Effect of diaphragmatic fatigue on control of respiratory muscles and ventilation during CO2 rebreathing

of respiratory muscles and ventilation during CO, rebreathing. J. Appl. Physiol. 75(3): 1364-1370, 1993.-We studied the influ-ence of diaphragmatic fatigue on the control of ventilation and respiratory muscle contribution to pressure swings in six nor-mal seated subjects. CO, was rebreathed before and after dia-phragmatic fatigue induced by breathing against an inspiratory resistance requiring 60 % maximal transdiaphragmatic pres-sure with each breath until exhaustion. After diaphragmatic fatigue for a given level of end-tidal Pco~, we found that tidal volume, breathing frequency, minute ventilation, duty cycle, and mean inspiratory flow did not change; esophageal pressure swings were the same, but gastric and transdiaphragmatic pressure swings were decreased; and the slope of the transpul-monary pressure-gastric pressure relationship determined at zero flow points at end expiration and end inspiration was in