Collapsibility of passive pharynx in patients with acromegaly

Sleep-disordered breathing (SDB), either central or obstructive in nature, is common in patients with acromegaly. However, no study has systematically examined the collapsibility of the pharynx in acromegaly to date. We evalu ated intrinsic mechanical properties of passive pharynx in 10 anesthetized and paralyzed patients with active acromegaly before transsphenoidal adenom ectomy for their pituitary adenoma. Static pressure-area relationships of t he velopharynx and oropharynx were obtained by step changes in airway press ure during endoscopic cross-sectional area measurement of each segment. Mor eover, curve fitting analysis by an exponential function estimated the clos ing pressure (P'close) of each segment. Preoperative nocturnal oximetry ide ntified five acromegalic patients with an oxygen desaturation index (ODI) g reater than 10 h(-1) and clinical symptoms suggesting presence of SDB. The pharyngeal airway of all five acromegalic patients with SDB was highly coll apsible at both velopharynx and oropharynx with positive P'close. Compared with age-, body mass index (BMI)-, and ODI-matched SDB patients without acr omegaly, SDB patients with acromegaly had a higher P'close of the oropharyn x, indicating that the etiology of SDB in acromegaly appears to differ from that of ordinary sleep apnea. Our results suggest that anatomic abnormalit y, especially at the base of the tongue, appears to play a significant role in development of SDB in acromegaly.