Nitrous oxide versus oral sedation for pain management of first-trimester surgical abortion - a randomized study.

OBJECTIVE: The objective of the study was to compare nitrous oxide with oxygen (N2 O/O2 ) to oral hydrocodone/acetaminophen and lorazepam for analgesia during first-trimester surgical abortion.

STUDY DESIGN: This double-blind randomized trial assigned women undergoing first-trimester surgical abortion at<11 weeks' gestation to inhaled N2 O/O2 vs. oral sedation for pain management. The N2 O/O2 group received up to 70:30 ratio during the procedure and placebo pills preprocedure; the oral group received inhaled oxygen during the procedure and oral hydrocodone/acetaminophen 5 mg/325 mg and lorazepam 1 mg preprocedure. The primary outcome was maximum procedural pain, assessed on a 100-mm visual analog scale (VAS; anchors 0=no pain and 100=worst pain) at 2 min postprocedure. A difference of 13 mm on the VAS was considered clinically significant. Satisfaction with pain management was measured on a 100-mm VAS (anchors 0=very unsatisfied, 100=very satisfied).

RESULTS: We randomized 140 women, 70 per study arm. Mean age of participants was 26±6.6 years; mean gestational age was 7.3±1.5 weeks. Mean maximum procedure pain scores were 52.5±26.7 and 60.8±24.4 for N2 O/O2 and oral groups, respectively (p=.09). Satisfaction with pain management was 69.3±28.4 and 61.5±30.4 for N2 O/O2 and oral groups. respectively (p=.15).

CONCLUSION: We found no difference in mean procedural pain scores between women assigned to N2 O/O2 vs. those assigned to oral sedation for first-trimester surgical abortion. Satisfaction with both options was high.

IMPLICATIONS: Women undergoing early surgical abortion experienced no differences in pain and satisfaction between those who used inhaled nitrous oxide and oral sedation. Nitrous oxide, with side effects limited to the duration of inhalation and no need for a ride home, is a viable alternative to oral sedation for first-trimester abortion pain management.