[Airflow resistance of shortened tracheal tubes.].

Background And Objectives: Tracheal tube length may be shortened just after the cuff probably without noxious influence on airflow resistance. This study aimed at determining the effects of such shortening under different inspiratory flows.

Methods: Flow resistance was measured in tubes with internal diameters of 7; 7.5; 8; 8.5; 9 and 9.5 millimeters. Measurements were undertaken on standard tubes and on those shortened just after the cuff level. Flows were 0.07 liters per second (L.s-1), 0.1; 0.2; 0.33; 0.5 and 1 L.s-1.

Results: Resistances were progressively lower for larger internal diameters, but were higher for a same diameter under higher flow, both, in standard and shortened tubes. Shortened tubes showed lower or equal flow resistance as compared to standard tubes with the same diameter.

Conclusions: Resistance has been lower or comparable on shortened tubes as compared to standard tubes.