title: Pregnancy is associated with a decrease in pharyngeal but not tracheal or laryngeal cross-sectional area: a pilot study using the acoustic reflection method.
abstract: BACKGROUND
  The risk of difficult upper airway access is increased during pregnancy, especially in labor. Changes in upper airway calibre have been poorly studied during pregnancy. The acoustic reflection method is a non-invasive technique that allows a longitudinal assessment of the cross-sectional area of the upper airway from the mouth to carina. We used this technique to evaluate upper airway calibre during normal pregnancy.
  
  
  METHODS
  We conducted a prospective, single centre, observational study with a clinical and upper airway acoustic reflection method evaluation of healthy women during the first, second and third trimesters of pregnancy, and up to two days and one month after delivery.
  
  
  RESULTS
  Fifty women participated to the study. The mean pharyngeal cross-sectional area decreased between the first and third trimesters (P < 0.001) with no significant change of the minimal and mean tracheal cross-sectional areas. The Mallampati score increased during pregnancy between the first and third trimesters (P< 0.001).
  
  
  CONCLUSIONS
  Using measurements with the acoustic reflection method, normal pregnancy is associated with a significant reduction in the cross-sectional area of the pharynx and a concomitant increase in the Mallampati score. No change was observed in the minimal and mean tracheal cross-sectional areas.
authors: Department of Head and Neck Surgery, Armand-Trousseau Hospital, Université Paris, Paris, France. Electronic address: nicolas.leboulanger@nck.aphp.fr.
authors: N
authors: N
authors: Leboulanger
authors: Department of Anesthesiology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: N
authors: N
authors: Louvet
authors: Department of Anesthesiology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: A
authors: A
authors: Rigouzzo
authors: Department of Anesthesiology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: M
authors: M
authors: de Mesmay
authors: INSERM, Unité U955, and CNRS, ERL 7240, Paris, France.
authors: B
authors: B
authors: Louis
authors: Department of Anesthesiology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: M
authors: M
authors: Farrugia
authors: Department of Anesthesiology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: L
authors: L
authors: Girault
authors: Department of Pulmonology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: A
authors: A
authors: Ramirez
authors: Department of Anesthesiology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: I
authors: I
authors: Constant
authors: Department of Obstetrics and Gynecology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: J-M
authors: JM
authors: Jouannic
authors: Department of Pulmonology, Armand-Trousseau Hospital, Université Paris, Paris, France.
authors: B
authors: B
authors: Fauroux
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000328:Adult; D000704:Analysis of Variance; D001837:Body Weights and Measures / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007830:Larynx / Q000033:anatomy & histology*; D010614:Pharynx / Q000033:anatomy & histology*; D010865:Pilot Projects; D011247:Pregnancy; D011446:Prospective Studies; D014132:Trachea / Q000033:anatomy & histology*
keywords: Acoustic reflection method; Larynx; Pharynx; Pregnancy; Trachea