Volume-timing relationships during cough and resistive loading in the cat

The relationship between pulmonary volume-related feedback and inspiratory (CTI) and expiratory (CTE) phase durations during cough was determined. Cough was produced in anesthetized cats by mechanical stimulation of the intrathoracic tracheal lumen. During eupnea, the animals were exposed to single-breath inspiratory and expiratory resistive loads. Cough was associated with large increases in inspiratory volume (VI) and expiratory volume (VE) but no change in phase durations compared with eupnea. There was no relationship between VI and CTI during coughing. A linear relationship with a negative slope existed between VI and eupneic inspiratory time during control and inspiratory resistive loading trials. There was no relationship between VE and CTE during all coughs. However, when the first cough in a series or a single cough was analyzed, the VE/CTE relationship had a positive slope. A linear relationship with a negative slope existed between VE and eupneic expiratory time during control and expiratory resistive loading trials. These results support separate ventilatory pattern regulation during cough that does not include modulation of phase durations by pulmonary volume-related feedback.