Barbara Binazzi

Exercise training improves exertional dyspnea in patients with COPD: evidence of the role of mechanical factors.

BACKGROUND To our knowledge, no data have been reported on the effects of exercise training (EXT) on central respiratory motor output or neuromuscular coupling (NMC) of the ventilatory pump, and their potential association with exertional dyspnea. Accurate assessment of these important clinical outcomes is integral to effective management of breathlessness of patients with COPD. MATERIAL AND METHODS Twenty consecutive patients with stable moderate-to-severe COPD were tested at 6-week intervals at baseline, after a nonintervention control period (pre-EXT), and after EXT. Patients entered an outpatient pulmonary rehabilitation program involving regular exercise on a bicycle. Incremental symptom-limited exercise testing (1-min increments of 10 W) was performed on an electronically braked cycle ergometer. Oxygen uptake (O(2)), carbon dioxide output (CO(2)), minute ventilation (E), time, and volume components of the respiratory cycle and, in six patients, esophageal pressure swings (Pessw), both as actual values and as percentage of maximal (most negative in sign) esophageal pressure during sniff maneuver (Pessn), were measured continuously over the runs. Exertional dyspnea and leg effort were evaluated by administering a Borg scale. RESULTS Measurements at baseline and pre-EXT were similar. Significant increase in exercise capacity was found in response to EXT: (1) peak work rate (WR), O(2), CO(2), E, tidal volume (VT), and heart rate increased, while peak exertional dyspnea and leg effort did not significantly change; (2) exertional dyspnea/O(2) and exertional dyspnea/CO(2) decreased while E/O(2) and E/CO(2) remained unchanged. The slope of both exertional dyspnea and leg effort relative to E fell significantly after EXT; (3) at standardized WR, E, and CO(2), exertional dyspnea and leg effort decreased while inspiratory capacity (IC) increased. Decrease in E was accomplished primarily by decrease in respiratory rate (RR) and increase in both inspiratory time (TI) and expiratory time; VT slightly increased, while inspiratory drive (VT/TI) and duty cycle (TI/total time of the respiratory cycle) remained unchanged. The decrease in Pessw and the increase in VT were associated with lower exertional dyspnea after EXT; (4) at standardized E, VT, RR, and IC, Pessw and Pessw(%Pessn)/VT remained unchanged while exertional dyspnea and leg effort decreased with EXT. CONCLUSION In conclusion, increases in NMC, aerobic capacity, and tolerance to dyspnogenic stimuli and possibly breathing retraining are likely to contribute to the relief of both exertional dyspnea and leg effort after EXT.

Clinical InvestigationsCOPDExercise Training Improves Exertional Dyspnea in Patients With COPDa: Evidence of the Role of Mechanical Factors

BACKGROUND To our knowledge, no data have been reported on the effects of exercise training (EXT) on central respiratory motor output or neuromuscular coupling (NMC) of the ventilatory pump, and their potential association with exertional dyspnea. Accurate assessment of these important clinical outcomes is integral to effective management of breathlessness of patients with COPD. MATERIAL AND METHODS Twenty consecutive patients with stable moderate-to-severe COPD were tested at 6-week intervals at baseline, after a nonintervention control period (pre-EXT), and after EXT. Patients entered an outpatient pulmonary rehabilitation program involving regular exercise on a bicycle. Incremental symptom-limited exercise testing (1-min increments of 10 W) was performed on an electronically braked cycle ergometer. Oxygen uptake (O(2)), carbon dioxide output (CO(2)), minute ventilation (E), time, and volume components of the respiratory cycle and, in six patients, esophageal pressure swings (Pessw), both as actual values and as percentage of maximal (most negative in sign) esophageal pressure during sniff maneuver (Pessn), were measured continuously over the runs. Exertional dyspnea and leg effort were evaluated by administering a Borg scale. RESULTS Measurements at baseline and pre-EXT were similar. Significant increase in exercise capacity was found in response to EXT: (1) peak work rate (WR), O(2), CO(2), E, tidal volume (VT), and heart rate increased, while peak exertional dyspnea and leg effort did not significantly change; (2) exertional dyspnea/O(2) and exertional dyspnea/CO(2) decreased while E/O(2) and E/CO(2) remained unchanged. The slope of both exertional dyspnea and leg effort relative to E fell significantly after EXT; (3) at standardized WR, E, and CO(2), exertional dyspnea and leg effort decreased while inspiratory capacity (IC) increased. Decrease in E was accomplished primarily by decrease in respiratory rate (RR) and increase in both inspiratory time (TI) and expiratory time; VT slightly increased, while inspiratory drive (VT/TI) and duty cycle (TI/total time of the respiratory cycle) remained unchanged. The decrease in Pessw and the increase in VT were associated with lower exertional dyspnea after EXT; (4) at standardized E, VT, RR, and IC, Pessw and Pessw(%Pessn)/VT remained unchanged while exertional dyspnea and leg effort decreased with EXT. CONCLUSION In conclusion, increases in NMC, aerobic capacity, and tolerance to dyspnogenic stimuli and possibly breathing retraining are likely to contribute to the relief of both exertional dyspnea and leg effort after EXT.

Mechanisms of dyspnoea and its language in patients with asthma

This study hypothesises that regardless of the global score of dyspnoea intensity, different descriptors may be selected by asthmatic patients during short cardiopulmonary exercise test (sCPET) and methacholine (Mch) inhalation. It also examines whether different qualitative dyspnoea sensations can help explain the underlying mechanisms of the symptom. Minute ventilation (V′E), tidal volume (VT) and inspiratory capacity (IC) were measured in 22 stable asthmatic patients, and the sensation of dyspnoea during Mch inhalation and sCPET was quantitatively (Borg scale) and qualitatively (descriptors) assessed. The work rate and oxygen uptake (V′O2) were also measured during sCPET. Airway obstruction and hyperinflation, as measured by IC reduction, were the best correlates for dyspnoea with Mch. During sCPET, changes in WR, V′O2, V′E and VT significantly correlated with Borg score, with V′E being the best predictor of dyspnoea; IC decreased in eight patients. Furthermore, chest tightness (68%) was the highest reported descriptor during Mch inhalation, whereas work/effort (72%) was the highest during sCPET. In conclusion, obstruction/hyperinflation and work rate are highly reliable predictors of Borg rating of dyspnoea during methacholine inhalation and short cardiopulmonary exercise testing, respectively. Regardless of the global score of intensity dyspnoea, different descriptors may be selected by patients during short cardiopulmonary exercise testing and methacholine inhalation. Various qualities of dyspnoea result from different pathophysiological abnormalities.

Breathing pattern and kinematics in normal subjects during speech, singing and loud whispering

Aims:  We used for the first time a non‐invasive optoelectronic plethysmography to assess breathing movements and to provide a quantitative description of chest wall kinematics during phonation.

Chest wall kinematics and Hoover's sign

BACKGROUND No attempt has been made to quantify the observed rib cage distortion (Hoovers sign) in terms of volume displacement. We hypothesized that Hoovers sign and hyperinflation are independent quantities. METHODS Twenty obstructed stable patients were divided into two groups according to whether or not they exhibited Hoovers sign during clinical examination while breathing quietly. We evaluated the volumes of chest wall and its compartments: the upper rib cage, the lower rib cage and the abdomen, using optoelectronic plethysmography. RESULTS The volumes of upper rib cage, lower rib cage and abdomen as a percentage of absolute volume of the chest wall were similar in patients with and without Hoovers sign. In contrast, the tidal volume of the chest wall, upper rib cage, lower rib cage, their ratio and abdomen quantified Hoovers sign, but did not correlate with level of hyperinflation. CONCLUSIONS Rib cage distortion and hyperinflation appear to define independently the functional condition of these patients.

Perception of airway obstruction and airway inflammation in asthma: a review.

Dyspnea has a multifactorial nature and the exact mechanism that causes breathlessness in asthma is not fully understood. There is compelling evidence that factors other than merely mechanical ones take part in the pathophysiology of breathlessness. Some recent reports attribute airway inflammation, which may contribute to the unexplained variability in the perception of dyspnea associated with bronchoconstriction. Eosinophil airway inflammation has been proposed as a determinant of breathlessness via mechanisms affecting either the mechanical pathways that control breathlessness or the afferent nerves involved in perception of dyspnea. In this review, data on the interrelation between inflammation and dyspnea sensation and the impact of treatment on dyspnea sensation are discussed. We conclude that regardless of whether mechanical or chemical inflammatory factors are involved, much variability in dyspnea scores remains unexplained.

Chest wall kinematics during voluntary cough in neuromuscular patients

Muscular diseases are characterized by progressive loss of muscle strength, resulting in cough ineffectiveness with its deleterious effects on the respiratory system. Assessment of cough effectiveness is therefore a prominent component of the clinical evaluation and respiratory care in these patients. Owing to uneven distribution of muscle weakness in neuromuscular patients, we hypothesized that forces acting on the chest wall may impact on the compartmental distribution of gas volume resulting in a decrease in cough effectiveness. Pulmonary volumes, respiratory muscle strength, peak cough flow and chest wall kinematics by optoelectronic plethysmography were studied in 8 patients and 12 healthy subjects as controls. Chest wall volume was modeled as the sum of volumes of the rib cage and abdomen. The plot of the volumes of upper to lower rib cage allowed assessment of rib cage distortion. Unlike controls, patients were unable to reduce end-expiratory chest wall volume, and exhibited greater rib cage distortion during cough. Peak cough flow was negatively correlated with rib cage distortion (the greater the former, the smaller the latter), but not with respiratory muscle strength. In conclusion, insufficient deflation of chest wall compartments and marked rib cage distortion resulted in cough ineffectiveness in these neuromuscular patients.

Chest wall kinematics and breathlessness during unsupported arm exercise in COPD patients

We hypothesised that chest wall displacement inappropriate to increased ventilation contributes to dyspnoea more than dynamic hyperinflation or dyssynchronous breathing during unsupported arm exercise (UAE) in COPD patients. We used optoelectronic plethysmography to evaluate operational volumes of chest wall compartments, the upper rib cage, lower rib cage and abdomen, at 80% of peak incremental exercise in 13 patients. The phase shift between the volumes of upper and lower rib cage (RC) was taken as an index of RC distortion. With UAE, no chest wall dynamic hyperinflation was found; sometimes the lower RC paradoxed inward while in other patients it was the upper RC. Phase shift did not correlate with dyspnoea (by Borg scale) at any time, and chest wall displacement was in proportion to increased ventilation. In conclusions neither chest wall dynamic hyperinflation nor dyssynchronous breathing per se were major contributors to dyspnoea. Unlike our prediction, chest wall expansion and ventilation were adequately coupled with each other.

Optoelectronic Plethysmography has Improved our Knowledge of Respiratory Physiology and Pathophysiology

It is well known that the methods actually used to track thoraco-abdominal volume displacement have several limitations. This review evaluates the clinical usefulness of measuring chest wall kinematics by optoelectronic plethysmography [OEP]. OEP provides direct measurements (both absolute and its variations) of the volume of the chest wall and its compartments, according to the model of Ward and Macklem, without requiring calibration or subject cooperation. The system is non invasive and does not require a mouthpiece or nose-clip which may modify the pattern of breathing, making the subject aware of his breathing. Also, the precise assessment of compartmental changes in chest wall volumes, combined with pressure measurements, provides a detailed description of the action and control of the different respiratory muscle groups and assessment of chest wall dynamics in a number of physiological and clinical experimental conditions.

Chest wall kinematics during cough in healthy subjects

Aim:  The study of kinematics of the chest wall (CW) could allow us to define the relative deflationary contribution of its compartments during fits of coughing. We hypothesized that if forces applied to the lung apposed rib cage are not commensurate with those applied to the abdomen‐apposed rib cage, cough could result in rib cage distortion.