Peak-potentialities of inspiratory musculature as disclosed by tracheal occlusion

Interest was focussed on maximal inspiratory efforts which anesthetized rabbits are able to display when acutely made dyspnoic by prolonged tracheal occlusion. Such efforts were characterized by the mean intrapleural pressure decrease per breath and by the maximum of intrapleural pressure decrease reached during inspiration. These efforts could not be intensified by additional biochemical and/or biophysical means such as hypercapnia, hypoxia, artificial pneumothorax, thoracic compression, etc. They were most pronounced around the 25th second after onset of tracheal occlusion.They could, however, be altered pharmacodynamically. Methylphenidate was found to be of particular interest. It enhanced the mean intrapleural pressure decrease per breath and intensified the maximum of inspiratory effort while, at the same time, leaving respiratory frequency nearly unaltered.The possible medicinal usefulness of the approach pursued is briefly discussed.