Chest wall kinematics during chemically stimulated breathing in healthy XXXX .

@entity1 @entity6987 @entity2944 @entity13091 @entity519 @entity121
Chest wall compartment kinematics and respiratory muscle coordinate activity, during either @entity2944 or @entity519 , have not been comparatively assessed in healthy @entity1 . We assessed the displacement volume of the chest wall (Vcw) in 5 normal subjects during @entity519 -normocapnic and hypercapnic-hyperoxic rebreathing by using linearized magnetometers. Vcw was divided into displacement volumes of the rib cage (Vrc) and the abdomen (Vab). Esophageal (Pes) and gastric ( @entity6987 ) pressures were simultaneously recorded and transdiaphragmatic pressure ( @entity13091 ) was calculated by subtracting Pes from Pga. Pressure swings (sw) from end expiration (EE) to end inspiration (EI) were also calculated. During both @entity519 and @entity2944 , from quiet breathing to 40 L/min VE, Vrc,EI increased consistently but Vrc,EE, and Vab,EI did not. Moreover, Vab,EE decreased significantly during @entity2944 and remained unchanged during @entity519 . PesEI decreased (more negative values) and PesEE increased (less negative values) during either stimulus, while PgaEE increased with @entity2944 . Pdisw, calculated as the difference between PdiEE and PdiEI, increased significantly with both @entity2944 and @entity519 ( p = 0.002 for both). On the plot of Pes vs Pga, the slope of a line from end expiratory to end inspiratory lung volume between 20 and 40 L/min VE progressively increased during @entity2944 indicating increasing @entity121 ( @entity121 ) contribution to inspiratory pressure swings relative to the diaphragm. From these results we conclude that in healthy @entity1 : (i) with both chemical stimuli @entity121 contribution accounts for increase in Vrc displacement; (ii) with @entity2944 , the decrease in Vab,EE displacement indicates abdominal muscle (ABM) contribution to tidal volume; (iii) @entity121 and ABM assist the diaphragmatic function during hypercapnic stimulation.
