Improvement of upper airway obstruction after 131I-treatment of multinodular nontoxic goiter evaluated by flow volume loop curves.

Symptoms of tracheal-esophageal compression are often related to a large nontoxic goiter. The aim of the present study was to evaluate to what degree upper airway obstruction, as measured by flow volume loops, FIF50% and FEF50%/FIF50% (Forced Expiratory Flow at 50% of the vital capacity/ Forced Inspiratory Flow at 50% of the vital capacity) exists in nontoxic multinodular goiter, and whether changes occur after 131I-treatment. Thirteen patients with large multinodular nontoxic goiters were evaluated by estimation of FIF50%, FEF50%/FIF50% ratio and a graphic plot of the flow volume loop curve before and three, six and 12 months after treatment with 131I. FIF50% increased over 12 months from median 1.79 l/sec (range 1.46-3.02) to 2.84 l/sec (1.13-5.69) (p = 0.01). A progressive increase was seen over time (p = 0.001, trend analysis). The FEF50%/FIF50% ratio decreased from in 1.45 (0.32-2.26) to 1.03 (0.43-2.13) 12 months after treatment (p < 0.001). A progressive decrease was seen over time (p = 0.001, trend analysis). By visual evaluation 11 had a flow volume loop curve typical for an upper airway obstruction and in 9 patients the FEF50%/FIF50% ratio was > 1.2. In conclusion we found that upper airway obstruction is present in patients with multinodular nontoxic goiter, and seems to be reduced after 131I-treatment. Flow volume loop curves and measurement of FEF50% and FIF50% are important estimates for upper airway obstruction in these patients.