The effective time and concentration of nitrous oxide to reduce venipuncture pain in children

J Clin Anesth. 2009 May;21(3):190-3. doi: 10.1016/j.jclinane.2008.07.005.


Study objective: To investigate the time of administration and concentration of inhaled nitrous oxide (N(2)O) needed to reduce the pain associated with intravenous (i.v.) cannulation in children.

Design: Prospective, randomized study.

Setting: Operating room of a children's hospital.

Patients: 73 ASA physical status I and II children, aged 6-15 years, scheduled for elective day or non-day surgery.

Interventions: Children were randomly allocated to one of 4 groups prior to i.v. insertion of a 24-gauge catheter in the dorsum of the hand: Group 1 (n = 18): 50% N(2)O in O(2) for three minutes; Group 2 (n = 18): 50% N(2)O in O(2) for 5 minutes; Group 3 (n = 18): 70% N(2)O in O(2) for three minutes; or Group 4 (n = 19): 70% N(2)O in O(2) for 5 minutes.

Measurements: Just after the venous cannulation, degree of pain was assessed by examining the faces of the patient by the parent and an operating room nurse.

Main results: Pain scores obtained from parents of children in Groups 3 and 4 were significantly lower than from those in Groups 1 and 2. Pain scores from the nurse in Group 3 was significantly lower than those in Group 1. However, there was no significant difference in pain score between Group 3 and Group 4. Frequency of side effects was similar among the 4 groups.

Conclusions: Seventy percent N(2)O in O(2) given for three minutes was effective for reducing venipuncture pain in children.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Anesthetics, Inhalation / administration & dosage
  • Anesthetics, Inhalation / adverse effects
  • Anesthetics, Inhalation / therapeutic use*
  • Child
  • Dose-Response Relationship, Drug
  • Facial Expression
  • Female
  • Hand
  • Hospitals, Pediatric
  • Humans
  • Male
  • Nitrous Oxide / administration & dosage
  • Nitrous Oxide / adverse effects
  • Nitrous Oxide / therapeutic use*
  • Pain / etiology
  • Pain / prevention & control*
  • Pain Measurement / methods
  • Phlebotomy / adverse effects*
  • Prospective Studies
  • Time Factors


  • Anesthetics, Inhalation
  • Nitrous Oxide