title: The effects of thermal softening of double-lumen endobronchial tubes on postoperative sore throat, hoarseness and vocal cord injuries: a prospective double-blind randomized trial.
abstract: BACKGROUND
  It is well known that thermal softening of polyvinyl chloride tracheal tubes reduces nasal damage during nasotracheal intubation. We hypothesized that thermal softening of double-lumen endobronchial tubes (DLTs) may be effective for reducing airway injury. This randomized double-blind study was performed to investigate whether thermal softening of DLTs decreased postoperative sore throat, hoarseness or vocal cord injuries.
  
  
  METHODS
  Patients (n=140) undergoing one lung anaesthesia were randomized into two groups (n=70 each) depending on whether the DLT was softened by warming or not before tracheal intubation. The DLTs were placed in warm saline [40(1)°C] in the thermal softening group or in room temperature saline in the control group for 10 min. The vocal cords were examined by using flexible laryngoscopy immediately after extubation. Sore throat and hoarseness were evaluated for three postoperative days. The primary outcomes were the incidence of sore throat, hoarseness, and vocal cord injuries.
  
  
  RESULTS
  Sore throat and vocal cord injuries occurred less frequently in the thermal softening group than in the control group [14/70 vs 27/70, risk ratio (95% CI): 0.52 (0.30-0.90), P=0.025 for sore throat; 15/70 vs 27/70, risk ratio (95% CI): 0.56 (0.32-0.95), P=0.042 for vocal cord injuries]. However, the incidence of hoarseness was comparable between the two groups.
  
  
  CONCLUSIONS
  Tracheal intubation with DLTs softened by warming decreased the postoperative incidence of sore throat and vocal cord injuries. Therefore, thermal softening of DLTs before intubation seems to be helpful in reducing airway injuries associated with DLT intubation.
  
  
  BACKGROUND
  NCT 01626365.
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea.
authors.forename: J-H
authors.initials: JH
authors.lastname: Seo
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: C W
authors.initials: CW
authors.lastname: Cho
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea.
authors.forename: D M
authors.initials: DM
authors.lastname: Hong
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea.
authors.forename: Y
authors.initials: Y
authors.lastname: Jeon
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Seoul National University Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea bahkjh@snu.ac.kr.
authors.forename: J-H
authors.initials: JH
authors.lastname: Bahk
mesh_terms: D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D005260:Female; D006685:Hoarseness / Q000209:etiology / Q000517:prevention & control*; D006358:Hot Temperature; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D010612:Pharyngitis / Q000209:etiology / Q000517:prevention & control*; D011143:Polyvinyl Chloride; D011183:Postoperative Complications / Q000209:etiology / Q000517:prevention & control*; D011446:Prospective Studies; D014827:Vocal Cords / Q000293:injuries*; D055815:Young Adult
chemical_list: D011143:Polyvinyl Chloride
keywords: airway management; anesthesia, general; bronchi; intubation, intratracheal; one-lung ventilation