Effects of inspiratory muscle unloading on the response of respiratory motor output to CO_2

摘要

Inspiratory muscle output is downregulated when the mechanical load is reduced in awake humans. It is not known whether this is related to reduction in Pco_2 or to removal of load-related neural re- sponses. To address this issue, we did Read CO_2 rebreathing tests in 13 normal subjects with and Without unloading and compared respiratory output at identical end-tidal Pco_2 (P_Etco_2) levels. Un- Loading was carried out with proportional assist ventilation (flow assist = 2 cm H_2O/L/s plus volume Assist = 4 cm H_2O/L, representing approximately 50/100 reduction of the normal resistance and Elastance).