and r=-0.53, p<0.05). Interestingly, there was a strong positive correlation (r=0.82, p<0.05) between six-minute walk distance (6MWD) and Δ LF/HF from rest to exercise.

CONCLUSION

HRV analysis in the transition from rest to submaximal exercise is associated with exercise ventilatory and hemodynamic abnormalities in COPD patients. Rehabilitative strategies to improve HRV responses may provide an important tool to clinical practice in these patients.

Short-term cardiovascular and autonomic effects of inhaled salbutamol

Asthma independently increases the risk of developing cardiovascular disease. As inhaled β-agonists have systemic cardiovascular effects, and elevations in arterial stiffness and sympathetic nerve activity are associated with increased cardiovascular morbidity/mortality, this study examines the effect of salbutamol use on pulse wave velocity (PWV) and muscle sympathetic nervous activity (MSNA). Healthy men and women (26.2±1.5years) were recruited for: Day 1: 4 inhalations of placebo followed by 4 inhalations of salbutamol (4×100μg); Day 2: placebo only; Day 3: carotid-femoral PWV measurements before/after placebo/salbutamol. Heart rate (HR), mean arterial pressure (MAP), and carotid-radial PWV were obtained on Day 1 and 2. MSNA was obtained on Day 1. Salbutamol increased HR and total MSNA (Baseline1: 2.8±2.8au; Placebo: 2.4±2.1au; Baseline2: 2.7±3.0au; Salbutamol: 3.3±2.9au; p=0.05), with no changes in MAP or PWV. There were no effects of placebo on HR, MSNA, or PWV. Acute salbutamol use increases sympathetic activity suggesting that salbutamol could contribute to cardiovascular morbidity/mortality in individuals using inhaled β-agonists.

Favorable effect of sympathetic nervous activity on rehabilitation outcomes in frail elderly

OBJECTIVES

Previous studies have suggested the relationship between physical function, mortality, and autonomic nervous activity in frail elderly and that maintaining sympathetic nervous activity might lead to improved physical function and mortality in the elderly population. The aim of this study was to investigate the utility of sympathetic nervous activity measured by heart rate variability in frail elderly patients undergoing inpatient rehabilitation, further focusing the nervous activity on the effect of rehabilitation therapy.

DESIGN

Prospective cohort study.

PARTICIPANTS

Sixty-one subjects aged 75 years or older were recruited after treatment of acute phase illness.

MEASUREMENTS

Before undergoing rehabilitation, data of 24-hour Holter monitoring and a blood venous sample were obtained. From RR intervals in the electrocardiogram, heart rate and SDs of all NN intervals in all 5-minute segments of the entire recording, power spectral density, low frequency (LF), high frequency (HF), and low frequency/high frequency (LF/HF) were calculated. Functional Independence Measure (FIM) and Barthel index were used to measure physical function.

RESULTS

FIM score and Barthel index were 46.8 ± 25.4 and 32.8 ± 31.7, respectively. Serum total protein, albumin, hemoglobin, and total cholesterol were all significantly related to FIM score and Barthel index before rehabilitation. Heart rate variability indices did not show a significant relationship with physical function, whereas the high LH/HF group showed significant improvement in physical function compared with the low LH/HF group. Moreover, LF/HF frequency was a predictive factor for improvement of physical function after 2 months of rehabilitation.

CONCLUSION

A favorable effect of preserved LF/HF on rehabilitation outcome was observed in elderly undergoing rehabilitation. Preservation of sympathetic nervous activity may lead to improved physical function in the elderly.

Relationship between linear and nonlinear dynamics of heart rate and impairment of lung function in COPD patients

BACKGROUND

In chronic obstructive pulmonary disease (COPD), functional and structural impairment of lung function can negatively impact heart rate variability (HRV); however, it is unknown if static lung volumes and lung diffusion capacity negatively impacts HRV responses. We investigated whether impairment of static lung volumes and lung diffusion capacity could be related to HRV indices in patients with moderate to severe COPD.

METHODS

Sixteen sedentary males with COPD were enrolled in this study. Resting blood gases, static lung volumes, and lung diffusion capacity for carbon monoxide (DLCO) were measured. The RR interval (RRi) was registered in the supine, standing, and seated positions (10 minutes each) and during 4 minutes of a respiratory sinus arrhythmia maneuver (M-RSA). Delta changes (Δsupine-standing and Δsupine-M-RSA) of the standard deviation of normal RRi, low frequency (LF, normalized units [nu]) and high frequency (HF [nu]), SD1, SD2, alpha1, alpha2, and approximate entropy (ApEn) indices were calculated.

RESULTS

HF, LF, SD1, SD2, and alpha1 deltas significantly correlated with forced expiratory volume in 1 second, DLCO, airway resistance, residual volume, inspiratory capacity/total lung capacity ratio, and residual volume/total lung capacity ratio. Significant and moderate associations were also observed between LF/HF ratio versus total gas volume (%), r=0.53; LF/HF ratio versus residual volume, %, r=0.52; and HF versus total gas volume (%), r=-0.53 (P<0.05). Linear regression analysis revealed that ΔRRi supine-M-RSA was independently related to DLCO (r=-0.77, r (2)=0.43, P<0.05).

CONCLUSION

Responses of HRV indices were more prominent during M-RSA in moderate to severe COPD. Moreover, greater lung function impairment was related to poorer heart rate dynamics. Finally, impaired lung diffusion capacity was related to an altered parasympathetic response in these patients.

A natural walking monitor for pulmonary patients using mobile phones

Mobile devices have the potential to continuously monitor health by collecting movement data including walking speed during natural walking. Natural walking is walking without artificial speed constraints present in both treadmill and nurse-assisted walking. Fitness trackers have become popular which record steps taken and distance, typically using a fixed stride length. While useful for everyday purposes, medical monitoring requires precise accuracy and testing on real patients with a scientifically valid measure. Walking speed is closely linked to morbidity in patients and widely used for medical assessment via measured walking. The 6-min walk test (6MWT) is a standard assessment for chronic obstructive pulmonary disease and congestive heart failure. Current generation smartphone hardware contains similar sensor chips as in medical devices and popular fitness devices. We developed a middleware software, MoveSense, which runs on standalone smartphones while providing comparable readings to medical accelerometers. We evaluate six machine learning methods to obtain gait speed during natural walking training models to predict natural walking speed and distance during a 6MWT with 28 pulmonary patients and ten subjects without pulmonary condition. We also compare our model's accuracy to popular fitness devices. Our universally trained support vector machine models produce 6MWT distance with 3.23% error during a controlled 6MWT and 11.2% during natural free walking. Furthermore, our model attains 7.9% error when tested on five subjects for distance estimation compared to the 50-400% error seen in fitness devices during natural walking.

A single exposure to acrolein desensitizes baroreflex responsiveness and increases cardiac arrhythmias in normotensive and hypertensive rats

Short-term exposure to air pollutants has been linked to acute cardiovascular morbidity and mortality. Even in the absence of overt signs or symptoms, pollutants can cause subtle disruptions to internal compensatory mechanisms, which maintain homeostatic balance in response to various environmental and physiological stressors. We hypothesized that a single exposure to acrolein, a ubiquitous gaseous air pollutant, would decrease the sensitivity of baroreflex (BRS), which maintains blood pressure by altering heart rate (HR), modify cardiac electrophysiological properties and increase arrhythmia in rats. Wistar-Kyoto normotensive (WKY) and spontaneously hypertensive (SH) rats implanted with radiotelemeters and a chronic jugular vein catheter were tested for BRS using phenylephrine and sodium nitroprusside 2 days before and 1 h after whole-body exposure to 3 ppm acrolein (3 h). HR and electrocardiogram (ECG) were continuously monitored for the detection of arrhythmia in the pre-exposure, exposure and post-exposure periods. Whole-body plethysmography was used to continuously monitor ventilation in conscious animals. SH rats had higher blood pressure, lower BRS and increased frequency of AV block as evidence by non-conducted p-waves when compared with WKY rats. A single exposure to acrolein caused a decrease in BRS and increased incidence of arrhythmia in both WKY and SH rats. There were minimal ECG differences between the strains, whereas only SH rats experienced irregular breathing during acrolein. These results demonstrate that acrolein causes immediate cardiovascular reflexive dysfunction and persistent arrhythmia in both normal and hypertensive animals. As such, homeostatic imbalance may be one mechanism by which air pollution increases risk 24 h after exposure, particularly in people with underlying cardiovascular disease.

Effects of interval and continuous exercise training on autonomic cardiac function in COPD patients

BACKGROUND AND AIM

Both interval (IT) and continuous (CT) exercise training results in an improvement of aerobic capacity in patients with chronic obstructive pulmonary disease (COPD); however, their effects on cardiac autonomic function remains unclear. The aim of our study was to evaluate the effect of a supervised CT vs IT on autonomic cardiac function in COPD patients.

METHODS

COPD patients were divided into two different groups according to training modality (IT or CT). Autonomic cardiac dysfunction (ACD) was defined as a heart rate recovery lower than 12 bpm heart rate after the first minute of maximal exercise (HRR1 ) and an abnormal chronotropic response (CR) to exercise (<80%).

RESULTS

A total of 29 patients {mean [standard deviation (SD)] age: 68 (8) years, %FEV1 : 42 (13) predicted} were trained (15 subjects in the CT group, 14 subjects in the IT group). After training, both groups increased peak oxygen consumption [mean difference ΔVO2 peak: 156 mL/min (P = 0.04) on IT; and 210 mL/min (P = 0.01) on CT], HRR1 [IT, from 10.4 (5) to 13.8 (5) bpm (P = 0.04); and CT, from 14.3 (5) to 17.7 (5) bpm (P = 0.04)] and CR [IT, from 57% (22) to 81% (9) (P = 0.001); and CT, from 48% (28) to 73% (17) (P = 0.001)]. Sixteen patients showed ACD. Among these patients, HRR1 (P = 0.01 for IT and P = 0.04 for CT) and CR (P = 0.001 for IT and P = 0.002 for CT) were enhanced after training.

CONCLUSIONS

Both IT and CT exercise training improve heart rate recovery and CR in COPD patients. These benefits could help to individualize exercise training.

Arterial stiffness in COPD

In patients with COPD, cardiovascular diseases are the most common concomitant chronic diseases, a leading cause of hospitalization, and one of the main causes of death. A close connection exists between COPD and cardiovascular diseases. Cardiovascular risk scores aim to predict the effect of cardiovascular comorbidities on COPD mortality, but there is a need to better characterize occult and suboccult cardiovascular disease, even in patients with mild to moderate COPD. Among various surrogate markers of cardiovascular risk, arterial stiffness plays a central role and is a strong independent predictor of cardiovascular events beyond classic cardiovascular risk factors. Its measurement is highly suitable, validated, and relatively easy to perform in routine COPD clinical practice. The growing awareness of the increased cardiovascular risk associated with COPD has led to a call for respiratory physicians to measure arterial pulse wave velocity in routine practice. Cross-sectional data establish elevated arterial stiffness as being independently linked to COPD. Candidate mechanisms have been proposed, but surprisingly, only limited data are available regarding the impact of the different COPD treatment modalities on arterial stiffness, although initial studies have suggested a significant positive impact. In this review, we present the various surrogate markers of cardiovascular morbidity in COPD and the central role of arterial stiffness and the underlying mechanisms explaining vascular remodeling in COPD. We also consider the therapeutic impact of COPD medications and exercise training on arterial stiffness and the assessments that should be implemented in COPD care and follow-up.

Measurement of activities of daily living in patients with COPD: a systematic review

BACKGROUND

The objectives of this systematic review were to synthesize the literature on measures of activities of daily living (ADLs) that have been used in individuals with COPD and to provide an overview of the psychometric properties of the identified measures and describe the relationship of the disease-specific instruments with other relevant outcome measures for individuals with COPD and health-care use.

METHODS

Studies that included a measure of ADLs in individuals with COPD were identified using electronic and hand searches. Two investigators performed the literature search. One investigator reviewed the study title, abstract, and full text of the articles to determine study eligibility and performed the data extraction and tabulation. In cases of uncertainty, a second reviewer was consulted.

RESULTS

A total of 679 articles were identified. Of those, 116 met the inclusion criteria. Twenty-seven ADLs instruments were identified, of which 11 instruments were respiratory disease-specific, whereas 16 were generic. Most instruments combined instrumental ADLs (IADLs) with basic ADLs (BADLs). The majority of the instruments were self-reported; only three instruments were performance based. Twenty-one studies assessed psychometric properties of 16 ADLs instruments in patients with COPD.

CONCLUSIONS

Although several ADLs instruments were identified, psychometric properties have only been reported in a few. Selection of the most appropriate measure should focus on the target construct (BADLs or IADLs or both), type of test (disease-specific vs generic and self-reported vs performance-based), depth of information obtained, and psychometric properties of the instruments. Given the relevance of ADLs to the lives of patients with COPD, its assessment should be more frequently incorporated as a clinical outcome in their management.

Effect of pursed-lip breathing in patients with COPD: Linear and nonlinear analysis of cardiac autonomic modulation

OBJECTIVE

The aim of the present study was to evaluate the effect of pursed-lip breathing (PLB) on cardiac autonomic modulation in individuals with chronic obstructive pulmonary disease (COPD) while at rest.

METHODS

Thirty-two individuals were allocated to one of two groups: COPD (n = 17; 67.29 ± 6.87 years of age) and control (n = 15; 63.2 ± 7.96 years of age). The groups were submitted to a two-stage experimental protocol. The first stage consisted of the characterization of the sample and spirometry. The second stage comprised the analysis of cardiac autonomic modulation through the recording of R-R intervals. This analysis was performed using both nonlinear and linear heart rate variability (HRV). In the statistical analysis, the level of significance was set to 5% (p ≤ 0.05).

RESULTS

PLB promoted significant increases in the SD1, SD2, RMSSD and LF (ms(2)) indices as well as an increase in α1 and a reduction in α2 in the COPD group. A greater dispersion of points on the Poincaré plots was also observed. The magnitude of the changes produced by PLB differed between groups.

CONCLUSION

PLB led to a loss of fractal correlation properties of heart rate in the direction of linearity in patients with COPD as well as an increase in vagal activity and impact on the spectral analysis. The difference in the magnitude of the changes produced by PLB between groups may be related to the presence of the disease and alterations in the respiration rate.

Association of decreased sympathetic nervous activity with mortality of older adults in long-term care

AIM

To investigate the relationship between physical function, mortality and autonomic nervous activity measured by heart rate variability of elderly in long-term care.

METHODS

Cross-sectional and longitudinal studies were carried out at hospitals and health service facilities for the elderly in Nagano prefecture, Japan, from July 2007 to March 2011. A total of 105 long-term care older adults and 17 control older adults with independent physical function were included. The Functional Independence Measure (FIM) and Barthel Index were determined as indices of physical function. Twenty-four-hour Holter monitoring was carried out. From RR intervals in electrocardiograms, heart rate and standard deviations of all NN intervals in all 5-min segments of the entire recording, power spectral density, low frequency, high frequency and low frequency/high frequency (LF/HF) were calculated.

RESULTS

FIM score and Barthel Index were 46 ± 26 and 30 ± 31, respectively, in long-term care elderly. FIM and Barthel index were significantly correlated with heart rate and the standard deviations of all NN intervals after adjustment for age, sex, cardiovascular risk factors and FIM. Furthermore, LF/HF was significantly decreased in long-term care elderly compared with control elderly after adjustment for covariates. In addition, decrease in LF/HF was an independent risk factor for mortality.

CONCLUSION

Low LF/HF activity was observed in long-term care elderly and was related to an increase of overall mortality.

C-reactive protein, lung hyperinflation and heart rate variability in chronic obstructive pulmonary disease --a pilot study

Chronic obstructive pulmonary disease (COPD) is associated to cardiovascular morbidity and mortality, and abnormalities of the autonomic nervous system have been described in subjects with severe disease. We studied heart rate variability (HRV) in COPD patients at rest and during the 6-minute Walk Test (6mWT) and the association with lung function impairment taking into account systemic inflammation. Thirty outpatients with stable COPD underwent lung function measurements, blood gas analysis, ECG Holter and transcutaneous pulse oximetry during 6mWT and then they were classified by BODE index. Also C-reactive protein (CRP) was measured. At rest, we observed a significant reduction of HRV for increasing BODE index. During the 6mWT, HRV tended to decrease in BODE 1 subjects whereas an increase was observed in BODE 2 and BODE 3-4 subjects. Subjects with elevated CRP values had a significant reduction in Standard Deviation of all normal RR intervals at rest (SDNN: p = 0.013), Total Power (TFA: p = 0.04) and Very Low Frequency band (VLF: p = 0.041). At rest, subjects with Inspiratory Capacity-to-Total Lung Capacity ratio (IC/TLC) < 36% had a significant reduced SDNN (p = 0.004), TFA (p = 0.001), VLF (p = 0.001), Low Frequency band (p = 0.007). During 6mWT, changes of HRV parameters were significantly related to airflow obstruction and static hyperinflation indices. At rest and during submaximal exercise, COPD patients with moderate and severe disease had an abnormal cardiac autonomic modulation which was related to both systemic inflammation and lung function impairment.

Physical activity monitoring by use of accelerometer-based body-worn sensors in older adults: a systematic literature review of current knowledge and applications

OBJECTIVES

To systematically review the literature on physical activity variables derived from body-worn sensors during long term monitoring in healthy and in-care older adults.

METHODS

Using pre-designed inclusion and exclusion criteria, a PubMed search strategy was designed to trace relevant reports of studies. Last search date was March 8, 2011.

STUDY SELECTION

Studies that included persons with mean or median age of >65 years, used accelerometer-based body-worn sensors with a monitoring length of >24h, and reported values on physical activity in the samples assessed.

RESULTS

1403 abstracts were revealed and 134 full-text papers included in the final review. A variety of variables derived from activity counts or recognition of performed activities were reported in healthy older adults as well as in in-care older adults. Three variables were possible to compare across studies, level of Energy Expenditure in kcal per day and activity recognition in terms of total time in walking and total activity. However, physical activity measured by these variables demonstrated large variation between studies and did not distinguish activity between healthy and in-care samples.

CONCLUSION

There is a rich variety in methods used for data collection and analysis as well as in reported variables. Different aspects of physical activity can be described, but the variety makes it challenging to compare across studies. There is an urgent need for developing consensus on activity monitoring protocols and which variables to report.

Improvement of heart rate variability by eurythmy therapy after a 6-week eurythmy therapy training

BACKGROUND

Eurythmy therapy (EYT) is a mind-body therapy used in anthroposophic medicine. Recently, the authors were able to show that at comparable workloads, EYT stimulated heart rate variability (HRV) whereas conventional ergometer training attenuated HRV. Furthermore, a long-term improvement of quality of life (QoL) and stress coping strategies by EYT could be shown.

OBJECTIVE

This study aimed to evaluate the long-term effects of EYT training on HRV.

DESIGN

A total of 23 healthy women (mean age = 44.57 ± 8.04 years) performed 10 hours of EYT over a period of 6 weeks. Electrocardiograms were recorded before and after the EYT trial. HRV was quantified by the extent of high (HF), low (LF), very low (VLF), and ultra low frequency (ULF) oscillations of heart rate.

RESULTS

Autonomic regulation was significantly changed following the EYT training compared with baseline. Especially the proportion referring to the total power (P) of HF/P and LF/P increased, whereas ULF/P and (ULF+VLF)/P decreased after the training period.

CONCLUSION

EYT shifted the autonomic regulation proportionally referring to the total power mainly caused by changes of ULF and VLF components of HRV. The LF and HF spectral components were also decreased following EYT while their proportion in relation to the total variance of the power spectrum was increased. The proportional enhancement of the higher frequency and the decrease of the ULF and VLF components are probably an indicator of an improvement of autonomic regulation processes by more relaxed physical activity after the EYT training, thus supporting the plausibility of the improved QoL and better stress coping strategies.

Early postural blood pressure response and cause-specific mortality among middle-aged adults

Orthostatic hypotension (OH) is associated with increased total mortality but contribution of specific death causes has not been thoroughly explored. In this prospective study, authors followed up 32,068 individuals without baseline history of cancer or cardiovascular disease (69% men; mean age, 46 years; range, 26-61 years) over a period of 24 years. Hazard ratios (HRs) for total and cause-specific mortality associated with presence of OH and by quartiles of postural systolic blood pressure response (∆SBP) were assessed using multivariate adjusted Cox regression model. A total of 7,145 deaths (22.3%, 9.4 deaths/1,000 person-years) occurred during follow-up. Those with OH (n = 1,943) had higher risk of death due to injury (HR, 1.88; 1.37-2.57) and neurological disease (HR, 2.21; 1.39-3.51). Analogically, risk of death caused by injury and neurological disease increased across the quartiles of ∆SBP from hyper- (Q1(SBP), +8.5 ± 4.7 mmHg) to hypotensive response (Q4(SBP), -13.7 ± 5.7 mmHg; HR, 1.32; 1.00-1.72, and 1.84; 1.20-2.82, respectively) as did also risk of death due to respiratory disease (Q4(SBP) vs. Q1(SBP): HR, 1.53; 1.14-2.04). In contrast, risk curve for cerebrovascular death was U-shaped with nadir in the mildly hypotensive 3rd quartile of ∆SBP (-5.0 ± 0.1 mmHg, Q3(SBP) vs. Q1(SBP): HR, 0.75; 0.54-1.03; P for linear trend = 0.021). Additionally, cardiovascular mortality was increased among 5,805 rescreened participants (mean age, 53 years; 9.8% OH positive: HR, 1.54; 1.24-1.89, and Q4(SBP) vs. Q1(SBP): 1.27; 1.02-1.57, respectively). In summary, increased mortality predicted by blood pressure fall on standing is associated with injuries, neurodegenerative, and respiratory diseases, as well as with cardiovascular disease in older adults. Moreover, both increase and pronounced decrease of SBP during early orthostasis indicate higher risk of cerebrovascular death.

Consequences of physical inactivity in chronic obstructive pulmonary disease

The many health benefits of regular physical activity underline the importance of this topic, especially in this period of time when the prevalence of a sedentary lifestyle in the population is increasing. Physical activity levels are especially low in patients with chronic obstructive pulmonary disease (COPD). Regular physical activity and an active lifestyle has shown to be positively associated with outcomes such as exercise capacity and health-related quality of life, and therefore could be beneficial for the individual COPD patient. An adequate level of physical activity needs to be integrated into daily life, and stimulation of physical activity when absent is important. This article aims to discuss in more detail the possible role of regular physical activity for a number of well-known outcome parameters in COPD.