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Table 2Key Question 2—Applicability

DomainDescription of Applicability of Evidence Compared With Question
PopulationThe study populations were healthy women in labor who should be similar to the target population. The eligibility criteria and participant characteristics were not always explicitly detailed. Some participants were excluded due to choice of alternate pain management methods.
InterventionMost studies used a 50/50 mix of nitrous and oxygen, often premixed in the form of Entonox. The 50/50 mix is available, although Entonox is not used in the U.S, and not currently approved by the FDA. In addition, mechanical equipment for delivery of N2O in labor and delivery has very limited availability in the U.S.
ComparatorsThe comparators include standard pain management methods, such as epidural, narcotics, and nonpharmacologic methods such as TENS. However, some comparators are not commonly used and/or available for laboring women in the U.S., such as other inhalational anesthetic gases.
OutcomesSatisfaction with pain management and the birth experience were the outcome measures, as reported by the women.
SettingOnly three of nine studies were conducted in the U.S. The standards of care are not comparable because nitrous is widely available outside of the U.S. All of the studies were conducted in hospitals, thus the satisfaction with the intervention in birth centers and the home setting has not been reported.

From: Appendix D, Applicability and Quality Tables

Cover of Nitrous Oxide for the Management of Labor Pain
Nitrous Oxide for the Management of Labor Pain [Internet].
Comparative Effectiveness Reviews, No. 67.
Likis FE, Andrews JC, Collins MR, et al.

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