title: Spray-as-you-go airway topical anesthesia in patients with a difficult airway: a randomized, double-blind comparison of 2% and 4% lidocaine.
abstract: BACKGROUND
  We designed this randomized, double-blind clinical study to compare the safety and efficacy of 2% and 4% lidocaine during airway topical anesthesia with a spray-as-you-go technique via the fiberoptic bronchoscope.
  
  
  METHODS
  Fifty-two adult patients with a difficult airway were randomly assigned to 1 of 2 study groups to receive 2% (Group 1) or 4% lidocaine (Group 2) by a spray-as-you-go technique with the fiberoptic bronchoscope, in a double-blind manner. After airway topical anesthesia, awake fiberoptic orotracheal intubation (FOI) was performed. Level of sedation, time for each lidocaine spray in different targeted areas, total times for airway sprays, total dosages of lidocaine used for airway sprays, intubation times, and number of intubation attempts were noted. An independent investigator scored patients' comfort during airway topical anesthesia, patients' reaction, coughing severity, and intubating condition during awake FOI, and observed changes of arterial blood pressure and heart rate during each stage in the airway manipulation process. Serial blood samples were obtained for analysis of plasma lidocaine concentrations.
  
  
  RESULTS
  Except for the total dosages and plasma concentrations of lidocaine, there were no significant differences in any of the observed variables between groups. All patients exhibited excellent or acceptable intubating conditions. The total dosages of lidocaine were significantly smaller in Group 1 (3.4 +/- 0.6 mg/kg) than in Group 2 (7.1 +/- 2.1 mg/kg). The plasma lidocaine concentrations in all observed points after the supraglottic sprays were larger in Group 2 than in Group 1.
  
  
  CONCLUSIONS
  Both 2% and 4% lidocaine administered topically by a spray-as-you-go technique can provide clinically acceptable intubating conditions for awake FOI in sedated patients with a difficult airway. As compared with 4% lidocaine, however, 2% lidocaine requires a smaller dosage and results in lower plasma concentrations.
authors.affiliation: Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 33 Ba-Da-Chu Rd, Shi-Jing-Shan District, Beijing, People's Republic of China 100144. fruitxue@yahoo.com.cn
authors.forename: Fu S
authors.initials: FS
authors.lastname: Xue
authors.forename: He P
authors.initials: HP
authors.lastname: Liu
authors.forename: Nong
authors.initials: N
authors.lastname: He
authors.forename: Ya C
authors.initials: YC
authors.lastname: Xu
authors.forename: Quan Y
authors.initials: QY
authors.lastname: Yang
authors.forename: Xu
authors.initials: X
authors.lastname: Liao
authors.forename: Xiu Z
authors.initials: XZ
authors.lastname: Xu
authors.forename: Xin L
authors.initials: XL
authors.lastname: Guo
authors.forename: Yan M
authors.initials: YM
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000336:Aerosols; D000769:Anesthesia, Inhalation; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D001794:Blood Pressure / Q000187:drug effects; D003371:Cough / Q000139:chemically induced / Q000453:epidemiology; D004311:Double-Blind Method; D005260:Female; D005336:Fiber Optic Technology; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives; D007431:Intraoperative Complications / Q000139:chemically induced / Q000453:epidemiology; D007442:Intubation, Intratracheal / Q000379:methods*; D008012:Lidocaine / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics; D008297:Male; D008874:Midazolam
chemical_list: D000336:Aerosols; D000779:Anesthetics, Local; D006993:Hypnotics and Sedatives; D008012:Lidocaine; D008874:Midazolam