Nitrous Oxide Use During Labor: Satisfaction, Adverse Effects, and Predictors of Conversion to Neuraxial Analgesia.

Women desire safe and effective choices for pain management during labor. Currently, neuraxial and opioid analgesia are the most common methods used in the United States. The purpose of this study was to investigate demographic characteristics, safety, and satisfaction in a cohort of parturients who used inhaled nitrous oxide (N2 O) analgesia and to determine predictors of conversion from N2 O to neuraxial analgesia. This was a prospective chart review study. Individuals aged at least 18 years who used inhaled N2 O during the first or second stage of labor between March 1, 2016, and July 23, 2017, on the labor and delivery unit of one academic medical center (N = 463) and their neonates were included. Data describing maternal and neonatal factors are reported. Logistic regression and chi-square tests were used to model the effects of oxytocin augmentation, labor induction, parity, prior cesarean birth, pre-N2 O cervical dilatation, and post-N2 O cervical dilatation on the odds of conversion from N2 O to neuraxial analgesia. In this cohort, 31% who chose N2 O for analgesia did not convert to any other analgesic method. Significant positive predictors for conversion from N2 O to neuraxial analgesia included labor induction (odds ratio [OR], 2.9; 95% CI, 1.7-5.0), oxytocin augmentation (OR, 3.1; 95% CI, 1.6-6.0), and labor after cesarean (OR, 6.4; 95% CI, 2.5-16.5). Multiparity (OR, 0.4; 95% CI, 0.2-0.6) and post-N2 O cervical dilatation (OR, 0.8; 95% CI, 0.7-0.9) were negative predictors. Adverse effects related to N2 O use during labor were rare (8%) and were not a significant reason for conversion to neuraxial analgesia. Parturients had moderately high satisfaction with N2 O for pain management (11-point scale, mean [SD], 7.4 [2.9]). Five-minute Apgar scores were 7 or greater in 97.8% of the newborns. Understanding predictors of conversion from inhaled N2 O to neuraxial analgesia may assist perinatal care providers in their discussions with women about analgesia options during labor. N2 O is a useful, safe option for labor analgesia in the United States.

Nodine PM ，Collins MR ，Wood CL ，Anderson JL ，Orlando BS ，McNair BK ，Mayer DC ，Stein DJ ... -  《-》

Nitrous oxide for labor analgesia: Utilization and predictors of conversion to neuraxial analgesia.

We examined the characteristics of women who choose nitrous oxide for labor analgesia and identified factors that predict conversion from nitrous oxide to labor neuraxial analgesia. Retrospective descriptive study. Labor and Delivery Ward. 146 pregnant women who used nitrous oxide for analgesia during labor and delivery between September 2014 and September 2015. Chart review only. Demographic, obstetric, and intrapartum characteristics of women using nitrous oxide were examined. Multivariable logistic regression was performed to identify factors associated with conversion from nitrous oxide to neuraxial analgesia. Data are presented as n (%), median [IQR], adjusted relative risk (aRR), and 95% confidence intervals (CI) as appropriate. During the study period, 146 women used nitrous oxide for labor analgesia (accounting for 3% of the total deliveries). The majority (71.9%) of women who used nitrous oxide were nulliparous, and over half (51.9%) had expressed an initial preference for "nonmedical birth." The conversion rate to neuraxial blockade was 63.2%, compared to a concurrent institutional rate of 85.1% in women who did not use nitrous oxide. Factors associated with conversion from nitrous oxide to neuraxial blockade were labor induction (aRR=2.0, CI 1.2-3.3) and labor augmentation (aRR=1.7, CI 1.0-2.9). Only a small number of women opted to use nitrous oxide during labor, analgesia was minimal, and most converted to neuraxial analgesia. Women with induced and augmented labors should be counseled about the increased likelihood that they will convert to neuraxial analgesia.

Sutton CD ，Butwick AJ ，Riley ET ，Carvalho B ... -  《-》

Nitrous Oxide Use for Pain in Labor, Conversion to Neuraxial Analgesia, and Birth Outcome.

A variety of labor pain management options is essential to patients and their care providers. Inhaled, patient controlled nitrous oxide (N2O) is a valuable addition to these options. The purpose of this study was to examine laboring patient, newborn, and provider characteristics associated with N2O use for pain relief in labor and to examine the association between N2O, conversion to neuraxial analgesia, and cesarean birth. This was a retrospective observational cohort study of the first year of N2O use in one large academic medical center. Patients at least 37 weeks' gestation who were admitted for labor with intended vaginal birth from August 1, 2018, to June 30, 2019, were included (N = 2605). Laboring patient and newborn factors and their relationship to N2O use were calculated as unadjusted and adjusted relative risks (RRs). Poisson regression was used to model the association between N2O use and subsequent use of neuraxial analgesia and type of birth for both nulliparous and multiparous patients. Overall, 20.2% of patients used N2O during labor. Multiparous patients were 24% less likely to use N2O than nulliparous patients (RR, 0.76; 95% CI, 0.69-0.84). Use of N2O did not differ significantly between patients cared for by midwives compared with patients cared for by physicians (RR, 0.95; 95% CI, 0.90-1.00). In multivariable modeling, N2O use in multiparous patients was associated with a 17% decrease in use of neuraxial analgesia (RR, 0.83; 95% CI, 0.73-0.94). There was no association between N2O use and use of neuraxial analgesia in nulliparous patients (RR, 0.99; 95% CI, 0.93-1.06). N2O use was not associated with cesarean birth in either group. N2O is an important pain management option for laboring patients and those who care for them. Study results may assist midwives, physicians, and nurses in counseling patients about analgesia options.

DeJoy S ，Killeen C ，Jackson-Köhlin D ，Psaltis A ，Knee A ... -  《-》

Nitrous Oxide During Labor: Maternal Satisfaction Does Not Depend Exclusively on Analgesic Effectiveness.

Richardson MG ，Lopez BM ，Baysinger CL ，Shotwell MS ，Chestnut DH ... -  《-》

Impact of nitrous oxide use on parturient recall of neuraxial analgesia risks.

Nitrous oxide affects memory and recall. We aimed to determine if using nitrous oxide during labor affected patients' ability to learn and recall the risks and benefits of neuraxial analgesia. Single-center, prospective cohort study. Labor and delivery unit in a large academic medical center. Nulliparous patients with spontaneous or planned induction of labor. Parturients chose whether to use nitrous oxide during labor. At the discussion for epidural consent, 4 risks were described: headache, infection, nerve damage, bleeding. Labor pain score, time from nitrous oxide discontinuation, and cervical dilation were documented at the discussion of epidural risks. Patients were assessed for unprompted recall and prompted recall of epidural risks on postpartum day 1 and unprompted recall at postpartum week 6. The number and proportion of patients who indicated each true risk (unprompted and prompted recall) or distractor (prompted recall only) were summarized by treatment group and results compared using Pearson χ2 tests. Of the 403 enrolled patients, 294 (73%) did not use nitrous oxide, and 109 (27%) did. The 2 groups were similar except women who used nitrous oxide were more likely to be cared for by midwives and had higher pain scores at their epidural request. Scores for unprompted or prompted recall of epidural risks were not different between women who received or did not receive nitrous oxide. All 4 risks were recalled unprompted by only 3% in the nitrous oxide group and by 6% in the group not receiving nitrous oxide (P = .18). The use of nitrous oxide for labor analgesia does not adversely influence a parturient's ability to recall the risks of epidural placement. Patients who receive nitrous oxide for labor analgesia should be considered eligible to provide consent for subsequent procedures.

Sharpe EE ，Warner LL ，Brakke BD ，Davis PR ，Finkel DM ，Burkle CM ，Hanson AC ，Pompeian RJ ，Arendt KW ，Butler Tobah YS ，Sviggum HP ... -  《-》