The effects of added elastic loads on the respiratory response to CO 2 in man

We have examined the effects of added elastic loads (of 14 and 23 cm H 2O/L) on the CO 2 response curve in six normal subjects. In one subject with the bigger load the slope of the ventilation/P CO 2 curve was reduced but in the others it was unchanged or enhanced. Inspiratory power/P CO 2 ; curves were similarly unaffected. In all subjects the slope of the ventilation/tidal volume curve was increased by loading. These changes in pattern of breathing enable ventilation to be sustained at control levels without any increase in inspiratory muscle power and with minimal increases in inspiratory muscle force and subjective discomfort.