Influence of thoracoabdominal pattern of breathing on respiratory resistance

The purpose of this study was to test the hypothesis that voluntary changes in thoracoabdominal pattern of breathing may increase total respiratory resistance. Thirty-one normal subjects were asked to control their thoracoabdominal pattern of breathing by using a visual feedback. Thoracic and abdominal volume changes were measured by inductance plethysmography. Respiratory resistance and elastance were measured by forced oscillometry. The mean (±SD) percent thoracic contributions to tidal volume during thoracic or abdominal breathing were 75 (±11) and 25% (±9), respectively. These changes induced small but significant increases in resistance ( P