title: Incidence and predictors of difficult nasotracheal intubation with airway scope.
abstract: OBJECTIVE
  The airway scope (AWS) improves views of the larynx during orotracheal intubation. However, the role of the AWS in routine nasotracheal intubation has not been studied adequately.
  
  
  METHODS
  One hundred and three patients undergoing dental and maxillofacial surgery that required general anesthesia and nasotracheal intubation were enrolled. The study was approved by our Institution Review Board, and written informed consent was obtained from all patients. We evaluated the success rate of AWS intubation and the incidence of difficult nasotracheal intubation using a modified intubation difficulty scale (IDS) to examine preoperative characteristics and intubation profiles. Categories were difficult intubation (IDS ≥5), mildly difficult (IDS = 1-4), and intubation without difficulty (IDS = 0). We also assessed the incidence of the use of Magill forceps or cuff inflation (the cuff of endotracheal tube is inflated with 10-15 ml air) to guide the endotracheal tube into the glottis.
  
  
  RESULTS
  AWS nasotracheal intubation was 100% successful. The cuff inflation technique was used in 37 patients. Neither Magill forceps nor other devices were needed for any patient during AWS use. The incidence of difficult nasotracheal intubation was 10% (n = 10). Of the patients, 61% (n = 63) had mildly difficult intubation and 29% (n = 30) had no difficulty. Patients with difficult intubation were more likely to be male and to have a larger tongue and a higher Cormack grade than in the other two groups. Complications, involving minor soft tissue injury, were observed in only 1 patient (1%).
  
  
  CONCLUSIONS
  The AWS achieves a high success rate for nasotracheal intubation with cuff inflation in patients undergoing dental and maxillofacial surgery.
authors.affiliation: Departments of Dentistry and Maxillofacial Surgery, Itoh Dento-Maxillofacial Hospital, 4-14 Kokaihonmachi, Kumamoto, 860-0851, Japan, hoku4koyu3@yahoo.co.jp.
authors.forename: Koyu
authors.initials: K
authors.lastname: Ono
authors.forename: Tomoko
authors.initials: T
authors.lastname: Goto
authors.forename: Daishi
authors.initials: D
authors.lastname: Nakai
authors.forename: Shuhei
authors.initials: S
authors.lastname: Ueki
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Takenaka
authors.forename: Tomomi
authors.initials: T
authors.lastname: Moriya
mesh_terms: D000328:Adult; D000768:Anesthesia, General / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005931:Glottis / Q000502:physiology; D006801:Humans; D015994:Incidence; D007442:Intubation, Intratracheal / Q000379:methods*; D007830:Larynx / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D019647:Oral Surgical Procedures / Q000295:instrumentation / Q000379:methods*; D014059:Tongue / Q000033:anatomy & histology; D055815:Young Adult