FLOW-VOLUME LOOPS IN THE EVALUATION OF UPPER AIRWAY-OBSTRUCTION

The flow volume loop is of great value in the diagnosis and evaluation of upper airway obstruction. Characteristic flattening or ''plateauin g'' of the flow volume loop occurs in most symptomatic patients. Extra thoracic lesions limit inspiration; intrathoracic lesions limit exhala tion. Fixed lesions limit both inspiration and exhalation. In the pres ence of chronic obstructive pulmonary disease or asthma, these changes may not be seen, and small lesions will be missed in patients with no rmal lungs. Visual inspection of the airways remains the most importan t diagnostic procedure in the evaluation of upper airway obstruction.