Inspiratory muscle interaction in the generation of changes in airway pressure

TYNA BUDZINSKA. Inspiratury muscle interaction in the gener-ation of changes in airway pressure. J. Appl. Physiol 66(6): 2573-2578, 1989.-The mechanical interaction of the inspira-tory muscles in the generation of changes in airway pressure is unclear. Using upper thoracic spinal cord stimulation to acti-vate the intercostal muscles (IC) and bilateral supramaximal phrenic nerve stimulation to activate the diaphragm (D), we measured the changes in airway pressure produced by separate and combined IC and D activation over a wide range of lung volumes. Changes in parasternal IC and D length were assessed by sonomicrometry. With increasing lung volume, activation of the IC and D resulted in progressive decrements in generated airway pressure. Combined IC and D contraction produced greater negative swings in airway pressure than the arithmetic sum of separate IC and D contraction alone, indicating