title: A double-blind, randomized controlled trial on the use of a 50:50 mixture of nitrous oxide/oxygen in pain relief during suction evacuation for the first trimester pregnancy termination.
abstract: BACKGROUND
  This prospective study assessed the role of a 50:50 mixture of nitrous oxide (N2O) and oxygen for pain relief during the termination of first trimester pregnancies by suction evacuation under conscious sedation.
  
  
  METHODS
  Ninety women undergoing suction evacuation up to 12 weeks of gestation were randomized by a computer-generated randomization list and allocated using sealed envelopes to receive the N2O/O2 mixture or air during the operation. Pain scores during and after suction evacuation, post-operative side effects and satisfaction level were compared.
  
  
  RESULTS
  No statistically significant differences in pain scores, post-operative side effects and satisfaction levels were found between the two groups.
  
  
  CONCLUSIONS
  N2O/O2 did not reduce the pain level during suction evacuation for the first trimester pregnancy termination under conscious sedation.
authors.affiliation: Department of Obstetrics and Gynaecology, Operation Theatre Service, Queen Mary Hospital, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China. kansy@ha.org.hk
authors.forename: Anita Sik Yau
authors.initials: AS
authors.lastname: Kan
authors.forename: Natalie
authors.initials: N
authors.lastname: Caves
authors.forename: Sylvia Yuen Wai
authors.initials: SY
authors.lastname: Wong
authors.forename: Ernest Hung Yu
authors.initials: EH
authors.lastname: Ng
authors.forename: Pak Chung
authors.initials: PC
authors.lastname: Ho
mesh_terms: D000028:Abortion, Induced; D000293:Adolescent; D000328:Adult; D001007:Anxiety; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D009609:Nitrous Oxide / Q000627:therapeutic use*; D010100:Oxygen / Q000627:therapeutic use*; D010146:Pain; D017060:Patient Satisfaction; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D013396:Suction; D014599:Uterus / Q000033:anatomy & histology
chemical_list: D009609:Nitrous Oxide; D010100:Oxygen