Effect of posture on the flow-volume loop in two patients with euthyroid goiter

In two patients with a goiter and respiratory symptoms occurring only in the recumbent posture, flow-volume loops (FVLs) were performed in various body postures: while sitting upright, supine, and left and right lateral decubitus. In both patients, how rates, upper airway obstruction indices, and FVL morphologic features with patients in recumbent postures indicated the appearance of upper airway flow limitation with patients in the recumbent posture as compared with the upright posture, In the one patient who underwent thyroid surgery, these posture-related changes disappeared, We conclude that in patients with a goiter (or any extrinsic mass near to the upper airway), the comparison of FVLs performed in various body positions may help to clarify the origin of posture-related respiratory symptoms.