Effect of nitrous oxide use on external cephalic version success rate; A
systematic review and meta-analysis
Abstract
Background Several adjuvant interventions have been evaluated for
improving the success rate of external cephalic version (ECV) and reduce
the rate of cesarean delivery (CD). Evidence regarding the effect of
Nitrous oxide (NO) is limited with inconsistent results on pain score
and success rate. Objective To examine the effect of inhaled NO on the
success rate and pain score for women undergoing ECV. Search strategy
MEDLINE, EMBASE, PubMed, Ovid Medline, ClinicalTrials.gov, the Cochrane
Library and Google Scholars from inception till June 2020. Selection
criteria Peer-review studies that examined the success rate of inhaled
NO use during ECV attempt compared with or without the use of other
analgesic agents were eligible for inclusion. Data collection and
analysis All ascertained records were screened independently for
eligibility by two authors. The study quality scores were evaluated as a
source of heterogeneity by fitting meta-regression models to the
individual study effect sizes. Results Of the 186 records, two
randomized trials and one prospective cohort study (434 in the NO group
and 286 in the controls) were deemed adequate for meta-analysis. ECV
success rate did not differ significantly between the NO and the
controls group (p=0.825; OR 1.036; 95% CI, 0.756-1.419). In addition,
the use of NO did not affect pain scores (p=0.457; OR 0.759; 95% CI,
-1.240-2.759) and there was no difference in the incidence of CD
(p=0.943; OR 1.013; 95% CI, 0.703-1.46). Conclusion Use of NO during
ECV is not associated with increase in ECV success rate and does not
affect pain score.