ABSTRACT
Airway resistance is the hindrance posed to airflow by the friction between the air itself and the respiratory mucosa. Airway resistance is a key factor in determining airflow, and so may be inferred from the FEV1 ratio. Airway resistance measurements are made routinely in many pulmonary function laboratories, and familiarisation with the measurement indices and their meaning will afford an increased understanding of airway function, mechanics, and characteristics. The total impedance to airflow comprises an elastic component due to recoil of the lung parenchyma and chest wall, and a resistive component originating from friction between flowing gas and the airway wall. The latter of these is quantified in the measurement of airway resistance. Multiple traces can be recorded consecutively until consistent results are achieved, with the most representative trace used to report results. However, patients may become uncomfortable if panting continues for too long, as the unnatural breathing pattern may produce transitory symptoms of hyperventilation.
