Should Nitrous Oxide Be Used for Laboring Patients?

Development of obstetric anesthesia core competencies for USA residency programs through a Delphi process

PURPOSE

The standard for anesthesia residency training in the USA mainly relies on the Accreditation Council for Graduate Medical Education (ACGME) Outcome Project, a framework that lacks specific directives for subspecialties including obstetric anesthesia. We aimed to identify core competencies in obstetric anesthesiology that can be adapted to different residency training programs to help improve the quality of training and accountability of the institutions within the USA.

METHODS

We identified a preliminary list of competencies from review of existing competency-based obstetric anesthesia training curricula and practice guidelines. We used a modified Delphi methodology to achieve expert consensus among members of the Society for Obstetric Anesthesia and Perinatology education committee. The panellists were asked to evaluate the importance of each competency using a five-point Likert scale, with consensus after two rounds defined at 80% agreement. The responders were also asked at which level of training each competency should be attained.

RESULTS

The Delphi rounds had 75% response rate and derived 94 competencies that were categorized under the six ACGME domains: patient care (38), medical knowledge (45), system-based practice (two), practice-based learning and improvement (five), interpersonal communication skills (two), and professionalism (two).

CONCLUSION

We generated a residency training competency list for obstetric anesthesiology through expert consensus. This list can be used by residency training programs to develop a structured competency-based curriculum with tangible milestones, thereby reducing heterogeneity in the standard of training.

Effect of nitrous oxide use on external cephalic version success rate; a systematic review and meta-analysis

INTRODUCTION

Several adjuvant interventions have been evaluated for improving the success rate of the external cephalic version (ECV) and reducing the rate of cesarean delivery (CD). Evidence regarding the effect of Nitrous oxide is limited to a small number of participants with inconsistent results on pain score and success rate. This study aims to examine the effect of inhaled nitrous oxide on the success rate and pain score for women undergoing ECV.

MATERIAL AND METHODS

Survey on ECV reports from inception till June 2020 were made from MEDLINE, EMBASE, PubMed, Ovid Medline, ClinicalTrials.gov, the Cochrane Library and Google Scholars. Peer-review studies that examined the success rate of ECV from the application of nitrous oxide during ECV attempts compared with or without the use of other analgesic agents were obtained. The study population comprising women with singleton pregnancies having a non-vertex presentation at least 36 weeks, were categorized into one of two treatment groups: ECV attempt with nitrous oxide (nitrous oxide group) and ECV attempt with or without another analgesia (control group). The primary outcome was the ECV success rate, defined by conversion to vertex-presentation following the procedure. The secondary outcomes were pain scores during ECV attempt and CD rate. 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 26 records identified, two randomized trials and one prospective cohort study (720 women; 434 in the nitrous oxide group and 286 controls) were deemed adequate for meta-analysis. ECV success rate did not differ significantly between the nitrous oxide group and the control group (p = .825; OR 1.036; 95% CI, 0.756, 1.419). In addition, the use of nitrous oxide did not affect pain scores during ECV attempt (p = .457; OR 0.759; 95% CI, -1.240, 2.759) and there was no difference in the incidence of CD as well (p = .943; OR 1.013; 95% CI, 0.703, 1.46).

CONCLUSION

The use of nitrous oxide during ECV attempts was not associated with an increase in ECV success rate and does not affect pain scores. PROSPERO Registration No. CRD42020197933.

Nitrous Oxide for Labor Analgesia: What We Know to Date

Background: Although nitrous oxide (N₂O) has been used since the 1880s for labor analgesia, its popularity has only recently increased in the United States. In 2011, only 3 centers in the country offered N₂O, but as of 2020, several hundred labor units have adopted its use.

Methods: We reviewed the literature and summarize the mechanism of action, clinical uses, and efficacy of N₂O for labor analgesia, as well as patient satisfaction related to its use.

Results: N₂O has several proposed mechanisms of action that make it a viable option for all 3 stages of labor and postpartum procedures. N₂O has been shown to be a safe option for both mom and baby during labor and delivery. Studies support N₂O as an analgesic for laboring. Even though 40% to 60% of women who use N₂O convert to a labor epidural analgesia, satisfaction surveys indicate that analgesia is not the only factor contributing to the use of N₂O during labor.

Conclusion: The use of N₂O has increased in labor and delivery units across the United States since 2011. Despite inferior analgesic properties compared to epidural analgesia, N₂O offers a safe alternative for many parturients who want a greater sense of control and mobility.

Pain management during labor and vaginal birth

Neuraxial analgesia provides excellent pain relief in labor. Optimizing initiation and maintenance of neuraxial labor analgesia requires different strategies. Combined spinal-epidurals or dural puncture epidurals may offer advantages over traditional epidurals. Ultrasound is useful in certain patients. Maintenance of analgesia is best achieved with a background regimen (either programmed intermittent boluses or a continuous epidural infusion) supplemented with patient-controlled epidural analgesia and using dilute local anesthetics combined with opioids such as fentanyl. Nitrous oxide and systemic opioids are also used for pain relief. Nitrous oxide may improve satisfaction despite variable effects on pain. Systemic opioids can be administered by healthcare providers or using patient-controlled analgesia. Appropriate choice of drug should take into account the stage and progression of labor, local safety protocols, and maternal and fetal/neonatal side effects. Pain in labor is complex, and women should fully participate in the decision-making process before any one modality is selected.

Effectiveness of nitrous oxide in external cephalic version on success rate: A randomized controlled trial

INTRODUCTION

Approximately 4% of singleton pregnancies at term are in breech presentation. External cephalic version (ECV) can reduce the risks of noncephalic birth and cesarean delivery, but this maneuver can be painful. Our aim was to analyze the effect of administering inhaled nitrous oxide for analgesia on the ECV success rate.

MATERIAL AND METHODS

This prospective, randomized, single-blind, controlled trial included women with singleton pregnancies in breech presentation at term who were referred for ECV in a tertiary care center. Women were assigned according to a balanced (1:1) restricted randomization design to inhale either nitrous oxide (N₂ O) in a 50:50 mix with oxygen or medical air during the procedure. The main outcomes reported are the ECV success rate, degree of pain, adverse event rate, and women's satisfaction.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01948115.

RESULTS

The study included 150 women (nitrous oxide group: n = 74; medical air: n = 76). Inhaled nitrous oxide was not associated with a higher ECV success rate than medical air (24.3 vs 19.7%, P = 0.51). Among parous women (n = 34 in each group), the ECV success rate appeared higher in the nitrous oxide group, respectively 47.1% (n = 16) vs 23.5% (n = 8) (P = 0.042). Neither the median pain level nor adverse event rates differed significantly in women with inhaled nitrous oxide compared with medical air.

CONCLUSIONS

Use of an equimolar mixture of oxygen and nitrous oxide during ECV appears safe. Although it does not seem to change the overall success rate, it may increase success in parous women.

Should maternal anesthesia delay breastfeeding? A systematic review of the literature

Introduction

The importance and benefits of breastfeeding for the babies and mothers are well established and documented in the literature. However, it is frequent that lactating mothers need to undergo general or spinal anesthesia and, due to the lack of information, many of them interrupt breastfeeding after anesthesia. There are limited data available regarding anesthetics transfer to breast milk. This review aims to develop some considerations and recommendations based on available literature.

Methods

A systematic search of the literature was conducted by using the following health science databases: Embase, Lilacs, Pubmed, Scopus, and Web of Science. The latest literature search was performed on April 6^th, 2018. Additional literature search was made via the World Health Organization's website. We used the following terms for the search strategy: “Anesthesia” and “Breastfeeding”, and their derivatives.

Results

In this research, 599 registers were found, and 549 had been excluded by different reasons. Fifty manuscripts have been included, with different designs of studies: prospective trials, retrospective observational studies, reviews, case reports, randomized clinical trials, case–control, and website access. Small concentrations of the most anesthetic agents, are transferred to the breast milk; however, their administration seem to be safe for lactating mothers when administered as a single dose during anesthesia and this should not contraindicate the breastfeeding. On the other hand, high-doses, continuous or repeated administration of drugs increase the risk of adverse effects on neonates, and should be avoided. Few drugs, such as diazepam and meperidine, produce adverse effects on breastfed babies even in single doses. Dexmedetomidine seems to be safe if breastfeeding starts 24 h after discontinuation of the drug.

Conclusions

Most of the anesthetic drugs are safe for nursing mothers and offer low risk to the breastfed neonates when administered in single-dose. However, high-dose and repeated administration of drugs significantly increase the risk of adverse effects on neonates. Moreover, diazepam and meperidine should be avoided in nursing women. Finally, anesthesiologists and pediatricians should consider individual risk/benefit, with special attention to premature neonates or babies with concurrent diseases since they are more susceptible to adverse effects.

[Should maternal anesthesia delay breastfeeding? A systematic review of the literature]

INTRODUCTION

The importance and benefits of breastfeeding for the babies and mothers are well established and documented in the literature. However, it is frequent that lactating mothers need to undergo general or spinal anesthesia and, due to the lack of information, many of them interrupt breastfeeding after anesthesia. There are limited data available regarding anesthetics transfer to breast milk. This review aims to develop some considerations and recommendations based on available literature.

METHODS

A systematic search of the literature was conducted by using the following health science databases: Embase, Lilacs, Pubmed, Scopus, and Web of Science. The latest literature search was performed on April 6^th, 2018. Additional literature search was made via the World Health Organization's website. We used the following terms for the search strategy: "Anesthesia" and "Breastfeeding", and their derivatives.

RESULTS

In this research, 599 registers were found, and 549 had been excluded by different reasons. Fifty manuscripts have been included, with different designs of studies: prospective trials, retrospective observational studies, reviews, case reports, randomized clinical trials, case-control, and website access. Small concentrations of the most anesthetic agents, are transferred to the breast milk; however, their administration seem to be safe for lactating mothers when administered as a single dose during anesthesia and this should not contraindicate the breastfeeding. On the other hand, high-doses, continuous or repeated administration of drugs increase the risk of adverse effects on neonates, and should be avoided. Few drugs, such as diazepam and meperidine, produce adverse effects on breastfed babies even in single doses. Dexmedetomidine seems to be safe if breastfeeding starts 24h after discontinuation of the drug.

CONCLUSIONS

Most of the anesthetic drugs are safe for nursing mothers and offer low risk to the breastfed neonates when administered in single-dose. However, high-dose and repeated administration of drugs significantly increase the risk of adverse effects on neonates. Moreover, diazepam and meperidine should be avoided in nursing women. Finally, anesthesiologists and pediatricians should consider individual risk/benefit, with special attention to premature neonates or babies with concurrent diseases since they are more susceptible to adverse effects.

Past, present, and future of nitrous oxide

INTRODUCTION

For a drug that has been omnipresent for nearly 200 years, nitrous oxide's (N2O) future seems less certain than its illustrious past. Environmental concerns are coming to the fore and may yet outweigh important clinical benefits.

SOURCES OF DATA

After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered.

AREAS OF AGREEMENT

The analgesic and anaesthetic advantages of N2O remain despite a plethora of newer agents.

AREAS OF CONTROVERSY

N2O greenhouse gas effect and its inhibition of key enzymes involved in protein and DNA synthesis have provided further fuel for those intent on eliminating its further clinical use.

GROWING POINTS

The use of N2O for treatment-resistant depression has gained traction.

AREAS TIMELY FOR DEVELOPING RESEARCH

Comparative studies for N2O role in combatting the prescription opioid analgesic epidemic may well provide further clinical impetus.