Partitioning of Large and Small Airway Resistance in Human Measured by an Anterograde Catheter with a Tip Micromanometer

We measured lateral pressure in airways 3 mm in internal diameter in three normal subjects using an anterograde catheter with a tip micromanometer. The pressure was used to partition total pulmonary resistance into a large airway resistance component between the mouth and the pressure sensor and a small airway resistance component between the pressure sensor and alveoli. Large airway resistance and small airway resistance during inspiration were 2.3±0.4 and 0.9±0.2 cmH₂0/liter/sec (mean±s.E.), respectively, and small airway resistance was 29% of the total pulmonary resistance. We suggest that the present technique may be useful for determining the localization of airway resistance in human subjects.