title: Nitrous oxide/oxygen mixture and the prevention of pain during injection of propofol.
abstract: OBJECTIVE
  The incidence of pain associated with the injection of propofol still remains a problem. This study sought to examine the analgesic effects of inhaled nitrous oxide in oxygen on the prevention of propofol injection pain.
  
  
  METHODS
  Nitrous oxide in oxygen was compared with a lidocaine (20 mg)-propofol mixture and with propofol alone (control) in a prospective, randomized, observer-blinded study. ASA I and II patients (n = 135) scheduled for elective surgical procedures were studied. A standard propofol injection technique and scoring system to measure the pain on injection was used.
  
  
  RESULTS
  Demographic variables were similar between the study groups. Without analgesia (control) 26 of 45 patients (58%) reported pain on injection compared with 11 of 45 patients (24%) in both the nitrous oxide (95% CI: 14-52%, P = 0.001) and lidocaine groups (95% CI: 14-52%, P = 0.001).
  
  
  CONCLUSIONS
  The inhalation of a nitrous oxide/oxygen mixture significantly reduces the incidence of pain during propofol injection. This therapeutic stratagem was as effective as a lidocaine-propofol mixture.
authors.affiliation: University College Hospital, Department of Anaesthesia, Galway, Ireland. dharmon@indigo.ie
authors.forename: D
authors.initials: D
authors.lastname: Harmon
authors.forename: C
authors.initials: C
authors.lastname: Rozario
authors.forename: D
authors.initials: D
authors.lastname: Lowe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use*; D000704:Analysis of Variance; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D000779:Anesthetics, Local / Q000627:therapeutic use; D004338:Drug Combinations; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008012:Lidocaine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000627:therapeutic use*; D010100:Oxygen / Q000627:therapeutic use*; D010146:Pain / Q000517:prevention & control*; D015742:Propofol / Q000008:administration & dosage*; D011446:Prospective Studies
chemical_list: D018712:Analgesics, Non-Narcotic; D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D004338:Drug Combinations; D008012:Lidocaine; D009609:Nitrous Oxide; D010100:Oxygen; D015742:Propofol