title: The effect of quiet tidal breathing on lateral cephalometric measurements.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medicine, Brooke Army Medical Center, Fort Sam Houston, TX, USA.
authors.forename: D I
authors.initials: DI
authors.lastname: Loube
authors.forename: P J
authors.initials: PJ
authors.lastname: Strollo
authors.forename: L J
authors.initials: LJ
authors.lastname: Epstein
authors.forename: W L
authors.initials: WL
authors.lastname: Davenport
mesh_terms: D000328:Adult; D002508:Cephalometry; D006801:Humans; D006928:Hyoid Bone / Q000473:pathology; D008297:Male; D008334:Mandible / Q000473:pathology; D008875:Middle Aged; D009295:Nasal Bone / Q000473:pathology; D010159:Palate / Q000473:pathology; D010991:Plethysmography; D017286:Polysomnography; D011446:Prospective Studies; D012123:Pulmonary Ventilation; D012119:Respiration; D012891:Sleep Apnea Syndromes / Q000473:pathology; D013990:Tidal Volume