Ventilatory Kinematics and Cardiocirculatory Adjustments to Exercise Before and After Pharmacological Bronchodilation in Patients with Moderate to Sevre COPD.
Year: 2013
Type: dissertation
Abstract: Introduction: The causes of exercise limitation in patients with COPD are multifactorial. It is known that one of the major pathophysiological consequences of COPD is the occurrence of dynamic hyperinflation (DH) during exercise which, besides causing limiting dyspnea, may negatively interfere with cardiac output. Recently, has been observed that there are several patterns of ventilatory behavior during exercise in COPD patients, and in some, the recruitment of the abdominal muscles, soften or even avoid the HD, could be deleterious and possibly cause impairment of hemodynamic adjustments. Considering that bronchodilators (BD) could interfere with the pattern and intensity of abdominal muscles recruitment, and variably influence in HD, it would be reasonable to suppose that such drugs could interfere in cardiovascular responses to exercise in these patients. Objectives: To investigate the effect of a single dose of shorting acting β2-adrenergic BD, compared with placebo, the dynamic behavior of the chest wall volume and its operational compartments (ventilatory kinematics by optoelectronic plethysmography) and its possible consequences in cardiocirculatory adjustments and exercise tolerance in patients with moderate to severe COPD. Methods: We prospectively evaluated 28 patients with moderate to severe COPD. Patients underwent pulmonary function tests and two of cardiopulmonary exercise tests (CPET) on a cycle ergometer with constant workload until the time limit of tolerance, one after inhalation of placebo and another after inhalation of BD. The load used was 75% of the peak load achieved in an incremental CPET performed previously. Besides the conventional responses of CPET, were obtained the chest wall and the operational lung volumes, rib cage and abdomen, breath-by-breath by optoelectronic plethysmography, and cardiac output by transthoracic cardioimpedância. The patients were divided into "responders" and "non-responders" regarding the response to BD obtained by measuring inspiratory capacity (increase greater than 300ml in test after BD). Results: Administration of BD was associated with a variable "volume" response and a significantly increased on exercise capacity in the "responder" group (24 ± 37% vs. -3 ± 24% in "non-responders", p < 0.05) and led to a greater recruitment of expiratory abdominal muscles (- 0.18 ± 0.02L vs. - 0.01 ± 0.02L in the "nonresponders, p <0.05). There was a reduction of chest wall operational lung compartments volume after the use of BD analyzing the group as a whole. Dividing the patients into "responders" (N = 13) or "non-responders" (N = 15) we observed a decrease in the chest wall and operational thoracic compartments volumes only in the first group, and this reduction was mainly due to the rib cage compartment, which was responsible for 57% of the reduction in end-expiratory lung volume. Although indirect evidence that such effects have improved dynamic compliance and expiratory flow limitation, these were not associated with better hemodynamic adjustments to exercise (p> 0.05). Conclusion: Our findings indicate that the primary effect of BD resides, in patients with reduced operational lung volumes in improving lung hyperinflation (rib cage), with secondary effect of increased recruitment of abdominal expiratory muscles. These consequences are generally beneficial - but not required - to occur to patients who improves the tolerance to effort and not appear to modulate the hemodynamic responses to a constant load exercise in this subgroup of patients.
Author: Cunha, Mhulio Marquez [UNIFESP]
Language: Portuguese
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7120473867