title: The effect of an expandable polyvinyl acetate (Merocel) pack on the healing of the nasal mucosa of sheep.
abstract: BACKGROUND
  There is a lack of knowledge about the healing of the nasal respiratory mucosa after endoscopic sinus surgery (ESS). Nasal packs often are placed after ESS in an attempt to improve hemostasis and reduce adhesion formation. Most nasal packs need to be removed in the postoperative period. This is uncomfortable for the patient and the affect of these packs on the healing process is unknown.
  
  
  METHODS
  We have standardized the sheep as a suitable animal model to examine the healing of the nasal epithelium after ESS. The nasal mucosa of sheep was wounded under endoscopic guidance and either packed with expandable polyvinyl acetate-based pack (Merocel), which was removed at the 5th postoperative day, or left unpacked to serve as control. Serial biopsies of the wounded area were taken every 28 days, up to 112 days postwounding, for examination using light and scanning electron microscopy.
  
  
  RESULTS
  There was no significant difference in the rate of reepithelialization between the packed and control sides of the sheep (p > 0.05). There was no significant difference in the total amount of surface cilia coverage between the packed and control sides at any time points (p > 0.05). There was no significant difference in the maturity of the cilia between the packed and control sides at any time points (p > 0.05).
  
  
  CONCLUSIONS
  The use of Merocel packing postoperatively neither impairs nor promotes wound healing in the postoperative period.
authors.affiliation: Department of Surgery-Otolaryngology, Head and Neck Surgery, Adelaide and Flinders Universities, South Australia.
authors.forename: David
authors.initials: D
authors.lastname: McIntosh
authors.forename: Allison
authors.initials: A
authors.lastname: Cowin
authors.forename: Damian
authors.initials: D
authors.lastname: Adams
authors.forename: Peter-John
authors.initials: PJ
authors.lastname: Wormald
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000187:drug effects / Q000648:ultrastructure; D005557:Formaldehyde / Q000008:administration & dosage* / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D009297:Nasal Mucosa / Q000187:drug effects* / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D011142:Polyvinyl Alcohol / Q000008:administration & dosage* / Q000494:pharmacology; D012756:Sheep; D014945:Wound Healing / Q000187:drug effects* / Q000502:physiology
chemical_list: D005557:Formaldehyde; C027490:polyvinyl alcohol formaldehyde foam; D011142:Polyvinyl Alcohol