INTRODUCTION: Thixotropy is a passive property of the skeletal muscle that depends on the muscle's immediate history of contraction and length change. Inspiratory-muscle thixotropy affects the end-expiratory position of the rib cage in normal subjects. OBJECTIVE: To determine whether a reduction in end-expiratory chest-wall volume occurs after thixotropy conditioning of inspiratory muscles in patients with chronic obstructive pulmonary disease. METHODS: Ten male subjects with chronic obstructive pulmonary disease (mean +/- SD forced expiratory volume in the first second 70+/-20% of predicted) showed an increased ratio of residual volume to total lung capacity (49 +/- 4.7%). The subjects conducted inspiratory muscle thixotropy conditioning maneuvers at 3 different chest-wall volumes (end-expiratory volume of baseline breathing, residual volume plus 40% of expiratory reserve volume, and residual volume) and with 3 levels of inspiratory effort (0%, 30%, and 100% of maximal inspiratory mouth pressure at each volume), with airway-closure, in the sitting position. Using respiratory induction plethysmography, we measured the effect of effort-intensity and volume at the time of the conditioning maneuver on the end-expiratory chest-wall volume of the 5 respiratory cycles immediately following the conditioning maneuver. RESULTS: There was a reduction in end-expiratory chest-wall volume after the conditioning maneuver, except when conditioning was performed at end-expiratory baseline with 0% effort. The reduction increased as effort intensity increased (p = 0.011) and as volume decreased (p < 0.001), and the reduction was attained by rib-cage movement rather than abdominal movement. CONCLUSIONS: Thixotropy conditioning of inspiratory muscles, at a reduced chest-wall volume, decreased end-expiratory chest-wall volume in the 5 subsequent breaths in patients with chronic obstructive pulmonary disease.
INTRODUCTION: Thixotropy is a passive property of the skeletal muscle that depends on the muscle's immediate history of contraction and length change. Inspiratory-muscle thixotropy affects the end-expiratory position of the rib cage in normal subjects. OBJECTIVE: To determine whether a reduction in end-expiratory chest-wall volume occurs after thixotropy conditioning of inspiratory muscles in patients with chronic obstructive pulmonary disease. METHODS: Ten male subjects with chronic obstructive pulmonary disease (mean +/- SD forced expiratory volume in the first second 70+/-20% of predicted) showed an increased ratio of residual volume to total lung capacity (49 +/- 4.7%). The subjects conducted inspiratory muscle thixotropy conditioning maneuvers at 3 different chest-wall volumes (end-expiratory volume of baseline breathing, residual volume plus 40% of expiratory reserve volume, and residual volume) and with 3 levels of inspiratory effort (0%, 30%, and 100% of maximal inspiratory mouth pressure at each volume), with airway-closure, in the sitting position. Using respiratory induction plethysmography, we measured the effect of effort-intensity and volume at the time of the conditioning maneuver on the end-expiratory chest-wall volume of the 5 respiratory cycles immediately following the conditioning maneuver. RESULTS: There was a reduction in end-expiratory chest-wall volume after the conditioning maneuver, except when conditioning was performed at end-expiratory baseline with 0% effort. The reduction increased as effort intensity increased (p = 0.011) and as volume decreased (p < 0.001), and the reduction was attained by rib-cage movement rather than abdominal movement. CONCLUSIONS: Thixotropy conditioning of inspiratory muscles, at a reduced chest-wall volume, decreased end-expiratory chest-wall volume in the 5 subsequent breaths in patients with chronic obstructive pulmonary disease.
Authors: Illia Nadinne Dantas Florentino Lima; Antonio Sarmento; Maria Clara Goes; Enrico Mazzuca; Antonella Lomauro; W Darlene Reid; Andrea Aliverti; Guilherme Augusto De Freitas Fregonezi Journal: Front Physiol Date: 2019-11-01 Impact factor: 4.566
Authors: Maria Clara Rodrigues de Góes; Antonio Sarmento; Illia Lima; Marina Lyra; Cristiane Lima; Andrea Aliverti; Vanessa Resqueti; Guilherme A F Fregonezi Journal: PLoS One Date: 2022-10-14 Impact factor: 3.752