Documentation of upper airway obstruction in unilateral vocal cord paralysis: Flow‐volume loop studies in 43 subjects

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Abstract
Upper airway impairment of variable severity occurs in unilateral vocal cord paralysis (UVCP). Among 43 subjects with UVCP all had voice disturbance, 22 had symptoms of airway impairment, and 27 had some disturbance of swallowing. The severity of the airway impairment was evaluated by flow-volume loop spirogram which demonstrated reduced inspiratory flow rates (maximal and midvital capacity). Clinical recovery from paralysis or intracordal Teflon injection was accompanied by improvement in inspiratory flow rates. Airway impairment is most severe in subjects having UVCP due to intrathoracic disorder or intraoperative nerve interruption. Vocal cord position did not correlate with the severity of airway disturbance. The FVC and FEV1 determinations were normal in 33 and 29 cases, respectively, whereas the VI-50 and VE-50/VI-50 were normal in only 11 and 7 instances. This selective restriction of inspiratory flow rates and the abnormally low VE-50/VI-50 ratio was observed regularly. The sensitivity and reproducibility of the flow-volume loop examination support the utilization of this test to evaluate the nature and severity of upper airway impairment; consecutive examinations can be utilized to monitor the clinical course or outcome from treatment.