title: Cuff depth and continuous chest auscultation method for determination of tracheal tube insertion depth in nasal intubation: observational study.
abstract: BACKGROUND
  Incorrect endobronchial placement of the tracheal tube can lead to serious complications. Hence, it is necessary to determine the accuracy of tracheal tube positioning. Markers are included on tracheal tubes, in the process of their manufacture, as indicators of approximate intubation depth. In addition, continuous chest auscultation has been used for determining the proper position of the tube. We examined insertion depth using the cuff depth and continuous chest auscultation method (CC method), compared with insertion depth determined by the marker method, to assess the accuracy of these methods.
  
  
  METHODS
  After induction of anesthesia, tracheal intubation was performed in each patient. In the CC method, the depth of tube insertion was measured when the cuff had passed through the glottis, and again when breath sounds changed in quality; the depth of tube insertion was determined from these values. In the marker method, the depth of tube insertion was measured and determined when the marker of the tube had reached the glottis, using insertion depth according to the marker as an index.
  
  
  RESULTS
  Insertion depth by the marker method was 26.6 ± 1.2 cm and by the CC method was 28.0 ± 1.2 cm (P < 0.0001). The CC method indicated a significantly greater depth than the marker method.
  
  
  CONCLUSIONS
  This study determined the safe range of tracheal tube placement. Tube positions determined by the CC method were about 1 cm deeper than those determined by the marker. This information is important to prevent accidental one-lung ventilation and accidental extubation.
  
  
  BACKGROUND
  UMIN No. UMIN000011375.
authors.affiliation: Department of Dental Anesthesiology, Field of Oral and Maxillofacial Rehabilitation, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan. ken2006anes@yahoo.co.jp.|Department of Dental Anesthesiology, Field of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University Graduate School, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan. ken2006anes@yahoo.co.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ouchi
authors.affiliation: Department of Dental Anesthesiology, Field of Oral and Maxillofacial Rehabilitation, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan.
authors.forename: Kazuna
authors.initials: K
authors.lastname: Sugiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000776:Anesthesiology; D001314:Auscultation / Q000379:methods*; D005260:Female; D005931:Glottis; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012135:Respiratory Sounds; D013909:Thorax; D055815:Young Adult
keywords: Continuous chest auscultation; Tracheal intubation; Tracheal tube