title: Balloon tracheal occlusion for congenital diaphragmatic hernia: experimental studies.
abstract: OBJECTIVE
  Temporary tracheal occlusion is an effective strategy to enlarge fetal lungs, but the optimal technique to accomplish occlusion is unknown. External clips are effective when applied fetoscopically (Fetendo clip), but require a difficult fetal neck dissection. This study was undertaken to assess the feasibility of intratracheal balloon occlusion, revisiting the internal occlusion strategy.
  
  
  METHODS
  (1) The internal diameter (ID) of human fetal trachea (53 fetuses; 14 to 41 weeks' gestation) was compared using a computer-assisted image analyzer and sonography, ex vivo. (2) Volume to diameter relationship of the balloon (balloon configuration curve) was defined using an image analyzing computer. (3) Using the trachea of fetal sheep, pressures that break balloon tracheal seal (seal pressure) were investigated.
  
  
  RESULTS
  (1) Between 16 and 41 weeks' gestation, tracheal ID (range, 0.7 to 5.4 mm) correlates significantly with gestational age. (2) Balloon volume required to achieve tracheal seal could be determined based on the tracheal growth curve and the balloon configuration curve. (3) Tracheal seal breaking points varied depending on the tracheal specimen tested.
  
  
  CONCLUSIONS
  Internal tracheal occlusion using a balloon is feasible with minimal tracheal damage if the balloon volume is adjusted to fetal tracheal growth.
authors.affiliation: The Fetal Treatment Center and the Department of Surgery, University of California San Francisco, 94143-0570, USA.
authors.forename: T
authors.initials: T
authors.lastname: Chiba
authors.forename: C T
authors.initials: CT
authors.lastname: Albanese
authors.forename: D L
authors.initials: DL
authors.lastname: Farmer
authors.forename: C F
authors.initials: CF
authors.lastname: Dowd
authors.forename: R A
authors.initials: RA
authors.lastname: Filly
authors.forename: G A
authors.initials: GA
authors.lastname: Machin
authors.forename: M
authors.initials: M
authors.lastname: Harrison
mesh_terms: D021721:Balloon Occlusion / Q000379:methods*; D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus; D005865:Gestational Age; D006548:Hernia, Diaphragmatic / Q000628:therapy*; D065630:Hernias, Diaphragmatic, Congenital; D006801:Humans; D011247:Pregnancy; D011336:Probability; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D014132:Trachea / Q000196:embryology*; D014133:Tracheal Diseases / Q000000981:diagnostic imaging / Q000628:therapy*; D016216:Ultrasonography, Prenatal