Ivan Peres Costa

Analysis of Autonomic Modulation During Maximal and Submaximal Work Rate and Functional Capacity in Asthmatic Children

Background. Children with asthma experience changes in functional capacity and autonomic control. The literature suggests that this imbalance is responsible for bronchial hyperresponsiveness, primarily during physical effort. Objective. The aim of the present study was to evaluate variables of autonomic modulation and functional capacity in asthmatic children after maximum and submaximum work rate. Methods. A cross-sectional study was carried out with 24 children [18 in the asthma group (AG) and 6 in the control group (CG)]. Evaluations involved heart rate variability (HRV) and functional capacity [shuttle walk test (SWT) and three-minute step test]. Pulmonary function was also evaluated through spirometry and the fractional concentration of expired nitric oxide (FeNO). Results. The asthma diagnostic variables FEV1 and FeNO differed significantly between groups (p = .01). Distance traveled on the SWT was lower in the AG (333.13 ± 97.25 m vs. 442.66 ± 127.21 m; p = .04). Perceived exertion was greater in the AG. The HRV variables rMSSD and HF did not decrease significantly during the SWT (maximum work rate) in the AG (p = .01 and .04). FeNO was negatively correlated with FEV1/FVC (r = −0.70; p = .004) and positively correlated with pNN50 (r = 0.50; p = .03) in the AG. Conclusion. From the autonomic standpoint, asthmatic and non-asthmatic children respond differently to stress. No withdrawal of parasympathetic cardiac modulation occurs in asthmatic children after maximum work rate. Children with asthma experience changes in functional capacity and lung function may vary depending on the degree of inflammation of the airways.

Peripheral muscle strength and functional capacity in patients with moderate to severe asthma.

BackgroundThe adequate control of asthma includes the absence of nocturnal symptoms, minimal use of medication, normal or nearly normal lung function and no limitations to physical activity. The choice of a more sedentary lifestyle can lead to physical de-conditioning, thereby aggravating asthma symptoms and increasing the risk of obesity.MethodsThis study aimed at performing a battery of function-related assessments in patients with asthma and comparing them to a healthy control group.A prospective, transversal and case–control study was designed.It was set up at Santa Casa de Misericórdia Hospital –Sao Paulo and Nove de Julho University on a population of outpatients.Subjects of the study were patients affected by moderate to severe asthma.A case–control study was carried out involving 20 patients with moderate to severe asthma and 15 healthy individuals (control group). All participants underwent body composition analysis (BMI and BIA) and a controlled walk test (Shuttle test), resistance muscle test (1RM) and answered a physical activity questionnaire (IPAQ). The group with asthma also answered a questionnaire addressing the clinical control of the illness (ACQ).ResultsIn comparison to the control group (unpaired Student’s t-test), the patients with asthma had a significantly higher BMI (31.09 ± 5.98 vs. 26.68 ± 7.56 kg/m2) and percentage of body fat (38.40 ± 6.75 vs. 33.28 ± 8.23%) as well as significantly lower values regarding distance traveled on the walk test (369 ± 110 vs. 494 ± 85 meters) and metabolic equivalents (3.74 ± 0.87 vs. 4.72 ± 0.60). A strong correlation was found between the distance completed and peripheral muscle strength (r: 0.57, p < 0.05) and METs (Metabolic equivalents – minutes/week) and peripheral muscle strength of 1RM (r: 0.61, p = 0.009).ConclusionsThe individuals with asthma had lower functional capacity and levels of physical activity as well as a higher percentage of body fat compared to healthy individuals. This suggests that such patients have a reduced physical performance stemming from a sedentary lifestyle.Despite the existence of few studies reporting moderate to severe asthmatic patients and functional capacity assessment, it is clear that the assessment presented in the current study is a valid and accessible tool in clinical practice.

Analysis of heart rate variability in individuals subjected to different positive end expiratory pressure levels using expiratory positive airway pressure.

Introduction The increase in the number of studies has led to greater security in the application of this method and the determination of its effectiveness in adults.. The purpose of the present study was to evaluate heart rate variability in healthy individuals submitted to different levels of positive expiratory pressure using an expiratory positive airway pressure (EPAP) device. Material and methods The study involved 27 healthy male individuals ranging in age from 20 to 35 years. Patient histories were taken and the subjects were submitted to a physical examination. The volunteers were monitored using the Polar 810s® and submitted to the EPAP experiment. Analyses were performed on variables of the frequency domain. Sympathetic and parasympathetic bands and their relationship with sympathovagal response were also analyzed. Results The mean value of this variable was 526.89 (55.50) ms2 in the first period, 2811.0 (721.10) ms2 in the fourth period and 726.52 (123.41) ms2 in the fifth period. Regarding the parasympathetic area, significant differences were detected when Periods 1 and 5 (no load) were compared with periods in which the individuals were subjected to the use of the therapy. Sympathetic and parasympathetic areas together, a significant difference was detected regarding the sympathetic/parasympathetic ratio in the comparison between Periods 1 and 4 (p < 0.01) as well as Periods 2 and 4 (p < 0.05). Conclusions The findings of the present study suggest that the therapeutic use of EPAP significantly alters the parameters of heart rate variability in the frequency domain, highlighting the importance of monitoring and care during the practice of EPAP.

Influence of bilevel positive airway pressure on autonomic tone in hospitalized patients with decompensated heart failure

[Purpose] This study evaluated the effect of Bilevel Positive Airway (BiPAP) on the autonomic control of heart rate, assessed by heart rate variability (HRV), in patients hospitalized with decompensated heart failure. [Subjects and Methods] This prospective cross-sectional study included 20 subjects (age: 69±8 years, 12 male, left ventricular ejection fraction: 36 ±8%) diagnosed with heart failure who were admitted to a semi-intensive care unit with acute decompensation. Date was collected for HRV analysis during: 10 minutes spontaneous breathing in the resting supine position; 30 minutes breathing with BiPAP application (inspiratory pressure = 20 cmH2O and expiratory pressure = 10 cmH2O); and 10 minutes immediately after removal of BiPAP, during the return to spontaneous breathing. [Results] Significantly higher values for indices representative of increased parasympathetic activity were found in the time and frequency domains as well as in nonlinear Poincaré analysis during and after BiPAP in comparison to baseline. Linear HRV analysis: standard deviation of the average of all R-R intervals in milliseconds = 30.99±4.4 pre, 40.3±6.2 during, and 53.3±12.5 post BiPAP. Non-linear HRV analysis: standard deviations parallel in milliseconds = 8.31±4.3 pre, 12.9±5.8 during, and 22.8 ±6.3 post BiPAP. [Conclusion] The present findings demonstrate that BiPAP enhances vagal tone in patients with heart failure, which is beneficial for patients suffering from acute decompensation.

Cardiorespiratory coupling during sleep in difficult-to-control asthmatic patients

Heart rate variability (HRV) and respiration recorded during sleep from 8 patients suffering from difficult-to-control asthma were studied to investigate autonomic nervous system control of cardiac and respiratory activities, and of cardio-respiratory coupling during different sleep stages. In healthy subjects, HRV monitoring during sleep reveals a predominant parasympathetic drive to the heart during nonrapid eye movement (NREM) sleep and an increased sympathetic activity during rapid eye movement (REM) sleep. Spectral analysis of HRV and cross-spectral analysis of HRV and respiration signals in the analyzed difficult-to-control asthma patients showed trends in the main spectral indices, which appeared similar to variations observed in non pathologic subjects, but which were possibly affected by a reduction in the sympathetic and cardiorespiratory modulations. The ratio between the tachogram power in the low frequency (LF) band and the tachogram power in the high frequency (HF) band, a marker of the sympatho-vagal balance, increased during deep sleep stage S3 (LF/HF = 0.855 ± 0.876, mean ± s.d.), indicating a predominance of the sympathetic component, and decreased during REM sleep (LF/HF = 0.748 ± 0.716, mean ± s.d.), indicating a drift of the sympatho-vagal balance towards the vagal component. The coherence between the tachogram and the respirogram in the HF band increased during deep sleep stages S2 (coherence = 0.855 ± 0.727, mean ± s.d.) and S4 (coherence = 0.843 ± 0.724, mean ± s.d.) and decreased during REM sleep (coherence = 0.808 ± 0.719, mean ± s.d.), suggesting that a stronger cardiorespiratory coupling was reached with synchronization of sleep.

Reliability of the Shuttle Walk Test with Controlled Incremental Velocity in Patients with Difficult-to-Control Asthma

Purpose: Asthma is a chronic inflammatory condition characterized by bronchial hypersensitivity to endogenous or exogenous agents and variable airflow limitation, which is reversible either spontaneously or with the use of medication. The evaluation of functional capacity in these patients is commonly performed using field tests to gauge activity of daily living. However, the reliability of the symptom-controlled shuttle walk test has not yet been determined for individuals with difficult-to-control asthma. The aim of the present study was to determine the reliability of the shuttle walk test in patients with severe, difficult-to-control asthma. Methods: Forty-five patients were evaluated including lung function tests, the International Physical Activity Questionnaire (IPAQ), and the Asthma Control Questionnaire. The participants performed a shuttle walk test twice, with a 20-min rest period between tests. Results: The mean distance walked for this cohort was 330.5 m (range, 50-570 m) on the first walk test and 336.3 m (range, 60-571 m) on the second test. There was no statistical difference between the mean distances walked. The Bland-Altman plots of the 2 tests revealed a mean difference of −12.7 m, with a 95% CI of 37.9 to −63.2 m. Significant correlations were found between the distance walked in meters and the IPAQ (r = 0.36, P < .01) and distance in meters and muscle mass (r = 0.39, P < .009). Conclusion: The shuttle walk test is reliable for individuals with difficult-to-control asthma and can be used in the evaluation of functional capacity.