title: Factors affecting the extrusion rate of ventilation tubes.
abstract: OBJECTIVE
  The objective of this study was to determine the various factors that affect the extrusion rate of ventilation tubes (VTs), including the nature of the middle ear effusion.
  
  
  METHODS
  A retrospective chart review of 82 pediatric patients (177 ears) who received VT insertion surgery under general anesthesia was carried out to evaluate the relationship between various factors and the VT extrusion rate. The factors we analyzed included age, gender, the adenoid size, the amount and content of the middle ear effusion after myringotomy, bleeding events, associated adenoidectomy and the findings of the tympanic membrane status, the tympanometry and the audiometry of the air bone gap.
  
  
  RESULTS
  The mean extrusion time was 254 days (range, 11 to 809 days). The patients with no history of previous VT insertion had a longer extrusion time (mean, 279 days) than did the patients who had undergone previous VT insertion (mean, 203 days). The patients with serous effusion had the shortest extrusion time (mean, 190 days) as compared to those patients with glue (273 days) and pus (295 days) effusions. Other factors had no statistical significant relationship with the extrusion time.
  
  
  CONCLUSIONS
  The mean VT extrusion time was 254 days. The VT extrusion time was significantly related to the characteristics of the middle ear effusion and a history of previous VT insertion. Thus, the nature of middle ear effusion can provide a clinical clue to predict the VT extrusion time.
authors.affiliation: Department of Otorhinolaryngology, Boramae Medical Center, Seoul Metropolitan Government-Seoul National University, Seoul, Korea.
authors.forename: Chang Myeon
authors.initials: CM
authors.lastname: Song
authors.forename: Min-Hyun
authors.initials: MH
authors.lastname: Park
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee