The effect of quiet tidal breathing on lateral cephalometric measurements

Abstract

Purpose : In the evaluation of the upper airway in patients with sleep apnea it has been suggested that cephalometric radiographs be performed at either end-inspiration or end-expiration during quiet tidal breathing. This study sought to determine if standard soft tissue cephalometric measurements vary significantly with tidal breathing. Patients and Methods : In this prospective, controlled study 22 adult male patients with the sleep apnea/hypopnea syndrome and 27 nonapneic, nonsnoring male controls had cephalometric radiographs performed at end-tidal inspiration and end-tidal expiration. The measurements obtained from each radiograph included the posterior airway space distance, the mandibular plane to hyoid distance, and the posterior nasal spine to tip of palate (PNS-P) distance. Results : There were no statistically significant differences between the inspiratory and expiratory measurements in either group. Only the PNS-P distance differed significantly between the two groups. Changes in cephalometric measurements did not occur uniformly in any one direction with tidal breathing. Conclusion : The data indicate that coordinating radiographic exposure to respiratory cycle phase is not necessary for soft-tissue measurements commonly used to assess upper airway patency in patients with the sleep apnea/ hypopnea syndrome.