Voluntary decrease in breathing frequency in exercising asthmatic subjects

Respiratory and thoracoabdominal motion pattern at rest and after sub-maximum effort in children with asthma

Asthma involves an increase in airway resistance even in periods between attacks, which generates changes in thoracoabdominal kinematics. The aim of the present study was to detect these adaptations at rest and after physical effort. Evaluations were performed using optoelectronic plethysmography at rest and immediately after physical effort of moderate intensity. Thirty-two children and adolescents participated in the present study (16 asthma- AG and 16 health controls-CG). After exercise, the AG exhibited a less variability of respiratory variables. The kinematic behavior of thoracoabdominal motion was the inverse of that found in healthy controls. These findings suggest mechanical and physiological adaptations to minimize the possible turbulence of the airflow and reduce the impact of airway resistance during physical exertion. Moreover, these changes are found even at rest and in patients whose asthma is clinically controlled.

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The contribution of the thoracic compartment to tidal volume is greater in asthmatics.

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The kinematic behavior of thoracoabdominal motion was the inverse of that found in healthy controls.

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The variations of the ventilatory variables in face of a submaximal effort are greater in the control group.

Ventilatory Efficiency in Children and Adolescents: A Systematic Review

Introduction. The index of ventilatory efficiency (VE/VCO₂) obtained by the progressive exercise test has been considered the gold standard in the prognosis of adults with heart failure, but few studies have evaluated this approach in children. Objective. To verify the scientific evidence about the VE/VCO₂ in pediatric and adolescents patients. Methods. A systematic literature review was carried out using the key words VE/VCO₂, children, and adolescents using the PEDro and PubMed/MedLine databases. Clinical trials published from 1987 to 2014, including children, adolescents, and young adults up to 25 years, addressing the VE/VCO₂ index as a method of evaluation, monitoring, and prognosis were considered. Results. Initially, 95 articles were found; 12 were excluded as the title/abstract did not contain the VE/VCO₂ index or because they included patients greater than 25 years of age. From the remaining 83, 58 were repeated between the databases. The final sample consisted of 32 studies including healthy children and children with respiratory and other diseases. Conclusion. There are few studies involving cardiorespiratory assessment by ventilatory efficiency. The studies highlight the fact that high VE/VCO₂ values are associated with a worse prognosis of patients due to the relationship with the decrease in pulmonary perfusion and cardiac output.

Systematic review of the effectiveness of breathing retraining in asthma management

In asthma management, complementary and alternative medicine is enjoying a growing popularity worldwide. This review synthesizes the literature on complementary and alternative medicine techniques that utilize breathing retraining as their primary component and compares evidence from controlled trials with before-and-after trials. Medline, PubMed, Cumulative Index to Nursing and Allied Health Literature and the Cochrane Library electronic databases were searched. Reference lists of all publications were manually checked to identify studies not found through electronic searching. The selection criteria were met by 41 articles. Most randomized controlled trials (RCTs) of the Buteyko breathing technique demonstrated a significant decrease in β(2)-agonist use while several found improvement in quality of life or decrease in inhaled corticosteroid use. Although few in number, RCTs of respiratory muscle training found a significant reduction in bronchodilator medication use. Where meta-analyses could be done, they provided evidence of benefit from yoga, Buteyko breathing technique and physiotherapist-led breathing training in improving asthma-related quality of life. However, considerable heterogeneity was noted in some RCTs of yoga. It is reasonable for clinicians to offer qualified support to patients with asthma undertaking these breathing retraining techniques.

Implementation and interpretation of respiratory sinus arrhythmia measures in psychosomatic medicine: practice against better evidence?

Respiratory sinus arrhythmia (RSA) or high-frequency heart rate variability has been widely used as a noninvasive measure of cardiac vagal tone. However, their dependency on both respiration rate and tidal volume is largely ignored. Only a minority of studies published in Psychosomatic Medicine in recent years has implemented precautions for controlling respiration rate in RSA measures, and tidal volume effects were only rarely addressed. We discuss methodologic issues related to respiratory control methods and present data that demonstrate that both respiration rate and tidal volume contribute substantially to the within-individual RSA variance under conditions of variable breathing, with tidal volume contributing up to one third beyond respiration rate. Finally, we outline a respiratory control method for the time-domain index of RSA and review research pertaining to its reliability, validity, and experimental application.

Behavioral interventions in asthma. Breathing training

Breathing exercises are frequently recommended as an adjunctive treatment for asthma. A review of the current literature found little that is systematic documenting the benefits of these techniques in asthma patients. The physiological rationale of abdominal breathing in asthma is not clear, and adverse effects have been reported in chronic obstructive states. Theoretical analysis and empirical observations suggest positive effects of pursed-lip breathing and nasal breathing but clinical evidence is lacking. Modification of breathing patterns alone does not yield any significant benefit. There is limited evidence that inspiratory muscle training and hypoventilation training can help reduce medication consumption, in particular beta-adrenergic inhaler use. Breathing exercises do not seem to have any substantial effect on parameters of basal lung function. Additional research is needed on the psychological and physiological mechanisms of individual breathing techniques in asthma, differential effects in subgroups of asthma patients, and the generalization of training effects on daily life.

[Pulmonary gas transfer in pediatrics (carbon monoxide and dioxide)]

In pediatrics, measurements of gaseous transfer in steady-state (SS) are easily applied. Nevertheless, interpretation of results is uncertain because predicted values depend on numerous metabolic and ventilatory parameters. In healthy subjects, the only invariant parameter of reference, beside the blood gas, is the CO uptake (VCO) when normalized by the reject of CO2 (VCO2). Theoretically, a deficit of VCO/VCO2 (VCOSpecifique = SpVCO) should not be observed on a young asthmatic in remission. Such a deficit should be due to either a circulatory impairment of the "gas-exchanging organ" or an alveolary ventilation failure. However, the respiratory equivalent for CO2 (V/VCO2) increases in case of hyperventilation. When not observed at rest, hyperventilation can occur at exercise, that can again induce a non specific bronchitic hyperreactivity.

AIM

To define links: 1) between the spirometry of the young asthmatic and the value of ERCO2 and CO tests; 2) between a circulatory anomaly and the value of SpVCO.

PATIENTS AND METHOD

The asthmatic adolescents aged between 10 and 20 were separated from infants (age < 10) and classified in three degrees of spirometrical alteration according to the maximum expiratory flow when 25% of the forced vital capacity remains in the lung (V25) and the residual volume (RV); 48 adolescents were examined at rest and 17 were exercising on a cyclo-ergometer. Two adolescents with circulatory anomaly, one by idiopathic pulmonary hemosiderosis (IPH), the other by agenesia of the left lung were examined at rest and exercise.

RESULTS

In asthmatics at rest the three degrees of spirometric alteration differed from one another in ERCO2 and classical CO tests; SpVCO alone was not altered at rest or during exercise. However the deficit of SpVCO, confirmed during the exercise, was significant in HPI.

CONCLUSION

Simple and quick simultaneous measurements of (FICO-FECO) and FECO2 allows one to detect hyperventilation of young asthmatic subjects at rest and during exercise, or can confirm a circulatory anomaly.