The cannulae contained side openings for measurement of pressure in the inlet (positive) and outlet (negative) ends from the trachea, and changes in tracheal size were recognized as changes in the inlet minus outlet pressure difference (P in cm H2O) utilizing a differential pressure transducer as the lumen was perfused with gassed MKH solution through the separate IL bath of MKH solution (IL bath) for a price of 34 ml/min

The cannulae contained side openings for measurement of pressure in the inlet (positive) and outlet (negative) ends from the trachea, and changes in tracheal size were recognized as changes in the inlet minus outlet pressure difference (P in cm H2O)